Layered body, assembly, and process for producing a layered body

Abstract

A method for producing a laminate includes the following steps: a. introducing a first powder and another powder into an internal volume to obtain a first powder layer and another powder layer in the internal volume, wherein the internal volume i. has a cross-sectional width W of at least 200 mm, and ii. is at least partially defined by an internal surface of a mold, wherein the mold has at least one wall, and wherein the wall comprises carbon; b. subjecting the first powder layer and the other powder layer to heat and pressure to obtain the laminate, wherein i. the heat is generated by a voltage applied across the mold, the internal volume, or both, and ii. the laminate comprises a first layer and another layer; c. subjecting the laminate to heat treatment in the presence of oxygen; wherein, after the heat treatment of the laminate, ρT > ρM, wherein ρT and ρM are densities measured in the other layer, wherein ρT is measured at a first position in the other layer, and ρM is measured at a second position in the other layer, wherein the first position is closer to the first layer than the second position.

Description

Technical Field

[0001] This invention generally relates to sintering under pressure and using an electric current, commonly known as spark plasma sintering (SPS). One specific embodiment of the invention relates to a spark plasma sintering method for obtaining a laminate comprising a first layer and another layer having a density gradient. A further embodiment of the invention relates to a laminate comprising a first layer and another layer having a density gradient, wherein the laminate is obtained by spark plasma sintering; and the use of a laminate comprising a first layer and another layer having a density gradient. Prior Technology

[0002] Sintering methods provide a way to form a bulk from powder by applying heat and pressure. In one method commonly known as spark plasma sintering (SPS), electric current is used to achieve heating. State-of-the-art spark plasma sintering methods have been applied to a variety of materials. Existing literature focuses on small-scale systems, providing portions with a bulk extension of up to about 150 mm. The problems of using SPS to prepare larger portions are theoretically assessed by Eugene A. Olevsky et al. in the following: "Fundamental Aspects of Spark Plasma Sintering: I. Experimental Analysis of Scalability" (J. Am. Ceram. Soc., 95 [8], 2406 to 2413 (2012)) and "Fundamental Aspects of Spark Plasma Sintering: II. Experimental Analysis of Scalability" (J. Am. Ceram. Soc., 95 [8], 2414 to 2422 (2012)). Several challenges and complexities associated with large-scale systems were identified. The produced multilayers can be used in plasma processing chambers in the semiconductor manufacturing industry. Use of the substrate in such industries requires high-quality substrates, specifically etch-resistant, robust, and with very high purity. The multilayers also require a diameter of at least 200 mm. WO2022154936 A9 and WO2022133180 A1 disclose the use of spark plasma sintering to produce multilayers. Summary of the Invention

[0003] The object of this invention is to overcome, at least in part, one of the disadvantages encountered in the current best technology.

[0004] A further object of the present invention is to provide a method for producing a laminate, wherein the laminate has a diameter of at least 200 mm.

[0005] A further object of the present invention is to provide a method for producing laminates, wherein the laminates have improved properties.

[0006] A further object of the present invention is to provide a method for producing laminates, wherein the laminates have increased strength.

[0007] A further object of the present invention is to provide a method for producing laminates, wherein the laminates have increased scratch resistance.

[0008] A further object of the present invention is to provide a method for producing laminates, wherein the laminates have a reduced defect rate.

[0009] A further object of the present invention is to provide a laminate having a diameter of at least 200 mm.

[0010] A further object of the present invention is to provide a laminate having improved properties (such as increased strength, increased scratch resistance, and reduced defect rate).

[0011] Any embodiment of the present invention contributes to at least partially achieving at least one of the objectives mentioned above.

[0012] An embodiment of the present invention is a method for producing laminates, comprising the following method steps: a. Introducing a first powder and another powder into an internal volume to obtain a first powder layer and another powder layer in the internal volume, wherein the internal volume i. Having a cross-sectional width W of at least 200 mm, preferably at least 300 mm, more preferably at least 400 mm, and even more preferably at least 500 mm, and ii. Delimited at least partially by the internal surface of the mold, wherein the mold has at least one wall, and wherein the wall comprises carbon; b. Exposing the first powder layer and the other powder layer to heat and pressure to obtain the laminate, wherein i. The heat is generated by a voltage applied across the mold, the internal volume, or both, and ii. The laminate comprises a first layer and another layer. c. The laminate is subjected to heat treatment in the presence of oxygen; in, After the heat treatment of the laminate, ρT > ρM, where ρT and ρM are densities measured in the other layer, and where ρT is measured at a first position in the other layer, and ρM is measured at a second position in the other layer, where the first position is closer to the first layer than the second position.

[0013] This independent embodiment is a first embodiment of a method for producing the laminate. In a preferred embodiment of the first embodiment of the method, the internal volume has a cross-sectional width W in the range of 200 mm to 650 mm, more preferably 300 mm to 650 mm, even more preferably 400 mm to 650 mm, and further preferably 500 mm to 650 mm. In a preferred embodiment of the first embodiment of the method, the first powder layer and the other powder layer are in contact with each other. In a preferred embodiment of the first embodiment of the method, the first layer and the other layer are in contact with each other. In a preferred embodiment of the first embodiment of the method, the other layer has a first surface and another surface opposite to the first surface, wherein the first surface faces the first layer. In this embodiment, it is preferable that the first position is located 5 mm or less from the first surface of the other layer. In a preferred embodiment of the first embodiment of the method, the second position is located 5 mm or less from the center of the other layer. In a preferred embodiment of the method, the first position is located 7 mm or less from the first centerline, which is perpendicular to the other layer and passes through the center of the other layer. In a preferred embodiment of the method, the second position is located 7 mm or less from the first centerline. In a preferred embodiment of the method, the second position is located 5 mm or less from another centerline, which is perpendicular to the first centerline and passes through the center of the other layer. In a preferred embodiment of the method, the other powder is introduced into the internal volume before or after the first powder layer has been obtained. More preferably, in this embodiment, the other powder is introduced into the internal volume after the first powder layer has been obtained.

[0014] In the following preferred embodiments, when "process" is mentioned, it should be understood to refer to the method used to produce laminates.

[0015] In a preferred embodiment of the method, the first powder comprises at least one or all of the following: yttrium, aluminum, zirconium, magnesium, or a combination of at least two of them.

[0016] This preferred embodiment of the invention is a second embodiment of the method, which is preferably based on the first embodiment of the method. A preferred combination of at least two of the chemical elements in the second embodiment of the method includes yttrium aluminum garnet, zirconium oxide-toughened alumina, and combinations thereof. In a particularly preferred embodiment of the second embodiment of the method, the first powder comprises yttrium oxide and alumina.

[0017] In a preferred embodiment of the method, the first powder comprises at least one oxide, preferably at least one oxide selected from the group consisting of: yttrium oxide, aluminum oxide, zirconium oxide, magnesium oxide, and combinations of at least two thereof.

[0018] This preferred embodiment of the invention is a third embodiment of the method, which is preferably based on any of the first to second embodiments of the method. In a particularly preferred embodiment of the third method, the first powder comprises yttrium oxide and aluminum oxide. In a preferred embodiment of the third method, if the at least one oxide comprises and / or is zirconium oxide, then the zirconium oxide is preferably partially stabilized zirconium oxide, stabilized zirconium oxide, or a combination thereof. In this embodiment, partially stabilized zirconium oxide is preferred over stabilized zirconium oxide.

[0019] In one preferred embodiment of the method, the first powder is a mixture of at least two component powders, preferably a mixture of two component powders.

[0020] This preferred embodiment of the present invention is the fourth embodiment of the method, which is preferably based on any of the first to third embodiments of the method. In one preferred embodiment of the fourth embodiment of the method, the at least two component powders are yttrium oxide powder and alumina powder. In this embodiment, the first powder is preferably a mixture of yttrium oxide powder and alumina powder.

[0021] In a preferred embodiment of the method, at least one or all of the following are applicable to the first powder: a. Contains at least 25 mol-%, preferably at least 30 mol-%, and even more preferably at least 35 mol-%, of yttrium oxide; b. Contains at least 50 mol-%, preferably at least 55 mol-%, and even more preferably at least 60 mol-%.

[0022] This preferred embodiment of the present invention is the fifth embodiment of the method, which is preferably dependent on any of the first to fourth embodiments of the method. In one embodiment of the fifth embodiment of the method, all feasible combinations of features a. and b. constitute the preferred embodiment. These combinations are, for example, a; b; a+b. In one preferred embodiment of the fifth embodiment of the method, feature a., the first powder contains yttrium oxide in the range of 28 mol-% to 48 mol-%, more preferably 32 mol-% to 44 mol-%, and even more preferably 36 mol-% to 40 mol-%. In one preferred embodiment of the fifth embodiment of the method, feature b., the first powder contains alumina in the range of 52 mol-% to 72 mol-%, more preferably 56 mol-% to 68 mol-%, and even more preferably 60 mol-% to 64 mol-%. In one of the fifth embodiments of the method, particularly a preferred embodiment, the first powder comprises yttrium oxide and aluminum oxide.

[0023] In a preferred embodiment of the method, at least one or all of the following are applicable to the first powder: a. Yttrium oxide contained in the range of 35.5 mol% to 39.5 mol%, preferably 36.5 mol% to 38.5 mol%, and even more preferably 37.4 mol% to 37.6 mol%. b. Alumina contained in the range of 60.5 mol-% to 64.5 mol-%, preferably 61.5 mol-% to 63.5 mol-%, and even more preferably 62.4 mol-% to 62.6 mol-%.

[0024] This preferred embodiment of the invention is the sixth embodiment of the method, which is preferably based on any of the first to fifth embodiments of the method. In one embodiment of the sixth method, all possible combinations of features a. and b. are preferred embodiments of this embodiment. These combinations are, for example, a; b; a+b. In one preferred embodiment of the sixth method, the first powder is a stoichiometric powder mixture of 37.4 mol-% to 37.6 mol-% yttrium oxide and 62.4% mol-% to 62.6% mol-% alumina. The following ratio is particularly preferred: 37.5 mol-% yttrium oxide and 62.5 mol-% alumina. In the sixth embodiment of the method, the combination of features a+b does not necessarily have to add up to 100 mol-%.

[0025] In a preferred embodiment of the method, the first powder is a mixture comprising a first component powder and another component powder, wherein the first component powder of the first powder has at least one or all of the following properties: a. A d10 particle size in the range of 1 µm to 7 µm, preferably 1.5 µm to 6 µm, more preferably 2 µm to 5.4 µm, even more preferably 2.5 µm to 4.7 µm, and even more preferably 2.9 µm to 4.3 µm; b. A d50 particle size in the range of 2 µm to 14 µm, preferably 3 µm to 12 µm, more preferably 4 µm to 10 µm, even more preferably 4.7 µm to 8 µm, and even more preferably 5.1 µm to 7.5 µm; c. A d90 particle size in the range of 3 µm to 20 µm, preferably 5 µm to 18 µm, more preferably 7 µm to 16 µm, even more preferably 7.5 µm to 14 µm, and even more preferably 8 µm to 12 µm.

[0026] This preferred embodiment of the invention is the seventh embodiment of the method, which is preferably dependent on any of the first to sixth embodiments of the method. In one embodiment of the seventh embodiment of the method, all feasible combinations of features a. to c. are preferred embodiments of this embodiment. These combinations are, for example, a; b; c; a+b; a+c; b+c; a+b+c. The values ​​given in at least one or all of features a. to c. in the seventh embodiment of the method are preferably applicable after the first powder has been heat-treated (e.g., calcined). In a preferred embodiment of the seventh embodiment of the method, the first component powder of the first powder is yttrium oxide.

[0027] In a preferred embodiment of the method, the first powder is a mixture comprising a first component powder and another component powder, wherein the first component powder of the other powder has at least one or all of the following properties: a. A d10 particle size in the range of 0.005 µm to 0.4 µm, more preferably 0.01 µm to 0.3 µm, more preferably 0.04 µm to 0.26 µm, even more preferably 0.06 µm to 0.21 µm, and even more preferably 0.1 µm to 0.17 µm; b. A d50 particle size in the range of 0.01 µm to 0.8 µm, preferably 0.05 µm to 0.65 µm, more preferably 0.1 µm to 0.5 µm, even more preferably 0.13 µm to 0.4 µm, and further preferably 0.17 µm to 0.34 µm; c. A d90 particle size in the range of 0.05 µm to 7 µm, preferably 0.1 µm to 5 µm, more preferably 0.2 µm to 3 µm, even more preferably 0.3 µm to 2.5 µm, and even more preferably 0.5 µm to 1.7 µm.

[0028] This preferred embodiment of the invention is the eighth embodiment of the method, which is preferably dependent on any of the first to seventh embodiments of the method. In one embodiment of the eighth method, all feasible combinations of features a. to c. are preferred embodiments of this embodiment. These combinations are, for example, a; b; c; a+b; a+c; b+c; a+b+c. The values ​​given in at least one or all of features a. to c. in the eighth embodiment of the method are preferably applicable before the first powder has been heat-treated (e.g., calcined). In a preferred embodiment of the eighth method, the other component powder of the first powder is alumina.

[0029] In one preferred embodiment of the method, the first powder layer has a thickness such that the first layer formed from the first powder layer has a thickness in the range of 0.5 mm to 12 mm, more preferably 1 mm to 10 mm, even more preferably 2 mm to 8 mm, and further preferably 4 mm to 5 mm.

[0030] This preferred embodiment of the present invention is the ninth embodiment of the method, which is preferably dependent on any of the first to eighth embodiments of the method. In one preferred embodiment of the ninth embodiment of the method, the first powder layer has a thickness such that the first layer formed from the first powder layer has a thickness in the range of 1 mm to 8 mm, more preferably 1 mm to 7 mm, and even more preferably 1 mm to 6 mm. In another preferred embodiment of the ninth embodiment of the method, the first powder layer has a thickness such that the first layer formed from the first powder layer has a thickness in the range of 2 mm to 7 mm, more preferably 2 mm to 6 mm, even more preferably 2 mm to 5 mm, and even more preferably 2 mm to 3 mm. In yet another preferred embodiment of the ninth embodiment of the method, the first powder layer has a thickness such that the first layer formed from the first powder layer has a thickness in the range of 3 mm to 7 mm, more preferably 3 mm to 6 mm, and even more preferably 4 mm to 5 mm.

[0031] In one preferred embodiment of the method, the first powder layer and the other powder layer are in physical contact (e.g., touching each other).

[0032] This preferred embodiment of the present invention is the tenth embodiment of the method, which is preferably based on any one of the first to ninth embodiments of the method.

[0033] In one preferred embodiment of the method, the other powder comprises aluminum, zirconium, or a combination thereof.

[0034] This preferred embodiment of the invention is the eleventh embodiment of the method, which is preferably based on any of the first to tenth embodiments of the method. In the eleventh embodiment of the method, the preferred combination of aluminum and zirconium is zirconium oxide-toughened alumina. Here, the zirconium oxide is preferably partially stable, stable, or a combination thereof, with partially stable zirconium oxide being particularly preferred.

[0035] In a preferred embodiment of the method, the other powder comprises at least one oxide, preferably at least one oxide selected from the group consisting of: aluminum oxide, zirconium oxide, and combinations thereof.

[0036] This preferred embodiment of the invention is the 12th embodiment of the method, which is preferably based on any one of the 1st to 11th embodiments of the method. In the preferred embodiment of the 12th embodiment of the method, if the at least one oxide comprises and / or is zirconium oxide, then the zirconium oxide is partially stable, stable, or a combination of at least two of the above. In this embodiment, partially stable zirconium oxide is preferred over stable zirconium oxide.

[0037] In a preferred embodiment of the method, the other powder is a mixture of at least two component powders, preferably alumina powder and zirconium oxide powder.

[0038] This preferred embodiment of the present invention is the 13th embodiment of the method, which is preferably based on any one of the 1st to 12th embodiments of the method.

[0039] In a preferred embodiment of the method, at least one or all of the following are applicable to the other powder: a. Containing alumina, which, based on the total weight of the other powder, preferably is in the range of 60 wt% to 92.5 wt%, more preferably 66 wt% to 89 wt%, even more preferably 71 wt% to 84 wt%, and further preferably in the range of 75 wt% to 79 wt%. b. Containing zirconium oxide, which, based on the total weight of the other powder, is preferably in the range of 7.5 wt% to 40 wt%, more preferably in the range of 11 wt% to 35 wt%, even more preferably in the range of 16 wt% to 29 wt%, and further preferably in the range of 21 wt% to 25 wt%.

[0040] This preferred embodiment of the invention is the 14th embodiment of the method, which is preferably dependent on any of the 1st to 13th embodiments of the method. In one embodiment of the 14th embodiment of the method, all possible combinations of features a. and b. are preferred embodiments of this embodiment. Such combinations are, for example, a; b; a+b. In one particularly preferred embodiment of the 14th embodiment of the method, the other powder comprises a mixture of alumina powder and zirconium oxide powder. In the 14th embodiment of the method, the zirconium oxide is preferably at least one of partially stabilized zirconium oxide and stabilized zirconium oxide, wherein partially stabilized zirconium oxide is particularly preferred.

[0041] In a preferred embodiment of the method, the other powder is a mixture comprising a first component powder and another component powder, wherein the first component powder of the other powder has at least one or all of the following properties: a. A d10 particle size in the range of 0.01 µm to 0.4 µm, more preferably 0.04 µm to 0.35 µm, even more preferably 0.06 µm to 0.27 µm, even more preferably 0.09 µm to 0.22 µm, and further preferably 0.11 µm to 0.18 µm; b. A d50 particle size in the range of 0.01 µm to 3 µm, more preferably 0.1 µm to 1.5 µm, more preferably 0.2 µm to 1 µm, even more preferably 0.26 µm to 0.6 µm, and further preferably 0.3 µm to 0.36 µm; c. A d90 particle size in the range of 0.3 µm to 10 µm, more preferably 0.4 µm to 7 µm, even more preferably 0.47 µm to 6 µm, even more preferably 0.53 µm to 3 µm, and even more preferably 0.57 µm to 1 µm.

[0042] This preferred embodiment of the invention is the 15th embodiment of the method, which is preferably dependent on any of the 1st to 14th embodiments of the method. In one embodiment of the 15th embodiment of the method, all feasible combinations of features a. to c. are preferred embodiments of this embodiment. Such combinations are, for example, a; b; c; a+b; a+c; b+c; a+b+c. In the 15th embodiment of the method, the values ​​given in at least one or all of features a. to c. are preferably applicable after the other powder has been heat-treated (e.g., calcined). In the preferred embodiment of the 15th embodiment of the method, the first component powder of the other powder is zirconium oxide.

[0043] In a preferred embodiment of the method, the other powder is a mixture comprising the first component powder and the other component powder, wherein the other component powder has at least one or all of the following properties: a. A d10 particle size in the range of 0.01 µm to 0.3 µm, more preferably 0.03 µm to 0.2 µm, and even more preferably 0.05 µm to 0.15 µm; b. A d50 particle size in the range of 0.01 µm to 1.5 µm, more preferably 0.05 µm to 1.0 µm, and even more preferably 0.1 µm to 0.8 µm; c. A d90 particle size in the range of 0.01 µm to 6.0 µm, more preferably 0.05 µm to 3.5 µm, and even more preferably 0.1 µm to 3.0 µm.

[0044] This preferred embodiment of the invention is the 16th embodiment of the method, which is preferably dependent on any of the 1st to 15th embodiments of the method. In the 16th embodiment of the method, all feasible combinations of features a. to c. are preferred embodiments of this embodiment. These combinations are, for example, a; b; c; a+b; a+c; b+c; a+b+c. In the 16th embodiment of the method, the values ​​given in at least one or all of features a. to c. are preferably applicable before the other powder has been heat-treated (e.g., calcined). In the preferred embodiment of the 16th embodiment of the method, the other component powder of the other powder is alumina.

[0045] In a preferred embodiment of the method, the other powder layer has a thickness such that the other layer formed from the other powder layer has a thickness in the range of 5 mm to 50 mm, preferably 15 mm to 40 mm, further preferably 20 mm to 35 mm, and even more preferably 25 mm to 30 mm.

[0046] This preferred embodiment of the invention is the 17th embodiment of the method, which is preferably based on any one of the 1st to 16th embodiments of the method. In one preferred embodiment of the 17th embodiment of the method, the other powder layer has a thickness such that the other layer formed from the other powder layer has a thickness in the range of 20 mm to 30 mm, more preferably 22 mm to 28 mm, and even more preferably 23 mm to 27 mm.

[0047] In a preferred embodiment of the method, one of the following applies: a. The first powder is capable of forming a first oxide under applied heat and pressure, preferably oxide A; b. The first powder is capable of forming another oxide, preferably oxide B, under applied heat and pressure.

[0048] This preferred embodiment of the invention is the 18th embodiment of the method, which is preferably based on any one of the 1st to 17th embodiments of the method. In the 18th embodiment of the method, feature a is particularly preferred.

[0049] In a preferred embodiment of the method, one of the following applies: a. The other powder is capable of forming the first oxide under applied heat and pressure; b. The other powder can form the other oxide under applied heat and pressure. c. The first powder and the other powder are capable of forming the first oxide under applied heat and pressure; d. The first powder and the other powder are capable of forming the other oxide under applied heat and pressure; e. The first powder is capable of forming the first oxide under applied heat and pressure, and the other powder is capable of forming the other oxide under applied heat and pressure; f. The first powder is capable of forming the other oxide under applied heat and pressure, and the other powder is capable of forming the first oxide under applied heat and pressure.

[0050] This preferred embodiment of the invention is the 19th embodiment of the method, which is preferably based on any one of the 1st to 18th embodiments of the method. In the 19th embodiment of the method, features e. and f. are particularly preferred, with feature e. being the most preferred. The first oxide and the other oxide are the same as those described in the aforementioned 18th embodiment of the method. In the preferred embodiment of the 19th embodiment of the method, the first oxide is oxide A. In another preferred embodiment of the 19th embodiment of the method, the other oxide is oxide B.

[0051] In a preferred embodiment of the method, the first oxide is one of the following: a. A cubic crystal phase, preferably a cubic crystal phase containing yttrium, more preferably a cubic crystal phase of yttrium aluminum oxide, and even more preferably YAG, and more preferably a composition having a yttrium oxide and aluminum oxide comprising a ratio of 3:5; b. Oxides containing magnesium, more preferably oxides containing both magnesium and aluminum, such as magnesium aluminate spinel (MgAl2O4); c. A combination of yttrium oxide and zirconium oxide, wherein the zirconium oxide is present in an amount within the following ranges: preferably 10 mol-% to 25 mol-%, more preferably 15 mol-% to 25 mol-%, and even more preferably 18 mol-% to 25 mol-%. More preferably 10 mol-% to 23 mol-%, more preferably 10 mol-% to 20 mol-%. More preferably 15 mol-% to 23 mol-%. The balance preferably includes yttrium oxide. Particularly preferably, the combination of yttrium oxide and zirconium oxide is in the form of a crystalline solid solution. d. YAG and at least one of the following: at least one perovskite, monoclinic, alumina, yttrium oxide, or a combination thereof, preferably YAG, and at least one of the following crystal phases: YAP (yttrium aluminum perovskite), YAM (yttrium aluminum monoclinic), yttrium oxide, alumina, or a combination thereof; at least one or all of YAP, YAM, yttrium oxide, and alumina are preferably present in an amount of less than 5% by volume; preferably at least one or all of the crystal phases of YAG, YAP, and YAM are polycrystalline.

[0052] This preferred embodiment of the invention is the 20th embodiment of the method, which is preferably dependent on any of the 18th to 19th embodiments of the method. Feature a of the 20th embodiment of the method is particularly preferred. In this embodiment, it is preferable that the first oxide contains less than 0.01 mol-% of at least one, preferably all, of the following: YAP, YAM, and yttrium oxide.

[0053] In a preferred embodiment of the method, the other oxide comprises at least one or all of the following: a. Aluminum oxide; b. Zirconia, preferably stabilized zirconia and / or partially stabilized zirconia, with partially stabilized zirconia being particularly preferred.

[0054] This preferred embodiment of the invention is the 21st embodiment of the method, which is preferably based on any of the 18th to 20th embodiments of the method. In the 21st embodiment of the method, all possible combinations of features a. and b. are preferred embodiments of this embodiment. These combinations are, for example, a; b; a+b. In a particularly preferred embodiment of the 21st embodiment of the method, the other oxide comprises alumina and zirconium oxide. In this embodiment, preferably, the other oxide comprises at least two separate crystalline phases of zirconium oxide and alumina, referred herein as a composite oxide or particulate composite or zirconium oxide dispersed toughened alumina (ZTA).

[0055] In a preferred embodiment of the method, during the step of subjecting the first powder layer and, preferably, the other powder layer (if present), to the heat and the pressure, the temperature in the internal volume is within the following ranges: 900°C to 2000°C, preferably 950°C to 1900°C, more preferably 1000°C to 1800°C, and even more preferably 1050°C to 1700°C; preferably 1000°C to 1700°C, more preferably 1100°C to 1700°C, even more preferably 1200°C to 1700°C, even more preferably 1300°C to 1700°C, and even even more preferably 1400°C to 1700°C.

[0056] This preferred embodiment of the present invention is the 22nd embodiment of the method, which is preferably based on any one of the 1st to 21st embodiments of the method.

[0057] In a preferred embodiment of the method, during the step of subjecting the first powder layer and, preferably, the other powder layer (if present), to the heat and the pressure, the first powder layer and, preferably, the other powder layer (if present), are subjected to the following pressures: at least 1 MPa, preferably at least 5 MPa, more preferably at least 10 MPa, and even more preferably at least 15 MPa; preferably 1 MPa to 100 MPa, more preferably 5 MPa to 60 MPa, even more preferably 5 MPa to 45 MPa, even more preferably 5 MPa to 30 MPa, and even more preferably 5 MPa to 15 MPa; preferably 10 MPa to 60 MPa, more preferably 10 MPa to 45 MPa, even more preferably 10 MPa to 30 MPa, and even more preferably 10 MPa to 15 MPa; preferably 15 MPa to 60 MPa, more preferably 15 MPa to 45 MPa, and even more preferably 15 MPa to 60 MPa, more preferably 15 MPa to 45 MPa, and even more preferably 15 MPa to 60 MPa, even ... even more preferably 15 MPa to 45 MPa, and even more preferably 15 MPa to 60 MPa, even more preferably 15 MPa to 60 MPa to 30 MPa, and even more preferably 15 MPa to 20 MPa.

[0058] This preferred embodiment of the present invention is the 23rd embodiment of the method, which is preferably based on any one of the 1st to 22nd embodiments of the method.

[0059] In a preferred embodiment of the method, the voltage (applied across the mold, the internal volume, or both) is in the range of 0.5 V to 10 V, more preferably 1 V to 8 V, more preferably 1.5 V to 7 V, and even more preferably 2 V to 6 V.

[0060] This preferred embodiment of the present invention is the 24th embodiment of the method, which is preferably based on any one of the 1st to 23rd embodiments of the method.

[0061] In a preferred embodiment of the method, the voltage (applied across the mold, the internal volume, or both) is obtained by providing current to a device containing the internal volume, wherein the current is in the range of 1 kA to 100 kA, preferably 5 kA to 90 kA, more preferably 10 kA to 80 kA, even more preferably 15 kA to 70 kA, and further preferably in the range of 20 kA to 60 kA; alternatively, the current may be greater than 100 kA.

[0062] This preferred embodiment of the invention is the 25th embodiment of the method, which is preferably based on any one of the 1st to 24th embodiments of the method. In the 25th embodiment of the method, the current is preferably provided by a power supply connected to the device.

[0063] In a preferred embodiment of the method, the laminate has a diameter of at least 200 mm, more preferably at least 300 mm, and more preferably at least 500 mm; the diameter can reach up to 2000 mm or more; the diameter is preferably no greater than 1500 mm, more preferably no greater than 900 mm, even more preferably no greater than 800 mm, further preferably no greater than 700 mm, and even more preferably no greater than 650 mm; the diameter is preferably in the following range: greater than 200 mm to 625 mm; more preferably 300 mm to 625 mm, even more preferably 400 mm to 625 mm, and even more preferably 500 mm to 625 mm.

[0064] This preferred embodiment of the present invention is the 26th embodiment of the method, which is preferably based on any one of the 1st to 25th embodiments of the method.

[0065] In one preferred embodiment of the method, the applied electrical power flux is in the range of 0.05 W / mm² to 1.6 W / mm², more preferably 0.1 W / mm² to 1.3 W / mm², and even more preferably 0.3 W / mm² to 1 W / mm², wherein the power flux is applicable to at least one or all of the following: the mold, the internal volume, the first powder layer, the other powder layer (if present), at least one punch (if present), or at least both of the above.

[0066] This preferred embodiment of the present invention is the 27th embodiment of the method, which is preferably based on any of the 1st to 26th embodiments of the method. In one preferred embodiment of the 27th embodiment of the method, when the laminate to be prepared has a diameter in the range of > 500 mm to 650 mm, the electrical power flux is in the range of 0.05 W / mm² to 1 W / mm², more preferably 0.1 W / mm² to 0.7 W / mm², and even more preferably 0.3 W / mm² to 0.5 W / mm². In one preferred embodiment of the 27th embodiment of the method, when the laminate to be prepared has a diameter in the range of 300 mm to 500 mm, the power flux is in the range of > 0.1 W / mm² to 1.6 W / mm², more preferably > 0.3 W / mm² to 1.3 W / mm², and even more preferably > 0.5 W / mm² to 1.0 W / mm².

[0067] In a preferred embodiment of the method, the internal volume is defined by the following: a. The inner surface of the first punch; b. The inner surface of the second punch; and c. The internal surface of the mold, and in I. The first punch and the second punch are adapted and configured to apply pressure to the first powder layer and, preferably, the other powder layer (if present), within the internal volume during the step of subjecting the first powder layer and, preferably, the other powder layer (if present), to the heat and the pressure. II. Apply the pressure along the compression axis, and III. The angle between the compression shaft and the cross-sectional width W of the internal volume is in the range of 88° to 92°, more preferably 89° to 91°, and even more preferably 89.5° to 90.5°.

[0068] This preferred embodiment of the present invention is the 28th embodiment of the method, which is preferably based on any one of the 1st to 27th embodiments of the method.

[0069] In a preferred embodiment of the method, the first powder is capable of forming at least one or all of the following under applied heat and pressure: a. Oxide A, comprising at least 1 mol-% of a Group 3 (formerly Group IIIB) element (preferably yttrium) and at least 1 mol-% of a Group 13 (formerly Group IIIA) element (preferably aluminum), wherein the mol-% is expressed as oxygen in oxide A; preferably, oxide A is a cubic phase of yttrium aluminum oxide, more preferably YAG; b. Oxide B, comprising at least 1 mol-% of a Group 4 (formerly Group IVB) element (preferably zirconium) and at least 1 mol-% of a Group 13 (formerly Group IIIA) element (preferably aluminum), wherein the mol-% is expressed as oxygen in oxide B; preferably, oxide B is ZTA.

[0070] This preferred embodiment of the invention is the 29th embodiment of the method, which is preferably dependent on any of the 1st to 28th embodiments of the method. In one embodiment of the 29th method, all possible combinations of features a. and b. are preferred embodiments of this embodiment. These combinations are, for example, a; b; a+b. In the 29th embodiment of the method, the groups refer to groups of the periodic table. Feature a. in the 29th embodiment of the method is particularly preferred. In the preferred embodiment of the 29th method, oxide A is an inorganic oxide. In one preferred embodiment of the 29th method, oxide B is an inorganic oxide. In one preferred embodiment of the 29th method, feature a., oxide A contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 3 (formerly Group IIIB) element. In a preferred embodiment of the 29th example of the method, feature a. the oxide A contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 13 (formerly Group IIIA) element. In a preferred embodiment of the 29th example of the method, feature b. the oxide B contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 4 (formerly Group IVB) element. In a preferred embodiment of the 29th example of the method, feature b. the oxide B contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 13 (formerly Group IIIA) element.

[0071] In a preferred embodiment of the method, the other powder is capable of forming at least one or all of the following under applied heat and pressure: a. Oxide A, comprising at least 1 mol-% of a Group 3 (formerly Group IIIB) element (preferably yttrium) and at least 1 mol-% of a Group 13 (formerly Group IIIA) element (preferably aluminum), wherein the mol-% is expressed as oxygen in oxide A; preferably, oxide A is a cubic phase of yttrium aluminum oxide, more preferably YAG; b. Oxide B, comprising at least 1 mol-% of a Group 4 (formerly Group IVB) element (preferably zirconium) and at least 1 mol-% of a Group 13 (formerly Group IIIA) element (preferably aluminum), wherein the mol-% is expressed as oxygen in oxide B; preferably, oxide B is ZTA.

[0072] This preferred embodiment of the invention is the 30th embodiment of the method, which is preferably dependent on any of the 1st to 29th embodiments of the method. In the 30th embodiment of the method, all possible combinations of features a. and b. are preferred embodiments of this embodiment. These combinations are, for example, a; b; a+b. In the 30th embodiment of the method, the groups refer to groups of the periodic table. Feature b. in the 30th embodiment of the method is particularly preferred. In one preferred embodiment of the 30th embodiment of the method, oxide A is an inorganic oxide. In the preferred embodiment of the 30th embodiment of the method, oxide B is an inorganic oxide. In the preferred embodiment of the 30th embodiment of the method, feature a., oxide A contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 3 (formerly Group IIIB) element. In the preferred embodiment of the method in the 30th example, feature a., the oxide A contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 13 (formerly Group IIIA) element. In the preferred embodiment of the method in the 30th example, feature b., the oxide B contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 4 (formerly Group IVB) element. In the preferred embodiment of the method in the 30th example, feature b., the oxide B contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 13 (formerly Group IIIA) element.

[0073] The preferred embodiments of this method for the first powder, and the preferred embodiments thereof, are also preferably applicable to the first powder layer. The preferred embodiments of this method for the first powder layer, and the preferred embodiments thereof, are also preferably applicable to the first powder. The preferred embodiments of this method for the other powder, and the preferred embodiments thereof, are also preferably applicable to the other powder layer. The preferred embodiments of this method for the other powder layer, and the preferred embodiments thereof, are also preferably applicable to the other powder.

[0074] In one preferred embodiment of the method, the first density change, defined as ρT / ρM – 1, is in the range of 5 x 10⁻⁵ to 1.000 x 10⁻², more preferably 7 x 10⁻⁵ to 8.00 x 10⁻³, more preferably 1.0 x 10⁻⁴ to 6.00 x 10⁻³, and even more preferably 1.2 x 10⁻⁴ to 4.50 x 10⁻³.

[0075] This preferred embodiment of the present invention is the 31st embodiment of the method, which is preferably based on any one of the 1st to 30th embodiments of the method.

[0076] In a preferred embodiment of the method, at least one or all of the following apply: a. The ρT value is in the range of 4.275 g / cm³ to 4.325 g / cm³, more preferably 4.285 g / cm³ to 4.315 g / cm³, and even more preferably 4.290 g / cm³ to 4.310 g / cm³; b. ρM is in the range of 4.262 g / cm3 to 4.322 g / cm3, more preferably 4.274 g / cm3 to 4.310 g / cm3, and even more preferably 4.282 g / cm3 to 4.302 g / cm3, with the constraint that ρT > ρM.

[0077] This preferred embodiment of the invention is the 32nd embodiment of the method, which is preferably based on any of the 1st to 31st embodiments of the method. In one embodiment of the 32nd embodiment of the method, all possible combinations of features a. and b. constitute the preferred embodiment. Such combinations are, for example, a; b; a+b.

[0078] In one preferred embodiment of the method, after the heat treatment of the laminate, ρT > ρB, where ρB is the density measured at another location in the other layer, and where the second location is closer to the first location than the other location.

[0079] This preferred embodiment of the present invention is the 33rd embodiment of the method, which is preferably attached to any of the 1st to 32nd embodiments of the method. In one embodiment of the 33rd embodiment of the method, the other layer has a first surface and another surface opposite to the first surface, wherein the first surface faces the first layer. In this embodiment, it is preferable that the other position is located closer to the other surface than the first position and the second position. In this embodiment, it is preferable that the other position is located at a distance of 5 mm or less from the other surface of the other layer. In one preferred embodiment of the method, the other position is located at a distance of 7 mm or less from the first centerline.

[0080] In one preferred embodiment of the method, another density variation, defined as ρT / ρB – 1, is in the range of 5 x 10⁻⁵ to 1.000 x 10⁻², more preferably 7 x 10⁻⁵ to 8.00 x 10⁻³, more preferably 1.0 x 10⁻⁴ to 6.00 x 10⁻³, and even more preferably 1.2 x 10⁻⁴ to 4.50 x 10⁻³.

[0081] This preferred embodiment of the present invention is the 34th embodiment of the method, which is more preferably based on the 33rd embodiment of the method.

[0082] In a preferred embodiment of the method, at least one or all of the following apply: a. The ratio ρM / ρB is in the range of 0.990 to 1.010, more preferably 0.995 to 1.005, and even more preferably 0.998 to 1.002; b. ρB is in the range of 4.262 g / cm3 to 4.322 g / cm3, more preferably 4.274 g / cm3 to 4.310 g / cm3, and even more preferably 4.282 g / cm3 to 4.302 g / cm3, with the constraint that ρT > ρB.

[0083] This preferred embodiment of the invention is the 35th embodiment of the method, which is preferably based on any of the 33rd to 34th embodiments of the method. In one embodiment of the 35th embodiment of the method, all possible combinations of features a. and b. constitute the preferred embodiment. Such combinations are, for example, a; b; a+b.

[0084] In one preferred embodiment of the method, the ratio of the thickness of the other layer to the thickness of the first layer is in the range of 0.5 to 15, more preferably 1 to 12, more preferably 2 to 9, and even more preferably 3 to 6.

[0085] This preferred embodiment of the present invention is the 36th embodiment of the method, which is preferably attached to any one of the 1st to 35th embodiments of the method. In one preferred embodiment of the 36th embodiment of the method, the ratio of the thickness of the other layer to the thickness of the first layer is in the range of 3 to 15, more preferably 6 to 15, even more preferably 7 to 14, and further more preferably 8 to 13.

[0086] In one preferred embodiment of the method, at least one or all of the following are applicable to the laminate: a. The first layer has a thickness in the range of 0.5 mm to 12 mm, preferably 1 mm to 10 mm, more preferably 2 mm to 8 mm, and even more preferably 4 mm to 5 mm. b. The other layer has a thickness in the range of 5 mm to 50 mm, preferably 15 mm to 40 mm, further preferably 20 mm to 35 mm, and even more preferably 25 mm to 30 mm.

[0087] This preferred embodiment of the invention is the 37th embodiment of the method, which is preferably dependent on any of the 1st to 36th embodiments of the method. In one embodiment of the 37th method, all possible combinations of features a. and b. are preferred embodiments of this embodiment. These combinations are, for example, a; b; a+b. In this embodiment, the combination a+b is particularly preferred. In one preferred embodiment of the 37th method, feature a., the first layer has a thickness in the range of 1 mm to 8 mm, more preferably 1 mm to 7 mm, and even more preferably 1 mm to 6 mm. In another preferred embodiment of the 37th method, feature a., the first layer has a thickness in the range of 2 mm to 7 mm, more preferably 2 mm to 6 mm, even more preferably 2 mm to 5 mm, and even more preferably 2 mm to 3 mm. In yet another preferred embodiment of the 37th embodiment of the method, feature a. the first layer has a thickness in the range of 3 mm to 7 mm, more preferably 3 mm to 6 mm, and even more preferably 4 mm to 5 mm. In another preferred embodiment of the 37th embodiment of the method, feature b. the other layer has a thickness in the range of 20 mm to 30 mm, more preferably 22 mm to 28 mm, and even more preferably 23 mm to 27 mm.

[0088] In one preferred embodiment of the method, the density of the first layer is in the range of 3.9 g / cm3 to 5 g / cm3, more preferably in the range of 4.1 g / cm3 to 4.8 g / cm3, and even more preferably in the range of 4.3 g / cm3 to 4.6 g / cm3.

[0089] This preferred embodiment of the present invention is the 38th embodiment of the method, which is preferably based on any one of the 1st to 37th embodiments of the method.

[0090] In one preferred embodiment of the method, the temperature of the heat treatment subjected to the laminate is in the range of 1250°C to 1550°C, more preferably 1300°C to 1500°C, more preferably 1350°C to 1450°C, and even more preferably 1385°C to 1415°C.

[0091] This preferred embodiment of the present invention is the 39th embodiment of the method, which is preferably based on any one of the 1st to 38th embodiments of the method.

[0092] In one preferred embodiment of the method, the laminate is subjected to the heat treatment in an environment containing at least 10 vol-%, preferably at least 14 vol-%, more preferably at least 18 vol-%, and even more preferably at least 20 vol-%.

[0093] This preferred embodiment of the invention is the 40th embodiment of the method, which is preferably any one of the 1st to 39th embodiments of the method. In one preferred embodiment of the 40th method, the environment contains oxygen in the range of 18 vol-% to 22 vol-% . For example, the environment has the same composition as the atmosphere.

[0094] In one preferred embodiment of the method, the laminate is subjected to the heat treatment in an environment with a pressure not exceeding 1 MPa, preferably not exceeding 0.5 MPa, and even more preferably not exceeding 0.2 MPa.

[0095] This preferred embodiment of the invention is the 41st embodiment of the method, which is preferably dependent on any of the 1st to 40th embodiments of the method. In one preferred embodiment of the 41st method, the pressure in the environment is at least 0.02 MPa, more preferably at least 0.05 MPa, and even more preferably at least 0.08 MPa. In one preferred embodiment of the 41st method, the pressure in the environment is air pressure. For example, during the step of subjecting the first powder layer to heat and pressure, the pressure is generated by the first and second punches of the device. For example, during the step of subjecting the laminate to the heat treatment, the pressure applied to the laminate is generated by the atmosphere.

[0096] In one preferred embodiment of the method, the heat treatment subjected to the laminate has a duration in the range of 400 to 560 minutes, more preferably 430 to 530 minutes, and even more preferably 460 to 500 minutes.

[0097] This preferred embodiment of the present invention is the 42nd embodiment of the method, which is preferably based on any one of the 1st to 41st embodiments of the method.

[0098] One embodiment of the present invention is a laminate comprising a first layer and another layer, preferably a laminate obtainable by means of the method for obtaining a laminate according to the present invention, and more preferably a laminate obtainable by means of any one of the first to 42 embodiments of the method. This embodiment is the first embodiment of the laminate.

[0099] In a preferred embodiment of the laminate, the first layer comprises yttrium, aluminum, zirconium, magnesium, or a combination of at least two of them.

[0100] This preferred embodiment of the invention is a second embodiment of the laminate, which is preferably attached to the first embodiment of the laminate. A preferred combination of at least two of the chemical elements in the second embodiment of the laminate includes yttrium aluminum garnet, zirconium oxide-toughened alumina, and combinations thereof. In a particularly preferred embodiment of the second embodiment of the laminate, the first layer comprises yttrium oxide and alumina.

[0101] In a preferred embodiment of the laminate, the first layer comprises at least one oxide, preferably at least one oxide selected from the group consisting of: yttrium oxide, aluminum oxide, zirconium oxide, magnesium oxide, and combinations of at least two thereof.

[0102] This preferred embodiment of the present invention is a third embodiment of the laminate, which is preferably attached to any of the first to second embodiments of the laminate. In a particularly preferred embodiment of the third embodiment of the laminate, the first layer comprises yttrium oxide and aluminum oxide. In a preferred embodiment of the third embodiment of the laminate, if the at least one oxide comprises and / or is zirconium oxide, then the zirconium oxide is preferably partially stabilized zirconium oxide, stabilized zirconium oxide, or a combination thereof. In this embodiment, partially stabilized zirconium oxide is preferred over stabilized zirconium oxide.

[0103] In a preferred embodiment of the laminate, at least one or all of the following apply to the first layer: a. Contains at least 25 mol-%, preferably at least 30 mol-%, and even more preferably at least 35 mol-%, of yttrium oxide; b. Contains at least 50 mol-%, preferably at least 55 mol-%, and even more preferably at least 60 mol-%.

[0104] This preferred embodiment of the present invention is the fourth embodiment of the laminate, which is preferably attached to any of the first to third embodiments of the laminate. In the fourth embodiment of the laminate, all possible combinations of features a. and b. are preferred embodiments of this embodiment. These combinations are, for example, a; b; a+b. In the preferred embodiment of the fourth embodiment of the laminate, feature a., the first layer contains yttrium oxide in the range of 28 mol-% to 48 mol-%, more preferably 32 mol-% to 44 mol-%, and even more preferably 36 mol-% to 40 mol-%. In the preferred embodiment of the fourth embodiment of the laminate, feature b., the first layer contains alumina in the range of 52 mol-% to 72 mol-%, more preferably 56 mol-% to 68 mol-%, and even more preferably 60 mol-% to 64 mol-%. In a particularly preferred embodiment of the fourth embodiment of the laminate, the first layer comprises yttrium oxide and aluminum oxide.

[0105] In a preferred embodiment of the laminate, at least one or all of the following apply to the first layer: a. Yttrium oxide contained in the range of 35.5 mol% to 39.5 mol%, preferably 36.5 mol% to 38.5 mol%, and even more preferably 37.4 mol% to 37.6 mol%. b. Alumina contained in the range of 60.5 mol-% to 64.5 mol-%, preferably 61.5 mol-% to 63.5 mol-%, and even more preferably 62.4 mol-% to 62.6 mol-%.

[0106] This preferred embodiment of the invention is the fifth embodiment of the laminate, which is preferably attached to any of the first to fourth embodiments of the laminate. In one embodiment of the fifth laminate, all feasible combinations of features a. and b. are preferred embodiments of this embodiment. These combinations are, for example, a; b; a+b. In the preferred embodiment of the fifth laminate, the first layer contains yttrium oxide in the range of 37.4 mol-% to 37.6 mol-% and aluminum oxide in the range of 62.4% mol and 62.6% mol. The following ratio is particularly preferred: 37.5 mol-% yttrium oxide and 62.5 mol-% aluminum oxide. In the fifth embodiment of the laminate, the combination of features a+b does not necessarily have to add up to 100 mol-%.

[0107] In a preferred embodiment of the laminate, the first layer comprises at least one or all of the following: a. Oxide A, comprising at least 1 mol-% of a Group 3 (formerly Group IIIB) element (preferably yttrium) and at least 1 mol-% of a Group 13 (formerly Group IIIA) element (preferably aluminum), wherein the mol-% is expressed as oxygen in oxide A; preferably, oxide A is a cubic phase of yttrium aluminum oxide, more preferably YAG; b. Oxide B, comprising at least 1 mol-% of a Group 4 (formerly Group IVB) element (preferably zirconium) and at least 1 mol-% of a Group 13 (formerly Group IIIA) element (preferably aluminum), wherein the mol-% is expressed as oxygen in oxide B; preferably, oxide B is ZTA.

[0108] This preferred embodiment of the present invention is the sixth embodiment of the laminate, which is preferably attached to any of the first to fifth embodiments of the laminate. In one state of the sixth embodiment of the laminate, all feasible combinations of features a. and b. are preferred states of this embodiment. These combinations are, for example, a; b; a+b. In the sixth embodiment of the laminate, the groups refer to the groups of the periodic table. Feature a. in the sixth embodiment of the laminate is particularly preferred. In one preferred state of the sixth embodiment of the method, oxide A is an inorganic oxide. In one preferred state of the sixth embodiment of the method, oxide B is an inorganic oxide. In one preferred state of the sixth embodiment of the laminate, feature a., oxide A contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 3 (formerly Group IIIB) element. In a preferred embodiment of the sixth embodiment of the laminate, characteristic a. the oxide A contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 13 (formerly Group IIIA) element. In a preferred embodiment of the sixth embodiment of the laminate, characteristic b. the oxide B contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 4 (formerly Group IVB) element. In a preferred embodiment of the sixth embodiment of the laminate, characteristic b. the oxide B contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 13 (formerly Group IIIA) element.

[0109] In one preferred embodiment of the laminate, the thickness of the first layer is in the range of 0.5 mm to 12 mm, more preferably 1 mm to 10 mm, even more preferably 2 mm to 8 mm, and further preferably 4 mm to 5 mm.

[0110] This preferred embodiment of the present invention is the seventh embodiment of the laminate, which is preferably attached to any of the first to sixth embodiments of the laminate. In one preferred embodiment of the seventh laminate, the first layer has a thickness in the range of 1 mm to 8 mm, more preferably 1 mm to 7 mm, and even more preferably 1 mm to 6 mm. In another preferred embodiment of the seventh laminate, the first layer has a thickness in the range of 2 mm to 7 mm, more preferably 2 mm to 6 mm, even more preferably 2 mm to 5 mm, and even more preferably 2 mm to 3 mm. In yet another preferred embodiment of the seventh laminate, the first layer has a thickness in the range of 3 mm to 7 mm, more preferably 3 mm to 6 mm, and even more preferably 4 mm to 5 mm.

[0111] In a preferred embodiment of the laminate, the first layer and the other layer are in contact with each other and are preferably connected.

[0112] This preferred embodiment of the present invention is the eighth embodiment of the laminate, which is preferably attached to any one of the first to seventh embodiments of the laminate.

[0113] In a preferred embodiment of the laminate, the other layer comprises aluminum, zirconium, or a combination thereof.

[0114] This preferred embodiment of the invention is the ninth embodiment of the laminate, which is preferably attached to any of the first to eighth embodiments of the laminate. In the ninth embodiment of the laminate, the preferred combination of aluminum and zirconium is zirconium oxide toughened alumina. Here, the zirconium oxide is preferably partially stable, stable, or a combination of at least two of them, wherein partially stable zirconium oxide is particularly preferred.

[0115] In a preferred embodiment of the laminate, the other layer comprises at least one oxide, preferably at least one oxide selected from the group consisting of: aluminum oxide, zirconium oxide, and combinations thereof.

[0116] This preferred embodiment of the present invention is the tenth embodiment of the laminate, which is preferably attached to any one of the first to ninth embodiments of the laminate. In the preferred embodiment of the tenth embodiment of the laminate, if the at least one oxide comprises and / or is zirconium oxide, then the zirconium oxide is partially stable, stable, or a combination of at least two of the above. In this embodiment, partially stable zirconium oxide is preferred over stable zirconium oxide.

[0117] In a preferred embodiment of the laminate, at least one or all of the following apply to the other layer: a. Alumina comprising the following ranges: 70 vol-% to 97 vol-%, preferably 75 vol-% to 95 vol-%, and further preferably 80 vol-% to 92 vol-%. More preferably 70 vol-% to 90 vol-%, even more preferably 75 vol-% to 95 vol-%, and still more preferably 80 vol-% to 90 vol-%. More preferably 75 vol-% to 86 vol-%, even more preferably 80 vol-% to 86 vol-%. The above are based on the total volume of another layer. b. Zirconia contained in the range of 3 vol-% to 30 vol-%, preferably in the range of 5 vol-% to 25 vol-%, and even more preferably in the range of 8 vol-% to 20 vol-%. More preferably, it is 10 vol-% to 30 vol-%, more preferably 10 vol-% to 25 vol-%, more preferably 10 vol-% to 20 vol-%. More preferably, it is 14 vol-% to 25 vol-%, more preferably 20 vol-% to 25 vol-%. More preferably, it is 14 vol-% to 20 vol-%. The above are based on the total volume of another layer.

[0118] This preferred embodiment of the present invention is the eleventh embodiment of the laminate, which is preferably attached to any of the first to tenth embodiments of the laminate. In one embodiment of the eleventh embodiment of the laminate, all possible combinations of features a. and b. are preferred embodiments of this embodiment. Such combinations are, for example, a; b; a+b. In a preferred embodiment of the eleventh embodiment of the laminate, it is preferable that the other layer comprises both alumina and zirconium oxide. In this embodiment, it is preferable that the other layer comprises alumina in the range of 80 vol-% to 92 vol-% and zirconium oxide in the range of 8 vol-% to 20 vol-%.

[0119] In a preferred embodiment of the laminate, the other layer comprises at least one or all of the following: a. Oxide A, comprising at least 1 mol-% of a Group 3 (formerly Group IIIB) element (preferably yttrium) and at least 1 mol-% of a Group 13 (formerly Group IIIA) element (preferably aluminum), wherein the mol-% is expressed as oxygen in oxide A; preferably, oxide A is a cubic phase of yttrium aluminum oxide, more preferably YAG; b. Oxide B, comprising at least 1 mol-% of a Group 4 (formerly Group IVB) element (preferably zirconium) and at least 1 mol-% of a Group 13 (formerly Group IIIA) element (preferably aluminum), wherein the mol-% is expressed as oxygen in oxide B; preferably, oxide B is ZTA.

[0120] This preferred embodiment of the invention is the 12th embodiment of the laminate, which is preferably attached to any of the 1st to 11th embodiments of the laminate. In one state of the 12th embodiment of the laminate, all feasible combinations of features a. and b. are preferred states of this embodiment. These combinations are, for example, a; b; a+b. In the 12th embodiment of the laminate, the groups refer to the groups of the periodic table. Feature b. in the 12th embodiment of the laminate is particularly preferred. In one preferred state of the 12th embodiment of the method, oxide A is an inorganic oxide. In one preferred state of the 12th embodiment of the method, oxide B is an inorganic oxide. In the preferred state of the 12th embodiment of the laminate, feature a., oxide A contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 3 (formerly Group IIIB) element. In the preferred sample of the 12th embodiment of the laminate, feature a., the oxide A contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 13 (formerly Group IIIA) element. In the preferred sample of the 12th embodiment of the laminate, feature b., the oxide B contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 4 (formerly Group IVB) element. In the preferred sample of the 12th embodiment of the laminate, feature b., the oxide B contains at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-%, of a Group 13 (formerly Group IIIA) element.

[0121] In a preferred embodiment of the laminate, at least one or all of the following apply: a. The thickness of the second layer is 1.5 to 15 times greater than the thickness of the first layer, more preferably 2 to 10 times greater, and even more preferably 3.5 to 8 times greater; b. The thickness of the other layer is in the range of 5 mm to 50 mm, preferably in the range of 15 mm to 35 mm, and even more preferably in the range of 20 mm to 30 mm;

[0122] This preferred embodiment of the present invention is the 13th embodiment of the laminate, which is preferably attached to any of the 1st to 12th embodiments of the laminate. In the 13th embodiment of the laminate, all possible combinations of features a. and b. are preferred embodiments of this embodiment. These combinations are, for example, a; b; a+b. In one preferred embodiment of the 13th embodiment of the laminate, feature a., the thickness of the other layer is greater than the thickness of the first layer by a factor of 3 to 15, more preferably 6 to 15, even more preferably 7 to 14, and further more preferably 8 to 13. In one preferred embodiment of the 13th embodiment of the laminate, feature b., the other layer has a thickness in the range of 20 mm to 30 mm, more preferably 22 mm to 28 mm, and further more preferably 23 mm to 27 mm.

[0123] In a preferred embodiment of the laminate, one of the following applies: a. The first layer comprises the first oxide, wherein the first oxide is preferably oxide A; b. The first layer contains the other oxide, wherein the other oxide is preferably oxide B.

[0124] This preferred embodiment of the invention is the 14th embodiment of the laminate, which is preferably attached to any one of the 1st to 13th embodiments of the laminate. In one embodiment of the 14th method, feature a is particularly preferred.

[0125] In a preferred embodiment of the laminate, one of the following applies: a. The other layer contains the first oxide; b. The other layer contains the other oxide; c. The first layer and the other layer contain the first oxide; d. The first layer and the other layer contain the other oxide; e. The first layer contains the first oxide and the other layer contains the other oxide; f. The first layer contains the other oxide and the other layer contains the first oxide.

[0126] This preferred embodiment of the present invention is the 15th embodiment of the laminate, which is preferably attached to any of the 1st to 14th embodiments of the laminate. In the preferred embodiment of the 15th embodiment of the laminate, features e. and f. are particularly preferred, with feature e. being the most preferred. The first oxide and the other oxide are the same as those described in the aforementioned 14th embodiment of the laminate. In the preferred embodiment of the 15th embodiment of the laminate, the first oxide is oxide A. In another preferred embodiment of the 15th embodiment of the laminate, the other oxide is oxide B.

[0127] In a preferred embodiment of the laminate, the first oxide is one of the following: a. A cubic crystal phase, preferably a cubic crystal phase containing yttrium, more preferably a cubic crystal phase of yttrium aluminum oxide, and even more preferably YAG, and more preferably a composition having a yttrium oxide and aluminum oxide comprising a ratio of 3:5; b. Oxides containing magnesium, more preferably oxides containing both magnesium and aluminum, such as magnesium aluminate spinel (MgAl2O4); c. A combination of yttrium oxide and zirconium oxide, wherein the zirconium oxide is present in an amount within the following ranges: preferably 10 mol-% to 25 mol-%, more preferably 15 mol-% to 25 mol-%, and even more preferably 18 mol-% to 25 mol-%. More preferably 10 mol-% to 23 mol-%, more preferably 10 mol-% to 20 mol-%. More preferably 15 mol-% to 23 mol-%. The balance preferably includes yttrium oxide. Particularly preferably, the combination of yttrium oxide and zirconium oxide is in the form of a crystalline solid solution. d. YAG and at least one of the following: at least one perovskite, monoclinic, alumina, yttrium oxide, or a combination thereof, preferably YAG, and at least one of the following crystal phases: YAP (yttrium aluminum perovskite), YAM (yttrium aluminum monoclinic), yttrium oxide, alumina, or a combination thereof; at least one or all of YAP, YAM, yttrium oxide, and alumina are preferably present in an amount of less than 5% by volume; preferably at least one or all of the crystal phases of YAG, YAP, and YAM are polycrystalline.

[0128] This preferred embodiment of the present invention is the 16th embodiment of the laminate, which is preferably based on any of the 14th to 15th embodiments of the laminate. Feature a. of the 16th embodiment of the laminate is particularly preferred. In this embodiment, it is preferable that the first oxide comprises less than 0.01 mol-% of at least one, preferably all, of the following: YAP, YAM, and yttrium oxide.

[0129] In a preferred embodiment of the laminate, the other oxide comprises at least one or all of the following: a. Aluminum oxide; b. Zirconia, preferably stabilized zirconia and / or partially stabilized zirconia, with partially stabilized zirconia being particularly preferred.

[0130] This preferred embodiment of the invention is the 17th embodiment of the laminate, which is preferably attached to any of the 14th to 16th embodiments of the laminate. In one embodiment of the 17th embodiment of the laminate, all possible combinations of features a. and b. are preferred embodiments of this embodiment. These combinations are, for example, a; b; a+b. In a particularly preferred embodiment of the 17th embodiment of the laminate, the other oxide comprises alumina and zirconium oxide. In this embodiment, preferably, the other oxide comprises at least two separate crystalline phases of zirconium oxide and alumina, referred herein as a composite oxide or particulate composite or zirconium oxide dispersed toughened alumina (ZTA).

[0131] In a preferred embodiment of the laminate, the first layer has at least one or all of the following properties: a. The value of density divided by theoretical density is in the range of 0.95 to 1, preferably in the range of 97 to 1, more preferably in the range of 98 to 1, and even more preferably in the range of 0.99 to 1; a value less than 1.0 is further preferred; b. The average grain size is in the range of 0.4 µm to 10 µm, more preferably 0.6 µm to 8 µm, even more preferably 0.8 µm to 6.5 µm, even more preferably 1 µm to 4 µm, further preferably 1.1 µm to 3 µm, even more preferably 1.2 µm to 3 µm, even more preferably 1.3 µm to 2.5 µm, and even more preferably 1.4 µm to 2.2 µm; c. The standard deviation of the average grain size distribution is in the range of 1.2 µm to 2.8 µm, more preferably 1.6 µm to 2.4 µm, and even more preferably 1.8 µm to 2.2 µm; d. A density in the range of 3.9 g / cm3 to 5 g / cm3, preferably in the range of 4.1 g / cm3 to 4.8 g / cm3, and even more preferably in the range of 4.3 g / cm3 to 4.6 g / cm3.

[0132] This preferred embodiment of the present invention is the 18th embodiment of the laminate, which is preferably attached to any of the 1st to 17th embodiments of the laminate. In the 18th embodiment of the laminate, all possible combinations of features a. to d. are preferred embodiments of this embodiment. Such combinations are, for example, a; b; c; d; a+b; a+c; a+d; b+c; b+d; c+d; a+b+c; a+b+d; a+c+d; b+c+d; a+b+c+d.

[0133] In a preferred embodiment of the laminate, the other layer has at least one of the following properties: a. The value of density divided by theoretical density is in the range of 0.95 to 1, preferably in the range of 97 to 1, more preferably in the range of 98 to 1, and even more preferably in the range of 0.99 to 1; a value less than 1.0 is further preferred; b. An average grain size of 5 µm or less, preferably 4.5 µm or less, more preferably 4 µm or less, even more preferably 3.5 µm or less, further preferably 3 µm or less, further preferably 2.5 µm or less, further preferably 2 µm or less, further preferably 1.5 µm or less, and even more preferably 1 µm or less; c. The standard deviation of the average grain size distribution is in the range of 1.2 µm to 2.8 µm, more preferably 1.6 µm to 2.4 µm, and even more preferably 1.8 µm to 2.2 µm; d. A density in the range of 3.9 g / cm³ to 4.8 g / cm³, more preferably 4.1 g / cm³ to 4.6 g / cm³, and even more preferably 4.19 g / cm³ to 4.46 g / cm³; e. The value of the density of the first layer divided by the theoretical density varies from the value of the density of the other layer divided by the theoretical density by less than 5%, preferably less than 3%, and even more preferably less than 1%.

[0134] This preferred embodiment of the present invention is the 19th embodiment of the laminate, which is preferably attached to any of the 1st to 18th embodiments of the laminate. In the 19th embodiment of the laminate, all possible combinations of features a to e are preferred embodiments of this embodiment. Such combinations are, for example, a; b; c; d; e; a+b; a+c; a+d; a+e; b+c; b+d; b+e; c+d; c+e; d+e; a+b+c; a+b+d; a+b+e; a+c+d; a+c+e; a+d+e; b+c+d; b+c+e; b+d+e; c+d+e; a+b+c+d; a+b+c+e; a+b+d+e; a+c+d+e; b+c+d+e; a+b+c+d+e. In the 19th embodiment of the laminate, the variation of the "density divided by the theoretical density" is preferably applicable to the maximum size of the laminate. In the 19th embodiment of the laminate, feature b., preferably, the average grain size is in the range of 1 µm to 3 µm.

[0135] In a preferred embodiment of the laminate, the laminate has a diameter of at least 200 mm, more preferably at least 300 mm, and more preferably at least 500 mm; the diameter can reach up to 2000 mm or more; the diameter is preferably no greater than 1500 mm, more preferably no greater than 900 mm, even more preferably no greater than 800 mm, further preferably no greater than 700 mm, and even more preferably no greater than 650 mm; the diameter is preferably in the following range: greater than 200 mm to 625 mm; more preferably 300 mm to 625 mm, even more preferably 400 mm to 625 mm, and even more preferably 500 mm to 625 mm.

[0136] This preferred embodiment of the present invention is the 20th embodiment of the laminate, which is preferably attached to any one of the 1st to 19th embodiments of the laminate.

[0137] In a preferred embodiment of the laminate, ρT > ρM, wherein ρT and ρM are densities measured in the other layer, and wherein ρT is measured at a first position in the other layer, and ρM is measured at a second position in the other layer, wherein the first position is closer to the first layer than the second position.

[0138] This preferred embodiment of the present invention is the 21st embodiment of the laminate, which is preferably attached to any of the 1st to 20th embodiments of the laminate. In one preferred embodiment of the 21st embodiment of the laminate, the first layer and the other layer are in contact with each other. In one preferred embodiment of the 21st embodiment of the laminate, the other layer has a first surface and another surface opposite to the first surface, wherein the first surface faces the first layer. In this embodiment, preferably, the first position is located at a distance of 5 mm or less from the first surface of the other layer. In one preferred embodiment of the 21st embodiment of the laminate, the second position is located at a distance of 5 mm or less from the center of the other layer. In one preferred embodiment of the 21st embodiment of the laminate, the first position is located at a distance of 7 mm or less from a first centerline, which is perpendicular to the other layer and passes through the center of the other layer. In a preferred embodiment of the 21st embodiment of the laminate, the second position is located 7 mm or less from the first centerline. In another preferred embodiment of the 21st embodiment of the laminate, the second position is located 5 mm or less from another centerline, which is perpendicular to the first centerline and passes through the center of the other layer.

[0139] In one preferred embodiment of the laminate, the first density variation, defined as ρT / ρM – 1, is in the range of 5 x 10⁻⁵ to 1.000 x 10⁻², more preferably 7 x 10⁻⁵ to 8.00 x 10⁻³, more preferably 1.0 x 10⁻⁴ to 6.00 x 10⁻³, and even more preferably 1.2 x 10⁻⁴ to 4.50 x 10⁻³.

[0140] This preferred embodiment of the present invention is the 22nd embodiment of the laminate, which is more preferably the 21st embodiment attached to the laminate.

[0141] In a preferred embodiment of the laminate, at least one or all of the following apply: a. The ρT value is in the range of 4.275 g / cm³ to 4.325 g / cm³, more preferably 4.285 g / cm³ to 4.315 g / cm³, and even more preferably 4.290 g / cm³ to 4.310 g / cm³; b. ρM is in the range of 4.262 g / cm3 to 4.322 g / cm3, more preferably 4.274 g / cm3 to 4.310 g / cm3, and even more preferably 4.282 g / cm3 to 4.302 g / cm3, with the constraint that ρT > ρM.

[0142] This preferred embodiment of the present invention is the 23rd embodiment of the laminate, which is preferably attached to any of the 21st to 22nd embodiments of the laminate. In one embodiment of the 23rd embodiment of the laminate, all possible combinations of features a. and b. are preferred embodiments of this embodiment. Such combinations are, for example, a; b; a+b.

[0143] In a preferred embodiment of the laminate, ρT > ρB, where ρB is the density measured at another location in the other layer, and the second location is closer to the first location than the other location.

[0144] This preferred embodiment of the present invention is the 24th embodiment of the laminate, which is preferably attached to any of the 21st to 23rd embodiments of the laminate. In one embodiment of the 24th embodiment of the laminate, the other layer has a first surface and another surface opposite to the first surface, wherein the first surface faces the first layer. In this embodiment, it is preferable that the other position is located closer to the other surface than the first position and the second position. In this embodiment, it is preferable that the other position is located at a distance of 5 mm or less from the other surface of the other layer. In one preferred embodiment of the 24th embodiment of the laminate, the other position is located at a distance of 7 mm or less from the first centerline.

[0145] In one preferred embodiment of the laminate, another density variation, defined as ρT / ρB – 1, is in the range of 5 x 10⁻⁵ to 1.000 x 10⁻², more preferably 7 x 10⁻⁵ to 8.00 x 10⁻³, more preferably 1.0 x 10⁻⁴ to 6.00 x 10⁻³, and even more preferably 1.2 x 10⁻⁴ to 4.50 x 10⁻³.

[0146] This preferred embodiment of the present invention is the 25th embodiment of the laminate, which is more preferably the 24th embodiment attached to the laminate.

[0147] In a preferred embodiment of the laminate, at least one or all of the following apply: a. The ratio ρM / ρB is in the range of 0.990 to 1.010, more preferably 0.995 to 1.005, and even more preferably 0.998 to 1.002; b. ρB is in the range of 4.262 g / cm3 to 4.322 g / cm3, more preferably 4.274 g / cm3 to 4.310 g / cm3, and even more preferably 4.282 g / cm3 to 4.302 g / cm3, with the constraint that ρT > ρB.

[0148] This preferred embodiment of the present invention is the 26th embodiment of the laminate, which is preferably attached to any of the 24th to 25th embodiments of the laminate. In one embodiment of the 26th embodiment of the laminate, all possible combinations of features a. and b. are preferred embodiments of this embodiment. Such combinations are, for example, a; b; a+b.

[0149] In one preferred embodiment of the laminate, the ratio of the thickness of the other layer to the thickness of the first layer is in the range of 0.5 to 15, more preferably 1 to 12, more preferably 2 to 9, and even more preferably 3 to 6.

[0150] This preferred embodiment of the present invention is the 27th embodiment of the laminate, which is preferably attached to any one of the 1st to 26th embodiments of the laminate. In one preferred embodiment of the 27th embodiment of the laminate, the ratio of the thickness of the other layer to the thickness of the first layer is in the range of 3 to 15, more preferably 6 to 15, even more preferably 7 to 14, and further preferably 8 to 13.

[0151] In a preferred embodiment of the laminate, at least one or all of the following apply: a. The first layer has a thickness in the range of 0.5 mm to 12 mm, preferably 1 mm to 10 mm, more preferably 2 mm to 8 mm, and even more preferably 4 mm to 5 mm; b. The other layer has a thickness in the range of 5 mm to 50 mm, preferably 15 mm to 40 mm, further preferably 20 mm to 35 mm, and even more preferably 25 mm to 30 mm.

[0152] This preferred embodiment of the present invention is the 28th embodiment of the laminate, which is preferably attached to any of the 1st to 27th embodiments of the laminate. In one embodiment of the 28th embodiment of the laminate, all possible combinations of features a. and b. are preferred embodiments of this embodiment. Such combinations are, for example, a; b; a+b. In this embodiment, the combination a+b is particularly preferred.

[0153] One embodiment of the present invention is an assembly comprising a multilayer (which in turn comprises a first layer), preferably an assembly comprising a multilayer according to the present invention, and more preferably an assembly comprising a multilayer according to any one of the first to 28 embodiments of the multilayer. This embodiment is the first embodiment of the assembly. In a preferred embodiment of the first embodiment of the assembly, the assembly is adapted and configured for the production of components and / or wafers in the semiconductor industry.

[0154] In one preferred embodiment of the assembly, the assembly is selected from the group consisting of: a plasma etcher, a plasma processing chamber (etching or deposition method), a wear-resistant liner for a bearing, a mill liner for a grinder, a dielectric window, an RF window, a focusing ring, a process ring, a deposition ring, a nozzle or gas injector, a spray head, a gas distribution plate, an etching chamber liner, a plasma source adapter, a gas inlet connector, a diffuser, an electrostatic wafer chuck (ESC), a chuck, a wafer, an ion suppressor element, a panel, an isolator, a spacer, a protective ring in the plasma processing chamber, or a combination of at least two of these.

[0155] This preferred embodiment of the invention is a second embodiment of the assembly, which is preferably attached to the first embodiment of the assembly. In a preferred embodiment of the second embodiment of the assembly, the assembly is a window, cover, chamber top, or combination thereof of a plasma etcher. In this embodiment, it is further preferred that the laminate includes a ZTA layer and a YAG layer.

[0156] An embodiment of the present invention is a device comprising an internal volume, the internal volume being defined by the following device components: i. The inner surface of the first punch; ii. The inner surface of the second punch; and iii. The inner surface of the mold; in: a. The first punch and the second punch are adapted and configured to apply a pressure of at least 1 MPa, preferably at least 5 MPa, more preferably at least 10 MPa, and even more preferably at least 15 MPa along the compression axis to the target material in the internal volume, preferably wherein the target material is at least one powder layer, such as a first powder layer; b. The first punch and the second punch are connected to a power source; c. Based on the total weight of the punches, the first punch and the second punch contain at least 50 wt% carbon; d. The internal volume has a cross-sectional width W of at least 200 mm, preferably at least 300 mm, more preferably at least 400 mm, and even more preferably at least 500 mm, wherein the cross-sectional width W is perpendicular to the compression axis.

[0157] This embodiment is the first embodiment of the device.

[0158] In one preferred embodiment of the present invention, at least one of the steps of the method according to any one of the first to 42 embodiments of the present invention is performed using the apparatus according to the first embodiment of the present invention.

[0159] One embodiment of the present invention relates to a density variation of another layer of a laminate used for at least one or all of the following purposes, wherein the laminate comprises a first layer and another layer: a. Increase the strength of the laminate; b. Reduce the defect rate of the laminate.

[0160] This embodiment is a first embodiment of the use of the present invention. In a preferred embodiment of this use, the laminated system is produced by sintering, more preferably by spark plasma sintering. In a preferred embodiment of this use, the laminate has a diameter of at least 200 mm, more preferably at least 300 mm, even more preferably at least 400 mm, and further preferably at least 500 mm. In this embodiment, the laminate preferably has a diameter in the range of 200 mm to 650 mm, more preferably 300 mm to 650 mm, even more preferably 400 mm to 650 mm, and further preferably 500 mm to 650 mm. In a preferred embodiment of this use, the first layer and the other layer are in contact with each other. In the first embodiment of this application, as given in the first to 42 embodiments of the method, the embodiments, preferred embodiments, and preferred states of the first layer and the other layer are also preferred embodiments and preferred states of the first layer and the other layer of the laminate of the first embodiment of this application. In one state of the first embodiment of this application, as given in the first to 28 embodiments of the laminate, the embodiments, preferred embodiments, and preferred states of the first layer and the other layer are also preferred embodiments and preferred states of the first layer and the other layer of the laminate of the first embodiment of this application. In one preferred state of the first embodiment of this application, the first layer comprises yttrium aluminum garnet (YAG). In one preferred state of the first embodiment of this application, the first layer contains at least 85 vol-%, more preferably at least 90 vol-%, even more preferably at least 95 vol-%, and further preferably at least 99 vol-% YAG based on the total volume of the first layer. In a preferred embodiment of the first embodiment of this application, the other layer comprises zirconia-toughened alumina (ZTA). In a preferred embodiment of the first embodiment of this application, the other layer comprises at least 85 vol-%, more preferably at least 90 vol-%, even more preferably at least 95 vol-%, and further preferably at least 99 vol-%, of ZTA based on the total volume of the first layer. In a preferred embodiment of the first embodiment of this application, the first layer has a thickness ranging from 0.5 mm to 12 mm, more preferably from 1 mm to 10 mm, even more preferably from 2 mm to 8 mm, and further preferably from 4 mm to 5 mm. In another preferred embodiment of the first embodiment of this application, the first layer has a thickness ranging from 1 mm to 8 mm, more preferably from 1 mm to 7 mm, and further preferably from 1 mm to 6 mm. In another preferred embodiment of the first embodiment of this use, the first layer has a thickness in the range of 2 mm to 7 mm, more preferably 2 mm to 6 mm, even more preferably 2 mm to 5 mm, and even more preferably 2 mm to 3 mm.In another preferred embodiment of the first embodiment of this application, the first layer has a thickness ranging from 3 mm to 7 mm, more preferably 3 mm to 6 mm, and even more preferably 4 mm to 5 mm. In one preferred embodiment of the first embodiment of this application, the other layer has a thickness ranging from 5 mm to 50 mm, more preferably 15 mm to 40 mm, even more preferably 20 mm to 35 mm, and even more preferably 25 mm to 30 mm. In yet another preferred embodiment of the first embodiment of this application, the other layer has a thickness ranging from 20 mm to 30 mm, more preferably 22 mm to 28 mm, and even more preferably 23 mm to 27 mm. Simple Explanation of the Diagram

[0161] Together with some illustrative figures, the following schematic diagrams show aspects of the invention intended to enhance understanding of the invention. Therefore, these figures should not be construed as limiting the invention. These figures are not drawn to scale. [Figure 1A] shows a cross-sectional side view of the device according to the present invention. [Figure 1B] shows a cross-sectional side view of the device of Figure 1A, in which the internal volume is loaded and ready for sintering. [Figure 2] is a flowchart showing the steps of the method for producing laminates according to the present invention. [Figure 3A] and [Figure 3B] show the core tests used in this paper. [Figure 4] shows how to measure the stationary angle of the powder. [Figure 5] shows how to measure the temperature of the sides and top of the laminate. [Figure 6] shows a schematic diagram of a laminate obtained by a method for producing laminates (according to the present invention). Implementation

[0162] Features described as preferred in one category of the invention (e.g., method) are similarly preferred in embodiments of other categories of the invention (e.g., apparatus). Preferred embodiments of the invention include: preferred embodiments of methods for producing laminates, preferred embodiments of laminates, preferred embodiments of assemblies, preferred embodiments of uses, and preferred embodiments of apparatuses.

[0163] In this document, the disclosure of a scope is preferably understood to include both endpoints of the scope. Furthermore, each disclosure of a scope in the document is preferably understood to also disclose a preferred sub-scope that excludes one endpoint or both endpoints. For example, the disclosure of a scope from X1 to X2 should be understood to disclose a scope that includes both endpoints X1 and X2. Additionally, it should also be understood to disclose a scope that includes endpoint X1 but excludes endpoint X2, a scope that excludes endpoint X1 but includes endpoint X2, and a scope that excludes both endpoints X1 and X2.

[0164] Some preferred embodiments and preferred models have various combinations of features as alternatives. Where these various combinations are disclosed, such combinations are separated by semicolons (";"). For example, a list of combinations of features "a; a+b; a+c+d" for preferred embodiments discloses preferred embodiments including feature "a", preferred embodiments including features "a" and "b", and preferred embodiments including features "a", "c", and "d".

[0165] The following abbreviations are used in this specification: AC (alternating current), DC (direct current), SPS (spark plasma sintering), RPM (revolutions per minute), YAG (yttrium aluminum garnet), and ZTA (zirconia toughened alumina).

[0166] "Spark plasma sintering" is also known as "field-assisted sintering technology" (FAST) and "direct current sintering" (DCS).

[0167] The term "powder" should be understood to refer collectively to both the first powder and the other powder (i.e., the first powder and the other powder are examples of powder). Therefore, the embodiments, preferred embodiments, and preferred states of the powder are respectively embodiments, preferred embodiments, and preferred states of the first powder. Similarly, the embodiments, preferred embodiments, and preferred states of the powder are respectively embodiments, preferred embodiments, and preferred states of another powder.

[0168] The term "purity" refers to the absence of various impurities in a) the starting material that can form a powder (e.g., component powder), b) the powder, and c) the laminate as disclosed herein. Higher purity, closer to 100%, indicates that the material is essentially free of impurities and contains only the intended material composition. A preferred intended material composition includes Y, Al, and O.

[0169] The term "impurity" refers to compounds / contaminants present in a) starting materials that can form powders (e.g., component powders), b) powders, and c) laminates as disclosed herein, other than the intended compounds themselves (e.g., component powders, powders, and laminates formed therefrom of magnesium oxide, aluminum oxide, yttrium oxide, and zirconium oxide). Impurities may be present in the starting materials or may be generated by processing (e.g., processing of component powders or powders) or during sintering.

[0170] The term "dopant" refers to a substance added to and / or to a component powder. An impurity differs from a dopant in that, as defined herein, a dopant is a substance intentionally added to a component powder and / or to achieve, for example, certain electrical, mechanical, optical, or other properties (such as grain size modification) in the laminate. As used herein, the term "dopant" does not include powder, provided that the powder can remain in the laminate.

[0171] The term "stabilizing compound" refers to a substance that is intentionally added to a powdered ingredient and / or powder. As defined herein, a stable compound should not be construed as an impurity.

[0172] The term "alumina" should be understood as referring to aluminum oxide, which has the chemical formula Al₂O₃. The term "yttrium oxide" should be understood as referring to yttrium oxide, which has the chemical formula Y₂O₃. The term "zirconia" should be understood as referring to zirconium dioxide, which has the chemical formula ZrO₂.

[0173] The term "calcination" should be understood as referring to the heat treatment of component powders and / or powders in air, which is used to, for example, remove moisture and / or impurities, increase crystallinity, and in some cases modify the specific surface area of ​​the powder.

[0174] The term "yttrium aluminum oxide" should be understood to refer to at least one of the crystal phases of yttrium aluminum oxide, including Y3Al5O12 (YAG; yttrium aluminum garnet / cubic phase), YAlO3 (YAP; yttrium aluminum perovskite phase), and Y4Al2O9 (YAM; yttrium aluminum monoclinic phase), and combinations thereof. YAG is preferably polycrystalline. Zirconia-toughened alumina (ZTA) should be understood to include at least two separate crystal phases of zirconium oxide and alumina.

[0175] The term "phase" should be understood as referring to the difference, crystal region, part or layer of a laminate with a specific crystal structure.

[0176] The term "layer" should be understood as referring to the thickness of a material, preferably one of several. The material can be, for example, powder or a region within a laminate.

[0177] An example of "target material in an internal volume" is one or more powder layers in an internal volume. An example of powder layers is a first powder layer and another powder layer.

[0178] The term "layered body" is preferably understood as a monolithic article formed by applying heat and pressure to one or more powder layers to create a monolithic body. Preferably, the layered system is formed by co-compacting at least two powder layers to create a monolithic body. The term "co-compacting" refers to the method of introducing at least two loose powders into an internal volume to form at least two powder layers, wherein the at least two powder layers are subsequently subjected to heat and pressure. The layered body according to the invention is preferably free of binders, dispersants, and other similar organic substances, as commonly found in the art for forming green bodies or bodies of a defined shape, or with desired properties. The layered body can be machined into components suitable for use as chamber components in plasma processing applications.

[0179] The term "unitary" should be understood as referring to a single workpiece or a single monolithic component that is complete in itself without any additional workpieces; that is, the component is a single workpiece formed as a unit. A monolithic component may have more than one layer.

[0180] The term "layered component" refers to a stacked body after a machining step, preferably one that produces the form or shape of a specific component for use in a semiconductor processing chamber.

[0181] The term "annealing" should be understood as referring to the heat treatment of a laminate in air, used for purposes such as stress relief and / or stoichiometry standardization.

[0182] The term "ambient temperature" refers to the temperature range of 22°C to 25°C. The term "ambient pressure" is better understood as atmospheric pressure.

[0183] As used in this article, the term "substantially" is a descriptive term that indicates an approximation and means "considerable in extent" or "largely but not wholly that which is specified," and is intended to avoid strict numerical boundaries for the specified parameter.

[0184] The terms "approximately" and "about" can vary by plus or minus 10% when used in conjunction with numbers. [ ] [device]

[0185] The apparatus according to the invention is adapted and configured for producing a laminate from at least one powder layer, preferably by sintering the at least one powder layer, and more preferably by spark plasma sintering. The apparatus according to the invention includes a mold, and preferably includes a first punch and a second punch.

[0186] The device according to the invention is preferably connected to a power source, wherein the power source is preferably a DC power source, and more preferably a rectified DC power source.

[0187] The apparatus according to the invention preferably comprises at least one or all of the following components: a housing, a vacuum device, a hydraulic piston, a foil liner on the inner surface of the mold, and a cooling system adapted and configured to cool the apparatus, preferably during the step of subjecting at least one powder layer to heat and pressure. The apparatus according to the invention preferably includes a sintering chamber adapted and configured to accommodate an internal volume (i.e., the sintering chamber is adapted and configured to accommodate the mold, a first punch, and a second punch).

[0188] The device according to the invention is preferably adapted and configured to apply an electrical power flux in the range of 0.05 W / mm² to 1.6 W / mm², more preferably 0.1 W / mm² to 1.3 W / mm², and even more preferably 0.3 W / mm² to 1 W / mm² to at least one or all of the following: the mold, the internal volume, the target material in the internal volume, and at least one punch. The electrical power flux is defined as the electrical power input Pw, which is calculated using the formula Pw = Iw*Vw / Aw, where Iw is the current supplied by the power source, Vw is the voltage applied across the mold, the internal volume, or both, and Aw is the surface area on which the voltage is applied.

[0189] The device according to the invention is adapted and configured to apply pressure to a target material in an internal volume, wherein the pressure is preferably applied along a compression axis. Preferably, the angle between the compression axis and the cross-sectional width W of the internal volume is in the range of 88° to 92°, more preferably 89° to 91°, and even more preferably in the range of 89.5° to 90.5°. [ ] [Internal volume]

[0190] The apparatus according to the invention includes an internal volume, wherein the internal volume is at least partially defined by the internal surface of the mold (i.e., the apparatus according to the invention includes a mold). Preferably, the internal volume is defined by the internal surface of the first punch of the first punch, the internal surface of the second punch of the second punch, and the internal surface of the mold (i.e., the apparatus includes a mold and preferably the first punch and the second punch). The internal volume may be defined solely by the internal surfaces of the first punch, the second punch, and the mold, or it may be additionally defined by one or more other surfaces. However, more preferably, the internal volume is defined solely by the internal surfaces of the first punch, the second punch, and the mold.

[0191] In a preferred embodiment of the invention, the mold is adjusted and configured to be removable from the device (i.e., the internal volume is removable from the device). In this embodiment, preferably, the first punch and / or the second punch are also adjusted and configured to be removable from the device.

[0192] According to the present invention, the internal volume is adapted and configured to accommodate at least one powder and / or at least one powder layer. Preferably, the internal volume is cylindrical. In a preferred embodiment of the invention, the cross-sectional width W of the internal volume is at least 300 mm, and more preferably at least 500 mm. The cross-sectional width W can reach a height of 2000 mm or greater. In a preferred embodiment of the invention, the cross-sectional width of the internal volume is not greater than 1500 mm, more preferably not greater than 900 mm, even more preferably not greater than 800 mm, further preferably not greater than 700 mm, and even more preferably not greater than 650 mm. In a preferred embodiment of the invention, the cross-sectional width W of the internal volume is preferably in the range of 200 mm to 650 mm, more preferably in the range of 300 mm to 650 mm, even more preferably in the range of 400 mm to 650 mm, and even more preferably in the range of 500 mm to 650 mm. In a preferred embodiment of the present invention, the cross-sectional width is in the range of 550 mm to 625 mm. [ ] [Mold]

[0193] The apparatus according to the invention includes a mold having an internal surface. Preferably, the mold is conductive. If the mold is conductive, it is preferably isotropic in conductivity.

[0194] The preferred mold contains one or more elements selected from Group 14 of the periodic table. Group 14 elements are sometimes also referred to as Group IVA elements or Group 4A elements. The mold preferably contains one or more elements selected from the group consisting of: C, Si, Ge, Sn, and Pb, more preferably selected from C, Si, Ge, and Sn, and even more preferably selected from C and Si. C-series elements are preferred Group 14 elements. By total weight of the mold, the preferred mold contains at least 50 wt%, more preferably at least 60 wt%, even more preferably at least 70 wt%, even more preferably at least 80 wt%, even more preferably at least 90 wt%, and even more preferably at least 95 wt% of Group 14 elements.

[0195] The preferred mold contains at least 50 wt%, more preferably at least 60 wt%, even more preferably at least 70 wt%, further preferably at least 80 wt%, further preferably at least 90 wt%, further preferably at least 95 wt%, and even more preferably at least 99 wt% carbon, wherein the wt% is based on the total weight of the mold. The preferred mold contains carbon in the form of graphite. The mold is preferably made of carbon material, most preferably graphite.

[0196] The preferred mold has at least one wall, wherein the wall contains at least 50 wt-%, preferably at least 60 wt-%, even more preferably at least 70 wt-%, further preferably at least 80 wt-%, further preferably at least 90 wt-%, further preferably at least 95 wt-%, and even more preferably at least 99 wt-%.

[0197] If the mold contains carbon, it may also contain one or more other Group 14 elements, preferably selected from Si, Ge, Sn, and Pb, even more preferably selected from Si, Ge, and Sn, further preferably selected from Si and Ge, and even more preferably Si. In addition to carbon, the other Group 14 elements are preferably also present in the mold, wherein the total content of the other Group 14 elements, based on the total weight of the mold, is at least 0.1 wt-%, more preferably at least 1 wt-%, and even more preferably at least 2 wt-%. Elements other than C, Si, Ge, Sn, and Pb may be present in the mold. If elements other than C, Si, Ge, Sn, and Pb are present in the mold, preferably, based on the total weight of the mold, these other elements are present in a total content of no more than 1 wt-%, more preferably no more than 0.5 wt-%, and even more preferably no more than 0.1 wt-%.

[0198] The mold can be a single piece or multiple pieces, preferably a single piece. More preferably, the mold is a single connected body, and even more preferably a single cylindrical body. If the mold has multiple pieces, it is preferable to have 2 to 10 pieces, more preferably 2 to 5 pieces, even more preferably 2 to 3 pieces, and even more preferably 2 pieces. [ ] [Punch]

[0199] The apparatus according to the present invention preferably includes a first punch and a second punch. The first punch preferably has an inner surface. The inner surface of the first punch is preferably substantially perpendicular to the inner surface of the mold. The inner surface of the first punch is preferably the lower surface of the first punch. The inner surface of the first punch is preferably substantially horizontal. The inner surface of the first punch is preferably substantially flat. The second punch preferably has an inner surface. The inner surface of the second punch is preferably substantially perpendicular to the inner surface of the mold. The inner surface of the second punch is preferably the upper surface of the second punch. The inner surface of the second punch is preferably substantially horizontal. The inner surface of the second punch is preferably substantially flat. The first punch is preferably disposed above the second punch. The first punch and the second punch are preferably vertically positioned above and below the internal volume, respectively.

[0200] The first and second punches are preferably adapted and configured to apply pressure to the target within the internal volume, and more preferably to generate increased pressure within the internal volume. The first and second punches are preferably adapted and configured to apply pressure along a compression axis. Preferably, the compression axis is substantially perpendicular to the internal surface of the first punch and / or the internal surface of the second punch. The first and / or second punches are preferably adapted and configured to be movable along the compression axis.

[0201] The first and second punches are preferably adjusted and configured to apply pressure of at least 1 MPa, more preferably at least 5 MPa, even more preferably at least 10 MPa, and even more preferably at least 15 MPa to the target material in the internal volume. The first and second punches can be adjusted and configured to apply pressure of up to 80 MPa or even more. The first and second punches are preferably adapted and configured to apply pressure to the target material in the internal volume, wherein the pressure is in the range of 1 MPa to 100 MPa, more preferably 5 MPa to 60 MPa, even more preferably 5 MPa to 45 MPa, further preferably 5 MPa to 30 MPa, and even more preferably in the range of 5 MPa to 15 MPa; preferably 10 MPa to 60 MPa, more preferably 10 MPa to 45 MPa, even more preferably 10 MPa to 30 MPa, and even more preferably in the range of 10 MPa to 15 MPa; preferably 15 MPa to 60 MPa, more preferably 15 MPa to 45 MPa, even more preferably 15 MPa to 30 MPa, and even more preferably in the range of 15 MPa to 20 MPa.

[0202] The first and second punches are preferably conductive. The first and second punches are preferably adapted and configured to allow a current of at least 5 kA, more preferably at least 10 kA, even more preferably at least 50 kA, and further preferably at least 60 kA across the internal volume. The first and second punches can be adapted and configured to allow a current of up to 100 kA or even more.

[0203] The first and second punches are preferably made of carbon material, and most preferably of graphite. Based on the total weight of the first and second punches, the dies preferably contain at least 50 wt%, more preferably at least 60 wt%, even more preferably at least 70 wt%, further preferably at least 80 wt%, further preferably at least 90 wt%, further preferably at least 95 wt%, further preferably at least 99 wt%, and even more preferably at least 99.5 wt% carbon.

[0204] The first and second punches preferably have a cross-sectional width equal to or less than the cross-sectional width W of the internal volume. More preferably, the first and second punches have a cross-sectional width that is smaller than the cross-sectional width W of the internal volume by 10 µm to 200 µm, even more preferably by 30 µm to 150 µm, and even more preferably by 50 µm to 100 µm. [ ] [power supply]

[0205] The power supply is preferably adapted and configured to generate Joule heating in the powder layer present in the internal volume. The power supply can be adapted and configured to generate alternating current, pulsed direct current, or continuous direct current. Continuous direct current is preferred.

[0206] In a preferred embodiment of the invention, the power supply is a rectified DC power supply. A rectified DC power supply is preferably understood to mean a power supply adapted and configured to convert alternating current (AC) to direct current (DC). Examples of rectified DC power supplies are those adapted and configured to perform partial-wave rectification, full-wave rectification (e.g., bridge rectifier), or both. Preferred rectified DC power supplies include silicon-controlled rectifiers (SCRs), insulated-gate bipolar transistors (IGBTs) based converters, or both. Here, IGBT transistors are preferred over SCR rectifiers.

[0207] In one preferred embodiment of the present invention, the power supply system is adapted and configured to perform one or more of the following: rectifying three-phase AC power into DC power; rectifying single-phase AC power into DC power.

[0208] The power supply is preferably adjusted and configured to provide a current of at least 5 kA, more preferably at least 10 kA, even more preferably at least 50 kA, further preferably at least 60 kA, and even more preferably at least 100 kA. The power supply is preferably adjusted and configured to provide a current in the range of 1 kA to 100 kA, more preferably 5 kA to 90 kA, more preferably 10 kA to 80 kA, even more preferably 15 kA to 70 kA, and even more preferably 20 kA to 60 kA; the power supply can be adjusted and configured to provide a current greater than 100 kA. [ ] [Types of contact]

[0209] If two components of the device are in electrical contact, this should preferably be understood as meaning that current can flow between the two components. If two elements are in physical contact, this should preferably be understood as meaning that the two elements touch each other. Examples of two elements include two components of the device, two powder layers (e.g., the first powder layer and another powder layer) within the internal volume of the device, and two layers of the laminate (e.g., the first layer and another layer). [ ] [powder]

[0210] The powder may consist of a single component powder or a mixture of at least two component powders. If the powder contains or is composed of a certain number (e.g., one or two) component powders, this should preferably not be construed as meaning that (one or more) component powders contain / do not contain, for example, impurities, stabilizing compounds, sintering aids, and dopants.

[0211] If the powder is a mixture of at least two component powders, it is preferable to mix these component powders before subjecting the powder to heat and pressure in an internal volume. If the powder is a mixture of at least two component powders, it is preferable to understand that at least one different property exists between the at least two component powders. Examples of at least one property include average particle size, specific surface area, and chemical composition. In one particularly preferred embodiment of the invention, the at least two component powders have different chemical compositions.

[0212] In this invention, the terms "first component powder" and "other component powder" are used to distinguish two component powders in the context of a mixture constituting a particular powder. For example, the first component powder of the first powder and the first component powder of the other powder may or may not have the same chemical composition. For example, the first component powder of the first powder and the other component powder of the other powder may or may not have the same chemical composition. For example, the other component powder of the first powder and the other component powder of the other powder may or may not have the same chemical composition. For example, the other component powder of the first powder and the first component powder of the other powder may or may not have the same chemical composition. The foregoing should preferably also be understood to apply to any powder, including mixtures of another powder and at least two component powders.

[0213] The first powder may consist of a single-component powder. However, more preferably, the first powder is a mixture of at least two, and more preferably, two-component powders. The other powder may consist of a single-component powder. However, more preferably, the other powder is a mixture of at least two-component powders.

[0214] In a preferred embodiment of the present invention, the first powder is polycrystalline or crystalline. In a preferred embodiment of the present invention, the other powder is polycrystalline or crystalline. Crystalline powder should preferably be understood as having a single-crystal structure.

[0215] Another powder may consist of a single-component powder. However, more preferably, the other powder is a mixture of at least three component powders. In a preferred embodiment of the invention, the other powder is a mixture of yttrium oxide powder, alumina powder, and at least one of partially stabilized and stabilized zirconium oxide (preferably partially stabilized zirconium oxide). In this embodiment, relative to the weight of the other powder, it is preferred that the other powder contains 1% to 57% by weight, more preferably 3% to 57% by weight, and even more preferably 5% to 57% by weight of yttrium oxide. In this embodiment, relative to the weight of the other powder, it is preferred that the other powder contains 1% to 40% by weight, more preferably 1% to 30% by weight, even more preferably 3% to 30% by weight, even more preferably 5% to 30% by weight, and even more preferably 5% to 15% by weight of yttrium oxide. In this sample, relative to the weight of the other powder, it is preferable that the other powder contains 43% to 92.5% by weight, and more preferably 65% ​​to 75% by weight of alumina. In this sample, relative to the weight of the other powder, it is preferable that the other powder contains 0.4% to 40% by weight, more preferably 4% to 40% by weight, even more preferably 15% to 40% by weight, and even more preferably 15% to 25% by weight of zirconium oxide. For example, relative to the weight of the other powder, the other powder contains 6% by weight of yttrium oxide, 73% by weight of alumina, and 21% by weight of zirconium oxide.

[0216] The preferred zirconium oxide powder may contain stabilizing compounds, which include at least one selected from the group consisting of: yttrium oxide, lanthanum oxide (La₂O₃), cerium oxide, magnesium oxide, samarium oxide (Sm₂O₃), calcium oxide, and combinations thereof. To form partially stabilized zirconium oxide, these stabilizing compounds may each be present in an amount of 0.5 mol-% to 50 mol-%, preferably 0.5 mol-% to 30 mol-%, preferably 0.5 mol-% to 15 mol-%, preferably 0.5 mol-% to 10 mol-%, preferably 1 mol-% to 50 mol-%, preferably 1 mol-% to 30 mol-%, preferably 1 mol-% to 10 mol-%, preferably 1 mol-% to 5 mol-%, and most preferably about 3 mol-%. In order to form stable zirconium oxide, these stabilizing compounds may each be present in an amount greater than 6 mol-% to 45 mol-%, preferably greater than 10 mol-% to 45 mol-%, preferably greater than 25 mol-% to 45 mol-%, preferably greater than 6 mol-% to 30 mol-%, preferably greater than 6 mol-% to about 15 mol-%, preferably greater than 8 mol-% to 15 mol-%.

[0217] Preferably, zirconia is partially or completely stabilized using yttrium oxide. More preferably, the zirconia is partially or completely stabilized by yttrium oxide. Partially stabilized yttrium oxide zirconia can be formed from a powder mixture containing 1 mol% to 10 mol% yttrium oxide, more preferably 1 mol% to 8 mol% yttrium oxide, more preferably 1 mol% to 5 mol% yttrium oxide, more preferably 2 mol% to 4 mol% yttrium oxide, and more preferably about 3 mol% yttrium oxide.

[0218] In one preferred embodiment of the present invention, the first powder and / or the other powder has a specific surface area (SSA) in the range of 1 m² / g to 18 m² / g, preferably 1 m² / g to 14 m² / g, preferably 1 m² / g to 10 m² / g, preferably 1 m² / g to 8 m² / g, preferably 2 m² / g to 18 m² / g, preferably 2 m² / g to 14 m² / g, preferably 2 m² / g to 10 m² / g, preferably 3 m² / g to 9 m² / g, preferably 3 m² / g to 6 m² / g.

[0219] The powder may contain at least one metal oxide. The constituent powder may be a metal oxide. Here, the metal element forming the oxide may be selected from one, two or more of the following: metalloid elements, such as boron (B), silicon (Si), germanium (Ge), antimony (Sb), and bismuth (Bi); representative elements, such as magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), aluminum (Al), indium (In), and tin (Sn); transition metal elements, such as scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (M), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), silver (Ag), and gold (Au); and lanthanides, such as lanthanum (La), cerium (Ce), pium (Pr), neodymium (Nd), samarium (Sm), europium (Er), and ilium (Lu). Preferably, the metallic element is selected from Mg, Y, Ti, Zr, Cr, Mn, Fe, Zn, Al, and Er, and more preferably from one or more elements selected from Y, Al, and Zr.

[0220] In a preferred embodiment of the invention, the powder has a d10 particle size in the range of 0.1 µm to 4 µm, more preferably 0.2 µm to 4 µm, more preferably 0.3 µm to 4 µm, and even more preferably 0.4 µm to 4 µm. In another preferred embodiment of the invention, the powder has a d10 particle size in the range of 0.1 µm to 3 µm, more preferably 0.1 µm to 2 µm, even more preferably 0.1 µm to 3 µm, even more preferably 0.1 µm to 2 µm, and even even more preferably 0.1 µm to 1 µm. In the preferred embodiment of the invention, at least one or all of the d10 particle sizes mentioned above are applicable after the powder has been heat-treated (e.g., calcined).

[0221] In a preferred embodiment of the present invention, the powder has a d50 particle size in the range of 3 µm to 50 µm, more preferably 3 µm to 40 µm, more preferably 3 µm to 30 µm, even more preferably 3 µm to 20 µm, further preferably 3 µm to 10 µm, and even more preferably 3 µm to 8 µm. In another preferred embodiment of the present invention, the powder has a d50 particle size in the range of 5 µm to 50 µm, more preferably 10 µm to 50 µm, even more preferably 20 µm to 50 µm, and even more preferably 30 µm to 50 µm. In yet another preferred embodiment of the present invention, the powder has a d50 particle size in the range of 5 µm to 10 µm. In a further preferred embodiment of the present invention, the powder has a d50 particle size in the range of 6 µm to 15 µm. In one preferred embodiment of the invention, at least one or all of the d50 particle sizes mentioned above are used after the powder has been heat-treated (e.g., calcined).

[0222] In a preferred embodiment of the present invention, the powder has a d90 particle size in the range of 10 µm to 350 µm, more preferably 10 µm to 300 µm, more preferably 10 µm to 250 µm, even more preferably 10 µm to 200 µm, further preferably 10 µm to 175 µm, further preferably 10 µm to 150 µm, further preferably 10 µm to 100 µm, further preferably 10 µm to 75 µm, further preferably 10 µm to 50 µm, further preferably 10 µm to 40 µm, and even more preferably 10 µm to 25 µm. In another preferred embodiment of the invention, the powder has a d90 particle size in the range of 20 µm to 350 µm, more preferably 40 µm to 350 µm, even more preferably 60 µm to 350 µm, further preferably 100 µm to 350 µm, even more preferably 150 µm to 350 µm, and even more preferably 200 µm to 350 µm. In yet another preferred embodiment of the invention, the powder has a d90 particle size in the range of 12 µm to 330 µm, more preferably 100 µm to 330 µm, and even more preferably 100 µm to 250 µm. In one preferred embodiment of the invention, at least one or all of the d90 particle sizes mentioned above are applicable after the powder has been heat-treated (e.g., calcined).

[0223] In a preferred embodiment of the present invention, the first powder has a purity of at least 95%, more preferably at least 97%, more preferably at least 99%, even more preferably at least 99.99%, further preferably at least 99.999%, and even further preferably at least 99.9999%.

[0224] Any powder that is considered suitable for this invention by one of ordinary skill in the art can be used. Suitable powders are well known and are available from several suppliers. [ ] [The components of the first powder]

[0225] In a preferred embodiment of the present invention, the first powder is a mixture comprising at least two component powders. In one preferred embodiment of the present invention, the first powder is a mixture of yttrium oxide powder and alumina powder. In this embodiment, preferably, the first powder is a stoichiometric mixture of 37.4 mol-% to 37.6 mol-% yttrium oxide and 62.6% mol and 62.4% mol alumina, and more preferably, 37.5 mol-% yttrium oxide and 62.5 mol-% alumina. By weight, the first powder can be formed from a mixture of about 42.9% to 43.4% alumina and 56.6% to 57.1% yttrium oxide. In this embodiment, the first component powder of the first powder is preferably yttrium oxide powder. In this embodiment, the other component powder of the first powder is preferably alumina powder.

[0226] In one preferred embodiment of the present invention, the first component powder of the first powder (e.g., yttrium oxide) has a specific surface area in the range of 0.1 m² / g to 8 m² / g, more preferably 0.5 m² / g to 7 m² / g, even more preferably 1 m² / g to 6 m² / g, and even more preferably 1.5 m² / g to 4 m² / g.

[0227] In one preferred embodiment of the invention, another component powder of the first powder (e.g., alumina) has a specific surface area in the range of 1 m² / g to 16 m² / g, more preferably 2 m² / g to 14 m² / g, even more preferably 4 m² / g to 12 m² / g, and even more preferably 6 m² / g to 10 m² / g.

[0228] In another preferred embodiment of the present invention, the first powder and / or component powder is YAG powder. In this embodiment, preferably, the YAG powder has a d50 particle size in the range of 3 µm to 10 µm, more preferably 4 µm to 9 µm, and even more preferably 5 µm to 8 µm.

[0229] In one preferred embodiment of the present invention, the first component powder of the first powder has a purity of at least 95%, preferably at least 97%, more preferably at least 99%, even more preferably at least 99.99%, further preferably at least 99.999%, and even more preferably at least 99.9999%. In another preferred embodiment of the present invention, the other component powder of the first powder has a purity of at least 95%, preferably at least 97%, more preferably at least 99%, even more preferably at least 99.99%, further preferably at least 99.999%, and even more preferably at least 99.9999%.

[0230] If the first powder comprises at least two component powders, any component powder that is considered suitable for the present invention by one of ordinary skill in the art can be used. Suitable component powders are well known and are available from several suppliers. [ ] [The other powder's components]

[0231] In one preferred embodiment of the invention, the other powder is a mixture comprising at least two component powders. In one preferred embodiment of the invention, the other powder is a mixture of alumina powder and at least one of partially stabilized and stabilized zirconia (preferably partially stabilized zirconia). In this embodiment, preferably, the other powder comprises 60% to 92.5% by weight, and more preferably 75% to 85% by weight, of alumina relative to the weight of the other powder. In this embodiment, preferably, the other powder comprises 7.5% to 40% by weight, and more preferably 15% to 25% by weight, of zirconia relative to the weight of the other powder. For example, the other powder is a mixture of 77% alumina and 23% zirconia. In this embodiment, the first component powder of the other powder is preferably zirconia powder, more preferably comprising at least one or all of the following: partially stabilized zirconia and stabilized zirconia, wherein partially stabilized zirconia is preferred. In this sample, the other component of the powder is preferably alumina powder.

[0232] In one preferred embodiment of the present invention, the first component powder of the other powder (e.g., zirconium oxide) has a specific surface area in the range of 1 m² / g to 16 m² / g, more preferably 2 m² / g to 14 m² / g, even more preferably 4 m² / g to 12 m² / g, and even more preferably 6 m² / g to 10 m² / g.

[0233] In one preferred embodiment of the invention, another component powder of another powder (e.g., alumina) has a specific surface area in the range of 1 m² / g to 16 m² / g, more preferably 2 m² / g to 14 m² / g, even more preferably 4 m² / g to 12 m² / g, and even more preferably 6 m² / g to 10 m² / g.

[0234] If the other powder comprises at least two component powders, any component powder that is considered suitable for the present invention by one of ordinary skill in the art can be used. Suitable component powders are well known and are available from several suppliers. [ ] [Heat Treatment of Powder]

[0235] In one embodiment of the invention, preferably, at least one powder and / or at least one component powder (used in a method for producing a laminate) is subjected to heat treatment (here, at least one powder is, for example, a first powder and another powder; here, at least one component powder is, for example, a first component powder of a first powder, another component powder of a first powder, a first component powder of another powder, and another component powder of another powder). In this embodiment, preferably, the at least one powder is subjected to heat and pressure within the internal volume of the apparatus. In this embodiment, preferably, the at least one powder is subjected to heat treatment before being introduced into the internal volume of the apparatus. In another preferred embodiment of the invention, the at least one component powder is subjected to heat treatment before being mixed to form a powder.

[0236] The preferred heat treatment for powders is calcination. The preferred heat treatment for component powders is calcination.

[0237] Heat treatment of powders and / or component powders is preferably performed in an oxygen-containing environment under ambient pressure, but other pressures and calcination environments may also be used. The preferred oxygen-containing environment is an ambient atmosphere.

[0238] The heat treatment of powders and / or component powders is preferably performed at a temperature in the range of 600°C to 1100°C, more preferably 600°C to 1000°C, and even more preferably 600°C to 900°C. The heat treatment of powders and / or component powders is preferably performed at a temperature in the range of 700°C to 1100°C, more preferably 800°C to 1100°C, even more preferably 800°C to 1000°C, and even more preferably 850°C to 950°C.

[0239] The heat treatment of powders and / or component powders preferably has a duration in the range of 4 to 12 hours, more preferably 4 to 10 hours, even more preferably 4 to 8 hours, and even more preferably 4 to 6 hours. Alternatively, the heat treatment of powders and / or component powders preferably has a duration in the range of 6 to 12 hours.

[0240] Heat treatment of powders and / or component powders is preferably performed in a container (e.g., a crucible and a kiln) containing a first cavity.

[0241] Any container that is deemed suitable by one of ordinary skill in the art can be used for the heat treatment of powders and / or component powders. Such containers are well known to those of ordinary skill in the art. An example of a suitable container is the VIK283 kiln, available from Paragon Industries, LP (Mesquite, Texas, USA). [ ] [Mixing and Grinding]

[0242] If the powder (e.g., a first powder and another powder) is a mixture of at least two component powders (e.g., a first component powder and another component powder), the mixing of the at least two component powders can be performed using at least one or all of the following: wet ball milling, dry ball milling, wet tumbling mixing, dry tumbling mixing, jet milling, or a combination of at least two of these. Preferred ball milling uses axial rotation to mix the at least two component powders. Preferred tumbling mixing uses end-over-end or vertical rotation to mix the at least two component powders. The at least two component powders are mixed in a volumetric section (such as a container or drum).

[0243] Ball milling (dry ball milling, wet ball milling) and / or rotary mixing (dry rotary mixing, wet rotary mixing) preferably uses high-purity (> 99.99%) alumina media (also referred to herein as a stirring means). In other cases where agglomeration may be a concern, harder media, such as zirconium oxide, are preferred. The media loading for ball milling and / or rotary mixing may vary between large-sized (approximately 30 mm) media elements and media loadings of approximately 50% by weight of the powder.

[0244] Dry ball milling and / or dry rotary mixing are preferably performed for a duration of 12 to 48 hours, more preferably 16 to 48 hours, and even more preferably 24 to 48 hours. Dry ball milling and / or dry rotary mixing are preferably performed in a volumetric section that rotates at a rate of 50 to 200 RPM, more preferably 75 to 150 RPM, and even more preferably 100 to 125 RPM.

[0245] Wet ball milling and / or wet rotary mixing are preferably performed by suspending at least two component powders in at least one solvent and / or water to form a slurry. Preferred solvents are alcohols, such as ethanol and methanol. Ethanol is particularly preferred. The slurry can be formed to have a powder loading of preferably 5% to 50% by weight of the powder, more preferably 10% to 40% by weight of the powder, and even more preferably 20% to 40% by weight of the powder during milling and / or mixing. When wet ball milling and / or wet rotary mixing are used, any number of commercially available dispersants, such as, for example, polymethyl methacrylate (PMMA) and polyvinyl pyrrolidone (PVP), can optionally be added to the slurry. Optionally, a dispersant amount from zero (no dispersant) to 0.2% by weight of the powder, and optionally from 0 to 0.1% by weight of the powder, can be added. The media loading can vary from no media used during wet ball milling to 50% by weight of powder and higher, more preferably from 40% by weight to 90% by weight, and even more preferably from 50% by weight to 80% by weight. Wet ball milling and / or wet rolling mixing are preferably performed for a duration of 8 to 48 hours, more preferably 12 to 48 hours, and even more preferably 16 to 48 hours. Wet ball milling and / or wet rolling mixing are preferably performed for a duration of 8 to 36 hours, more preferably 8 to 24 hours, and even more preferably 8 to 12 hours. Wet ball milling is preferably performed in a volumetric section rotating at a rate ranging from 50 to 200 RPM, more preferably 75 to 150 RPM, and even more preferably 100 to 125 RPM. The RPM value is preferably for a volumetric section with a diameter of up to 200 mm. Wet rolling mixing is preferably performed at 10 to 30 RPM, and more preferably 15 to 25 RPM.

[0246] Jet milling methods, well known to those skilled in the art, can also be used to mix at least two component powders to form a powder. Jet milling uses a high-speed jet of inert gas and / or air to cause particle collisions between at least two component powders without the use of a grinding or mixing media. The volumetric section can be designed so that larger particles can preferentially decrease in size, which can provide a narrow particle size distribution in the powder. Preferably, the powder exits the volumetric section when it reaches the desired particle size determined at the time of setting the jet mill before mixing.

[0247] At least two component powders and / or powders may be subjected to jet milling at a pressure of about 100 psi, whether alone or in combination with any or all of the powder milling / mixing methods disclosed herein. After jet milling, the powders may optionally be sieved and / or blended using any number of sieves (which may have openings of, for example, 45 μm to 400 μm), but there is no limitation on the repetition or sequence.

[0248] Any apparatus that is considered suitable for mixing and / or grinding by one of ordinary skill in the art may be used. Such apparatus is well known. An example is a wet rotary mixer, such as the Morse Manufacturing Company, Inc. (Syracuse, New York, USA) 309-E3 55-gallon drum mixer. [ ] [Introducing powder into the internal volume]

[0249] In a preferred embodiment of the invention, when powder is introduced into the internal volume, the powder is introduced simultaneously with the removal of the internal volume from the apparatus (i.e., removal of the mold, the first punch, and the second punch from the apparatus). Here, "removed" is preferably understood to mean that the internal volume is located outside the apparatus, for example, outside the sintering chamber of the apparatus. In another preferred embodiment of the invention, after the powder is introduced into the internal volume, the powder is dispersed to form a powder layer. In yet another preferred embodiment of the invention, when one or more (more preferably all) powder layers are present in the internal volume, the internal volume is placed within the apparatus, more preferably within the sintering chamber of the apparatus (i.e., the mold, the first punch, and the second punch are placed within the sintering chamber of the apparatus). [ ] [Powder Layer]

[0250] In one preferred embodiment of the present invention, the first powder and the first powder layer preferably have the same chemical composition. In one preferred embodiment of the present invention, the first powder layer comprises at least 75 wt%, more preferably at least 85 wt%, even more preferably at least 95 wt%, and further preferably at least 99 wt% of the first powder, based on the total weight of the first powder layer. In one preferred embodiment of the present invention, the first powder layer is composed of the first powder.

[0251] In one preferred embodiment of the present invention, the other powder and the other powder layer preferably have the same chemical composition. In one preferred embodiment of the present invention, the other powder layer contains at least 75 wt%, more preferably at least 85 wt%, even more preferably at least 95 wt%, and further preferably at least 99 wt% of the other powder, based on the total weight of the other powder layer. In one preferred embodiment of the present invention, the other powder layer is composed of the other powder. [ ] [Oxide A] [and B]

[0252] The terms "oxide A" and "oxide B" are used to distinguish these oxides and to indicate oxides that have one or more of the properties indicated below.

[0253] Oxide A comprises at least 1 mol-% of a Group 3 (formerly Group IIIB) element (preferably yttrium) and at least 1 mol-% of a Group 13 (formerly Group IIIA) element (preferably aluminum), wherein mol-% refers to oxygen in oxide A. Preferably, oxide A is a cubic phase of yttrium aluminum oxide, more preferably YAG. In one preferred embodiment of the invention, oxide A comprises at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-% of a Group 3 (formerly Group IIIB) element. In one preferred embodiment of the invention, oxide A comprises at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-% of a Group 13 (formerly Group IIIA) element. Particularly preferred is that the first oxide as used herein is oxide A.

[0254] Oxide B comprises at least 1 mol-% of a Group 4 (formerly Group IVB) element (preferably zirconium) and at least 1 mol-% of a Group 13 (formerly Group IIIA) element (preferably aluminum), wherein the mol-% is expressed as oxygen in oxide B. Preferably, oxide B is ZTA. In one preferred embodiment of the invention, oxide B comprises at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-% of a Group 4 (formerly Group IVB) element. In one preferred embodiment of the invention, oxide B comprises at least 3 mol-%, more preferably at least 5 mol-%, and even more preferably at least 7 mol-% of a Group 13 (formerly Group IIIA) element. Particularly preferred is another oxide system, as used herein, oxide B. [ ] [Methods for producing laminates]

[0255] One aspect of this invention relates to a method for producing laminates. In this aspect, a preferred method is a sintering method, more preferably a spark plasma sintering method. The preferred spark plasma sintering method produces laminates by applying heat and pressure to at least one powder layer. The heat is preferably obtained by using an electric current.

[0256] A preferred method for producing laminates is to increase the density of at least one powder layer to produce laminates.

[0257] A preferred method for producing multilayers may employ dopants. As used herein, the term "dopant" refers to a substance added to powders and / or multilayers to produce desired properties (e.g., altered electrical properties) in the multilayer. If one or more dopants are used, it is preferred that the powders and / or multilayers contain the one or more dopants in amounts ranging from 0.002 wt% to < 0.05 wt%, more preferably from 0.0035 wt% to 0.02 wt%, and even more preferably from 0.0075 wt% to 0.01 wt%. Examples of dopants include Sc, La, Er, Ce, Cr, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb, Lu, Zr, and oxides and combinations thereof.

[0258] A preferred method for producing laminates does not employ sintering aids. As used herein, the term "sintering aid" refers to compounds such as silicon dioxide (SiO2), lithium oxide (Li2O), lithium fluoride (LiF), magnesium oxide (MgO), and / or calcium oxide (CaO), which are added to powders to enhance densification during the production of laminates, thereby reducing porosity. If sintering aids are used, it is preferable that the powder contains 5 ppm or less, and more preferably 2 ppm or less of the sintering aid. [ ] [Application of heat and pressure]

[0259] In this embodiment of the invention, subjecting the first powder layer in the internal volume and / or any other powder layer present in the internal volume to heat and pressure results in a laminate. Preferably, it should be understood that the laminate typically begins to form before the step of subjecting the first powder layer to heat and pressure is completed (e.g., a partially formed or formed laminate may be present in the internal volume during the step of subjecting the first powder layer to heat and pressure). Therefore, the step of subjecting the first powder layer to heat and pressure preferably further includes subjecting at least one or all of the following to heat and pressure: a partially formed laminate (in the internal volume), a formed laminate (in the internal volume). The step of subjecting the first powder layer to heat and pressure is preferably terminated by removing the voltage applied across the mold, the internal volume, or both.

[0260] During the steps of applying heat and pressure to a first powder layer and another powder layer in the internal volume, and / or any other powder layer present in the internal volume, the order of applying heat and pressure may vary to obtain the desired pressure and temperature for producing the laminate, as disclosed herein. In one embodiment of the invention, preferably, pressure is applied to obtain the desired pressure for producing the laminate, and then heat is applied to obtain the desired temperature for producing the laminate. In another embodiment of the invention, preferably, heat is applied to obtain the desired temperature for producing the laminate, and then pressure is applied to obtain the desired pressure for producing the laminate. In yet another embodiment of the invention, preferably, heat and pressure are applied at least partially simultaneously, and more preferably simultaneously, to obtain the desired temperature and pressure for producing the laminate. In yet another embodiment of the invention, the step of applying heat and pressure may comprise at least two sub-steps, wherein the at least two sub-steps are distinguished from each other by a change in the temperature of the applied heat and / or pressure.

[0261] In one embodiment of the invention, preferably, the first powder layer and the other powder layer in the internal volume, as well as any other powder layer present in the internal volume, are heated by a mold, a punch, or both. In this embodiment, preferably, the heating is accomplished via a mold and a punch.

[0262] Applying heat and pressure to a powder layer results in the formation of a laminate. For example, applying heat and pressure to a first powder layer and another powder layer results in the formation of a first layer and another layer of the laminate, respectively.

[0263] In a preferred embodiment of the present invention, the steps of applying heat and pressure are performed for a duration of 4 to 20 hours, more preferably 6 to 16 hours, even more preferably 8 to 14 hours, and even more preferably 10 to 12 hours.

[0264] In one preferred embodiment of the invention, during the step of applying heat and pressure, the duration of applying maximum temperature and pressure is 0.5 to 180 minutes, more preferably 0.5 to 120 minutes, even more preferably 0.5 to 100 minutes, further preferably 0.5 to 80 minutes, further preferably 0.5 to 60 minutes, further preferably 0.5 to 40 minutes, further preferably 0.5 to 20 minutes, further preferably 0.5 to 10 minutes, and even more preferably 0.5 to 5 minutes. In another preferred embodiment of the invention, during the step of applying heat and pressure, the duration of applying maximum temperature and pressure is 5 to 120 minutes, more preferably 10 to 120 minutes, even more preferably 20 to 120 minutes, further preferably 40 to 120 minutes, further preferably 60 to 120 minutes, and even more preferably 100 to 120 minutes. In one preferred embodiment of the invention, the maximum temperature and pressure are applied for a duration of 30 to 90 minutes during the step of applying heat and pressure.

[0265] In one preferred embodiment of the invention, during the step of subjecting the first powder layer and another powder layer, and / or any other powder layer present in the internal volume to heat and pressure, the maximum temperature in the internal volume is between 900°C and 2000°C, preferably between 950°C and 1900°C, more preferably between 1000°C and 1800°C, and even more preferably between 1050°C and 1700°C; more preferably between 1000°C and 1700°C, more preferably between 1100°C and 1700°C, even more preferably between 1200°C and 1700°C, even more preferably between 1300°C and 1700°C, and even even more preferably between 1400°C and 1700°C.

[0266] In a preferred embodiment S1 of the present invention, the step of applying heat and pressure to a first powder layer and another powder layer, and / or any other powder layer present in the internal volume, comprises a first sub-step SRAMP and a second sub-step SSINT. In this embodiment S1, preferably, during the first sub-step SRAMP, the temperature in the internal volume increases at a rate ranging from 1°C / min to 100°C / min, more preferably from 2°C / min to 50°C / min, even more preferably from 3°C / min to 25°C / min, further preferably from 3°C / min to 10°C / min, and even more preferably from 5°C / min to 10°C / min. In this embodiment S1, preferably, the maximum temperature during the first sub-step SRAMP is in the range of 900°C to 1300°C. In this sample S1, preferably, during the other sub-step SSINT, the temperature in the internal volume increases at a rate ranging from 0.5°C / min to 5°C / min, more preferably from 1°C / min to 4°C / min, and even more preferably from 1.5°C / min to 3°C / min. In this sample S1, preferably, during the other sub-step SSINT, the maximum temperature in the internal volume is in the range of 1100°C to 2000°C, more preferably from 1300°C to 1850°C, more preferably from 1450°C to 1750°C, and even more preferably from 1575°C to 1675°C. In this state S1, preferably, during the other sub-step SSINT, the pressure in the internal volume increases at a rate in the range of 0.5 MPa / min to 30 MPa / min, more preferably in the range of 0.75 MPa / min to 10 MPa / min, and even more preferably in the range of 1 MPa / min to 5 MPa / min. [ ] Cooling of laminates

[0267] In a preferred embodiment C1, the method for producing a laminate includes the step of reducing the temperature of the laminate once it has been obtained. In one preferred embodiment C1, the laminate system is passively cooled by removing a heat source (e.g., by removing the application of voltage across the mold, internal volume, or both; by removing the power applied to the apparatus used to produce the laminate). In another embodiment C1, the laminate system is cooled by convection with an inert gas, such as argon or nitrogen at 1 bar. Other gas pressures greater than or less than 1 bar may also be used. In yet another embodiment C1, the laminate system is cooled under forced convection conditions in an oxygen environment.

[0268] In a preferred embodiment of Example C1, during the step of reducing the temperature of the laminate, the pressure applied to the internal volume is also reduced (e.g., the pressure applied by the first and second punches is removed). In a preferred embodiment of Example C1, the temperature of the laminate can be reduced under vacuum conditions.

[0269] The temperature of the laminate can be reduced at the following rates: preferably from 0.5°C / min to 20°C / min, more preferably from 1°C / min to 10°C / min, even more preferably from 1°C / min to 8°C / min, and even more preferably from 1°C / min to 5°C / min; preferably from 2°C / min to 10°C / min, more preferably from 2°C / min to 8°C / min, and even more preferably from 2°C / min to 5°C / min. [ ] [Further variations of this method]

[0270] In one preferred embodiment V1 of the present invention, the method for producing a laminated body further includes a step of reducing the gas pressure in the internal volume, wherein the reducing step is preferably performed after the first powder and another powder are introduced into the internal volume and / or after any other powder present is introduced into the internal volume.

[0271] In state V1, preferably, the gas pressure is reduced before the first powder layer and the other powder layer, and / or any other powder layer present in the internal volume are subjected to heat and pressure. In state V1, preferably, the gas pressure is reduced to 10 mPa or lower, more preferably 5 mPa or lower, and even more preferably 1 mPa or lower. Preferably, the gas pressure is reduced to the range of 1 mPa to 10 mPa.

[0272] In one preferred embodiment V1 of the present invention, the method for producing the laminate is performed in at least one or all of the following: a non-oxidizing atmosphere; an inert atmosphere, more preferably an atmosphere containing argon. [ ] [Laminated body]

[0273] The laminate according to the invention comprises at least a first layer and another layer. This should not be construed as meaning that the laminate must comprise at least two layers, that is, it should not be construed as meaning that the laminate comprises one or more additional layers besides the first layer and the other layer. The laminate may consist of only the first layer and the other layer. Preferably, the first layer and the other layer are in contact with each other.

[0274] According to the method of the present invention, a laminate is produced wherein the laminate system is obtained from at least two powder layers, which have been subjected to heat and pressure within an internal volume of a device. For example, the first and second layers of the laminate are obtained from the first and second powder layers by subjecting the first and second powder layers to heat and pressure within an internal volume of a device. Preferably, the first layer of the laminate is obtained from the first powder layer. Preferably, the second layer is obtained from the other powder layer.

[0275] One layer of the preferred laminate has a higher density than the powder layer from which it is obtained. One layer of the preferred laminate has at least 95% of its theoretical density, more preferably at least 99%, and even more preferably at least 99.9%. The preferred laminate system comprises connected objects.

[0276] The preferred laminate contains at least one element selected from the group consisting of: oxygen, nitrogen, carbon, yttrium, zirconium, aluminum, titanium, silicon, boron, phosphorus, and beryllium. These elements may be components of oxides, nitrides, or carbides.

[0277] If the laminate contains oxygen, the laminate is typically quantified in terms of the amount of simple oxide required to prepare it. Some preferred oxide compositions are silicon dioxide, boron oxide, beryllium oxide, yttrium oxide, aluminum oxide, zirconium oxide, titanium oxide, silica, quartz, calcium oxide, cerium oxide, nickel oxide, copper oxide, strontium oxide, scandium oxide, samarium oxide, hafnium oxide, vanadium oxide, niobium oxide, tungsten oxide, manganese oxide, tantalum oxide, tantalum oxide, thallium oxide, europium oxide, neodymium oxide, yttrium aluminate oxide, zirconium aluminate oxide, lanthanum oxide, diurethane oxide, and erbium oxide.

[0278] If the laminate contains nitrogen, the laminate is typically quantified in terms of the amount of the desired simple nitride it contains. Some preferred nitride compositions are selected from one or more of the following groups: silicon nitride, titanium nitride, yttrium nitride, aluminum nitride, boron nitride, beryllium nitride, and tungsten nitride.

[0279] If the laminate contains carbon, the laminate is typically quantified in terms of the amount of the desired simple carbide used in its preparation. Some preferred carbide compositions are silicon carbide, tungsten carbide, chromium carbide, vanadium carbide, niobium carbide, molybdenum carbide, tantalum carbide, titanium carbide, zirconium carbide, hafnium carbide, and boron carbide.

[0280] The laminate may contain one or more borides. Some preferred boride compositions of the laminate are selected from one or more of the following groups: molybdenum boride, chromium boride, hafnium boride, zirconium boride, tantalum boride, titanium boride, and titanium diboride.

[0281] The preferred laminate comprises one or more materials selected from the group consisting of: sapphire, aluminum oxide, yttrium aluminum monoclinic (YAM) (preferably Y4Al2O9), yttrium aluminum garnet (YAG) (preferably Y3Al5O12), yttrium aluminum perovskite (YAP) (preferably YAlO3), lapis lazuli, andalusite, magnesium aluminate spinel, zirconium oxide, erbium aluminum garnet (EAG), yttrium oxynitride, silicon oxynitride, magnesium silicate, aluminum nitride, and silicon carbide.

[0282] In one preferred embodiment A1 of the present invention, the first layer of the laminate contains YAG based on the volume of the first layer, more preferably in the following amounts: at least 90 vol-%, even more preferably at least 95 vol-%, and even more preferably at least 99 vol-%. In this embodiment A1, based on the volume of the first layer, the first layer preferably contains YAG in the range of 90 vol-% to 99.9 vol-%, more preferably 90 vol-% to 99.8 vol-%, even more preferably 90 vol-% to 99.8 vol-%, even more preferably 90 vol-% to 99.8 vol-%, even more preferably 93 vol-% to 99.8 vol-%, even more preferably 93 vol-% to 99.7 vol-%, and even more preferably 93 vol-% to 99.6 vol-%.

[0283] In one embodiment A2 of the present invention, the laminate comprises a first layer and another layer. In this embodiment A2, preferably, the first layer comprises YAG, more preferably as described in the aforementioned embodiment A1. In embodiment A2, preferably, based on the volume of the other layer, the other layer comprises ZTA in the following amounts: at least 90 vol-%, even more preferably at least 95 vol-%, and further preferably at least 99 vol-%.

[0284] In another preferred embodiment A3 of the present invention, the first layer comprises aluminum nitride. In yet another preferred embodiment A4 of the present invention, the first layer comprises silicon carbide. In embodiments A3 and A4, the laminate comprises a first layer and another layer, wherein the other layer comprises ZTA, more preferably as described in embodiment A2 above.

[0285] Preferred laminated ceramic systems. Preferred ceramic-based inorganic materials. Preferred ceramic-based nonmetals. Some preferred ceramic-based oxides, nitrides, carbides, or combinations thereof. Preferred ceramic-based refractory materials.

[0286] Preferred oxide ceramics may be single-element oxides or mixed oxides of more than one element. Oxide ceramics may contain nitride or carbide contents, or both. Oxide ceramics may be free of nitrides or carbides, or both. Preferred oxide ceramics may be stoichiometric or non-stoichiometric. Stoichiometric oxides preferably have an integer ratio between the atomic numbers of their component elements. Oxide ceramics may contain two or more elemental groups, each element being stoichiometric with other elements in its own group, but non-stoichiometric with members of other groups.

[0287] Some preferred mixed oxide systems are selected from one or more of the following groups: zirconium silicate oxide, hafnium aluminate oxide, hafnium silicate oxide, titanium silicate oxide, lanthanum silicate oxide, lanthanum aluminate oxide (LAO), yttrium silicate oxide, titanium silicate oxide, tantalum silicate oxide, nitrogen oxides, barium titanate, lead titanate, and lead zirconate titanate.

[0288] Nitrogen-containing ceramics are often quantified by the amount of simple nitrides required for their preparation. Some preferred nitride compositions are selected from one or more of the following groups: silicon nitride, titanium nitride, yttrium nitride, aluminum nitride, boron nitride, beryllium nitride, and tungsten nitride.

[0289] Preferred nitride ceramics may be single-element nitrides or mixed nitrides of more than one element. Nitride ceramics may contain some oxide or carbide content, or both. Nitride ceramics may be free of oxides or carbides, or both. Preferred nitride ceramics may be stoichiometric or non-stoichiometric. Stoichiometric nitrides preferably have an integer ratio between the atomic numbers of their component elements. Nitride ceramics may contain two or more elemental groups, each element being stoichiometric to other elements in its own group, but non-stoichiometric to members of other groups.

[0290] Preferred carbide ceramics may be single-element carbides or mixed carbides of more than one element. Carbide ceramics may contain some oxide or nitride contents, or both. Carbide ceramics may be free of oxides or nitrides, or both. Preferred carbide ceramics may be stoichiometric or non-stoichiometric. Stoichiometric carbides preferably have an integer ratio between the atomic numbers of their component elements. Carbide ceramics may contain two or more elemental groups, each element being stoichiometric with other elements in its own group, but non-stoichiometric with members of other groups.

[0291] The preferred laminate has a size of at least 200 mm, more preferably at least 300 mm, and even more preferably at least 500 mm. The size of the laminate can be as high as 2000 mm or more. In one preferred embodiment of the invention, the size of the laminate is no greater than 1500 mm, more preferably no greater than 900 mm, even more preferably no greater than 800 mm, even more preferably no greater than 700 mm, and even even more preferably no greater than 650 mm. In one preferred embodiment of the invention, the size of the laminate is preferably in the range of 200 mm to 650 mm, more preferably 300 mm to 650 mm, even more preferably 400 mm to 650 mm, and even more preferably 500 mm to 650 mm. In one preferred embodiment of the invention, the size of the laminate is in the range of 550 mm to 625 mm. In the above preferred example, the size of the laminate should be understood as the maximum dimension of the laminate (e.g., diameter).

[0292] In one preferred embodiment of the invention, the first layer is polycrystalline or crystalline. In another preferred embodiment of the invention, if the laminate includes another layer, it is preferable that the other layer is polycrystalline or crystalline. A crystalline layer should preferably be understood as having a single-crystal structure.

[0293] The laminate according to the invention is preferably used in a plasma processing chamber. [ ] [Heat treatment of laminated materials]

[0294] In one embodiment of the invention, the laminate is subjected to heat treatment. A preferred heat treatment of the laminate is annealing. A heat-treated laminate may be referred to as a treated laminate. An annealed laminate may be referred to as an annealed laminate.

[0295] In a preferred embodiment of the present invention, the heat treatment of the laminate is performed at a temperature in the range of 900°C to 1800°C, more preferably 1000°C to 1700°C, even more preferably 1100°C to 1600°C, even more preferably 1200°C to 1500°C, further preferably 1300°C to 1475°C, and even more preferably 1350°C to 1450°C.

[0296] In a preferred embodiment of the present invention, the heat treatment of the laminate is performed at a heating and / or cooling rate in the range of 0.05°C / min to 50°C / min, more preferably 0.1°C / min to 25°C / min, even more preferably 0.3°C / min to 10°C / min, and even more preferably 0.5°C / min to 5°C / min. In a preferred embodiment of the present invention, the heat treatment of the laminate is performed at a cooling rate in the range of 1°C / min to 50°C / min, more preferably 3°C / min to 50°C / min, even more preferably 5°C / min to 50°C / min, and even more preferably 25°C / min to 50°C / min. In a preferred embodiment of the present invention, the heat treatment of the laminate is performed at a heating rate in the range of 0.05°C / min to 10°C / min, more preferably 0.1°C / min to 5°C / min, even more preferably 0.3°C / min to 2°C / min, and even more preferably 0.5°C / min to 1°C / min.

[0297] In one preferred embodiment of the present invention, the heat treatment of the laminate is performed for a duration of 1 to 24 hours, more preferably 1 to 18 hours, even more preferably 1 to 16 hours, and further preferably 1 to 8 hours. The heat treatment of the laminate is preferably performed for a duration of 4 to 24 hours, more preferably 8 to 24 hours, and even more preferably 12 to 24 hours. The heat treatment of the laminate is preferably performed for a duration of 4 to 12 hours, and more preferably 6 to 10 hours.

[0298] The heat treatment of laminates is preferably performed under oxidizing conditions (such as forced convection) or in air. The heat treatment of laminates is preferably performed under ambient pressure.

[0299] Heat treatment of the laminate can be performed while the laminate is located within the internal volume of the device. Alternatively, heat treatment of the laminate can be performed outside the internal volume of the device. For example, the laminate can be removed from the internal volume of the device and placed in another cavity, where the laminate is subjected to heat treatment.

[0300] Another example of a cavity is the cavity of a furnace. Any furnace that is considered suitable for the heat treatment of laminates by those skilled in the art can be used. Such furnaces are well known to those skilled in the art. One example is the STD-1200-17 type industrial box furnace, which is available from JinYu Electric Material Co., Ltd. (Dengfeng City, China). [ ] [Applications of laminates]

[0301] In a preferred embodiment, the laminate disclosed herein can be machined into a process ring. Examples of process rings include insertion rings, focusing rings, venting rings, capping rings, deposition rings, etching rings, shielding rings, carrier rings, or substrate picking rings, which are components of a plasma vacuum processing chamber. Each process ring includes: an annular body, wherein the body preferably contains 90% to 99.8% by volume of polycrystalline yttrium aluminum garnet, wherein the annular body has at least one surface having a surface area; and an opening surrounded by the annular body. Preferably, the polycrystalline yttrium aluminum garnet contains pores on the at least one surface, the pores having a pore size of no more than 5 µm, and preferably having a maximum pore size of 1.5 µm for at least 95% of the pores.

[0302] In another preferred embodiment, the laminate disclosed herein can be machined into a "spray head" gas flow manifold, also known as a spray head assembly or gas distribution assembly. This device is generally used to distribute process gases across the surface of a wafer. The process gases can flow out from the spray head and be distributed across the wafer; the wafer can be supported by a base assembly within a processing chamber housing the spray head. The distribution of process gases across the wafer can be achieved through a pattern of gas distribution holes that guide the gas flow from inside the spray head assembly to the wafer.

[0303] A spray head assembly generally includes: a back plate portion having at least one gas inlet; a front plate portion opposite to the back plate portion, wherein the front plate portion includes a plurality of gas distribution holes; and an internal volume communicating with the gas distribution holes and the gas inlet. Preferably, the back plate portion and the front plate portion each contain 90% to 99.8% by volume of polycrystalline yttrium aluminum garnet and have at least one surface, wherein the polycrystalline yttrium aluminum garnet preferably contains pores on the at least one surface, and wherein such pores preferably have a pore size of no more than 5 µm and preferably have a maximum pore size of 1.5 µm for at least 95% of the pores.

[0304] In a preferred embodiment, the laminate disclosed herein can be machined into a gas distribution nozzle, comprising: a body having at least one gas injection channel and at least one surface having a surface area, wherein the body preferably comprises 90% to 99.8% by volume of polycrystalline yttrium aluminum garnet, wherein the polycrystalline yttrium aluminum garnet preferably comprises pores on the at least one surface, and wherein the pores preferably have a pore size of no more than 5 µm and preferably have a maximum pore size of 1.5 µm for at least 95% of the pores.

[0305] In yet another embodiment, the laminate disclosed herein can be machined into a dielectric window, preferably through which RF or microwave energy can pass when the dielectric window is used in a plasma processing chamber. The dielectric window comprises: a body having at least one surface having a surface area, wherein the body preferably comprises 90% to 99.8% by volume of polycrystalline yttrium aluminum garnet, wherein the polycrystalline yttrium aluminum garnet preferably includes pores on the at least one surface, and wherein the pores preferably have a pore size of no more than 5 µm and preferably have a maximum pore size of 1.5 µm for at least 95% of the pores.

[0306] The dielectric window disclosed herein may be a single layer or may have more than one layer (i.e., a multilayer dielectric window), as long as it allows the transmission of radiation / energy. If the dielectric window is multilayered, it may contain at least one layer containing a material other than YAG. Exemplary materials include alumina or quartz. The dielectric window may have any shape, such as a disc or a circle, and be large enough to form the ceiling of the processing chamber. [ ] [Diagram Explanation]

[0307] Figure 1A shows a cross-sectional side view of the device 100 according to the present invention. The device has a first punch 003 and a second punch 008, the first punch having a first punch inner surface 004 and the second punch having a second punch inner surface 007. Punches 003 and 008 are made of solid graphite. The punch inner surfaces 004 and 007 are therefore also graphite. The first punch 003 is positioned above the second punch 008. The first punch 003 is horizontal and downward oriented with the first punch inner surface 004 as its horizontal orientation. The first punch 003 can be moved vertically by a first pushing member 001 connected via a first piston 002. The second punch 008 is horizontal and upward oriented with the second punch inner surface 007 as its horizontal orientation. The second punch 008 can be moved vertically by a second pushing member 010 connected via a second piston 009. The first punch inner surface 004 and the second punch inner surface 007 can therefore move toward each other along the direction of the compression shaft 011.

[0308] The device has a mold 006, which is shaped as a hollow graphite cylinder with walls 015 and an inner surface 005. The device has a power supply 012, which is adjusted and configured to supply direct current (DC). The power supply 012 is electrically connected to a first punch 003 and a second punch 008. The internal volume 013 is defined (or delimited) by the inner surface 004 of the first punch from above, the inner surface 007 of the second punch from below, and the inner surface 005 of the mold 006. In the case of FIG. 1A, both the inner surfaces 004 and 007 of the punches are circular, while the inner surface 005 is cylindrical. Therefore, the internal volume 013 is also cylindrical.

[0309] Figure 1B shows a cross-sectional side view of the apparatus of Figure 1A, wherein the internal volume 013 is loaded and ready for sintering. The internal volume 013 is filled with a first powder for sintering, wherein the first powder is configured to form a first powder layer 014. Prior to sintering, the inner surfaces 004 and 007 of the punches move inward to abut against the first powder layer 014. The inner surfaces 004 and 007 of the punches move inward along the compression axis 011 as indicated by the arrows. During sintering, the inner surfaces 004 and 007 of the punches apply force to the first powder layer 014, thus generating pressure in the internal volume 013. During sintering, a voltage is also applied across the internal volume 013 (between the first inner surface 004 of the punches and the second inner surface 007 of the punches) and / or the die 006. The voltage is obtained using a power supply 012. Heat is generated in the internal volume 013 due to the applied voltage. The first powder layer 014 is sintered by being subjected to heat and pressure, thereby obtaining a laminate. When the sintering process is complete, the laminate is allowed to cool. During cooling, punches 003 and 008 retract (i.e., the punches do not apply pressure to the laminate). Voltage is also removed during cooling.

[0310] Although only the first powder layer 014 is shown in Figure 1B, one or more additional powders may be introduced into the internal volume 013 prior to sintering. For example, once the first powder layer 014 has been obtained, another powder is introduced into the internal volume 013 to obtain another powder layer. The other powder layer is above and in contact with the first powder layer 014. During sintering, pressure is applied to both the first powder layer 014 and the other powder layer in the internal volume 013. The other powder layer is also heated together with the first powder layer. By subjecting the first powder layer 014 and the other powder layer to heat and pressure, the first powder layer 014 and the other powder layer are sintered, thereby obtaining a laminate. The laminate comprises a first layer and another layer. The first layer is obtained from the first powder layer, and the other layer is obtained from the other powder layer.

[0311] Figure 2 is a flowchart illustrating the steps of a method 200 for producing a laminate according to the present invention. In step 201, a first powder and another powder are introduced into an internal volume of an apparatus to obtain a first powder layer and another powder layer in the internal volume. The first powder layer and the other powder layer are in contact with each other. The internal volume is defined by the internal surface of a mold, the internal surface of a first punch of a first punch, and the internal surface of a second punch of a second punch. The internal volume has a cross-sectional width of at least 200 mm. The mold and the first and second punches are made of graphite. The apparatus is adapted and configured for spark plasma sintering. In step 202, the first powder layer and the other powder layer are subjected to heat and pressure to obtain a laminate. Heat is generated by a voltage applied across the mold, the internal volume, or both. The laminate comprises a first layer and another layer. In step 203, the laminate is subjected to heat treatment (e.g., annealing) in the presence of oxygen.

[0312] Figures 3A and 3B show the core test 300 used in this paper. Figure 3A shows a perspective view before the test begins. The core removal tool 301 is positioned above the first flat surface 302 of the stack 306. In Figure 3A, the stack 306 is a flat stack and is in the form of a cylindrical disk. The tool 301 is oriented along an axis perpendicular to the first flat surface 302. Arrow 308 shows the direction of travel of the tool 301 along the axis toward the stack 306. Once in contact with the stack 306, the core removal tool 301 moves in a circular motion within a core removal region 307, which has a diameter larger than the diameter of the tip 309 of the core removal tool 301. The circular motion is parallel to the first flat surface 302 and results in the removal of the cylindrical region (or core) from the stack 306. Furthermore, the geometric center 305 of the first flat surface 302 is also the geometric center 305 of the core removal region 307. Figure 3B shows a cross-sectional view seen from the side during the core test. Tool 301 has been advanced a distance 303 into the laminate 306 having a sample thickness 304. Figure 3B shows that the core-removing tool 301 has removed the cylindrical segment 310 from the laminate 306. The distance 303 is determined between the first flat surface 302 and the end of tool 301. The test is completed when a crack is first observed in the laminate 306. The success level is determined as the ratio of the core-removing distance 303 at the end of the test to the total thickness of the laminate 306, expressed as a percentage.

[0313] Figure 4 shows how to measure the angle of repose of the powder. A coarse filter 401 is fixed at a distance 402 above the working surface 403. The coarse filter 401 is positioned such that its center 404 is above the center of the working surface 403. Powder 405 is added to the coarse filter 401 and allowed to flow through it (as indicated by the arrow in Figure 4). As a result, the powder collects on the working surface 403 in a cone-shaped form 406. Once the coarse filter 401 has been emptied, a tangent 407 is fitted to one side of the cone-shaped form 406, and a protractor is used to measure the angle 408 formed between the tangent 407 and the working surface 403. This angle 408 is the angle of repose of the powder.

[0314] Figure 5 shows how the temperature of the side and top of the laminate is measured. Figure 5 shows the mold 006, the first punch 003, and the second punch 008 that form the internal volume 013. The laminate 501 exists in and occupies the internal volume 013. In Figure 5, the internal volume 013 is located in the sintering apparatus. A pyrometer 502 is also located in the sintering apparatus. A quartz observation window 503 is connected between the pyrometer 502 and the internal volume 013. Figure 5 also shows a recess 504 on one side of the mold 006 (i.e., the side facing the pyrometer 502). The pyrometer 502 is used to measure the temperature in the recess 504. The temperature of the recess 504 is defined as the temperature of the side 505 of the laminate 501. A thermocouple 507 is used to measure the temperature at the top 506 of the laminate 501. Thermocouple 507 is located at the center of the first punch 003 (at the position of compression shaft 011 - see Figure 1).

[0315] Figure 6 is a schematic diagram of a laminate 600 obtained by a method for producing a laminate (according to the present invention). The laminate 600 has a first layer 601 and another layer 602 that are in contact with each other. The other layer 602 has a first surface 603 facing the first layer 601. The other layer 602 also has another surface 604 opposite to the first surface 603 (the other surface 604 faces away from the first layer 601). A first center line 605 is configured to be perpendicular to the first layer 601 and the other layer 602 (and therefore perpendicular to the first surface 603 and the other surface 604). Another center line 606 is configured to be perpendicular to the first center line 605. The first center line 605 and the other center line 606 pass through the center 607 of the other layer 602. Figure 6 also shows a first region 608, a second region 609, and another region 610. The first region 608 is closer to the first layer 601 than the second region 609 (and the other region 610). Compared to the first region 608 and the second region 609, another region 610 is closer to another surface 604 of the other layer 602. Therefore, the second region 609 is closer to the first region 608 than the other region 610. Preferably, at least one (more preferably all) of regions 608, 609, and 610 is selected such that a first center line 605 passes through the middle of these regions. Furthermore, it is preferable to select the second region 609 such that another center line 606 passes through the middle of the other region 609. Preferably, the first region 608 forms part of the first surface 603 of the other layer 602. Preferably, the center 607 of the other layer 602 is also the center (or middle) of the second region 609. Preferably, the other region 610 forms part of the other surface 604 of the other layer 602. Density ρT is measured at a first location in the first region 608. Density ρM is measured at a second location in the second region 609. Measure the density ρB at another location within another region 610. Measure the thickness (or height) of regions 608, 609, and 610 along the first centerline 605. Measure the width (or diameter) of regions 608, 609, and 610 along the other centerline 606. The first region 608 preferably has a height of 5 mm or less. The first region 608 preferably has a width of 14 mm or less. The second region 609 preferably has a height of 5 mm or less. The second region 609 preferably has a width of 14 mm or less. Another region 610 preferably has a height of 5 mm or less. Another region 610 preferably has a width of 14 mm or less. [ ] [Testing Method]

[0316] The following test methods are used within the scope of this invention. Unless otherwise stated, measurements are performed at an ambient temperature of 23°C and an ambient pressure of 100 kPa (0.986 atm). Carbon content and other element content

[0317] The carbon content of the powder is expressed in ppm (by weight), based on the total weight of the powder. Carbon content is measured using an EMIA series carbon / sulfur analyzer (EMIA-Expert model, available from Horiba Instruments Inc. (USA)). The carbon content is analyzed as follows: 0.5 g of powder is placed in a crucible, which is then placed in the carbon / sulfur analyzer. Before placing the powder in the crucible, the crucible is heated in a muffle furnace to at least 1000°C for 60 minutes. Afterward, the crucible is removed from the furnace and placed in a desiccator. The crucible is allowed to return to room temperature before placing the powder sample in it.

[0318] Regarding the content of other elements in the powder: the sulfur content of the powder is expressed in ppm (by weight) based on the total weight of the powder. The same carbon / sulfur analyzer and measurement method used for carbon are also used to measure the sulfur content of the powder. The chlorine content of the powder is expressed in ppm (by weight) based on the total weight of the powder. The chlorine content of the powder is measured using inductively coupled plasma mass spectrometry (ICP-MS), as described below. For this measurement, an Agilent 7900 ICP-MS (G8403 model), available from Agilent Technologies, Inc. (USA), is used.

[0319] Place the powder sample in a 15 ml vial. Dissolve the powder using one or more acids while simultaneously applying heat via microwave radiation. The amount of powder used is indicated in the table below. Select an amount of acid sufficient to dissolve the powder and obtain a solution. The solution in the vial should not exceed 10 ml. For the application of heat, use an ultraWave single-chamber microwave. Apply heat for 50 minutes, maintaining the solution temperature at 240 ± 10 °C for at least 25 minutes. [ ] [ [surface]] [Amount of powder and acid used for measurement] [powder] [acid] Yttrium oxide (Y2O3): 36 mg HNO3 Aluminum oxide (Al2O3): 40 mg HNO3 Al2O3-Y2O3 mixture: 40 mg HNO3 + H2SO4 + H3PO4 + HF YAG (Y3Al5O12): 40 mg HNO3 + H2SO4 + H3PO4 + HF Zirconia (ZrO2): 36 mg HNO3 + H2SO4 + H3PO4 + HF ZrO2 - Y2O3 mixture: 36 mg HNO3 + H2SO4 + H3PO4 + HF Magnesium oxide (MgO): 36 mg HNO3

[0320] For powders not indicated in the table above, use the amount of powder and acid as indicated for zirconium oxide.

[0321] Once the powder has dissolved, the vial is swirled for 10 seconds and placed in an Agilent 7900 ICP-MS for chlorine content measurement. The ICP-MS obtains the sample from the vial, atomizes it to form an aerosol, and exposes the aerosol to plasma. The ICP-MS then uses a mass spectrometer to count the resulting ions.

[0322] For measurements, the argon regulator on the Agilent 7900 ICP-MS was set to 100 psi, the helium regulator to 10 psi, and the nitrogen regulator to 10 psi. Additionally, the plasma used for the measurement was warmed for 30 minutes before execution. The Agilent 7900 ICP-MS also features a cooler set to 55 psi and 15°C. Powder and its components: purity of powder

[0323] Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the purity of powders and component powders (e.g., alumina, yttrium oxide). Purity is reported as a percentage relative to 100% purity, indicating that the material contains only the desired component and is free of impurities, dopants, sintering aids, and the like. Angle of rest

[0324] The angle of repose of the powder was measured as shown in Figure 4. The distance between the coarse filter and the working surface was between 17.78 cm and 20.32 cm (7 to 8 inches). The working surface was a circle with a diameter of 20.32 cm (8 inches). The angle of repose was measured at 10 evenly spaced locations around the circumference of the working surface. The average of these 10 measurements was defined as the angle of repose of the powder, as asserted herein. Specific surface area

[0325] The specific surface area of ​​the powder was measured according to standard ASTM C1274. For this measurement, a Horiba BET surface area analyzer (model SA-9601) was used, which is capable of measuring specific surface areas from 0.01 m² / g to 2000 m² / g. Particle size

[0326] The particle size of powders, component powders, and powder layers was measured using a Horiba LA-960 laser scattering particle size analyzer capable of measuring particle sizes from 10 nm to 5 mm. In the Horiba LA-960 analyzer, particle size measurement was performed by adding a 1 g sample of powder along with a drop of Na₄P₂O₇ (obtained using a pipette) to deionized water. During the measurement, circulation, stirring, and ultrasound were activated in the analyzer. For this measurement, both circulation and stirring were set to level 5, and ultrasound was used at power level 6 for 12 minutes.

[0327] Particle size measurement is also used to obtain the particle size distribution of powders and component powders. Particle size and particle size distribution are volume-based; for example, the values ​​of d10, d50, and d90 are volume-based. Core Tests

[0328] Core removal is performed on the laminate to determine the presence of excessive internal stress. The laminate system is a planar laminate with a first flat surface and a thickness perpendicular to the first flat surface. A 10 mm diamond core removal tool, available from companies such as Schott Diamantwerkzeuge GmbH of Stadtoldendorf, Germany, is used. The core removal tool is used in a commercially available CNC machine to remove the core from the laminate under test. The hole formed in the laminate by removing the core is 56 mm to 60 mm in diameter and has a nominal diameter of 58 mm. The core is removed by drilling a hole in the laminate by passing the tool through the surface of the laminate in a helical pattern. Suitable CNC machines that can be used for this test are available from companies such as DMG Mori Company Limited of Los Angeles, California, USA (such as their Ultrasonic 60 eVo linear model). Another supplier of suitable CNC machines is Fair Friend Ent.Co. Ltd. of Taiwan (such as the Feeler HV-1650 model). The test ends when the core extends through the laminate or when fracture of the laminate is observed, whichever occurs first. The success score is given as a percentage of the core thickness cut from the tested laminate. A 100% success rating indicates low internal stress (if any); a success rating above 75% but below 100% indicates low internal stress; a success rating between 25% and 75% indicates moderate stress; and a success rating below 25% indicates high internal stress. The above test method is further illustrated in Figures 3A and 3B. Volumetric porosity

[0329] If the volumetric porosity is 2% or higher, the volumetric porosity of the laminate and one layer of the laminate shall be calculated from the density measurement performed in accordance with ASTM B962-17. If the volumetric porosity is less than 2%, the measurement shall be performed in accordance with ASTM B311-17. Grain size

[0330] The average grain size was measured using the Heyn linear intercept method as described in ASTM standard E112-2010. Etch resistance

[0331] To determine the etch resistance of one layer (e.g., the first layer) of a laminate, 100 samples of that layer were selected. Each sample had a width and length of 6 mm x 6 mm and a thickness of 2 mm. Each sample was mounted onto the c-side sapphire wafer using a silicone-based thermally conductive composite. Areas of the sample were protected from etching by bonding 5 mm x 5 mm square sapphire ceramic pieces to the sample surface.

[0332] Dry etching was then performed on each sample using a DESC PDC Deep Silicon Etch, available from Plasma-Therm (USA). The etching was performed at a pressure of 10 ml, a bias of 600 volts, and an ICP power of 2000 watts. Furthermore, a two-step etching method was used, with a total duration of 6 hours. The first etching step had a CF4 flow rate of 90 standard cubic centimeters per minute (sccm), an oxygen flow rate of 30 sccm per minute (sccm), and an argon flow rate of 20 sccm per minute (sccm). The second etching step had an oxygen flow rate of 100 sccm per minute (sccm) and an argon flow rate of 20 sccm per minute (sccm). Both the first and second etching steps were performed for 300 seconds each, and the process was repeated for a combined duration of 6 hours. After the etching process was completed, the surface roughness parameters Sa, Sz, and Sdr were measured using the methods disclosed herein. Surface roughness

[0333] The surface roughness parameters Sa, Sz, and Sdr are measured according to standard ISO 25178-2:2012, section 4.1.7. Density and theoretical density of laminates

[0334] The density of the laminate was measured according to standard ASTM B962–17. The theoretical density was calculated from X-ray diffraction (XRD) data. Unit parameters a, b, and c were obtained from the XRD data. The unit cell volume was calculated using these unit parameters. The number of molecular units present in each unit cell was determined based on the material's crystal structure. Since the chemical structure was known, the molecular weight of the laminate was also known. Using the aforementioned data, the theoretical density was calculated as follows: Theoretical density = (molecular weight x number of molecules per unit cell) / (volume of unit cell x number of Avogadros). fracture toughness

[0335] The fracture toughness is determined according to the standard ASTM E1820-18. Flexural strength

[0336] The flexural strength is determined according to standard ASTM C1161-18. temperature

[0337] The temperature system on the side of the laminate is determined as shown in Figure 5.

[0338] The temperature in the recess of the mold was measured using a model E2MH-R08-V-0-0 pyrometer (available from Fluke Process Instruments). The diameter of the recess was 1.27 cm (0.5 inches). The recess extended to a depth of 13.46 cm (5.3 inches) into the mold wall. The wall thickness measured at the recess was approximately 15.24 cm (6 inches). The pyrometer was positioned at a distance of 30.48 cm (12 inches) from the recess.

[0339] The temperature at the top of the laminate was measured as shown in Figure 5. For this measurement, a thermocouple of model A14A-N51700-1, available from Nanmac Corporation (USA), was used. The thermocouple was positioned at a distance between 15.24 cm and 20.32 cm (6 inches to 8 inches) from the top of the laminate.

[0340] The temperature in the internal volume is measured using the same thermocouple used to measure the temperature at the top of the laminate. That is, the temperature of the internal volume and the temperature at the top of the laminate (once the laminate has been formed) are the same measured values.

[0341] The temperature used for calcining the (component) powder is obtained by using digital readings on the kiln used in the calcination process.

[0342] The environment (i.e., the environment outside the internal volume) such as the temperature of the storage room was measured using EXTECH visual particle counters (0.3, 0.5, 1.0, 2.5, and 10 µm). pressure

[0343] A load cell (available from Interface Force Measurement Solutions (USA)) was used to measure the force within the internal volume. The load cell used was model 1290CHG-2000K with a capacity of 2000 Klbf. The pressure within the internal volume was then calculated by dividing the force by the area of ​​the internal volume. The area of ​​the internal volume is given by π(DINT / 2)², where DINT is the diameter of the internal volume. [ ] [Example]

[0344] The invention is further illustrated by examples. The invention is not limited to these examples. In the tables of the examples, the magnitude of the effect is indicated by one or more "+" or "-". The following scales are used: "-----", "----", "---", "-", "-", "+", "++", "+++", "++++", "+++++". Reference values ​​are indicated by "Ref". No change relative to the reference value is indicated by "0". [ ] [Basic Settings]

[0345] Unless otherwise stated, the basic settings described below apply to all instances.

[0346] Two component powders are provided, wherein the first component powder is yttrium oxide powder and the other component powder is alumina powder. The alumina has a d10 particle size in the range of 0.05 µm to 0.15 µm, a d50 particle size in the range of 0.2 µm to 0.5 µm, and a d90 particle size in the range of 0.4 µm to 1 µm. The yttrium oxide has a d10 particle size in the range of 2 µm to 4 µm, a d50 particle size in the range of 6 µm to 8 µm, and a d90 particle size in the range of 11 µm to 13 µm.

[0347] Alumina and yttrium oxide were mixed using a wet ball mill to obtain a first powder. The wet ball milling was performed using a high-purity (>99.9%) alumina medium, wherein the weight of the alumina medium was approximately 90% to approximately the same as the weight of the powder, i.e., approximately 50% loading. A slurry was formed by adding ethanol to the alumina and yttrium oxide, wherein the ethanol comprised approximately 40 wt% to 50 wt% of the total weight of the slurry (the weight of ethanol and the first powder together). The slurry was mixed at 150 RPM for approximately 15 to 20 hours. After milling, ethanol was extracted from the slurry using a rotary evaporator. The dried powder was then tumbled and sieved according to methods known to those skilled in the art to obtain the first powder. The first powder was then calcined (heat-treated) at 800°C to 1050°C for 7 hours, depending on the size of the container (larger containers require longer calcination times). After calcination, the first powder has a d50 particle size in the range of 9 µm to 13 µm, and by total weight, the first powder contains alumina in the range of 42.9 wt% to 43.4 wt% and yttrium oxide in the range of 56.6 wt% to 57.1 wt%.

[0348] Two additional component powders are provided, wherein the first component powder is partially stabilized zirconia powder, and the other component powder is alumina powder. The alumina has a d10 particle size in the range of 0.05 µm to 0.15 µm, a d50 particle size in the range of 0.2 µm to 0.5 µm, and a d90 particle size in the range of 0.4 µm to 1 µm. The zirconia has a d10 particle size in the range of 0.08 µm to 0.2 µm, a d50 particle size in the range of 0.2 µm to 0.5 µm, and a d90 particle size in the range of 0.5 µm to 1.2 µm.

[0349] Alumina and zirconium oxide were mixed using a wet ball mill to obtain another powder. The wet ball milling was performed using a high-purity (>99.9%) alumina medium at a loading of approximately 80% relative to the powder weight. A slurry was formed by adding ethanol to the alumina and yttrium oxide, wherein the ethanol comprised approximately 50 wt% of the total slurry weight. The slurry was mixed at 20 RPM for approximately 20 hours. After milling, ethanol was extracted from the slurry using a rotary evaporator. The dried powder was then tumbled and sieved according to methods known to those skilled in the art to obtain another powder. This other powder was then calcined (heat-treated) at 900°C for 7 hours, depending on the container size (smaller containers require less time). After calcination, the other powder has a d50 particle size in the range of 90 µm to 110 µm, and the first powder further comprises, by total weight, alumina in the range of 77.1 wt% to 78.3 wt% and zirconium oxide in the range of 21.7 wt% to 22.9 wt% of the other powder. Alternatively, the alumina and zirconium oxide can be jet-milled instead of wet ball milling.

[0350] A first powder is introduced into the internal volume of the apparatus (spark plasma sintering apparatus) shown in Figure 1. The first powder is evenly dispersed to obtain a first powder layer. Then, another powder is introduced into the internal volume by placing it on the first powder layer. The other powder is evenly dispersed to obtain another powder layer on the first powder layer. The first powder and the other powder are introduced simultaneously as the internal volume is removed from the apparatus. The internal volume is then placed in the sintering chamber of the apparatus, and the internal volume is evacuated to obtain a pressure in the internal volume within the range of 10⁻³ to 10⁻² Torr.

[0351] The first powder layer and the second powder layer are subjected to heat and pressure. During this step of subjecting the first powder layer and the second powder layer to heat and pressure, the temperature and pressure within the internal volume are increased to 1625°C and 15 MPa, respectively. The first powder layer and the second powder layer are subjected to a temperature of 1625°C and a pressure of 15 MPa for 60 to 75 minutes. Afterward, the sintering chamber is filled with an inert gas, preferably nitrogen, and allowed to cool for several hours. The resulting laminate has a first layer and another layer that are adjacent to each other (i.e., in contact with each other). The first layer is made of YAG, and the second layer is made of ZTA. Applying heat and pressure to the first powder layer causes alumina and yttrium oxide to react to form the YAG layer of the laminate. Similarly, applying heat and pressure to the second powder layer causes alumina and zirconium oxide to form the ZTA layer of the laminate.

[0352] Once the laminate reaches a temperature of approximately 25°C, it is removed and placed in a furnace under normal atmospheric pressure and oxygen conditions. The laminate is then heat-treated at 1400°C for 8 hours. [ ] [Example 1]

[0353] As shown in Table 1 below, Example 1 was repeated by changing the density of another layer (another layer of the laminate). The first layer had a thickness of 5 mm, and the other layer had a thickness of 25 mm. In Example 1, the internal volume of the device had a cross-sectional width of 600 mm. The laminate thus produced also had a diameter of 600 mm. [ ] [ [surface] [1] [Example] [1.1] [1.2] [1.3] [settings] Density change in another layer ρT > ρM ρT < ρM ρT = ρM (The difference between ρT and ρM is less than 0.01%) [The produced laminates] strength ++ - - Scratch resistance ++ -- - Core test success rate [%] + -- -

[0354] The technical effects shown in Table 1 are as follows: - Strength: The external force or stress required to permanently deform or fracture the laminate when applied to it. "+" indicates a higher strength, and "-" indicates a lower strength. The desired result is increased strength. - Scratch resistance: The scratch resistance of the laminate. "+" indicates greater scratch resistance, and "-" indicates less scratch resistance. Increased scratch resistance is desired. - Core Test Success Rate: The percentage of laminates that pass the core test. If a laminate breaks or fractures during the core test, it fails the core test. "+" indicates a higher success rate, and "-" indicates a lower success rate. A higher core test success rate is desirable. [ ] [Example 2]

[0355] Tables 2 and 3 indicate how densities ρT, ρM, and ρB vary relative to each other with respect to the thickness of the first and second layers, respectively. Table 4 indicates the temperature and time required for heat treatment of the laminate, varying with the thickness of the first and second layers, to obtain ρT > ρM. The laminate system of Example 2 was prepared as described in the "Basic Setup" above, except for the parameter differences indicated in Tables 2 to 4. In Example 2, the internal volume of the apparatus has a cross-sectional width of 600 mm. Therefore, the produced laminate also has a diameter of 600 mm.

[0356] Table 2 indicates how densities ρT, ρM, and ρB vary relative to each other with the thickness of the first layer. [ ] [ [surface] [2] [settings] Heat treatment At 1400℃ for 8 hours The thickness of another layer 25 mm [Example] [Thickness of the first layer] [[mm]] 2.1 1 ρT = ρM ≈ ρB 2.2 3 ρT > ρM > ρB 2.3 5 ρT > ρM > ρB 2.4 16 ρT = ρM >> ρB

[0357] Table 3 indicates how densities ρT, ρM, and ρB vary relative to each other with the thickness of another layer. [ ] [ [surface] [3] [settings] Heat treatment At 1400℃ for 8 hours Thickness of the first layer 3 mm [Example] [The thickness of another layer] [[mm]] 2.5 3 ρT = ρM = ρB 2.6 15 ρT > ρM > ρB 2.7 25 ρT > ρM > ρB 2.8 30 ρT > ρM > ρB 2.9 60 ρT > ρM > ρB

[0358] Table 4 indicates the temperature and time (duration) required for heat treatment of the laminate to obtain ρT > ρM > ρB. In Table 4, the thickness of the first layer and the thickness of the second layer vary as shown. In other words, Table 4 shows the temperature and time (duration) required for various thicknesses of the first and second layers. [ ] [ [surface] [4] [settings] For the stacked volumes in Table 4: ρT > ρM > ρB [thickness] [Heat Treatment] [Example] [First Floor] [[mm]] [Another layer] [[mm]] [Duration] [[] [Hour]] [temperature] [[℃]] 2.10 1 25 4 1400 2.11 2 25 8 1400 2.12 16 25 100 1400 2.13 5 3 12 1300 2.14 5 60 20 1500 [Example 3]

[0359] As shown in Table 5 below, Example 3 was repeated by changing the density of another layer (another layer of the laminate). The thicknesses of the first and second layers are also indicated in Table 5. In Example 3, the internal volume of the apparatus had a cross-sectional width of 600 mm. Therefore, the produced laminate also had a diameter of 600 mm. [ ] [ [surface] [5] [Example] [3.1] [3.2] [3.3] [settings] thickness First layer [mm] 5 3 15 Another layer [mm] 25 25 25 Density change in another layer ρT > ρM ρT > ρM ρT = ρM (The difference between ρT and ρM is less than 0.01%) [The produced laminates] strength + +++ -- Scratch resistance ++ +++ -- Core test success rate [%] + ++ -

[0360] The technical effect predictions in Table 5 are the same as those described in Table 1. [ ] [Component Symbol] 100 Device according to the present invention 001 First propulsion component 002 First piston 003 First punch 004 The inner surface of the first punch 005 The inner surface of the mold 006 mold 007 The inner surface of the second punch 008 Second punch 009 Second piston 010 Second propulsion component 011 compression shaft 012 power supply 013 Internal volume 014 First powder layer 015 mold wall 200 Methods for producing laminates 201 A first powder and another powder are introduced into the internal volume to obtain a first powder layer and another powder layer. 202 The first powder layer and another powder layer are subjected to heat and pressure to obtain a laminate. 203 The laminate is subjected to heat treatment 300 Core test settings 301 Core extraction tools 302 First flat surface 303 Drilling depth 304 Sample thickness 305 Geometric Center 306 Flat-form lamination 307 Take the core area 308 Perpendicular to the direction of movement of the flat-form lamination 309 Take the tip of the core tool 310 Cylindrical section removed from flat-form lamination 400 Stationary angle measurement 401 coarse filter 402 Distance between the funnel and the working surface 403 working surface 404 Center of coarse filter 405 Powder added to the funnel 406 Powder collected in a cone-shaped form 407 Tangent 408 Angle of rest 500 Temperature measurement of the sides and top of the laminate 501 laminated body 502 pyrometer 503 Observation window 504 Concave part in the mold 505 Side of the laminate 506 Top of the stacked body 507 thermocouple 600 laminated body 601 First layer 602 Another layer 603 The first surface of another layer 604 Another layer of another surface 605 First Center Line 606 Another center line 607 The center of another layer 608 First District 609 Second Zone 610 Another area

[0361] 100: Device 001: First Propulsion Component 002: First Piston 003: First Punch 004: The inner surface of the first punch; the inner surface of the punch 005: Internal surface of the mold 006: Mold 007: The inner surface of the second punch; the inner surface of the punch 008: Second Punch 009: Second Piston 010: Second Propulsion Component 011: Compression Shaft 012: Power Supply 013: Internal volume 014: First powder layer 015: wall; mold wall 200: Method 201: Steps 202: Steps 203: Steps 300: Core Test 301: Retrieve core tools; tools 302: First flat surface 303: Distance; Drilling depth 304: Sample thickness 305: Geometric Center 306: Laminated body 307: Take the core area 308: Arrow; perpendicular to the direction of movement of the flat-form laminated body. 309: Tip 310: Cylindrical section 400: Measurement of the angle of rest 401: Coarse Filter 402: Distance; the distance between the funnel and the working surface. 403: Working surface 404: The center of the coarse filter 405: Powder 406: Conical shape 407: Tangent 408: Angle 500: Temperature measurement of the sides and top of the laminated body 501: Laminated body 502: High Temperature Gauge 503: Observation Window 504: concave part 505: Side View 506: Top 507: Thermocouple 600: Laminated body 601: First Floor 602: Another floor 603: First Surface 604: Another surface 605: First Center Line 606: Another centerline 607: Center 608: Area 1 609: Second Zone 610: Another area

Claims

1. A method for producing a laminate, comprising the following steps: a. introducing a first powder and another powder into an internal volume to obtain a first powder layer and another powder layer in the internal volume, wherein the internal volume i. has a cross-sectional width W of at least 200 mm, and ii. is at least partially defined by an internal surface of a mold, wherein the mold has at least one wall, and wherein the wall comprises carbon; b. subjecting the first powder layer and the other powder layer to heat and pressure to obtain the laminate, wherein i. the heat is generated by a voltage applied across the mold, the internal volume, or both, and ii. the laminate comprises a first layer and another layer; c. subjecting the laminate to heat treatment in the presence of oxygen; wherein, After the heat treatment of the laminate, ρT > ρM, where ρT and ρM are densities measured in the other layer, and where ρT is measured at a first position in the other layer, and ρM is measured at a second position in the other layer, wherein the first position is closer to the first layer than the second position.

2. The method of claim 1, wherein the first density variation, defined as ρT / ρM – 1, is in the range of 5 x 10⁻⁵ to 1.000 x 10⁻².

3. The method of claim 1 or 2, wherein at least one or all of the following applies: a. ρT is in the range of 4.275 g / cm3 to 4.325 g / cm3; b. ρM is in the range of 4.262 g / cm3 to 4.322 g / cm3, with the constraint that ρT > ρM.

4. The method of claim 1 or 2, wherein the first powder comprises at least one or all of the following: yttrium, aluminum, zirconium, magnesium, or a combination of at least two thereof.

5. The method of claim 1 or 2, wherein the first powder is capable of forming at least one or all of the following under applied heat and pressure: a. oxide A, comprising at least 1 mol-% of a Group 3 (formerly Group IIIB) element and at least 1 mol-% of a Group 13 (formerly Group IIIA) element, wherein the mol-% is expressed as oxygen in oxide A; b. oxide B, comprising at least 1 mol-% of a Group 4 (formerly Group IVB) element and at least 1 mol-% of a Group 13 (formerly Group IIIA) element, wherein the mol-% is expressed as oxygen in oxide B.

6. The method of claim 1 or 2, wherein at least one or all of the following are applicable to the first powder: a. containing at least 25 mol-% yttrium oxide; b. containing at least 50 mol-% alumina.

7. The method of claim 1 or 2, wherein after the heat treatment of the laminate, ρT > ρB, wherein ρB is the density measured at another location in the other layer, and wherein the second location is closer to the first location than the other location.

8. The method of claim 7, wherein another density variation, defined as ρT / ρB – 1, is in the range of 5 x 10⁻⁵ to 1.000 x 10⁻².

9. The method of claim 7, wherein at least one or all of the following applies: a. the ratio ρM / ρB is in the range of 0.990 to 1.010; b. ρB is in the range of 4.262 g / cm3 to 4.322 g / cm3, subject to the condition that ρT > ρB.

10. The method of claim 1 or 2, wherein the ratio of the thickness of the other layer to the thickness of the first layer is in the range of 0.5 to 15.

11. The method of claim 1 or 2, wherein at least one or all of the following are applicable to the laminate: a. the first layer has a thickness in the range of 0.5 mm to 12 mm; b. the other layer has a thickness in the range of 5 mm to 50 mm.

12. A stack that can be obtained by any of the methods described in claims 1 to 11.

13. A laminate comprising a first layer and another layer, wherein ρT > ρM, wherein ρT and ρM are densities measured in the other layer, and wherein ρT is measured at a first position in the other layer, and ρM is measured at a second position in the other layer, wherein the first position is closer to the first layer than the second position.

14. An assembly comprising a stack as claimed in any one of claims 12 and 13.

15. A laminate comprising a first layer and another layer, wherein the other layer has a density variation configured to: a. increase the strength of the laminate; and / or b. reduce the defect rate of the laminate.

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