Cordierite Sintered Body and Its Manufacturing Method

Abstract

This invention relates to a cordierite sintered body containing all elements belonging to element group M1, which includes calcium, magnesium, aluminum, and silicon. In oxide form, the calcium content is 0.06% by mass to 3.40% by mass, the magnesium content is 12.9% by mass or more, and the content of metallic elements other than those belonging to element group M1 (element M2) is 1.5% by mass or less. The cordierite sintered body has a porosity of 3.0% by volume or less, a four-point flexural strength of 170 MPa or more, and a Weber modulus of 9.5 or more.

Description

Technical Field

[0001] This invention relates to a cordierite sintered body and its manufacturing method. Prior Technology

[0002] Previously, sintered bodies containing cordierite (cordierite sintered bodies) were used as components exposed to plasma (Patent Document 1). Previous technical documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 9-295863 Summary of the Invention

[0004] [The problem the invention aims to solve]

[0005] The inventors found through their research that the previous cordierite sintered body had insufficient plasma resistance. Furthermore, cordierite sintered bodies may require excellent thermal shock resistance depending on their intended use.

[0006] The present invention was made in view of the above circumstances, and its purpose is to provide a cordierite sintered body with excellent plasma resistance and thermal shock resistance, and a method for manufacturing the same. [Technical means to solve the problem]

[0007] The inventors conducted intensive research and discovered that the above-mentioned objective can be achieved by adopting the following structure, thereby completing the present invention.

[0008] That is, the present invention provides the following [1] to

[11] . [1] A cordierite sintered body containing all elements belonging to element group M1, which includes calcium, magnesium, aluminum and silicon, wherein the calcium content is 0.06% by mass or more and 3.40% by mass in oxide form, the magnesium content is 12.9% by mass or more in oxide form, the content of metallic elements other than elements belonging to element group M1, i.e., element M2, is 1.5% by mass or less in oxide form, the porosity of the cordierite sintered body is 3.0% by volume or less, the four-point bending strength is 170 MPa or more, and the Weber modulus is 9.5 or more. [2] The cordierite sintered body described in [1] above, wherein the calcium content is 0.09% by mass or more and 1.80% by mass or less when converted to oxides. [3] The cordierite sintered body described in [1] or [2] above, wherein the aluminum content is less than 39.0% by mass when converted to oxides. [4] The cordierite sintered body described in any of [1] to [3] above, wherein the titanium content is less than 0.5% by mass when converted to oxides. [5] The cordierite sintered body described in any of [1] to [4] above, wherein the total content of iron, nickel, chromium and manganese, converted to oxides, is less than 0.6% by mass. [6] The cordierite sintered body described in any of [1] to [5] above, wherein the content of alkali metals is less than 0.30% by mass when converted to oxides. [7] The cordierite sintered body described in any of [1] to [6] above has a thermal conductivity of 4.0 W / (m·K) or higher. [8] The cordierite sintered body described in any of [1] to [7] above, wherein the number of foreign particles containing the above-mentioned element M2 with a circumference of 5 μm or more is less than 150 particles / cm2. [9] A method for manufacturing a cordierite sintered body, which is a method for manufacturing a cordierite sintered body as described in any one of [1] to [8] above, and using raw material powder to make a molded body, heating the molded body, and using a mixed powder containing cordierite powder, mullite powder and magnesium oxide powder manufactured by electrofusion as the raw material powder.

[10] The method for manufacturing cordierite sintered body as described in [9] above, wherein the above mixed powder further contains calcium oxide powder.

[11] The method for manufacturing cordierite sintered body as described in [9] or

[10] above uses cordierite powder after magnetic separation. [Effects of the Invention]

[0009] According to the present invention, a cordierite sintered body with excellent plasma resistance and thermal shock resistance, and a method for manufacturing the same, can be provided. Implementation

[0010] The meanings of the terms used in this invention are as follows. The range of values ​​represented by "~" refers to the range of values ​​before and after "~" as both the lower and upper limits.

[0011] [Sintered body] The cordierite sintered body of this invention contains all elements belonging to element group M1, which includes calcium, magnesium, aluminum, and silicon. The calcium content, converted from oxides, is 0.06% by mass to 3.40% by mass, the magnesium content, converted from oxides, is 12.9% by mass or more, the content of metallic elements other than those belonging to element group M1 (i.e., element M2), converted from oxides, is 1.5% by mass or less, the porosity is 3.0% by volume or less, the four-point bending strength is 170 MPa or more, and the Weber modulus is 9.5 or more.

[0012] Hereinafter, the cordierite sintered body will be referred to simply as "sintered body", and the cordierite sintered body of the present invention will be referred to as "this sintered body".

[0013] This sintering system comprises sintered bodies of cordierite metal oxides. Examples of chemical formulas for cordierite include 2MgO-2Al₂O₃-5SiO₂, but it is not limited to these. In addition to cordierite (2MgO-2Al₂O₃-5SiO₂), this sintered body also contains a specific amount of calcium (Ca). Furthermore, the magnesium (Mg) content of this sintered body is higher than that of ordinary cordierite. Furthermore, the porosity, four-point bending strength, and Weber modulus of this sintered body represent specific values. This type of sintered body exhibits excellent plasma resistance and thermal shock resistance. The sintered body will now be described in more detail.

[0014] <Element Group M1> As mentioned above, in addition to cordierite (2MgO-2Al 2O 3-5SiO 2), this sintered body also contains calcium (Ca). Therefore, this sintered body contains all elements belonging to element group M1, which includes calcium (Ca), magnesium (Mg), aluminum (Al) and silicon (Si).

[0015] 《Ca》 To achieve excellent plasma resistance in this sintered body, the Ca content, converted from oxides, should be 0.06% by mass or more, preferably 0.09% by mass or more, even more preferably 0.12% by mass or more, further preferably 0.18% by mass or more, particularly preferably 0.24% by mass or more, and most preferably 0.40% by mass or more. For the same reason, and in order to improve the values ​​of four-point bending strength and Weber modulus, the Ca content is 3.40% by mass or less, preferably 2.50% by mass or less, more preferably 1.80% by mass or less, even more preferably 1.20% by mass or less, and especially preferably 0.80% by mass or less. The Ca content converted to oxides specifically refers to the CaO content. It is believed that an appropriate amount of Ca enables the particles constituting the sintered body to bond together or to solidify within the particles, thereby strengthening the particles themselves, thus reducing the rate of degradation caused by plasma and improving plasma resistance.

[0016] Mg To achieve excellent plasma resistance in this sintered body, the Mg content, converted from oxides, should be 12.9% by mass or more, preferably 13.2% by mass or more, even more preferably 13.5% by mass or more, further preferably 14.0% by mass or more, even more preferably 14.5% by mass or more, particularly preferably 15.0% by mass or more, and most preferably 15.5% by mass or more. For the same reason, the content of Mg, converted to oxides, is preferably 17.5% by mass or less, more preferably 17.0% by mass or less, further preferably 16.5% by mass or less, and especially preferably 16.0% by mass or less. The Mg content converted to oxides specifically refers to the MgO content.

[0017] 《Al》 In this sintered body, if the amount of Al is too high, the amount of Mg will be relatively low. Therefore, from the viewpoint of ensuring the required amount of Mg, the Al content, converted in oxide form, is preferably 40.0% by mass or less, more preferably 39.0% by mass or less, further preferably 38.0% by mass or less, particularly preferably 37.5% by mass or less, and most preferably 37.0% by mass or less. Furthermore, if the Al content is too high, the Weber modulus value tends to decrease. In this case, the Al content is also preferably within the aforementioned range. On the other hand, there is no particular lower limit. The content of Al is converted into oxides, for example, 30.0% by mass or more, preferably 33.0% by mass or more, more preferably 34.0% by mass or more, further preferably 34.5% by mass or more, further preferably 35.0% by mass or more, especially preferably 35.5% by mass or more, and most preferably 36.0% by mass or more. The Al content converted to oxides specifically refers to the Al₂O₃ content.

[0018] The content of metallic elements (elements belonging to element group M1 and element M2, but excluding Si) in the sintered body was determined using inductively coupled plasma mass spectrometry (ICP-MS). Specifically, the sample was immersed in an extraction solution of HF:HNO3 = 4:1 (mass ratio) for 2 days, followed by heating at 80°C for 1 hour. The sample was then removed using tweezers, yielding an extract from which the metal element was extracted. After drying the extract, it was diluted to 10 mL with HNO3 solution and analyzed using an Agilent Technologies instrument (Agient 8800).

[0019] Si The Si content, converted from oxides, is preferably 43.0% by mass or more, more preferably 44.0% by mass or more, further preferably 45.0% by mass or more, further preferably 46.0% by mass or more, especially preferably 46.5% by mass or more, and most preferably 47.0% by mass or more. On the other hand, the Si content, converted to oxides, is preferably 55.0% by mass or less, more preferably 51.0% by mass or less, further preferably 50.0% by mass or less, particularly preferably 49.0% by mass or less, and most preferably 48.0% by mass or less. The Si content converted to oxides specifically refers to the SiO2 content.

[0020] The Si content in the sintered body is determined by the following method. First, a powdered sample was collected from the center of the sintered body by grinding. The total oxygen content Z1 in the sintered body was determined by infrared absorption method using an oxygen-hydrogen analysis device (LECO ROH-600). The oxygen content Z3 is calculated by subtracting the oxygen content Z2 of the elements (excluding silicon atoms) bonded in the sintered body in stoichiometric form from the total oxygen content Z1 in the sintered body. That is, oxygen content Z3 = total oxygen content Z1 - oxygen content Z2. Assuming the total oxygen content Z3 is used for bonding with silicon atoms, the oxygen content Z3 is converted into SiO2 content. The SiO2 content obtained in this way is taken as the Si content in the sintered body in terms of oxides (SiO2 content).

[0021] <Element M2> In this sintered body, the content of metallic elements (i.e., impurities) other than those belonging to element group M1 is relatively low. As a result, this sintered body exhibits excellent plasma resistance and thermal shock resistance. Specifically, the content of metallic elements other than those belonging to element group M1, i.e., element M2, is 1.5% by mass or less when converted to oxides, preferably 1.1% by mass or less, more preferably 0.7% by mass or less, further preferably 0.5% by mass or less, even more preferably 0.3% by mass or less, particularly preferably 0.2% by mass or less, and most preferably 0.1% by mass or less. The lower limit is preferably zero (0% by mass).

[0022] Element M2 can be exemplified by at least one element selected from the group consisting of titanium (Ti), iron (Fe), nickel (Ni), chromium (Cr), manganese (Mn), and alkali metals.

[0023] Ti To achieve better plasma resistance in this sintered body, the Ti content, converted from oxides, is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, further preferably 0.2% by mass or less, further preferably 0.1% by mass or less, particularly preferably 0.05% by mass or less, and most preferably 0.03% by mass or less. The Ti content converted to oxides specifically refers to the TiO2 content.

[0024] Fe, Ni, Cr and Mn The total content of Fe, Ni, Cr and Mn, converted to oxides, is preferably 0.6% by mass or less, more preferably 0.4% by mass or less, further preferably 0.3% by mass or less, further preferably 0.2% by mass or less, particularly preferably 0.1% by mass or less, and most preferably 0.05% by mass or less. In this case, the generation of foreign particles is suppressed, the four-point bending strength and Weber modulus are improved, and the thermal shock resistance of the sintered body is even better.

[0025] The Fe content converted to oxides specifically refers to the Fe₂O₃ content. The Ni content converted to oxides specifically refers to the NiO content. The Cr content converted to oxides specifically refers to the Cr₂O₃ content. The Mn content converted to oxides specifically refers to the MnO content.

[0026] Alkali Metals To achieve lower porosity and better plasma resistance and thermal shock resistance in the sintered body, the alkali metal content, converted from oxides, is preferably below 0.30% by mass, more preferably below 0.20% by mass, further preferably below 0.15% by mass, particularly preferably below 0.12% by mass, and most preferably below 0.09% by mass. However, for the same reasons, it is preferable to include a small amount of alkali metals. Specifically, the alkali metal content, converted to oxides, is preferably 0.01% by mass or more, and more preferably 0.03% by mass or more.

[0027] Examples of alkali metals include lithium (Li), sodium (Na), and potassium (K). The Li content converted to oxides specifically refers to the Li₂O content. The Na content converted to oxides specifically refers to the Na₂O content. The K content converted to oxides specifically refers to the K2O content.

[0028] Other Elements Other elements besides those listed above, such as copper (Cu), zinc (Zn), zirconium (Zr), gallium (Ga), phosphorus (P), and sulfur (S), are examples of M2. Furthermore, while P and S are not metallic elements, they are treated as such when used as element M2. The content of other elements, converted from oxides, is preferably less than 0.04% by mass, more preferably less than 0.04% by mass, and even more preferably less than 0.03% by mass. The Cu content converted to oxides specifically refers to the CuO content. The Zn content converted to oxides specifically refers to the ZnO content. The Zr content converted to oxides specifically refers to the ZrO2 content. The Ga content converted to oxides specifically refers to the Ga₂O₃ content. The content of P converted to oxides specifically refers to the content of P₂O₅. The S content converted to oxides specifically refers to the SO3 content.

[0029] Porosity To ensure excellent plasma resistance and thermal shock resistance of the sintered body, the porosity of the sintered body should be 3.0 vol% or less, preferably 1.5 vol% or less, more preferably 0.5 vol% or less, further preferably 0.3 vol% or less, particularly preferably 0.1 vol% or less, and most preferably 0.05 vol% or less. The lower limit is preferably zero (0 vol%).

[0030] In order to keep the porosity within the above range, it is preferable to set each component to the above content, and to manufacture the sintered body by the following method (this manufacturing method). It is particularly preferable to use cordierite powder produced by electrofusion as the raw material powder.

[0031] The porosity was calculated according to the method for calculating open porosity described in JIS R 1634:1998 "Determination of density and open porosity of sintered body of precision ceramics".

[0032] Four-point bending strength To achieve excellent thermal shock resistance, the four-point bending strength of the sintered body should be above 170 MPa, preferably above 180 MPa, more preferably above 190 MPa, even more preferably above 200 MPa, even more preferably above 210 MPa, particularly preferably above 220 MPa, and most preferably above 230 MPa. There is no particular upper limit, but the four-point bending strength of this sintered body is, for example, below 300 MPa, preferably below 250 MPa.

[0033] The four-point bending strength was determined according to JIS R 1601 (2008) at 25°C on a sintered specimen (flat plate, 50 mm in length, 4 mm in width, and 3 mm in thickness).

[0034] In order to ensure that the four-point bending strength is within the above range, it is preferable to set each component to the above content and to manufacture the sintered body by the following method (this manufacturing method). Especially when the content of Fe, Ni, Cr and Mn is relatively high, it is not easy to obtain this kind of four-point bending strength.

[0035] <Weber Modulus> To achieve excellent thermal shock resistance, the Weber modulus of the sintered body should be 9.5 or higher, preferably 10.0 or higher, even better 10.5 or higher, further preferably 11 or higher, even better 11.5 or higher, especially better 12 or higher, and best 12.5 or higher. There is no particular upper limit, but the Weber modulus of this sintered body is preferably 14 or less, and more preferably 13 or less.

[0036] The Weber modulus (the Weber modulus of four-point bending strength) is an indicator of the degree of deviation in four-point bending strength. The larger the value, the smaller the deviation in four-point bending strength. The Weber modulus was determined as follows: First, the four-point bending strength of 30 specimens was measured using the method described above. Then, using the measured bending strength data of the 30 specimens, the Weber modulus was calculated according to JIS R 1625 (2010).

[0037] In order to make the Weber modulus within the above range, it is preferable to set each component to the above content and to manufacture the sintered body by the following method (this manufacturing method). This Weber modulus is particularly difficult to obtain when the content of Fe, Ni, Cr and Mn is relatively high.

[0038] Thermal conductivity To achieve better thermal shock resistance, the thermal conductivity of this sintered body is preferably 4.0 W / (m·K) or higher, more preferably 4.2 W / (m·K) or higher, even more preferably 4.4 W / (m·K) or higher, even more preferably 4.6 W / (m·K) or higher, particularly preferably 4.8 W / (m·K) or higher, and most preferably 5.0 W / (m·K) or higher. There is no particular upper limit, but the thermal conductivity of this sintered body is, for example, below 6.0 W / (m·K), preferably below 5.5 W / (m·K).

[0039] Thermal conductivity was measured using a NETZSCH LFA 467 HyperFlash laser flash thermophysical property measuring instrument at 21°C on sintered body specimens (12 mm × 12 mm plate, 6.0 mm thick).

[0040] To ensure the thermal conductivity is within the aforementioned range, it is preferable to set the components to the aforementioned amounts and manufacture the sintered body using the method described below (this manufacturing method). This is preferably used to obtain a dense sintered body with fewer impurities.

[0041] <Outlier (Number of foreign particles)> The sintered body was observed at 1,000x magnification using a scanning electron microscope (SEM), and SEM images of any 50 fields of view were obtained. For the obtained SEM images, the EDX (Energy Dispersive X-ray Spectrometry) device built into the SEM was used to identify foreign particles containing element M2 (particles composed of element M2). The number of foreign particles with a circular equivalent diameter of 5 μm or more among the identified foreign particles (unit: particles / cm2) was measured, and the average value of 50 fields of view was calculated. The obtained average value was taken as the number of foreign particles in the sintered body. Furthermore, in this specification, for ease of explanation, the number of foreign particles is sometimes referred to as "heterogeneous phase quantity".

[0042] To achieve good four-point flexural strength, Weber modulus, and superior thermal shock resistance in this sintered body, the heterogeneous quantity (i.e., the number of foreign particles containing element M2 with a circumferential diameter of 5 μm or more) is preferably 150 particles / cm² or less, more preferably 100 particles / cm² or less, further preferably 50 particles / cm² or less, further preferably 30 particles / cm² or less, particularly preferably 10 particles / cm² or less, and most preferably 5 particles / cm² or less. The lower limit is preferably zero (0 particles / cm²).

[0043] In order to keep the heterogeneous phase content within the above range, it is preferable to set each component to the above content and manufacture the sintered body by the following method (this manufacturing method).

[0044] <Shape and Use> Examples of possible shapes for this sintered body include: plate-shaped (e.g., circular plate-shaped, flat plate-shaped), spherical, elongated spherical, etc., which can be appropriately selected according to the application. This sintered body is suitable as a substrate material for supporting wafers in semiconductor manufacturing equipment, but its use is not limited to this.

[0045] [Manufacturing Method of Sintered Body] Next, the method for manufacturing this sintered body (hereinafter also referred to as "this manufacturing method") will be explained. Generally speaking, this manufacturing method involves using raw material powder to form a molded body and then heating the molded body. The manufacturing method will now be described in detail.

[0046] <Raw Material Powder> The raw material powder is a mixture of cordierite powder, mullite powder, and magnesium oxide powder produced by electrofusion.

[0047] Iolite powder Cordierite (2MgO-2Al 2O 3-5SiO 2) powder is the raw material for Mg, Al and Si that constitute this sintered body. Furthermore, the cordierite powder may contain Ca as an impurity, in which case Ca is supplied to the sintered body.

[0048] (Fused cordierite powder) In this manufacturing method, cordierite powder manufactured by electrofusion (also referred to as "electrofused cordierite powder" for ease of explanation) is used. The method for obtaining fused cordierite powder is generally as follows. First, the raw material for fused cordierite powder is added to the crucible. Examples of raw materials for fused cordierite powder include magnesium oxide (MgO), aluminum oxide (Al₂O₃), and silicon dioxide (SiO₂). These raw materials may contain impurities such as calcium (Ca). Subsequently, for example, a carbon electrode is used to generate a plasma, thereby melting the raw materials in the crucible. Subsequently, the molten raw material is air-crushed and rapidly cooled. This process yields fused cordierite powder. Fused cordierite powder is a predominantly amorphous substance (powder) containing a small amount of crystals. The particles constituting the fused cordierite powder are spherical and uniform in size, i.e., homogeneous. Therefore, fused cordierite powder is easily sintered in the presence of mullite powder, which is used as a sintering aid. That is, it exhibits good sinterability. As a result, a dense sintered body can be obtained, and the porosity can be reduced. Furthermore, by using the electrofusion method for manufacturing, impurities such as Ti can also be reduced. As an electrically fused cordierite powder, commercially available products can be used, such as ELP-150FINE (manufactured by AGC Ceramics Inc.).

[0049] Mullite powder Mullite is represented by chemical formulas such as 3Al₂O₃-2SiO₂ and 2Al₂O₃-SiO₂. Mullite powder can be used as a sintering aid. By using mullite powder as a sintering aid, dense sintered bodies can be obtained. Mullite powder is the raw material for Al and Si that constitute this sintered body.

[0050] Magnesium Oxide Powder Magnesium oxide (MgO) powder is the raw material for Mg that constitutes this sintered body. As mentioned above, the Mg content of this sintered body is higher than that of ordinary cordierite, therefore magnesium oxide powder is used as the raw material powder.

[0051] Calcium oxide powder The raw material powder may further contain calcium oxide (CaO) powder. As described above, this sintered body contains Ca in addition to cordierite. Therefore, when the Ca contained in the cordierite powder as an impurity is insufficient, calcium oxide powder is used as the raw material powder.

[0052] "magnetic separation" For powders used as raw material powders, especially fused cordierite powder, it is preferable to use them after magnetic separation. In this way, the content of metallic elements other than those belonging to element group M1 (Ca, Mg, Al and Si), namely element M2 (Ti, Fe, etc.), can be reduced in the final sintered body. As a method of magnetic separation, a suitable example is the use of a wet magnetic filter. There are no particular limitations on the conditions for magnetic separation; for example, it is sufficient to adjust the conditions appropriately so that the element M2 in the resulting sintered body reaches the desired content.

[0053] Preparation of Raw Material Powders The powders described above are then magnetically separated and mixed as appropriate. This yields a raw material powder that serves as a mixture of the powders. The mixing method is not particularly limited and can be any previously known method. The content of each powder in the raw material powder (mixed powder) is appropriately adjusted in such a way that the content of each component in the final sintered body is the required amount. From the viewpoint of improving the sintering properties during the following heating process, it is preferable to pulverize the mixed powder to reduce the particle size. Specifically, the average particle size of the pulverized mixed powder is preferably 10 μm or less, and more preferably 2 μm or less. The average particle size is the particle size at the 50% cumulative value of the particle size distribution obtained by laser diffraction scattering (D 50) (the same applies below). There are no particular limitations on the method of pulverization; ball mills, grinding mills, bead mills, jet mills, etc., can be used for pulverization. When wet grinding is used, the mixed powder after grinding is dried.

[0054] <Making of Shaped Objects> Next, the raw material powder (mixed powder) is used to make a molded body. That is, molding is carried out. There are no particular limitations on the forming method; general forming methods can be used. For example, an isostatic press can be used to form the material at a pressure of 100 MPa to 200 MPa. As another method, the mixture obtained by adding an organic binder to a mixed powder can be shaped into a specified shape by means of pressure molding, extrusion molding, sheet forming, etc. The shape obtained by forming can be appropriately selected according to the intended use of the sintered body.

[0055] <Heating> The resulting shaped body is then heated. This yields a sintered body. From the viewpoint of improving sinterability, the heating temperature (the highest temperature during heating) is preferably 1400°C or higher, more preferably 1410°C or higher, and even more preferably 1430°C or higher. On the other hand, if the heating temperature is too high, the following situations may occur: a portion of the resulting sintered body may melt and break, or a sintered body of the required size may not be obtained. Therefore, the heating temperature is preferably below 1450°C, and more preferably below 1440°C. The heating time (time at the highest temperature) is preferably more than 1 hour, more preferably more than 2 hours, and even more preferably more than 5 hours. On the other hand, the heating time is preferably less than 48 hours, more preferably less than 12 hours, and even more preferably less than 8 hours. There are no particular limitations on the atmosphere used for heating (heating atmosphere). Examples include: atmospheric atmosphere; inert atmospheres such as nitrogen and argon atmospheres; reducing atmospheres such as hydrogen atmospheres and mixed atmospheres of hydrogen and nitrogen; etc.

[0056] The resulting sintered body is preferably densified. Densification is carried out, for example, using a hot isostatic press. Specifically, for example, a hot isostatic press is used to apply a pressure of 100 MPa to 200 MPa while heating is performed at a temperature of 1000°C to 1350°C. Example

[0057] The present invention will now be described in detail with examples. However, the present invention is not limited to the examples described below. Examples 1-2, 5-9, 11-12, 14-17, 19-21 and 23-25 ​​are examples, and examples 3-4, 10, 13, 18 and 22 are comparative examples.

[0058] <Example 1~25> The sintered bodies of each example were obtained by the following methods.

[0059] Raw Material Powder Fused cordierite (2MgO-2Al 2O 3-5SiO 2) powder, mullite (3Al 2O 3-2SiO 2) powder, magnesium oxide (MgO) powder, and calcium oxide (CaO) powder, which are used as sintering aids, are mixed together. "ELP-150FINE" (average particle size: 14.1 μm) manufactured by AGC Ceramics Co., Ltd. was used as the fused cordierite powder. KM101 (average particle size: 0.8 μm) manufactured by Kyoritsu Materials Co., Ltd. was used as the mullite powder. Specifically, the powders are mixed such that the contents of elements belonging to element group M1 and element M2 in the sintered body are as shown in Tables 1 to 3 below, thereby obtaining raw material powder as mixed powder. At this point, other metal oxide powders such as titanium dioxide (TiO2) powder may be added as appropriate.

[0060] Each powder was magnetically separated before mixing. Specifically, a wet magnetic filter (NIPPON MAGNETIC DRESSING FG type wet high flux testing machine) was used to perform three magnetic separations on the slurry (concentration: 15% by volume) in which each powder was dispersed in water at a temperature of 2.8 Tesla. However, in Examples 16-18, magnetic separation was not performed on each powder.

[0061] For the raw material powder (mixed powder), a ball mill equipped with high-purity alumina balls was used, with ethanol as the dispersion medium, for wet mixing and pulverization. The average particle size (D50) of the pulverized raw material powder was 2.0 μm.

[0062] Fabrication and Heating of Molded Components At room temperature, the obtained raw material powder (mixed powder) is pressurized at a pressure of 180 MPa using an isostatic press to produce a molded body. Subsequently, a sintered body is obtained by heating the molded body in the atmosphere. The heating temperature is set to 1430°C and the heating time is set to 5 hours. Furthermore, the resulting sintered body is densified. Specifically, a pressure of 145 MPa is applied using a hot isostatic press while heating at 1300°C. However, in Examples 24 and 25, densification was not performed.

[0063] <Elements belonging to element group M1 and the abundance of element M2> For each example of sintered body, the content of elements belonging to element group M1 and element M2, converted to oxides, was determined using the method described above. The results are shown in Tables 1-3 below.

[0064] <Porosity, etc.> For each example of sintered body, the porosity, heterogeneity, four-point flexural strength, Weber modulus, and thermal conductivity were determined using the methods described above. The results are shown in Tables 1-3 below.

[0065] <Thermal Shock Resistance Test> A test piece measuring 15 mm × 5 mm × 100 mm was cut from the sintered body. After heating the test piece at 350°C for 60 minutes, it was immersed in water at room temperature. Then, the test piece was removed from the water, and the cracks on the test piece were stained with a dye penetrant testing agent (manufactured by TASETO Co., Ltd., penetrant FP-S and developer FD-S) and confirmed by visual inspection. The case with no cracks longer than 3 mm is marked as "○", the case with 1 to 2 cracks longer than 3 mm is marked as "△", and the case with 3 or more cracks longer than 3 mm is marked as "×". These are recorded in Tables 1 to 3 below. If it is "○" or "△", it is rated as having excellent thermal shock resistance.

[0066] <Etching Amount> The etching amount was determined for each sintered body, and the plasma resistance was evaluated. Specifically, a 10 mm × 5 mm × 4 mm specimen was cut from the sintered body, and the 10 mm × 5 mm surface was mirror-finished. Kapton (registered trademark) tape was applied to a portion of the mirror-finished surface to mask it, and plasma gas etching was performed. Subsequently, a stylus-type surface shape measuring machine (ULVAC, Dectak 150) was used to measure the step difference between the etched and unetched areas to determine the etching amount. EXAM (manufactured by Shinko Seiki Co., Ltd., model: POEM) was used as the plasma etching apparatus. Etching was performed for 390 minutes using CF4 gas at a pressure of 10 Pa and an output of 350 W in RIE mode (reactive ion etching mode). The smaller the etching amount (unit: nm), the better the plasma resistance. Specifically, if the etching depth is below 420 nm, it is evaluated as having excellent plasma resistance.

[0067] [Table 1] Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 M1 CaO quality% 0.104 0.097 0.123 0.022 0.452 0.247 1.602 0.795 2.864 MgO quality% 14.655 14.900 12.545 14.355 15.221 15.751 13.236 13.876 12.923 Al₂O₃ quality% 37.103 36.874 37.572 37.222 37.032 37.224 36.934 35.979 37.031 SiO 2 quality% 47.887 47.823 49.529 48.088 47.201 46.562 48.022 49.142 46.941 M2 TiO2 quality% 0.023 0.052 0.024 0.045 0.024 0.028 0.012 0.017 0.019 Fe₂O₃ quality% 0.044 0.089 0.047 0.078 0.018 0.054 0.053 0.032 0.031 NiO quality% 0.007 0.012 0.002 0.007 0.000 0.000 0.002 0.003 0.000 Cr₂O₃ quality% 0.000 0.003 0.000 0.002 0.000 0.000 0.002 0.000 0.000 MnO quality% 0.005 0.000 0.000 0.004 0.002 0.000 0.002 0.000 0.000 Li 2O quality% 0.000 0.001 0.000 0.002 0.000 0.000 0.000 0.001 0.000 Na₂O quality% 0.100 0.121 0.093 0.098 0.012 0.087 0.036 0.074 0.102 K 2O quality% 0.008 0.006 0.005 0.007 0.003 0.005 0.008 0.002 0.004 La 2O 3 quality% 0.052 0.006 0.048 0.055 0.023 0.028 0.078 0.064 0.072 other quality% 0.012 0.016 0.012 0.015 0.012 0.014 0.013 0.015 0.013 Fe₂O₃ + NiO + Cr₂O₃ + MnO quality% 0.056 0.104 0.049 0.091 0.020 0.054 0.059 0.035 0.031 Li₂O + Na₂O + K₂O quality% 0.108 0.128 0.098 0.107 0.015 0.092 0.044 0.077 0.106 M2 total quality% 0.251 0.306 0.231 0.313 0.094 0.216 0.206 0.208 0.241 M1+M2 total quality% 100.000 100.000 100.000 100.000 100.000 100.000 100.000 100.000 100.000 Porosity volume% 0.06 0.00 0.02 0.03 0.01 0.09 0.11 0.07 0.31 heterogeneous pcs / cm 2 6 twenty four 8 31 4 10 10 9 8 Four-point bending strength MPa 231 226 221 232 207 199 201 221 188 Weber Modulus - 12.7 12.4 11.9 13.1 12.2 13.1 11.2 11.5 10.5 thermal conductivity W / (m·K) 4.8 4.5 4.2 4.7 5.2 5.0 4.5 4.5 4.7 Thermal shock test - ○ ○ ○ ○ ○ △ ○ ○ △ Etching amount nm 372 375 456 422 348 357 385 369 398

[0068] [Table 2] Table 2 Example 10 Example 11 Example 12 Example 13 Example 14 Example 15 Example 16 Example 17 Example 18 M1 CaO quality% 6.876 0.087 0.074 0.039 0.092 0.102 0.100 0.112 0.047 MgO quality% 12.569 16.432 14.956 14.874 15.022 14.659 14.984 15.321 15.019 Al₂O₃ quality% 37.072 35.653 37.025 37.012 36.087 37.568 38.012 38.091 37.874 SiO 2 quality% 43.252 47.514 47.552 47.597 48.115 46.712 46.435 45.697 45.879 M2 TiO2 quality% 0.024 0.087 0.212 0.256 0.472 0.762 0.054 0.032 0.017 Fe₂O₃ quality% 0.047 0.077 0.043 0.052 0.047 0.041 0.189 0.480 0.730 NiO quality% 0.002 0.011 0.002 0.000 0.000 0.002 0.045 0.052 0.022 Cr₂O₃ quality% 0.000 0.002 0.002 0.000 0.000 0.000 0.007 0.008 0.002 MnO quality% 0.000 0.000 0.000 0.001 0.000 0.003 0.008 0.002 0.006 Li 2O quality% 0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Na₂O quality% 0.093 0.114 0.089 0.083 0.093 0.077 0.092 0.099 0.105 K 2O quality% 0.005 0.003 0.004 0.004 0.009 0.005 0.002 0.003 0.008 La 2O 3 quality% 0.048 0.006 0.032 0.067 0.053 0.058 0.049 0.072 0.273 other quality% 0.012 0.013 0.009 0.015 0.010 0.011 0.023 0.031 0.018 Fe₂O₃ + NiO + Cr₂O₃ + MnO quality% 0.049 0.090 0.047 0.053 0.047 0.046 0.249 0.542 0.760 Li₂O + Na₂O + K₂O quality% 0.098 0.118 0.093 0.087 0.102 0.082 0.094 0.102 0.113 M2 total quality% 0.231 0.314 0.393 0.478 0.684 0.959 0.469 0.779 1.181 M1+M2 total quality% 100.000 100.000 100.000 100.000 100.000 100.000 100.000 100.000 100.000 Porosity volume% 0.51 0.01 0.03 0.04 0.06 0.07 0.03 0.02 0.01 heterogeneous pcs / cm 2 20 18 33 41 37 33 76 148 332 Four-point bending strength MPa 169 201 232 218 223 220 204 193 173 Weber Modulus - 9.3 10.7 12.2 12.2 12.8 12.3 10.5 9.9 9.2 thermal conductivity W / (m·K) 4.2 4.2 5.1 5.0 4.7 4.8 4.7 4.4 4.1 Thermal shock test - × ○ ○ ○ ○ ○ ○ △ × Etching amount nm 423 350 384 421 399 411 385 376 433

[0069] [Table 3] Table 3 Example 19 Example 20 Example 21 Example 22 Example 23 Example 24 Example 25 M1 CaO quality% 0.111 0.117 0.104 0.101 0.087 0.102 0.099 MgO quality% 15.785 14.653 14.655 14.892 14.155 14.635 14.912 Al₂O₃ quality% 33.642 38.811 39.903 41.435 36.103 37.093 36.745 SiO 2 quality% 50.214 46.202 45.077 43.349 49.104 47.926 47.959 M2 TiO2 quality% 0.009 0.007 0.022 0.027 0.044 0.033 0.042 Fe₂O₃ quality% 0.044 0.033 0.045 0.038 0.057 0.034 0.088 NiO quality% 0.002 0.002 0.007 0.006 0.006 0.005 0.014 Cr₂O₃ quality% 0.000 0.002 0.000 0.001 0.001 0.000 0.003 MnO quality% 0.000 0.000 0.000 0.000 0.002 0.003 0.001 Li 2O quality% 0.000 0.000 0.000 0.001 0.001 0.000 0.003 Na₂O quality% 0.118 0.106 0.112 0.087 0.357 0.108 0.111 K 2O quality% 0.007 0.004 0.009 0.008 0.009 0.004 0.005 La 2O 3 quality% 0.057 0.050 0.052 0.044 0.057 0.045 0.005 other quality% 0.011 0.013 0.014 0.011 0.017 0.012 0.013 Fe₂O₃ + NiO + Cr₂O₃ + MnO quality% 0.046 0.037 0.052 0.045 0.066 0.042 0.106 Li₂O + Na₂O + K₂O quality% 0.125 0.110 0.121 0.096 0.367 0.112 0.119 M2 total quality% 0.248 0.217 0.261 0.223 0.551 0.244 0.285 M1+M2 total quality% 100.000 100.000 100.000 100.000 100.000 100.000 100.000 Porosity volume% 0.00 0.03 0.05 0.06 0.21 0.33 0.59 heterogeneous pcs / cm 2 19 17 15 11 32 8 7 Four-point bending strength MPa 200 206 209 211 201 204 189 Weber Modulus - 11.3 11.5 10.8 9.4 11.0 10.7 10.1 thermal conductivity W / (m·K) 4.4 5.1 5.3 4.6 4.3 4.8 4.6 Thermal shock test - ○ ○ △ × ○ ○ ○ Etching amount nm 386 381 378 390 407 379 388

[0070] <Summary of Evaluation Results> As shown in Tables 1-3 above, the sintered bodies of Examples 1-2, 5-9, 11-12, 14-17, 19-21 and 23-25 ​​exhibit excellent plasma resistance and thermal shock resistance.

[0071] In contrast, the sintered bodies of Examples 3-4, 10, 13, 18 and 22 have insufficient plasma resistance and thermal shock resistance. Specifically, as described below. In Example 3, the MgO content did not reach 12.9% by mass, the etching amount was relatively large, and the plasma resistance was insufficient. In Example 4, the CaO content was less than 0.06% by mass, the etching amount was relatively large, and the plasma resistance was insufficient. In Example 10, the MgO content did not reach 12.9% by mass, the etching amount was relatively large, and the plasma resistance was insufficient. Furthermore, in Example 10, the CaO content exceeded 3.40% by mass, the four-point bending strength did not reach 170 MPa, and the Weber modulus did not reach 9.5, indicating insufficient thermal shock resistance. In Example 13, the CaO content was less than 0.06% by mass, the etching amount was relatively large, and the plasma resistance was insufficient. In Example 18, the CaO content was less than 0.06% by mass, the etching amount was relatively large, and the plasma resistance was insufficient. Furthermore, in Example 18, the Weber modulus did not reach 9.5, indicating insufficient thermal shock resistance. In Example 22, the Weber modulus did not reach 9.5, indicating insufficient thermal shock resistance.

[0072] The present invention has been described in detail with reference to specific embodiments, but those skilled in the art will understand that various changes or modifications may be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2021-035458, filed on March 5, 2021, the contents of which are incorporated herein by reference.

Claims

1. A cordierite sintered body containing all elements belonging to element group M1, which includes calcium, magnesium, aluminum, and silicon, wherein the calcium content, converted to oxides, is 0.06% by mass to 3.40% by mass, the magnesium content, converted to oxides, is 12.9% by mass or more, the content of metallic elements other than those belonging to element group M1, i.e., element M2, is 1.5% by mass or less, converted to oxides, and the combined content of iron, nickel, chromium, and manganese is 0.1% by mass or less, the porosity of the cordierite sintered body is 3.0% by volume or less, the four-point flexural strength is 170 MPa or more, and the Weber modulus is 9.5 or more.

2. The cordierite sintered body as claimed in Item 1, wherein the calcium content, converted to oxides, is more than 0.09% by mass and less than 1.80% by mass.

3. The cordierite sintered body as claimed in item 1 or 2, wherein the aluminum content, converted to oxides, is less than 39.0% by mass.

4. The cordierite sintered body as requested in item 1 or 2, wherein the titanium content, converted to oxides, is less than 0.5% by mass.

5. The cordierite sintered body as claimed in item 1 or 2, wherein the calcium content, converted to oxides, is less than 0.247% by mass.

6. The cordierite sintered body as requested in item 1 or 2, wherein the aluminum content, converted to oxides, is 35.5% by mass or more.

7. The cordierite sintered body as claimed in item 1 or 2, wherein the content of the aforementioned magnesium, converted to oxides, is 13.5% by mass or more.

8. The cordierite sintered body as requested in item 1 or 2, wherein the alkali metal content, converted to oxides, is less than 0.30% by mass.

9. The cordierite sintered body of request item 1 or 2 has a thermal conductivity of 4.0 W / (m·K) or higher.

10. In the cordierite sintered body of claim 1 or 2, the number of foreign particles containing the aforementioned element M2 with a circumference of 5 μm or more is less than 150 particles / cm2.

11. A method for manufacturing a cordierite sintered body, comprising a method for manufacturing a cordierite sintered body as claimed in any one of claims 1 to 10, wherein a shaped body is formed using raw material powder, the shaped body is heated, and a mixed powder containing cordierite powder, mullite powder, and magnesium oxide powder manufactured by electrofusion is used as the raw material powder.

12. The method for manufacturing cordierite sintered body as claimed in claim 11, wherein the above-mentioned mixed powder further contains calcium oxide powder.

13. The method for manufacturing cordierite sintered body as claimed in claim 11 or 12, wherein the cordierite powder is magnetically separated before use.