A composite ceramic mold plate and its application

Abstract

The present invention discloses a composite ceramic mold plate and its application, which relates to the field of microcrystalline glass mold plates, and comprises the following parts by weight of raw materials: 30-95 parts of surface oxidation-modified aluminum nitride powder, 10-75 parts of silicon nitride powder, 12-35 parts of boron nitride powder, 1-10 parts of tungsten carbide powder, 1-10 parts of bonding phase and 3-10 parts of sintering aid. The method for preparing the composite ceramic mold plate comprises the following steps: S1. ball milling, drying and sieving the prepared raw materials to obtain a dried material; S2. sequentially performing low-temperature low-hot pressing sintering, high-temperature high-hot pressing sintering and nitrogen overpressure sintering on the dried material to obtain a composite ceramic mold plate. The composite ceramic mold plate prepared by the present invention has high density, high strength and excellent thermal conductivity through reasonable raw material formula and sintering conditions. When it is used as a microcrystalline glass mold plate, it can achieve the effects of high precision and long life.

Description

Technical Field

[0001] The invention belongs to the technical field of microcrystalline glass mold plates, and in particular to a complex phase ceramic mold plate and application thereof. Background Art

[0002] The traditional metal back cover of smartphones is gradually being eliminated due to signal shielding. Therefore, the curved glass with low cost, easy processing, high yield rate, good feel and stable performance stands out and quickly expands to other 3C electronic product fields. At present, the curved glass has covered the front and back covers of mobile phones.

[0003] The hot bending temperature of glass-ceramics used in smartphone screens can reach 900°C or above, which places higher requirements on mold materials. Traditional hot bending glass mold plates are made of high-strength graphite materials. When hot bending glass-ceramics, due to the hardness and oxidation resistance of the graphite mold, the life span is drastically shortened to about 100 pieces, and the yield rate is greatly reduced, making it almost unusable.

[0004] At present, CN118598666A uses boron carbide skeleton and layered boron nitride as the main phase, and improves the material strength by adjusting the ratio and particle size of the two; CN108298991A uses BN powder as the main phase, improves the density of mold materials through organic binders, and also improves the antioxidant ability, so it is more suitable for high temperature environments. However, the mechanical properties of the mold plate materials in the prior art, such as density and strength, are relatively low, and boron nitride itself is relatively soft, prone to powdering and powdering, and has a low thermal conductivity. Summary of the invention

[0005] In order to overcome the above technical problems, the present invention provides a composite ceramic mold plate and its application. The composite ceramic mold plate prepared by the present invention has high density, high strength and excellent thermal conductivity through reasonable raw material formula and improved sintering conditions. When used as a microcrystalline glass mold plate, it can achieve high precision and long life.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The present invention provides a composite ceramic mold plate, comprising the following raw materials in parts by weight: 30-95 parts of surface oxidation-modified aluminum nitride powder, 10-75 parts of silicon nitride powder, 12-35 parts of boron nitride powder, 1-10 parts of tungsten carbide powder, 1-10 parts of a binder phase and 3-10 parts of a sintering aid;

[0008] The method for preparing the surface oxidation-modified aluminum nitride powder comprises: pre-oxidizing the aluminum nitride raw material at 650-800° C. using an oxidizing gas for 1-5 hours; the oxidizing gas used for the pre-oxidation is 20-50% by volume O 2 and margin N 2composition;

[0009] The method for preparing the composite ceramic mold plate comprises the following steps:

[0010] S1. The raw materials are wet-milled, dried and sieved to obtain a dry material;

[0011] S2. The dried material is sequentially subjected to low temperature and low hot pressing sintering, high temperature and high hot pressing sintering and nitrogen overpressure sintering to obtain a composite ceramic mold plate;

[0012] The low temperature and low hot pressing sintering has a pressure of 5-15 MPa, a temperature of 1500-1600°C, and a holding time of 40-80 min;

[0013] The high temperature and high hot pressing sintering has a pressure of 20-30 MPa, a temperature of 1750-1900°C, and a holding time of 40-80 min;

[0014] The nitrogen overpressure sintering is carried out at a temperature of 1500-1650° C. for 5-15 minutes, and then the nitrogen pressure is applied at 5-6 MPa for 30-60 minutes.

[0015] In some preferred embodiments, the composite ceramic mold plate comprises the following raw materials in parts by weight: 40 to 95 parts of surface oxidation-modified aluminum nitride powder, 10 to 45 parts of silicon nitride powder, 12 to 35 parts of boron nitride powder, 1 to 7 parts of tungsten carbide powder, 1 to 5 parts of a bonding phase and 3 to 8 parts of a sintering aid.

[0016] In some preferred embodiments, the composite ceramic mold plate comprises the following raw materials in parts by weight: 50 to 60 parts of surface oxidation-modified aluminum nitride powder, 10 to 25 parts of silicon nitride powder, 15 to 35 parts of boron nitride powder, 1 to 4 parts of tungsten carbide powder, 1 to 3 parts of a bonding phase and 3 to 6 parts of a sintering aid.

[0017] In the present invention, the particle size of the silicon nitride powder is ≤1 μm.

[0018] In the present invention, the silicon nitride powder comprises α-Si 3 N 4 and β-Si 3 N 4 Preferably, the silicon nitride powder comprises 40-70wt% α-Si 3 N 4 and the balance β-Si 3 N 4 .

[0019] In the present invention, the particle size of the boron nitride powder is ≤500nm, preferably 300~500nm.

[0020] In the present invention, the boron nitride powder is nano hexagonal boron nitride powder.

[0021] In the present invention, the particle size of the tungsten carbide powder is 0.2-0.6 μm.

[0022] In the present invention, the pre-oxidation temperature is 700-750°C, for example, 700°C and 750°C.

[0023] In the present invention, the pre-oxidation time is 1 to 3 hours, for example 2 hours.

[0024] In the present invention, the oxidizing gas used in the pre-oxidation is 30% O 2 and margin N 2 composition.

[0025] Furthermore, the surface oxidation-modified aluminum nitride powder consists of an aluminum nitride core and an aluminum oxide coating layer.

[0026] Furthermore, the oxygen content in the surface oxidation-modified aluminum nitride powder is 2-5wt%, preferably 2.3-4.2%.

[0027] In the present invention, the aluminum nitride raw material D50=1~3μm.

[0028] In the present invention, the bonding phase is cobalt powder and nickel powder; the bonding phase is 40-60wt% cobalt powder and the balance nickel.

[0029] In the present invention, the sintering aid is at least one of yttrium oxide, calcium fluoride, calcium oxide, lithium oxide and lithium fluoride; preferably, the sintering aid is calcium fluoride and yttrium oxide; more preferably, the sintering aid is 40-70wt% calcium fluoride and the balance yttrium oxide.

[0030] In S1, the ball milling step includes: firstly ball milling silicon nitride powder and boron nitride powder for 40 to 60 hours, with a ball-to-material ratio of 15 to 20:1, to obtain a secondary phase;

[0031] Then, the tungsten carbide powder, the binder phase and the sintering aid are ball-milled for 5-15 hours, with a ball-to-material ratio of 5-6:1, to obtain the additive phase;

[0032] Add surface oxidation-modified aluminum nitride powder (main phase) to the auxiliary phase and the additional phase and ball mill for 6 to 12 hours, with a ball-to-material ratio of 5 to 6:1.

[0033] In the material of the present invention, the main phase is aluminum nitride powder with surface oxidation modification, and the secondary phase includes silicon nitride powder and boron nitride powder. The main function of the secondary phase is to isolate the main phase to reduce the hardness of the material. Among them, boron nitride will form a complete isolation layer between the main phase particles, hindering the contact and bonding of the main phase particles, causing the mechanical properties to decline; while silicon nitride can act as a bridge between the boron nitride isolation layer and the main phase particles, forming a "silicon nitride skeleton" connection, which not only maintains isolation but also achieves connection. The strength and hardness of silicon nitride can support the isolation layer to prevent it from softening, deforming or being stuck by materials such as glass under high temperature and other conditions, thereby ensuring the stability of material performance. The liquid phase formed by the sintering aid during the low-temperature and low-heat pressing sintering process plays a shrinking role under pressure, and the activity of the added phase is increased during the high-temperature and high-heat pressing sintering process, and the shrinkage and densification are further increased.

[0034] In the present invention, both the low-temperature low-hot pressing sintering and the high-temperature high-hot pressing sintering are performed in a vacuum environment with a vacuum degree of 0.1-10Pa.

[0035] In the present invention, the low-temperature low-hot-pressing sintering and the high-temperature high-hot-pressing sintering adopt a vacuum hot-pressing sintering furnace.

[0036] In S1, the drying is carried out by a spray drying process.

[0037] In S1, the mesh number of the sieving is 60-200 meshes.

[0038] In the present invention, the density of the composite ceramic mold plate is 2.9-3.6 g / cm 3 , preferably 2.9~3.2g / cm 3 .

[0039] In the present invention, the flexural strength of the composite ceramic mold plate is 380-700 MPa, preferably 380-420 MPa.

[0040] In the present invention, the hardness of the composite ceramic mold plate is 80-90 HRA.

[0041] In the present invention, the thermal conductivity of the composite ceramic mold plate is 62-90 W / (m·K).

[0042] The application of the composite ceramic mold plate as described in any of the above items is applied to microcrystalline glass mold plates.

[0043] The hot bending heating temperature of the microcrystalline glass mold plate is ≤1000°C.

[0044] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] 1. In terms of formula design, the present invention uses surface oxidation-modified aluminum nitride powder as the main phase. This modification process forms an aluminum oxide coating layer on the surface of the aluminum nitride powder. Aluminum oxide can promote the sintering aid to form a uniform liquid phase during the sintering process, effectively coating the main phase and promoting material densification. In the secondary phase, the introduction of silicon nitride powder not only prevents boron nitride from being completely isolated by aluminum nitride, but also further improves the overall performance of the material through a similar precipitation strengthening effect. In addition, the particle size of the boron nitride powder is controlled at the nanometer level, which helps to improve the density and thermal conductivity of the material.

[0047] 2. In terms of process flow, the sintering process of the present invention is divided into three stages: low-temperature low-hot-pressing sintering, high-temperature high-hot-pressing sintering, and nitrogen overpressure sintering. In the low-temperature low-hot-pressing sintering stage, the liquid phase formed by the added phase shrinks under pressure, while in the high-temperature high-hot-pressing sintering stage, the activity of the added phase increases, further promoting the densification of the material. In addition, nitrogen overpressure sintering can provide a stable nitrogen atmosphere at high temperature to prevent material oxidation and promote the densification of aluminum nitride.

[0048] 3. The composite ceramic mold plate material prepared by the present invention has excellent performance. First, it has a high density of 2.9~3.6g / cm³, which helps to improve the strength and stability of the material. Secondly, the flexural strength is as high as 380~700MPa, which can withstand large mechanical stress and is suitable for various complex mold applications. In addition, the hardness is between 80~90HRA, indicating that the material has good wear resistance and can effectively resist wear. Finally, the thermal conductivity coefficient is 62~90W / (m·K), which maintains the strength and hardness of the material while also having good thermal conductivity, which helps to quickly conduct heat in high-temperature applications.

[0049] 4. Through the improvement of the above formula and process, the composite ceramic mold plate of the present invention can meet the requirements of high temperature and high strength applications such as microcrystalline glass mold plates. In the application of microcrystalline glass mold plates, it can withstand the hot bending heating temperature of up to 800~1000℃, and the curved glass obtained after one hot pressing molding has high flatness accuracy, which meets the precision requirements of microcrystalline glass processing. The mold has a long wear life. When the flatness accuracy of the curved glass exceeds ±0.1mm, the mold is used more times, which shows that the material has good wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of the glass-ceramic mold plate.

[0051] Figure 2 It is a partial comparison diagram of the apparent quality of the composite ceramic mold plate of Example 1 (A) and Comparative Example 1 (B). DETAILED DESCRIPTION

[0052] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully in combination with preferred embodiments below, but the protection scope of the present invention is not limited to the following specific embodiments.

[0053] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0054] The "range" disclosed in the present invention is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The range defined in this way can be inclusive or exclusive of end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60-120 and 80-110 is listed for a specific parameter, it is understood that the range of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present invention, unless otherwise specified, the numerical range "ab" represents an abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" represents that all real numbers between "0-5" have been fully listed herein, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0055] If not otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form a new technical solution.

[0056] Unless otherwise specified, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.

[0057] If not otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0058] If there is no special explanation, the "include" and "comprising" mentioned in the present invention represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0059] If not specifically stated, in the present invention, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0060] The detailed information of the raw materials used in the following examples is shown in Table 1.

[0061] .

[0062] Example 1

[0063] 1. The raw material formula for preparing the composite ceramic mold plate of this embodiment is as follows:

[0064] 60 parts of surface oxidation-modified aluminum nitride powder (oxygen content 4.2%), 16 parts of silicon nitride powder, 16 parts of boron nitride powder, 2 parts of tungsten carbide powder, 2 parts of binder phase (1 part of cobalt and 1 part of nickel), 4 parts of sintering aid (2 parts of calcium fluoride and 2 parts of yttrium oxide);

[0065] 2. The preparation method of the composite ceramic mold plate of this embodiment is as follows:

[0066] Preparation method of surface oxidation modified aluminum nitride powder: aluminum nitride raw material (D50 = 2~3μm) is pre-oxidized at 750℃ for 2h, and the oxygen in the oxidizing gas is 2 The volume content is 30% and the balance is nitrogen.

[0067] S1. First, silicon nitride powder and boron nitride powder were ball-milled for 48 hours with a ball-to-material ratio of 15:1 to obtain a composite phase;

[0068] Then, the tungsten carbide powder, the binder phase and the sintering aid are ball-milled for 8 hours with a ball-to-material ratio of 5:1 to obtain the additive phase;

[0069] Finally, the surface oxidation-modified aluminum nitride powder (main phase) was added to the auxiliary phase and the additive phase and ball milled for 8 hours, with a ball-to-material ratio of 5:1;

[0070] Then spray drying is performed, and the dried material is obtained after passing through a 150-mesh sieve twice;

[0071] S2. The dried material is sequentially subjected to low temperature and low hot pressing sintering, high temperature and high hot pressing sintering and nitrogen overpressure sintering to obtain a composite ceramic mold plate;

[0072] The low temperature and low hot pressing sintering pressure is 10MPa and the temperature is kept at 1500℃ for 60min;

[0073] The high temperature and hot pressing sintering pressure is 30MPa, and the temperature is kept at 1850℃ for 60min;

[0074] The vacuum degree of low-temperature low-hot-pressing sintering and high-temperature high-hot-pressing sintering is controlled at <2Pa, and the heating rate is 10℃ / min;

[0075] The nitrogen overpressure sintering was carried out at 1600°C for 10 min, and this temperature was maintained for 50 min under a nitrogen pressure of 5 MPa.

[0076] 3. The product performance of the composite ceramic mold plate of this embodiment is as follows:

[0077] Density: 3.08g / cm 3 ;

[0078] Flexural strength: 397MPa;

[0079] Hardness: 84HRA;

[0080] Thermal conductivity: 87W / (m·K).

[0081] Example 2

[0082] 1. The raw material formula for preparing the composite ceramic mold plate of this embodiment is as follows:

[0083] 50 parts of surface oxidation-modified aluminum nitride powder (oxygen content 2.3%), 20 parts of silicon nitride powder, 20 parts of boron nitride powder, 2.5 parts of tungsten carbide powder, 2.5 parts of binder phase (1.25 parts of cobalt and 1.25 parts of nickel), 5 parts of sintering aid (2.5 parts of calcium fluoride and 2.5 parts of yttrium oxide);

[0084] 2. The preparation method of the composite ceramic mold plate of this embodiment is as follows:

[0085] Preparation method of surface oxidation-modified aluminum nitride powder: aluminum nitride raw material (D50 = 1~2μm) is pre-oxidized at 700℃ for 2h, and the oxygen in the oxidizing gas is 2 The volume content is 30% and the balance is nitrogen.

[0086] S1. First, silicon nitride powder and boron nitride powder were ball-milled for 60 hours with a ball-to-material ratio of 20:1 to obtain a secondary phase;

[0087] Then, the tungsten carbide powder, the binder phase and the sintering aid are ball-milled for 10 hours with a ball-to-material ratio of 5:1 to obtain the additive phase;

[0088] The surface oxidation-modified aluminum nitride powder was added to the auxiliary phase and the added phase and ball-milled for 10 hours, with a ball-to-material ratio of 6:1.

[0089] Then spray drying is performed, and the dried material is obtained after passing through a 150-mesh sieve twice;

[0090] S2. The dried material is sequentially subjected to low temperature and low hot pressing sintering, high temperature and high hot pressing sintering and nitrogen overpressure sintering to obtain a composite ceramic mold plate;

[0091] The low temperature and low hot pressing sintering pressure is 10MPa and the temperature is kept at 1500℃ for 60min;

[0092] The high temperature and hot pressing sintering pressure is 25MPa, and the temperature is kept at 1900℃ for 60min;

[0093] The vacuum degree of low-temperature low-hot-pressing sintering and high-temperature high-hot-pressing sintering is controlled at <1.8Pa, and the heating rate is 10℃ / min;

[0094] The nitrogen overpressure sintering was carried out at 1600°C for 10 min, and then the temperature was maintained and the nitrogen pressure was applied at 4.5 MPa for 45 min.

[0095] 3. The product performance of the composite ceramic mold plate of this embodiment is as follows:

[0096] Density: 3.11g / cm 3 ;

[0097] Flexural strength: 417MPa;

[0098] Hardness: 88HRA;

[0099] Thermal conductivity: 69W / (m·K).

[0100] Example 3

[0101] 1. The raw material formula for preparing the composite ceramic mold plate of this embodiment is as follows:

[0102] 60 parts of surface oxidation-modified aluminum nitride powder (oxygen content 4.2%), 10 parts of silicon nitride powder, 20 parts of boron nitride powder, 2.5 parts of tungsten carbide powder, 2.5 parts of binder phase (1.25 parts of cobalt and 1.25 parts of nickel), 5 parts of sintering aid (2.5 parts of calcium fluoride and 2.5 parts of yttrium oxide);

[0103] 2. The preparation method of the composite ceramic mold plate of this embodiment is as follows:

[0104] Preparation method of surface oxidation modified aluminum nitride powder: aluminum nitride raw material (D50 = 2~3μm) is pre-oxidized at 750℃ for 2h, and the oxygen in the oxidizing gas is 2 The volume content is 30% and the balance is nitrogen.

[0105] S1. First, silicon nitride powder and boron nitride powder were ball-milled for 48 hours with a ball-to-material ratio of 15:1 to obtain a secondary phase;

[0106] Then, the tungsten carbide powder, the binder phase and the sintering aid are ball-milled for 10 hours with a ball-to-material ratio of 5:1 to obtain the additive phase;

[0107] The surface oxidation-modified aluminum nitride powder was added to the auxiliary phase and the added phase and ball-milled for 10 hours, with a ball-to-material ratio of 6:1.

[0108] Then spray drying is performed, and the dried material is obtained after passing through a 150-mesh sieve twice;

[0109] S2. The dried material is sequentially subjected to low temperature and low hot pressing sintering, high temperature and high hot pressing sintering and nitrogen overpressure sintering to obtain a composite ceramic mold plate;

[0110] The low temperature and low hot pressing sintering pressure is 10MPa and the temperature is kept at 1500℃ for 60min;

[0111] The high temperature and high hot pressing sintering pressure is 25MPa, and the temperature is kept at 1850℃ for 60min;

[0112] The vacuum degree of low-temperature low-hot-pressing sintering and high-temperature high-hot-pressing sintering is controlled at <3.4Pa, and the heating rate is 10℃ / min;

[0113] The nitrogen overpressure sintering was carried out at 1600°C for 10 min, and then the temperature was maintained and the nitrogen pressure was applied at 5 MPa for 50 min.

[0114] 3. The product performance of the composite ceramic mold plate of this embodiment is as follows:

[0115] Density: 3.10g / cm 3 ;

[0116] Flexural strength: 406MPa;

[0117] Hardness: 83HRA;

[0118] Thermal conductivity: 73W / (m·K).

[0119] Example 4

[0120] 1. The raw material formula for preparing the composite ceramic mold plate of this embodiment is as follows:

[0121] 50 parts of surface oxidation-modified aluminum nitride powder (oxygen content 2.3%), 10 parts of silicon nitride powder, 32 parts of boron nitride powder, 1.5 parts of tungsten carbide powder, 1.5 parts of binder phase (0.75 parts of cobalt and 0.75 parts of nickel), 5 parts of sintering aid (2 parts of calcium fluoride and 3 parts of yttrium oxide);

[0122] 2. The preparation method of the composite ceramic mold plate of this embodiment is as follows:

[0123] Preparation method of surface oxidation-modified aluminum nitride powder: aluminum nitride raw material (D50 = 1~2μm) is pre-oxidized at 700℃ for 2h, and the oxygen in the oxidizing gas is 2 The volume content is 30% and the balance is nitrogen.

[0124] S1. First, silicon nitride powder and boron nitride powder were ball-milled for 60 hours with a ball-to-material ratio of 20:1 to obtain a secondary phase;

[0125] Then, the tungsten carbide powder, the binder phase and the sintering aid are ball-milled for 8 hours with a ball-to-material ratio of 6:1 to obtain the additive phase;

[0126] The surface oxidation-modified aluminum nitride powder was added to the auxiliary phase and the added phase and ball-milled for 10 hours, with a ball-to-material ratio of 6:1.

[0127] Then spray drying is performed, and the dried material is obtained after passing through a 150-mesh sieve twice;

[0128] S2. The dried material is sequentially subjected to low temperature and low hot pressing sintering, high temperature and high hot pressing sintering and nitrogen overpressure sintering to obtain a composite ceramic mold plate;

[0129] The low temperature and low hot pressing sintering pressure is 10MPa and the temperature is kept at 1500℃ for 60min;

[0130] The high temperature and hot pressing sintering pressure is 20MPa, and the temperature is kept at 1900℃ for 60min;

[0131] The vacuum degree of low-temperature low-hot-pressing sintering and high-temperature high-hot-pressing sintering is controlled at <5Pa, and the heating rate is 10℃ / min;

[0132] The nitrogen overpressure sintering was carried out at 1600°C for 10 min, and then the temperature was maintained and the nitrogen pressure was applied at 5.5 MPa for 50 min.

[0133] 3. The product performance of the composite ceramic mold plate of this embodiment is as follows:

[0134] Density: 2.91g / cm 3 ;

[0135] Flexural strength: 382MPa;

[0136] Hardness: 80HRA;

[0137] Thermal conductivity: 64W / (m·K).

[0138] Example 5

[0139] The difference between this embodiment and embodiment 1 is that:

[0140] The pre-oxidation temperature of the aluminum nitride raw material is 900° C., and the pre-oxidation obtains surface-oxidized modified aluminum nitride powder (oxygen content 5.3%).

[0141] Other steps and parameters are the same as in Example 1.

[0142] The pre-oxidation temperature of aluminum nitride is too high, and the oxygen content of the surface-oxidized aluminum nitride powder increases after excessive oxidation. Although aluminum oxide itself has good antioxidant properties, the increase in oxygen content will lead to a decrease in its own thermal conductivity, an increase in surface roughness, and make the raw material more brittle, thereby affecting the strength of the composite ceramic mold plate.

[0143] The product performance of the composite ceramic mold plate of this embodiment is as follows:

[0144] Density: 3.02g / cm 3 ;

[0145] Flexural strength: 366MPa;

[0146] Hardness: 68HRA;

[0147] Thermal conductivity: 74W / (m·K).

[0148] Comparative Example 1

[0149] The difference between this comparative example and Example 3 is that:

[0150] The raw material formula for preparing the composite ceramic mold plate of this embodiment is as follows: 60 parts of surface oxidation-modified aluminum nitride powder, 30 parts of boron nitride powder, 2.5 parts of tungsten carbide powder, 2.5 parts of bonding phase (1.25 parts of cobalt and 1.25 parts of nickel), and 5 parts of sintering aid (2.5 parts of calcium fluoride and 2.5 parts of yttrium oxide).

[0151] Other steps and parameters are the same as in Example 3.

[0152] The product performance of the composite ceramic mold plate of this comparative example is as follows:

[0153] Density: 2.85g / cm 3 ;

[0154] Flexural strength: 303MPa;

[0155] Hardness: 72HRA;

[0156] Thermal conductivity: 51W / (m·K).

[0157] Comparative Example 2

[0158] The difference between this comparative example and Example 1 is:

[0159] This comparative example does not use surface oxidation-modified aluminum nitride powder, but directly uses aluminum nitride powder.

[0160] Other steps and parameters are the same as in Example 1.

[0161] The product performance of the composite ceramic mold plate of this comparative example is as follows:

[0162] Density: 2.93g / cm 3 ;

[0163] Flexural strength: 351MPa;

[0164] Hardness: 64HRA;

[0165] Thermal conductivity: 64W / (m·K).

[0166] Comparative Example 3

[0167] The difference between this comparative example and Example 1 is:

[0168] The dried material of this comparative example was subjected to pressureless low-temperature sintering and nitrogen overpressure sintering in sequence;

[0169] Pressure-free high-temperature sintering was carried out at 1800°C for 60 minutes and the vacuum degree was 0.8 Pa;

[0170] Nitrogen overpressure sintering was carried out at 1600°C and a nitrogen pressure of 5 MPa for 2 h.

[0171] Other steps and parameters are the same as in Example 1.

[0172] The product performance of the composite ceramic mold plate of this comparative example is as follows:

[0173] Density: 2.87 g / cm 3 ;

[0174] Flexural strength: 318MPa;

[0175] Hardness: 73HRA;

[0176] Thermal conductivity: 63W / (m·K).

[0177] Comparative Example 4

[0178] The difference between this embodiment and embodiment 2 is that:

[0179] The temperature of nitrogen overpressure sintering is 1800℃.

[0180] Other steps and parameters are the same as in Example 2.

[0181] The product performance of the composite ceramic mold plate of this comparative example is as follows:

[0182] Density: 3.03g / cm 3 ;

[0183] Flexural strength: 347MPa;

[0184] Hardness: 76HRA;

[0185] Thermal conductivity: 58W / (m·K).

[0186] Application Examples

[0187] The application process and effect of the composite ceramic mold plate of the embodiment and the comparative example as a glass-ceramic mold plate are as follows:

[0188] Use the above-mentioned glass-ceramic mold plate (see Figure 1 Schematic diagram), the flat glass is heated to 800~1000℃ in the glass bending machine to soften, and the curved glass is obtained after one-time hot pressing.

[0189] The wear life of the mold is shown in Table 2; the wear life refers to the number of times the microcrystalline glass mold plate is used when the flatness accuracy of the curved glass exceeds ±0.1 mm.

[0190] .

[0191] According to the embodiments and comparative examples and the corresponding Table 2 and accompanying data:

[0192] Comparative Example 1 uses only boron nitride as the isolation layer, but boron nitride has severe adhesion at high temperatures. Figure 2 Comparison chart of the apparent quality of the composite ceramic mold plate of Example 1 and Comparative Example 1. Figure 2 (A) is a surface image of the composite ceramic mold plate obtained in Example 1, Figure 2 (B) is a surface image of the composite ceramic mold plate obtained in Comparative Example 1. Figure 2 It can be seen that the surface of the composite ceramic mold plate of Example 1 is smooth and has no defects, while the surface of the composite ceramic mold plate of Comparative Example 1 is pockmarked and has a large surface roughness, and is not suitable as a microcrystalline glass mold plate.

[0193] Comparative Example 2 uses aluminum nitride without pre-oxidation, but the sintering aid and aluminum oxide have a good commingling effect. Since there is no liquid phase sintering aid to help form the glass phase, the material is not dense enough during the sintering process.

[0194] Comparative Example 3 was first subjected to pressureless low-temperature sintering and then to nitrogen overpressure sintering. The material had many vacuum holes and low densification degree. Even after nitrogen sintering, it could not be densified again.

[0195] In Comparative Example 4, the material is already basically dense during the nitrogen overpressure sintering stage, with only a very small number of vacuum holes formed. These holes cannot be further densified due to the effect of the volatile vapor pressure of the liquid phase and the closure of the overflow channel. When the temperature is lowered, the liquid phase inside the material squeezes and flows, thereby compressing the fine diffuse holes inside the material, further increasing the density. The nitrogen overpressure at this stage does not require hot pressing. However, the nitrogen overpressure sintering temperature of Comparative Example 4 is too high, so it is less helpful for densification.

[0196] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods. The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite ceramic mold plate, characterized in that: The preparation comprises the following raw materials in parts by weight: 30~95 parts of surface oxidation-modified aluminum nitride powder, 10~75 parts of silicon nitride powder, 12~35 parts of boron nitride powder, 1~10 parts of tungsten carbide powder, 1~10 parts of binder phase, 3~10 parts of sintering aid; The method for preparing the surface oxidation-modified aluminum nitride powder comprises: pre-oxidizing the aluminum nitride raw material at 650-800° C. using an oxidizing gas for 1-5 hours; the oxidizing gas used for the pre-oxidation is composed of 20-50% O2 by volume and the remainder N2; The method for preparing the composite ceramic mold plate comprises the following steps: S1. The raw materials are ball-milled, dried, and sieved to obtain a dried material; S2. The dried material is sequentially subjected to low temperature and low hot pressing sintering, high temperature and high hot pressing sintering and nitrogen overpressure sintering to obtain a composite ceramic mold plate; The low temperature and low hot pressing sintering has a pressure of 5-15 MPa, a temperature of 1500-1600°C, and a holding time of 40-80 min; The high temperature and high hot pressing sintering has a pressure of 20-30 MPa, a temperature of 1750-1900°C, and a holding time of 40-80 min; The nitrogen overpressure sintering is carried out at a temperature of 1500-1650° C. for 5-15 minutes, and then the nitrogen pressure is applied at 5-6 MPa for 30-60 minutes.

2. The composite ceramic mold plate according to claim 1, characterized in that: Meet at least one of the following conditions ①~⑤: ① The particle size of the silicon nitride powder is ≤1 μm; ② The silicon nitride powder includes α-Si3N4 and β-Si3N4; ③ The particle size of the boron nitride powder is ≤500nm; ④ The boron nitride powder is nano hexagonal boron nitride powder; ⑤ The particle size of the tungsten carbide powder is 0.2~0.6μm.

3. The composite ceramic mold plate according to claim 1, characterized in that: The pre-oxidation temperature is 700-750°C; The pre-oxidation time is 1 to 3 hours; The oxidizing gas used in the pre-oxidation is composed of 30% by volume of O2 and the remainder of N2.

4. The composite ceramic mold plate according to claim 3, characterized in that: Meet at least one of the following conditions ①~③: ① The surface oxidation-modified aluminum nitride powder consists of an aluminum nitride core and an aluminum oxide coating layer; ② The D50 of the aluminum nitride raw material is 1-3 μm; ③ The oxygen content in the surface oxidation-modified aluminum nitride powder is 2-5wt%.

5. The composite ceramic mold plate according to claim 1, characterized in that: Meet at least one of the following conditions ①~②: ① The bonding phase is cobalt powder and nickel powder; ② The sintering aid is at least one of yttrium oxide, calcium fluoride, calcium oxide, lithium oxide and lithium fluoride.

6. The composite ceramic mold plate according to claim 1, characterized in that: The ball milling step comprises: firstly ball milling silicon nitride powder and boron nitride powder for 40 to 60 hours, with a ball-to-material ratio of 15 to 20:1, to obtain a secondary phase; Then, the tungsten carbide powder, the binder phase and the sintering aid are ball-milled for 5-15 hours, with a ball-to-material ratio of 5-6:1, to obtain the additive phase; Add surface oxidation-modified aluminum nitride powder to the auxiliary phase and the added phase and ball mill for 6 to 12 hours, with a ball-to-material ratio of 5 to 6:

1.

7. The composite ceramic mold plate according to claim 1, characterized in that: The low-temperature low-hot pressing sintering and the high-temperature high-hot pressing sintering are both carried out in a vacuum environment with a vacuum degree of 0.1-10Pa.

8. The composite ceramic mold plate according to claim 1, characterized in that: The mesh number of the sieving is 60 to 200 meshes.

9. The composite ceramic mold plate according to claim 1, characterized in that: Meet at least one of the following conditions ①~④: ① The density of the composite ceramic mold plate is 2.9~3.6g / cm 3 ; ② The flexural strength of the composite ceramic mold plate is 380~700MPa; ③The hardness of the composite ceramic mold plate is 80~90HRA; ④ The thermal conductivity of the composite ceramic mold plate is 62~90W / (m·K).

10. The use of the composite ceramic mold plate according to any one of claims 1 to 9, characterized in that: Applied to glass-ceramic mold plates.

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