A particle-dispersion toughened silicon nitride ceramic substrate and its preparation method

Abstract

This application relates to the field of silicon nitride ceramic substrates, specifically disclosing a particle-dispersion toughened silicon nitride ceramic substrate and its preparation method. The particle-dispersion toughened silicon nitride ceramic substrate comprises the following raw materials in parts by weight: 80-120 parts silicon nitride, 60-110 parts alcohol solvent, 5-10 parts binder, 5-12 parts toughening particles, 1-5 parts dispersant, 0.5-1 part defoamer, and 2-5 parts sintering aid. The toughening particles are composed of molybdenum silicide, polyetheretherketone, and aerogel in a mass ratio of 1:0.1-0.5:0.05-0.1. The preparation method is as follows: silicon nitride, alcohol solvent, and toughening particles are ball-milled and mixed evenly; binder, dispersant, defoamer, and sintering aid are added, and ball milling continues until evenly mixed and defoamed to obtain a mixture; the mixture is then cast, dried, isostatically pressed, cut, debinded, sintered at high temperature, and cooled to obtain the finished product; it has the advantages of high strength and good toughness.

Description

Technical Field

[0001] This application relates to the field of silicon nitride ceramic substrates, and more specifically, to a particle dispersion toughened silicon nitride ceramic substrate and a method for preparing the same. Background Technology

[0002] Silicon nitride ceramics are inorganic ceramic materials that do not shrink during sintering. Silicon nitride has high strength and advantages such as high strength, low density, and high temperature resistance.

[0003] A substrate is a material used to support and connect circuit elements or devices, playing a role in bearing and connecting electronic components. Substrates made of silicon nitride ceramics have advantages such as high hardness, high temperature resistance, corrosion resistance, and acid and alkali resistance. However, silicon nitride ceramic plates are relatively brittle and have poor toughness, making them prone to breakage under external forces.

[0004] Therefore, the question is how to prepare a new silicon nitride ceramic substrate that possesses the advantages of high strength and high toughness. Summary of the Invention

[0005] In order to prepare a silicon nitride ceramic substrate with high strength and good toughness, this application provides a particle dispersion toughened silicon nitride ceramic substrate and its preparation method.

[0006] In a first aspect, this application provides a particle-dispersion toughened silicon nitride ceramic substrate, which adopts the following technical solution: a particle-dispersion toughened silicon nitride ceramic substrate, wherein the silicon nitride ceramic substrate comprises the following raw materials in parts by weight: 80-120 parts of silicon nitride, 60-110 parts of alcohol solvent, 5-10 parts of binder, 5-12 parts of toughening particles, 1-5 parts of dispersant, 0.5-1 part of defoamer, and 2-5 parts of sintering aid; wherein the toughening particles are composed of molybdenum silicide, polyether ether ketone, and aerogel in a mass ratio of 1:0.1-0.5:0.05-0.1.

[0007] By adopting the above technical solution, silicon nitride and toughening particles are uniformly mixed under the action of alcohol solvent, and the binder can dissolve in alcohol solvent. With the dispersing effect of dispersant, silicon nitride and toughening particles can be bonded together relatively stably and uniformly. With the defoaming effect of defoamer, the porosity inside silicon nitride ceramic substrate is reduced. Combined with the high strength of silicon nitride and the good toughness of toughening particles, the finished silicon nitride ceramic substrate has the advantages of high strength and high toughness.

[0008] The combination of molybdenum silicide, polyetheretherketone (PEEK), and aerogel enhances the toughness of silicon nitride ceramic substrates by leveraging the inherent toughness of these materials. Both molybdenum silicide and silicon nitride are silicon-phase materials; under high temperatures, the metallic bonds between molybdenum and silicon are elongated, transforming molybdenum silicide into a tougher material. This not only increases the contact between molybdenum silicide and silicon nitride but also enhances the toughness of the silicon nitride ceramic substrate. The tetragonal layered structure of molybdenum silicide facilitates the insertion and uniform contact of silicon nitride, thus balancing the brittleness of silicon nitride and improving the toughness of the substrate. PEEK itself possesses high toughness; during the hot pressing process of high-temperature sintering of silicon nitride ceramic substrates, its high toughness allows it to deform and be compressed. The compressed PEEK reduces its space occupation, and the adhesive effect prevents deformation of the pressed preform. As high-temperature sintering progresses, solvents such as alcohols evaporate first; the aerogel provides a channel for these gases, reducing their dispersion and thus minimizing the impact on the silicon nitride ceramic substrate. The probability of pores forming in the internal structure of the ceramic substrate is reduced, and it also has high toughness, thus improving the toughness of the finished silicon nitride ceramic substrate. As the alcohol solvent and binder that originally occupied the space gradually disappear, some pores will gradually form inside the ceramic substrate. The resilience of polyetheretherketone (PEEK) can buffer the micropores that appear around it, avoiding the problem of adjacent silicon nitride, molybdenum silicide and other raw materials not contacting each other, and reducing the internal porosity of the finished product, thereby ensuring the strength of the silicon nitride ceramic plate. As the temperature rises, PEEK gradually melts and flows, and its bonding effect further improves the bonding stability between silicon nitride, molybdenum silicide and other raw materials. Finally, under the highest temperature conditions of sintering, PEEK gradually decomposes thermally. Although some carbides remain inside the silicon nitride ceramic substrate, the PEEK that originally occupied the space can provide space for the slight expansion inside the silicon nitride ceramic substrate caused by high temperature, ensuring the density of the silicon nitride ceramic substrate, thus giving the silicon nitride ceramic substrate the advantages of high strength and high toughness.

[0009] Preferably, the silicon nitride is composed of needle-shaped silicon nitride and hexagonal silicon nitride in a mass ratio of 1:1-2.

[0010] By adopting the above technical solution, needle-shaped silicon nitride and hexagonal silicon nitride are combined. The needle-shaped structure of the needle-shaped silicon nitride facilitates its intercalation into molybdenum silicide, improving the contact between silicon nitride and molybdenum silicide, thereby improving the toughness of the finished silicon nitride ceramic plate. Meanwhile, the layered structure of the hexagonal silicon nitride facilitates its interweaving with the layered structure of molybdenum silicide, further increasing the contact area between silicon nitride and molybdenum silicide. The high toughness of molybdenum silicide is then utilized to improve the toughness of the finished silicon nitride ceramic substrate.

[0011] Preferably, the adhesive is composed of polyethylene glycol and shellac in a mass ratio of 1:0.2-0.5.

[0012] By adopting the above technical solution, polyethylene glycol and shellac are dissolved in alcohol solvent to obtain an adhesive liquid with bonding effect. The viscosity of the adhesive liquid facilitates the bonding of silicon nitride, toughening particles and other substances. As high-temperature sintering proceeds, polyethylene glycol and shellac gradually melt and decompose, and the positions originally occupied by polyethylene glycol and shellac are filled by silicon nitride that expands slightly at high temperature, forming a silicon nitride ceramic substrate with a dense structure and low porosity. This gives the finished silicon nitride ceramic substrate the advantages of high strength and high toughness.

[0013] Shellac has a certain elasticity. Shellac adhesive solution obtained by dissolving shellac in alcohol solvent is easy to bond between raw materials such as silicon nitride and toughening particles. Utilizing its elasticity, it can not only deform during extrusion to improve structural density, but also the carboxyl and hydroxyl groups in shellac can easily cross-link and bond with the hydroxyl groups in polyethylene glycol, thereby improving the overall bonding effect of the finished silicon nitride ceramic substrate and giving the silicon nitride ceramic substrate high strength and toughness.

[0014] Preferably, the molybdenum silicide is made from molybdenum silicide particles, molybdenum telluride particles and polyvinyl alcohol solution in a mass ratio of 1:0.1-0.2:0.1-0.3.

[0015] By employing the above technical solution, molybdenum silicide microparticles, molybdenum telluride microparticles, and a polyvinyl alcohol solution are combined. The adhesive effect of the polyvinyl alcohol solution facilitates the bonding of molybdenum telluride microparticles to the surface of molybdenum silicide microparticles. The lubricating effect of molybdenum telluride, combined with the contact between molybdenum telluride and molybdenum silicide, improves the mixing uniformity of silicon nitride and molybdenum silicide. As high-temperature sintering proceeds, the initial high temperature causes the molybdenum telluride to gradually melt. The melted molybdenum telluride enhances the bonding and folding effect between silicon nitride and molybdenum silicide, and, combined with the lubricating effect of molybdenum telluride... The effect is that it is easy to fill and bond the pores between silicon nitride and molybdenum silicide, improving the structural density of silicon nitride ceramics during the gradual heating process; finally, under high-temperature sintering conditions above 1500℃, molybdenum telluride gradually decomposes, and at this time, the high temperature causes silicon nitride, molybdenum silicide and other substances to expand slightly, further filling the structural pores generated by the thermal decomposition of molybdenum telluride, polyvinyl alcohol and other substances, thereby improving the structural density of silicon nitride ceramic substrates, so that the finished silicon nitride ceramic substrates have the advantages of high strength and high toughness.

[0016] Preferably, the polyetheretherketone is made from polyetheretherketone powder, tetra-needle-shaped zinc oxide whiskers, and polyvinyl alcohol solution in a mass ratio of 1:0.2-0.5:0.1-0.4.

[0017] By adopting the above technical solution, polyetheretherketone powder and tetra-needle zinc oxide whiskers are combined. The four-sided needle-like structure of the tetra-needle zinc oxide whiskers can increase the contact area between polyetheretherketone powder and materials such as silicon nitride and molybdenum silicide. Furthermore, its needle-like structure facilitates insertion into the layered structure of silicon nitride and molybdenum silicide. The high toughness of polyetheretherketone improves the toughness of the silicon nitride ceramic substrate. At the same time, when the polyetheretherketone powder reaches its melting point during sintering, it is easily guided through the tetra-needle zinc oxide whiskers to fill the pores between silicon nitride and toughening particles, thereby ensuring the structural density of the silicon nitride ceramic substrate. This results in the finished silicon nitride ceramic substrate having the advantages of high strength and high toughness.

[0018] Preferably, the aerogel is made of silica aerogel, silane coupling agent KH-570, and magnesium silicide microparticles in a mass ratio of 1:0.2-0.5:0.1-0.3.

[0019] By employing the above technical solution, silica aerogel, magnesium silicide microparticles, and silane coupling agent KH-570 are combined. The good hydrophobic effect of KH-570 imparts hydrophobicity to the silica aerogel, preventing moisture from affecting the internal structural density of the silicon nitride ceramic substrate. Furthermore, the silane coupling agent can improve the adhesion between the silica aerogel and molybdenum silicide, binders, and other substances. Combined with the good filling effect of the silica aerogel, the gases generated by thermal decomposition are easily released through the porous structure of the silica aerogel, minimizing the increase in porosity within the silicon nitride ceramic substrate during gas escape, thus resulting in a high-strength finished silicon nitride ceramic substrate. The high toughness of the magnesium silicide microparticles allows them to deform during the filling process, increasing the structural density of the silicon nitride ceramic substrate. Magnesium silicide has a melting point of approximately 1100℃ and can be thermally melted during high-temperature sintering. The melted magnesium silicide, with its silicon and magnesium phases, can further improve the structural density and toughness of the silicon nitride ceramic substrate.

[0020] Preferably, the dispersant is composed of polyethylene glycol and microcrystalline wax in a mass ratio of 1:0.5-1.

[0021] By adopting the above technical solution, polyethylene glycol and microcrystalline wax are combined. The low viscosity lubrication effect of polyethylene glycol after dissolving in alcohol, combined with the lubrication effect of microcrystalline wax in the high-temperature process, improves the bonding and cross-linking degree between silicon nitride and toughening particles. Combined with the cross-linking bonding effect of hydroxyl groups in polyethylene glycol and polyvinyl alcohol, the internal structural density of silicon nitride ceramic substrate is further improved. At the same time, polyethylene glycol and microcrystalline wax can be thermally decomposed, and the voids generated in situ can fill the micro-expansion of silicon nitride, so that the silicon nitride ceramic substrate as a whole has the advantages of high strength and high toughness.

[0022] Preferably, the sintering aid is siliconized graphite.

[0023] Preferably, the defoamer is an organosilicone defoamer.

[0024] By adopting the above technical solution, siliconized graphite possesses the self-lubricating and thermal shock resistant properties of carbon graphite materials, giving the finished silicon nitride ceramic substrate the advantages of high strength and high toughness. Combined with the defoaming effect of organosilicon defoamer, the porosity of the internal structure of the silicon nitride ceramic substrate is reduced, thereby improving the strength and toughness of the finished silicon nitride ceramic substrate.

[0025] Secondly, this application provides a method for preparing a particle-dispersion toughened silicon nitride ceramic substrate, employing the following technical solution:

[0026] A method for preparing a particle-dispersion toughened silicon nitride ceramic substrate includes the following steps:

[0027] S1. The silicon nitride, alcohol solvent, and toughening particles are ball-milled and mixed evenly to obtain a preliminary mixture; then binder, dispersant, defoamer, and sintering aid are added and ball-milled again until evenly mixed. After vacuum degassing, a final mixture is obtained.

[0028] S2. The mixture is cast, dried, and isostatically pressed to obtain a green blank. The green blank is then cut, debonded, sintered at high temperature, and cooled to obtain the finished product.

[0029] By adopting the above technical solution, silicon nitride and toughening particles can be mixed evenly under the dispersion effect of solvent. Then, after adding a binder, the silicon nitride and toughening particles are stably bonded under the condition that the binder is alcohol-soluble. During the hot pressing and drying process, the structural density of the preform is improved and the internal porosity of the preform is reduced. Finally, after high-temperature sintering, the finished silicon nitride ceramic substrate has a high structural density, thus giving the finished silicon nitride ceramic substrate the advantages of high strength and high toughness.

[0030] In summary, this application has the following beneficial effects:

[0031] 1. Under the action of alcohol solvent, silicon nitride and toughening particles are uniformly mixed, and the binder can dissolve in alcohol solvent. With the dispersing effect of dispersant, silicon nitride and toughening particles can be bonded together relatively stably and uniformly. With the defoaming effect of defoamer, the porosity inside silicon nitride ceramic substrate is reduced. Combined with the high strength of silicon nitride and the good toughness of toughening particles, the finished silicon nitride ceramic substrate has the advantages of high strength and high toughness.

[0032] 2. The combination of molybdenum silicide microparticles, molybdenum telluride microparticles, and polyvinyl alcohol solution, along with the high-temperature sintering process, initially causes the molybdenum telluride to gradually melt. The melted molybdenum telluride improves the bonding and folding effect between silicon nitride and molybdenum silicide. Combined with the lubricating effect of molybdenum telluride, it facilitates filling and bonding in the pores between silicon nitride and molybdenum silicide, increasing the structural density of the silicon nitride ceramic during the gradual heating process. Finally, under high-temperature sintering conditions above 1500℃, the molybdenum telluride gradually decomposes. At this point, the high temperature causes silicon nitride, molybdenum silicide, and other substances to slightly expand, further filling the structural pores created by the thermal decomposition of molybdenum telluride, polyvinyl alcohol, and other substances. This further increases the structural density of the silicon nitride ceramic substrate, resulting in a finished silicon nitride ceramic substrate with high strength and high toughness.

[0033] 3. The combination of polyetheretherketone (PEEK) powder and tetra-needle zinc oxide whiskers utilizes the four-sided needle-like structure of the tetra-needle zinc oxide whiskers to increase the contact area between PEEK powder and materials such as silicon nitride and molybdenum silicide. Furthermore, its needle-like structure facilitates insertion into the layered structure of silicon nitride and molybdenum silicide. The high toughness of PEEK enhances the toughness of the silicon nitride ceramic substrate. Simultaneously, when the PEEK powder reaches its melting point during sintering, it is easily guided through the tetra-needle zinc oxide whiskers, filling the pores between silicon nitride and toughening particles. This ensures the structural density of the silicon nitride ceramic substrate, resulting in a finished silicon nitride ceramic substrate with high strength and high toughness. Detailed Implementation

[0034] The present application will be further described in detail below with reference to the embodiments.

[0035] All of the following ingredients are commercially available.

[0036] Example of molybdenum silicide preparation

[0037] Preparation Example 1: Molybdenum silicide was prepared by the following method:

[0038] 0.2 kg of polyvinyl alcohol solution was uniformly sprayed onto the surface of 1 kg of molybdenum silicide microparticles. The average particle size of the molybdenum silicide microparticles was 40 μm. The polyvinyl alcohol solution was a 2% (w / w) aqueous solution of polyvinyl alcohol. Then, 0.15 kg of molybdenum telluride microparticles with an average particle size of 5 μm were added at a rate of 30 g / min. During the addition process, the molybdenum silicide microparticles were stirred at a speed of 80 r / min. After uniform mixing, the microparticles were dried and dispersed to obtain the finished molybdenum silicide product, which passed through a 200-mesh sieve.

[0039] Preparation Example 2: The difference between this preparation example and Preparation Example 1 is that:

[0040] 0.1 kg of polyvinyl alcohol solution was uniformly sprayed onto the surface of 1 kg of molybdenum silicide microparticles. The average particle size of the molybdenum silicide microparticles was 40 μm. The polyvinyl alcohol solution was a 2% (w / w) aqueous solution of polyvinyl alcohol. Then, 0.1 kg of molybdenum telluride microparticles with an average particle size of 5 μm were added at a rate of 30 g / min. During the addition process, the molybdenum silicide microparticles were stirred at a speed of 80 r / min. After uniform mixing, the microparticles were dried and dispersed to obtain the finished molybdenum silicide product.

[0041] Preparation Example 3: The difference between this preparation example and Preparation Example 1 is that:

[0042] 0.3 kg of polyvinyl alcohol solution was uniformly sprayed onto the surface of 1 kg of molybdenum silicide microparticles. The average particle size of the molybdenum silicide microparticles was 40 μm. The polyvinyl alcohol solution was a 2% (w / w) aqueous solution of polyvinyl alcohol. Then, 0.2 kg of molybdenum telluride microparticles with an average particle size of 5 μm were added at a rate of 30 g / min. During the addition process, the molybdenum silicide microparticles were stirred at a speed of 80 r / min. After uniform mixing, the microparticles were dried and dispersed to obtain the finished molybdenum silicide product.

[0043] Preparation example of polyetheretherketone

[0044] Preparation Example 4: Polyetheretherketone (PEEK) was prepared by the following method:

[0045] 0.3 kg of polyvinyl alcohol solution was uniformly sprayed onto the surface of 1 kg of polyetheretherketone powder. The average particle size of the polyetheretherketone powder was 80 μm. The polyvinyl alcohol solution was a 2% (w / w) aqueous solution of polyvinyl alcohol. Then, 0.35 kg of tetraneedle-shaped zinc oxide whiskers with an average particle size of 20 μm were added at a rate of 30 g / min. During the addition process, the polyetheretherketone powder was stirred at a speed of 100 r / min. After uniform mixing, the mixture was dried and dispersed to obtain the finished polyetheretherketone product, which passed through a 100-mesh sieve.

[0046] Preparation Example 5: The difference between this preparation example and Preparation Example 4 is that:

[0047] 0.1 kg of polyvinyl alcohol solution was uniformly sprayed onto the surface of 1 kg of polyetheretherketone powder. The average particle size of the polyetheretherketone powder was 80 μm. The polyvinyl alcohol solution was a 2% (w / w) aqueous solution of polyvinyl alcohol. Then, 0.2 kg of tetraneedle-shaped zinc oxide whiskers with an average particle size of 20 μm were added at a rate of 30 g / min. During the addition process, the polyetheretherketone powder was stirred at a speed of 100 r / min. After uniform mixing, the mixture was dried and dispersed to obtain the finished polyetheretherketone product.

[0048] Preparation Example 6: The difference between this preparation example and Preparation Example 4 is that:

[0049] 0.4 kg of polyvinyl alcohol solution was uniformly sprayed onto the surface of 1 kg of polyetheretherketone powder. The average particle size of the polyetheretherketone powder was 80 μm. The polyvinyl alcohol solution was a 2% (w / w) aqueous solution of polyvinyl alcohol. Then, 0.5 kg of tetraneedle-shaped zinc oxide whiskers with an average particle size of 20 μm were added at a rate of 30 g / min. During the addition process, the polyetheretherketone powder was stirred at a speed of 100 r / min. After uniform mixing, the mixture was dried and dispersed to obtain the finished polyetheretherketone product.

[0050] Preparation example of aerogel

[0051] Preparation Example 7: Aerogels were prepared using the following method:

[0052] 0.35 kg of silane coupling agent KH-570 was uniformly sprayed onto the surface of 1 kg of silica aerogel, and then 0.2 kg of magnesium silicide microparticles were added. The average particle size of the silica aerogel was 50 μm, and the average particle size of the magnesium silicide microparticles was 60 μm. After drying and dispersion until the silica aerogel particles did not stick together and agglomerate, the aerogel was obtained.

[0053] Preparation Example 8: The difference between this preparation example and Preparation Example 7 is that:

[0054] 0.2 kg of silane coupling agent KH-570 was uniformly sprayed onto the surface of 1 kg of silica aerogel, and then 0.1 kg of magnesium silicide particles were added. After drying and dispersion, the aerogel was obtained.

[0055] Preparation Example 9: The difference between this preparation example and Preparation Example 7 is that:

[0056] 0.5 kg of silane coupling agent KH-570 was uniformly sprayed onto the surface of 1 kg of silica aerogel, and then 0.3 kg of magnesium silicide particles were added. After drying and dispersion, the aerogel was obtained.

[0057] Example

[0058] Example 1: A particle-dispersion toughened silicon nitride ceramic substrate:

[0059] The composition includes 100 kg of silicon nitride, 90 kg of alcohol solvent, 8 kg of binder, 8 kg of toughening particles, 3 kg of dispersant, 0.8 kg of defoamer, and 3.2 kg of sintering aid. The silicon nitride is composed of needle-shaped silicon nitride and hexagonal silicon nitride in a 1:1 mass ratio. The needle-shaped silicon nitride consists of needle-shaped silicon nitride with an average particle size of 20 μm and needle-shaped silicon nitride with an average particle size of 60 μm in a 1:1 mass ratio. The hexagonal silicon nitride consists of hexagonal silicon nitride with an average particle size of 40 μm and hexagonal silicon nitride with an average particle size of 150 μm in a 1:1 mass ratio. The composition is siliconized; the alcohol solvent is 95% ethanol by mass; the binder is composed of polyethylene glycol and shellac in a mass ratio of 1:0.35, and the polyethylene glycol is polyethylene glycol 8000; the toughening particles are composed of molybdenum silicide prepared in Preparation Example 1, polyetheretherketone prepared in Preparation Example 4, and aerogel prepared in Preparation Example 7 in a mass ratio of 1:0.33:0.07; the dispersant is composed of polyethylene glycol and microcrystalline wax in a mass ratio of 1:1, and the polyethylene glycol is polyethylene glycol 1000; the defoamer is an organosilicon defoamer; the sintering aid is siliconized graphite;

[0060] The preparation method is as follows:

[0061] S1. Place silicon nitride, solvent, and toughening particles in a ball mill and ball mill for 4 hours to mix evenly, obtaining a preliminary mixture. Then add binder, dispersant, defoamer, and sintering aid and continue ball milling for 4 hours. After mixing evenly, degas under vacuum to obtain a final mixture. S2. Cast the mixture on a casting machine at a casting speed of 0.1 m / min, then press and dry to obtain a preform. The preform is isostatically pressed at 90 MPa and 300℃ for 30 minutes to obtain a green preform. The green preform is cut and then heated to 200℃ at a heating rate of 2℃ / min and held for 3 hours. Then it is heated to 500℃ and held for 2 hours for debinding at a pressure of 0.5 MPa to obtain a semi-finished product. The semi-finished product is heated to 1800℃ at a heating rate of 5℃ / min and sintered for 1 hour at a sintering pressure of 0.8 MPa. Then it is heated to a high temperature at a heating rate of 2℃ / min and cooled to obtain the finished product.

[0062] Example 2: The difference between this example and Example 1 is that:

[0063] The composition includes 80 kg of silicon nitride, 60 kg of alcohol solvent, 5 kg of binder, 5 kg of toughening particles, 1 kg of dispersant, 0.5 kg of defoamer, and 2 kg of sintering aid. The silicon nitride is composed of needle-shaped silicon nitride and hexagonal silicon nitride in a mass ratio of 1:0.5. The needle-shaped silicon nitride consists of needle-shaped silicon nitride with an average particle size of 20 μm and needle-shaped silicon nitride with an average particle size of 60 μm in a mass ratio of 1:2. The hexagonal silicon nitride consists of needle-shaped silicon nitride with an average particle size of 60 μm in a mass ratio of 1:1. The mixture consists of 40 μm hexagonal silicon nitride and 150 μm hexagonal silicon nitride; the alcohol solvent is 95% ethanol by mass; the binder consists of polyethylene glycol and shellac in a mass ratio of 1:0.2; the toughening particles consist of molybdenum silicide prepared in Preparation Example 2, polyetheretherketone prepared in Preparation Example 5, and aerogel prepared in Preparation Example 8 in a mass ratio of 1:0.1:0.05; the dispersant consists of polyethylene glycol and microcrystalline wax in a mass ratio of 1:0.5.

[0064] Example 3: The difference between this example and Example 1 is that:

[0065] The following ingredients are required: 120 kg silicon nitride, 110 kg alcohol solvent, 10 kg binder, 12 kg toughening particles, 5 kg dispersant, 1 kg defoamer, and 5 kg sintering aid. The silicon nitride consists of acicular silicon nitride and hexagonal silicon nitride in a 1:1 mass ratio. The acicular silicon nitride comprises acicular silicon nitride with an average particle size of 20 μm and acicular silicon nitride with an average particle size of 60 μm, both in a 1:1 mass ratio. The hexagonal silicon nitride comprises acicular silicon nitride with an average particle size of 60 μm in a 1:1 mass ratio. The mixture consists of hexagonal silicon nitride with a diameter of 40 μm and hexagonal silicon nitride with an average particle size of 150 μm; the alcohol solvent is 95% ethanol by mass; the binder consists of polyethylene glycol and shellac in a mass ratio of 1:0.5; the toughening particles consist of molybdenum silicide prepared in Preparation Example 3, polyether ether ketone prepared in Preparation Example 6, and aerogel prepared in Preparation Example 9 in a mass ratio of 1:0.5:0.1; and the dispersant consists of polyethylene glycol and microcrystalline wax in a mass ratio of 1:1.

[0066] Example 4: The difference between this example and Example 1 is that:

[0067] The silicon nitride is hexagonal silicon nitride.

[0068] Example 5: The difference between this example and Example 1 is that:

[0069] The binder is ethyl cellulose.

[0070] Example 6: The difference between this example and Example 1 is that:

[0071] No molybdenum telluride particles or polyvinyl alcohol solution were added during the preparation of molybdenum silicide.

[0072] Example 7: The difference between this example and Example 1 is that:

[0073] No tetra-needle zinc oxide whiskers or polyvinyl alcohol solution were added during the preparation of polyetheretherketone.

[0074] Example 8: The difference between this example and Example 1 is that:

[0075] The aerogel is a silica aerogel.

[0076] Comparative Example

[0077] Comparative Example 1: The difference between this comparative example and Example 1 is that:

[0078] No polyetheretherketone (PEEK) or aerogel was added during the preparation of the toughening particles.

[0079] Comparative Example 2: This comparative example differs from Example 1 in that:

[0080] No molybdenum silicide was added to the toughening particles.

[0081] Performance testing

[0082] 1. Strength testing

[0083] Finished silicon nitride ceramic substrates were prepared using the preparation methods of Examples 1-8 and Comparative Examples 1-2, respectively. The bending strength was tested and the data were recorded in accordance with GB / T6569-2006.

[0084] 2. Toughness testing

[0085] Finished silicon nitride ceramic substrates were prepared using the preparation methods of Examples 1-8 and Comparative Examples 1-2, respectively. The fracture toughness was tested and the data were recorded in accordance with GB / T23806-2009.

[0086] Except for the changes in the silicon nitride ceramic substrate in Examples 1-8 and Comparative Examples 1-2, the test conditions in the above detection methods remain unchanged, following the principle of a single variable.

[0087] Table 1 Performance Test Table

[0088]

[0089]

[0090] As can be seen from Examples 1-3 and Table 1, the silicon nitride ceramic substrate prepared in this application has the advantages of high strength and high toughness.

[0091] Combining Examples 1 and 4-8 with Table 1, it can be seen that the silicon nitride in Example 4 is hexagonal silicon nitride. Compared with Example 1, the strength and toughness of the silicon nitride ceramic substrate prepared in Example 4 are worse than those in Example 1. This indicates that the needle-like structure of the needle-like silicon nitride facilitates its intercalation into molybdenum silicide, improving the contact between silicon nitride and molybdenum silicide, thereby improving the toughness of the finished silicon nitride ceramic plate. On the other hand, the layered structure of the hexagonal silicon nitride facilitates its interweaving with the layered structure of molybdenum silicide, further increasing the contact area between silicon nitride and molybdenum silicide. Utilizing the high toughness of molybdenum silicide, the toughness of the finished silicon nitride ceramic substrate is improved.

[0092] In Example 5, the binder was ethyl cellulose. Compared with Example 1, the silicon nitride ceramic substrate prepared in Example 5 had poorer strength and toughness. This indicates that ethyl cellulose cannot be cross-linked and bonded with other raw materials, which easily affects the structural density. Moreover, ethyl cellulose is brittle and cannot be densely filled, which easily affects the strength and toughness.

[0093] In Example 6, no molybdenum telluride particles or polyvinyl alcohol solution were added during the preparation of molybdenum silicide. Compared to Example 1, the silicon nitride ceramic substrate prepared in Example 6 had inferior strength and toughness. This indicates that the lubricating effect of molybdenum telluride facilitates its filling and bonding in the pores between silicon nitride and molybdenum silicide, improving the structural density of the silicon nitride ceramic during the gradual heating process. Finally, under high-temperature sintering conditions, molybdenum telluride gradually decomposes thermally. At this time, the high temperature causes silicon nitride, molybdenum silicide, and other substances to expand slightly, further filling the structural pores generated by the thermal decomposition of molybdenum telluride, polyvinyl alcohol, and other substances, thereby improving the structural density of the silicon nitride ceramic substrate. This results in the finished silicon nitride ceramic substrate having the advantages of high strength and high toughness.

[0094] In Example 7, no tetraneedle-shaped zinc oxide whiskers and polyvinyl alcohol solution were added during the preparation of polyetheretherketone (PEEK). Compared to Example 1, the silicon nitride ceramic substrate prepared in Example 7 had inferior strength and toughness. This indicates that the needle-like structure of the tetraneedle-shaped zinc oxide whiskers facilitates insertion into the layered structure of silicon nitride and molybdenum silicide. The high toughness of PEEK improves the toughness of the silicon nitride ceramic substrate. At the same time, when the PEEK powder reaches its melting point during sintering, it is easily guided through the tetraneedle-shaped zinc oxide whiskers, thus filling the pores between silicon nitride and toughening particles. This ensures the structural density of the silicon nitride ceramic substrate, giving the finished silicon nitride ceramic substrate the advantages of high strength and high toughness.

[0095] Example 8 uses silica aerogel. Compared to Example 1, the silicon nitride ceramic substrate prepared in Example 8 has lower strength and toughness. This indicates that the gaseous substances generated by thermal decomposition can be easily released through the porous structure of silica aerogel, minimizing the increase in internal porosity of the silicon nitride ceramic substrate during gas escape. Combined with the high toughness of magnesium silicide particles, the magnesium silicide particles can increase the structural density of the silicon nitride ceramic substrate through deformation during the filling process. Magnesium silicide has a melting point of approximately 1100°C and can be thermally melted by high-temperature sintering. The thermally melted magnesium silicide, with its silicon phase and magnesium, can further improve the structural density and toughness of the silicon nitride ceramic substrate.

[0096] Combining Example 1 and Comparative Examples 1-2 with Table 1, it can be seen that no polyetheretherketone (PEEK) or aerogel was added during the preparation of the toughening particles in Comparative Example 1, and no molybdenum silicide was added to the toughening particles in Comparative Example 2. Compared with Example 1, the strength and toughness of the silicon nitride ceramic substrates prepared in Comparative Examples 1 and 2 are worse than those in Example 1. This indicates that the good toughness of molybdenum silicide, PEEK, and aerogel can improve the toughness of silicon nitride ceramic substrates. During the hot pressing of silicon nitride ceramic substrates, the squeezed PEEK reduces the space occupied, ensuring the density of the finished product structure. As high-temperature sintering proceeds, aerogel can provide a flow channel for volatile gases, reducing the generation of pores in the internal structure of silicon nitride ceramic substrates. Finally, under the highest temperature conditions of sintering, PEEK gradually decomposes thermally, and the PEEK that originally occupied space can provide storage space for the slight expansion inside the silicon nitride ceramic substrate caused by high temperature, improving the density of the silicon nitride ceramic substrate, thus giving the silicon nitride ceramic substrate the advantages of high strength and high toughness.

[0097] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A particulate dispersion toughened silicon nitride ceramic substrate, characterized by, The silicon nitride ceramic substrate comprises the following raw materials by weight: 80-120 parts of silicon nitride, 60-110 parts of alcohol solvent, 5-10 parts of binder, 5-12 parts of toughening particles, 1-5 parts of dispersant, 0.5-1 part of defoaming agent, and 2-5 parts of sintering aid; the toughening particles are composed of molybdenum silicide, polyether ether ketone and aerogel in a mass ratio of 1:0.1-0.5:0.05-0.

1.

2. The particle dispersed, toughened silicon nitride ceramic substrate of claim 1, wherein: The silicon nitride is composed of acicular silicon nitride and hexagonal silicon nitride in a mass ratio of 1:1-2.

3. The particle dispersed, silicon nitride ceramic substrate of claim 1, wherein, The binder is composed of polyethylene glycol and shellac in a mass ratio of 1:0.2-0.

5.

4. The particle dispersed, silicon nitride ceramic substrate of claim 1, wherein, The molybdenum silicide is made of molybdenum silicide particles, molybdenum telluride particles and polyvinyl alcohol solution in a mass ratio of 1:0.1-0.2:0.1-0.

3.

5. The particle dispersed, silicon nitride ceramic substrate of claim 1, wherein, The polyether ether ketone is made of polyether ether ketone powder, tetra-acicular zinc oxide whisker and polyvinyl alcohol solution in a mass ratio of 1:0.2-0.5:0.1-0.

4.

6. The particle dispersed, silicon nitride ceramic substrate of claim 1, wherein, The aerogel is made of silica aerogel, silane coupling agent KH-570 and magnesium silicide particles in a mass ratio of 1:0.1-0.3:0.1-0.

2.

7. The particle dispersed, silicon nitride ceramic substrate of claim 1, wherein, The dispersant is composed of polyethylene glycol and microcrystalline wax in a mass ratio of 1:0.5-1.

8. The particle dispersed, silicon nitride ceramic substrate of claim 1, wherein, The sintering aid is siliconized graphite.

9. The particle dispersed, silicon nitride ceramic substrate of claim 1, wherein, The defoaming agent is silicone defoaming agent.

10. A method of making a particle dispersed toughened silicon nitride ceramic substrate according to any one of claims 1 to 9, characterised in that, The method comprises the following steps: S1, uniformly ball-milling silicon nitride, alcohol solvent and toughening particles to obtain a preliminary mixture; then adding binder, dispersant, defoaming agent and sintering aid for continuous ball-milling and uniform mixing, and then vacuum degassing to obtain a mixture; S2, the mixture is subjected to flow casting, drying, isostatic pressing to obtain a blank, and the blank is cut, degreased, high-temperature sintered and cooled to obtain a finished product.

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