Manufacturing method of high-strength low-carbon-residue silicon nitride ceramic green body for electronic ceramics

Abstract

The invention discloses a manufacturing method of a high-strength low-carbon-residue silicon nitride ceramic green body for electronic ceramics, which achieves the purpose of enhancing strength by increasing the content of PVB (polyvinyl butyral) in tape casting slurry or increasing the molecular weight of PVB because a three-dimensional network structure formed by PVB in the green body can be enhanced by larger addition amount of PVB and PVB with higher molecular weight. The green body defect caused by non-uniform dispersion of silicon nitride powder can be eliminated to a certain extent through PVB with larger molecular weight and more PVB increment, the strength and mechanical property of the green body are improved, meanwhile, the effect of electrostatic repulsion brought by the surface of the coated powder is improved through reasonable proportion matching of ammonium polyacrylate and ammonium citrate, and the strength and mechanical property of the green body are improved. Meanwhile, polyethylene glycol and salmon fish oil are creatively added and reasonably matched, the steric hindrance dispersion effect of large and small molecule matching is provided, the proportion of the four dispersion effect media is adjusted to be optimal, and under the condition that the high strength of the green body is guaranteed, the carbon content of the product obtained after glue discharging is low.

Description

Technical Field

[0001] This invention relates to the field of electronic ceramics, and in particular to a method for manufacturing high-strength, low-residue silicon carbon nitride ceramic green bodies for electronic ceramics. Background Technology

[0002] Silicon nitride, as an advanced ceramic material with excellent mechanical properties and high thermal conductivity, typically exhibits a thermal conductivity of 45-90 W / (m·K) and a flexural strength of 600-1000 MPa when manufactured with proper processes. It also possesses excellent thermal shock resistance. Its performance in all aspects far surpasses that of conventional and widely used alumina ceramics. Currently, it is mainly used as a superior replacement for conventional alumina ceramics in the HTCC (High Temperature Metal-Ceramic Co-fired) field of the materials industry, such as the packaging of power modules like IGBTs and SiC. This covers application scenarios including electric drive controllers for new energy vehicles, traction converters for rail transit, photovoltaic and wind power inverters, and aerospace. In this process, ceramic powder is formed into ceramic green bodies through a casting method. Then, high-temperature metals such as tungsten and molybdenum are combined with the green bodies through punching, printing, etc. The green bodies are debonded at a relatively low temperature, such as 400-500℃, to remove organic matter. Finally, they are co-fired at high temperature in a reducing atmosphere to produce ceramic components. Although silicon nitride has excellent properties such as high flexural strength and high thermal conductivity, it has problems such as high sintering temperature and difficulty in densification. Usually, magnesium oxide, aluminum oxide, yttrium oxide and other sintering aids are introduced to lower the sintering temperature and increase its densification.

[0003] Silicon nitride casting refers to a molding method in which solvents, dispersants, binders, plasticizers and other components are added to silicon nitride ceramic powder, and a uniformly dispersed and stable slurry is obtained by ball milling or other mixing methods. After degassing and viscosity adjustment, a film of the required thickness is formed on a casting machine.

[0004] In summary, due to the characteristics of the HTCC manufacturing process, the cast green body requires extensive processing, including drilling, cutting, bending, and high-strength stacking. This poses a severe challenge to the performance of the green body, requiring the silicon nitride cast green body to possess high flatness, high tensile strength, and extremely low residual carbon after binder removal. This is because the pre-co-fired body contains metal elements such as tungsten and molybdenum, and the oxygen content usually needs to be controlled during the binder removal process to prevent oxidation of these metals, which would affect the performance of the final sintered product. However, this makes controlling the residual carbon after binder removal even more difficult, as the ideal conditions for removing organic matter from the green body are oxygen-rich. This allows the organic matter to fully decompose into carbon dioxide and water, preventing it from remaining inside the green body as carbon. Residual carbon has a significant impact on the ceramic performance of silicon nitride after sintering. It not only reduces the thermal conductivity of the silicon nitride ceramic but also affects the density of the sintered silicon nitride ceramic, reduces the flexural strength of the ceramic, and seriously affects the core performance of the final product.

[0005] The strength of silicon nitride cast green bodies is mainly affected by the dispersibility and uniformity of the cast slurry powder, as well as the amount and molecular weight of PVB (polyvinyl butyral). As a binder, PVB can form a three-dimensional molecular network after drying, encapsulating the silicon nitride ceramic powder within it. The integrity and strength of the three-dimensional network directly affect the macroscopic strength of the green body. If the powder is not dispersed uniformly, it is easy to destroy the three-dimensional network built by PVB. Uneven areas are usually stress release fracture points when bending or under pressure. Currently, the industry mainly solves this problem by increasing the content of PVB and increasing the molecular weight of PVB. However, as a high molecular polymer, PVB is not easy to expel and decompose, and it is the main source of residual carbon after the green body is debonded. Therefore, it is urgent to propose a method for manufacturing high-strength silicon nitride green bodies with low residual carbon after debonding for electronic ceramics. Summary of the Invention

[0006] In view of this, the present invention addresses the deficiencies of the prior art, and its main objective is to provide a method for manufacturing high-strength, low-residual-carbon silicon nitride ceramic green bodies for electronic ceramics, which can effectively solve the problems of low strength and high residual carbon in existing silicon nitride green body manufacturing methods.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for manufacturing a high-strength, low-residue silicon carbon nitride ceramic green body for electronic ceramics includes the following steps:

[0009] (1) The silicon nitride powder, the first organic solvent, and the ceramic powder dispersing aid are fed into a ball mill for ball milling; the silicon nitride powder includes alpha-state silicon nitride powder and beta-state crystalline silicon nitride powder, and the mass ratio of the alpha-state silicon nitride powder to the beta-state crystalline silicon nitride powder is 0.05-0.1:0.95-0.9; the ratio of the amount of ceramic powder dispersing aid added to the amount of silicon nitride powder added is 0.02:1; the ceramic powder dispersing aid is composed of ammonium polyacrylate, ammonium citrate, polyethylene glycol, and salmon oil in a mass ratio of 0.1-0.2:0.15-0.3:0.3-0.4:0.2-0.3.

[0010] (2) PVB, DBP and a second organic solvent are mixed to form a sol and added to the ball milling jar described in step (1) to continue ball milling and mixing to obtain silicon nitride slurry;

[0011] (3) Vacuum stirring and defoaming and viscosity control of silicon nitride slurry. The final slurry viscosity after vacuum defoaming is 6000-6500 mpa·s, and the defoaming time is at least 30 min.

[0012] (4) The silicon nitride slurry is fed into the casting machine for casting and forming of green blanks. The casting thickness is controlled to be 0.15-0.30 mm.

[0013] (5) Cut the molded blank to the required size for testing, and put it into the degumming furnace for degumming and testing.

[0014] As a preferred embodiment, the particle sizes D10, D50, and D90 of the silicon nitride powder are 0.2–0.3 μm, 0.8–0.9 μm, and 1.7–1.9 μm, respectively, and the specific surface area of ​​the silicon nitride powder is 10–11 m². 2 / g, wherein the oxygen content of the silicon nitride powder is 0.5-1%.

[0015] As a preferred embodiment, in step (1), the grinding balls in the grinding jar of the ball mill are made of 99% pure alumina. The diameter of the grinding balls is 2mm, 4mm, 6mm, 8mm, 10mm and 12mm, and they are proportioned according to the closest packing ratio. The grinding balls account for 33% of the total volume of the grinding jar. After feeding, the total volume of the material plus the grinding balls does not exceed 66% of the total volume of the grinding jar. The grinding speed during the grinding process is 400-500r / min, and the grinding time is 16-24h.

[0016] As a preferred embodiment, the first organic solvent in step (1) is ethyl acetate and ethanol, and the mass ratio of ethyl acetate to ethanol is 0.69:0.31.

[0017] As a preferred embodiment, the second organic solvent in step (2) is ethyl acetate and ethanol, and the mass ratio of ethyl acetate to ethanol is 0.69:0.31.

[0018] As a preferred embodiment, the PVB is a combination of models B30H and B60H produced by Kuraray Co., Ltd. of Japan, with the ratio of PVB of model B30H to PVB of model B60H being 0.2:0.8. The total amount of PVB added is 12% of the total powder amount, and the amount of DBP added is 90% of the total PVB amount. The DBP is used as a plasticizer to increase the toughness of the green body, and its manufacturer is Xilong Chemical.

[0019] As a preferred embodiment, the rotation speed during the PVB dissolution and stirring is 1000-1200 r / min, and the rotation speed after complete dissolution is 50-100 r / min. After the bubbles are completely expelled, the prepared sol is added to the silicon nitride slurry prepared in step (1) and then the mixture is ball-milled for 24 hours.

[0020] As a preferred embodiment, in step (4), the casting speed is 0.2-0.6 m / min, the casting blade height is controlled at 0.75-0.85 mm, the material height is controlled at 25-30 mm, and the casting temperature is in 6 segments, each segment being 0.8-1 m long, with temperatures of 25-30℃, 30-35℃, 35-40℃, 40-45℃, 45-50℃, and 50-55℃ respectively, and the drying time is 12-15 h.

[0021] As a preferred embodiment, in step (5), the molded green blank is cut into a dumbbell shape, with the width of the thinner part in the middle being 8mm and the length of the thinner part being 80mm. The tensile strength is tested using a universal mechanical testing instrument. The molded green blank is cut into 50×50mm squares and placed in a debinding furnace for debinding. Then the carbon content is tested.

[0022] As a preferred embodiment, the protective atmosphere for adhesive removal is a mixture of nitrogen and hydrogen, wherein the ratio of nitrogen to hydrogen is 0.85–0.9:0.15–0.1, and the gas flow rate is 0.08–0.1 m³ / s. 3 / h; the maximum temperature for discharging adhesive is 450-500℃, the heating rate is 0.8℃ / min, and the maximum temperature is maintained for 24-48h.

[0023] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution:

[0024] The strength is increased by increasing the PVB content or molecular weight of the cast slurry. Larger PVB additions and higher molecular weight PVB enhance the three-dimensional network structure of PVB within the green body. Larger molecular weight PVB and increased PVB content can also mitigate defects caused by uneven dispersion of silicon nitride powder, improving green body strength and mechanical properties. However, PVB, as a high-molecular-weight organic compound, has a complex structure and long branches, making it difficult to remove during the debinding process, especially in the HTCC field where debinding under a protective atmosphere is required. Therefore, this invention improves the electrostatic repulsion effect of ammonium polyacrylate and ammonium citrate by using a reasonable ratio to coat the powder surface, significantly enhancing the effect compared to using either alone. Simultaneously, the innovative addition and reasonable combination of polyethylene glycol and salmon oil provide steric dispersion effects based on the combination of large and small molecules. The optimal ratio of the four dispersion media ensures high green body strength while maintaining low carbon content in the debinded product, addressing industry pain points and providing a new approach for the development of the HTCC industry. Detailed Implementation

[0025] This invention discloses a method for manufacturing high-strength, low-residue silicon carbon nitride ceramic green bodies for electronic ceramics, comprising the following steps:

[0026] (1) Silicon nitride powder, a first organic solvent, and a ceramic powder dispersing agent are fed into a ball mill for ball milling; the silicon nitride powder includes alpha-state silicon nitride powder and beta-state crystalline silicon nitride powder, and the mass ratio of the alpha-state silicon nitride powder to the beta-state crystalline silicon nitride powder is 0.05-0.1:0.95-0.9; the ratio of the amount of ceramic powder dispersing agent added to the amount of silicon nitride powder added is 0.02:1. The particle sizes D10, D50, and D90 of the silicon nitride powder are 0.2-0.3 μm, 0.8-0.9 μm, and 1.7-1.9 μm, respectively, and the specific surface area of ​​the silicon nitride powder is 10-11 m². 2 The oxygen content of the silicon nitride powder is 0.5-1% per gram. The ceramic powder dispersing agent is composed of ammonium polyacrylate, ammonium citrate, polyethylene glycol, and salmon oil in a mass ratio of 0.1-0.2:0.15-0.3:0.3-0.4:0.2-0.3. The grinding balls in the ball mill jar are made of 99% pure alumina, with diameters of 2mm, 4mm, 6mm, 8mm, 10mm, and 12mm, arranged in a close-packed ratio. The grinding balls occupy 33% of the total volume of the ball mill jar, and the total volume of the material plus the grinding balls after feeding does not exceed 66% of the total volume of the ball mill jar. The ball milling speed is 400-500 r / min (taking a 10L ball mill jar as an example), and the ball milling time is 16-24 h. The first organic solvent is ethyl acetate and ethanol, and the mass ratio of ethyl acetate to ethanol is 0.69:0.31.

[0027] (2) PVB (polyvinyl butyral), DBP (dibutyl phthalate), and a second organic solvent are mixed to form a sol, which is then added to the ball mill jar described in step (1) and ball milled to obtain a silicon nitride slurry. The second organic solvent is ethyl acetate and ethanol, and the mass ratio of ethyl acetate to ethanol is 0.69:0.31. The PVB is a combination of B30H and B60H models produced by Kuraray Co., Ltd. of Japan. The ratio of PVB of model B30H to PVB of model B60H is 0.2:0.8. The total amount of PVB added is 12% of the total amount of powder, and the amount of DBP added is 90% of the total amount of PVB. DBP is used as a plasticizer to increase the toughness of the green body, and the manufacturer is Xilong Chemical. The stirring speed during the dissolution of PVB is 1000-1200 r / min, and the stirring speed after complete dissolution is 50-100 r / min. Once the bubbles are completely expelled, the prepared sol is added to the silicon nitride slurry prepared in step (1) and then the mixture is ball-milled for 24 hours.

[0028] (3) Vacuum stirring and defoaming and viscosity control of silicon nitride slurry. The final slurry viscosity after vacuum defoaming is 6000-6500 mpa·s, and the defoaming time is at least 30 min.

[0029] (4) The silicon nitride slurry is fed into a casting machine for casting to form a green body. The casting thickness is controlled to be 0.15-0.30 mm. The casting speed is 0.2-0.6 m / min, the casting blade height is controlled to be 0.75-0.85 mm, the material height is controlled to be 25-30 mm, and the casting temperature is divided into 6 sections, each section is 0.8-1 m long, and the temperature of each section is 25-30℃, 30-35℃, 35-40℃, 40-45℃, 45-50℃, and 50-55℃ respectively. The drying time is 12-15 h.

[0030] (5) Cut the molded preform to the required size for testing, and put it into the debinding furnace for debinding and testing. In this step (5), the molded preform is cut into a dumbbell shape, with the narrower part in the middle being 8mm wide and 80mm long. Tensile strength is tested using a universal testing instrument. The molded preform is cut into 50×50mm squares and placed in the debinding furnace for debinding, and then the carbon content is tested. The debinding protective atmosphere is a mixture of nitrogen and hydrogen, and the ratio of nitrogen to hydrogen is 0.85~

[0031] 0.9:0.15~0.1, air flux 0.08~0.1m 3 / h; the maximum temperature for discharging adhesive is 450-500℃, the heating rate is 0.8℃ / min, and the maximum temperature is maintained for 24-48h.

[0032] The present invention will be further described in detail below with several embodiments and comparative examples. The ceramic powders and additives used are as described in the technical solution. For parts where parameters and manufacturers are not specified, it is assumed that they were carried out under conventional conditions or conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be purchased commercially.

[0033] Example 1:

[0034] A method for manufacturing a high-strength, low-residue silicon carbon nitride ceramic green body for electronic ceramics includes the following steps:

[0035] (1) Silicon nitride powder, a first organic solvent, and a ceramic powder dispersing agent were fed into a ball mill for ball milling. The parameters of the silicon nitride powder were as described above. The first organic solvent was ethyl acetate and ethanol, with a mass ratio of 0.69:0.31. The ceramic powder dispersing agent was ammonium polyacrylate, ammonium citrate, polyethylene glycol, and salmon oil added in a ratio of 0.2:0.3:0.3:0.2, with a total addition amount of 2% of the silicon nitride powder. The ratio of the milling ball and the milling jar was as described in the technical solution. The ball milling speed was 450 r / min, and the ball milling time was 24 h.

[0036] (2) PVB, DBP, and a second organic solvent are mixed to form a sol, which is then added to the ball mill jar described in step (1) and ball milled to obtain a silicon nitride slurry. The second organic solvent is ethyl acetate and ethanol, with a mass ratio of 0.69:0.31. The prepared sol is added after step (1). The PVB is a combination of B30H and B60H produced by Kuraray Co., Ltd. of Japan, in a ratio of 0.2:0.8, with a total addition amount of 12% of the total powder. The amount of DBP added is 95% of the total amount of PVB added. The mixture is ball milled for 24 hours.

[0037] (3) Vacuum stirring and defoaming of silicon nitride slurry and viscosity control, with viscosity controlled at 6000-6500 mpa·s and defoaming time at least 30 min.

[0038] (4) The silicon nitride slurry is fed into the casting machine for casting. The thickness of the casting is controlled at 0.30 mm. The casting speed is 0.2 m / min, the casting blade height is controlled at 0.75 mm, the material height is controlled at 25 mm, and the casting temperature is divided into 6 sections, each section is 0.8-1 m long, and the temperature of each section is 25℃, 30℃, 35℃, 40℃, 45℃ and 50℃ respectively. The drying time is 15 h.

[0039] (5) Cut the molded green blank to the required size for testing, then place it in the debinding furnace for debinding, followed by testing. The debinding protective atmosphere is a mixture of nitrogen and hydrogen in a ratio of 0.85:0.15, with a gas flow rate of 0.1 m³ / s. 3 / h. The maximum temperature for glue removal is 500℃, the heating rate is 0.8℃ / min, and the maximum temperature is maintained for 48 hours.

[0040] Example 2:

[0041] A method for manufacturing a high-strength, low-residue silicon carbon nitride ceramic green body for electronic ceramics includes the following steps:

[0042] (1) Silicon nitride powder, a first organic solvent, and a ceramic powder dispersing agent were fed into a ball mill for ball milling. The parameters of the silicon nitride powder were as described above. The first organic solvent was ethyl acetate and ethanol, with a mass ratio of 0.69:0.31. The ceramic powder dispersing agent was ammonium polyacrylate, ammonium citrate, polyethylene glycol, and salmon oil added in a ratio of 0.1:0.3:0.4:0.2, with a total addition amount of 2% of the ceramic powder. The ratio of the ball mill and the ball mill jar was as described in the technical solution. The ball mill speed was 450 r / min, and the ball milling time was 24 h.

[0043] (2) PVB, DBP, and a second organic solvent are mixed to form a sol, which is then added to the ball mill jar described in step (1) and ball milled to obtain a silicon nitride slurry. The second organic solvent is ethyl acetate and ethanol, with a mass ratio of 0.69:0.31. The prepared sol is added after step (1). The PVB is a combination of B30H and B60H produced by Kuraray Co., Ltd. of Japan, in a ratio of 0.2:0.8, with a total addition amount of 12% of the total powder. The amount of DBP added is 95% of the total amount of PVB added. The mixture is ball milled for 24 hours.

[0044] (3) Vacuum stirring and defoaming of silicon nitride slurry and viscosity control, with viscosity controlled at 6000-6500 mpa·s and defoaming time at least 30 min.

[0045] (4) The silicon nitride slurry is fed into the casting machine for casting. The thickness of the casting is controlled at 0.30 mm. The casting speed is 0.2 m / min, the casting blade height is controlled at 0.75 mm, the material height is controlled at 25 mm, and the casting temperature is divided into 6 sections, each section is 0.8-1 m long, and the temperature of each section is 25℃, 30℃, 35℃, 40℃, 45℃ and 50℃ respectively. The drying time is 15 h.

[0046] (5) Cut the molded green blank to the required size for testing, then place it in the debinding furnace for debinding, followed by testing. The debinding protective atmosphere is a mixture of nitrogen and hydrogen in a ratio of 0.85:0.15, with a gas flow rate of 0.1 m³ / s. 3 / h. The maximum temperature for glue removal is 500℃, the heating rate is 0.8℃ / min, and the maximum temperature is maintained for 48 hours.

[0047] Example 3:

[0048] A method for manufacturing a high-strength, low-residue silicon carbon nitride ceramic green body for electronic ceramics includes the following steps:

[0049] (1) Silicon nitride powder, a first organic solvent, and a ceramic powder dispersing agent were fed into a ball mill for ball milling. The parameters of the silicon nitride powder were as described above. The first organic solvent was ethyl acetate and ethanol, with a mass ratio of 0.69:0.31. The ceramic powder dispersing agent was ammonium polyacrylate, ammonium citrate, polyethylene glycol, and salmon oil added in a ratio of 0.15:0.2:0.35:0.3, with a total addition amount of 2% of the ceramic powder. The ratio of the milling ball and the milling jar was as described in the technical solution. The ball milling speed was 450 r / min, and the ball milling time was 24 h.

[0050] (2) PVB, DBP, and a second organic solvent are mixed to form a sol, which is then added to the ball mill jar described in step one and ball milled to obtain a silicon nitride slurry. The second organic solvent is ethyl acetate and ethanol, with a mass ratio of 0.69:0.31. The prepared sol is added after step (1). The PVB is Kuraray Co., Ltd. of Japan, model B30H and B60H used together in a ratio of 0.2:0.8, with a total addition amount of 12% of the total powder. The amount of DBP added is 95% of the total amount of PVB added. The mixture is ball milled for 24 hours.

[0051] (3) Vacuum stirring and defoaming of silicon nitride slurry and viscosity control, with viscosity controlled at 6000-6500 mpa·s and defoaming time at least 30 min.

[0052] (4) The silicon nitride slurry is fed into the casting machine for casting. The thickness of the casting is controlled at 0.30 mm. The casting speed is 0.2 m / min, the casting blade height is controlled at 0.75 mm, the material height is controlled at 25 mm, and the casting temperature is divided into 6 sections, each section is 0.8-1 m long, and the temperature of each section is 25℃, 30℃, 35℃, 40℃, 45℃ and 50℃ respectively. The drying time is 15 h.

[0053] (5) Cut the molded green body to the required size for testing, then place it in the debinding furnace for debinding, followed by testing. The debinding protective atmosphere is a nitrogen-hydrogen mixture with a ratio of 0.85:0.15 and a gas flow rate of 0.1 m³ / s. 3 / h. The maximum temperature for glue removal is 500℃, the heating rate is 0.8℃ / min, and the maximum temperature is maintained for 48 hours.

[0054] Example 4:

[0055] A method for manufacturing a high-strength, low-residue silicon carbon nitride ceramic green body for electronic ceramics includes the following steps:

[0056] (1) Silicon nitride powder, a first organic solvent, and a ceramic powder dispersing agent were fed into a ball mill for ball milling. The parameters of the silicon nitride powder were as described above. The first organic solvent was ethyl acetate and ethanol, with a mass ratio of 0.69:0.31. The ceramic powder dispersing agent was ammonium polyacrylate, ammonium citrate, polyethylene glycol, and salmon oil added in a ratio of 0.2:0.3:0.3:0.2, with a total addition amount of 2% of the ceramic powder. The ratio of the ball mill and the ball mill jar was as described in the technical solution. The ball mill speed was 450 r / min, and the ball milling time was 24 h.

[0057] (2) PVB, DBP, and a second organic solvent are mixed to form a sol, which is then added to the ball mill jar described in step one and ball milled to obtain a silicon nitride slurry. The second organic solvent is ethyl acetate and ethanol, with a mass ratio of 0.69:0.31. The prepared sol is added after step (1). The PVB is Kuraray Co., Ltd. of Japan, model B30H and B60H used together in a ratio of 0.2:0.8, with a total addition amount of 12% of the total powder. The amount of DBP added is 95% of the total amount of PVB added. The mixture is ball milled for 24 hours.

[0058] (3) Vacuum stirring and defoaming of silicon nitride slurry and viscosity control, with viscosity controlled at 6000-6500 mpa·s and defoaming time at least 30 min.

[0059] (4) The silicon nitride slurry is fed into the casting machine for casting. The thickness of the casting is controlled at 0.30 mm. The casting speed is 0.2 m / min, the casting blade height is controlled at 0.75 mm, the material height is controlled at 25 mm, and the casting temperature is divided into 6 sections, each section is 0.8-1 m long, and the temperature of each section is 25℃, 30℃, 35℃, 40℃, 45℃ and 50℃ respectively. The drying time is 15 h.

[0060] (5) Cut the molded green blank to the required size for testing, then place it in the debinding furnace for debinding, followed by testing. The debinding protective atmosphere is a mixture of nitrogen and hydrogen in a ratio of 0.9:0.1, with a gas flow rate of 0.1 m³ / s. 3 / h. The maximum temperature for glue removal is 500℃, the heating rate is 0.8℃ / min, and the maximum temperature is maintained for 48 hours.

[0061] Example 5:

[0062] A method for manufacturing a high-strength, low-residue silicon carbon nitride ceramic green body for electronic ceramics includes the following steps:

[0063] (1) Silicon nitride powder, a first organic solvent, and a ceramic powder dispersing agent were fed into a ball mill for ball milling. The parameters of the silicon nitride powder were as described above. The first organic solvent was ethyl acetate and ethanol, with a mass ratio of 0.69:0.31. The ceramic powder dispersing agent was ammonium polyacrylate, ammonium citrate, polyethylene glycol, and salmon oil added in a ratio of 0.1:0.3:0.4:0.2, with a total addition amount of 2% of the ceramic powder. The ratio of the ball mill and the ball mill jar was as described in the technical solution. The ball mill speed was 450 r / min, and the ball milling time was 24 h.

[0064] (2) PVB, DBP, and a second organic solvent are mixed to form a sol, which is then added to the ball mill jar described in step (1) and ball milled to obtain a silicon nitride slurry. The second organic solvent is ethyl acetate and ethanol, with a mass ratio of 0.69:0.31. The prepared sol is added after step (1). The PVB is a combination of B30H and B60H produced by Kuraray Co., Ltd. of Japan, in a ratio of 0.2:0.8, with a total addition amount of 12% of the total powder. The amount of DBP added is 95% of the total amount of PVB added. The mixture is ball milled for 24 hours.

[0065] (3) Vacuum stirring and defoaming of silicon nitride slurry and viscosity control, with viscosity controlled at 6000-6500 mpa·s and defoaming time at least 30 min.

[0066] (4) The silicon nitride slurry is fed into the casting machine for casting. The thickness of the casting is controlled at 0.30 mm. The casting speed is 0.2 m / min, the casting blade height is controlled at 0.75 mm, the material height is controlled at 25 mm, and the casting temperature is divided into 6 sections, each section is 0.8-1 m long, and the temperature of each section is 25℃, 30℃, 35℃, 40℃, 45℃ and 50℃ respectively. The drying time is 15 h.

[0067] (5) Cut the molded green blank to the required size for testing, then place it in the debinding furnace for debinding, followed by testing. The debinding protective atmosphere is a mixture of nitrogen and hydrogen in a ratio of 0.85:0.15, with a gas flow rate of 0.08 m³ / h. 3 / h. The maximum temperature for glue removal is 500℃, the heating rate is 0.8℃ / min, and the maximum temperature is maintained for 48 hours.

[0068] Example 6:

[0069] A method for manufacturing a high-strength, low-residue silicon carbon nitride ceramic green body for electronic ceramics includes the following steps:

[0070] (1) Silicon nitride powder, a first organic solvent, and a ceramic powder dispersing agent were fed into a ball mill for ball milling. The parameters of the silicon nitride powder were as described above. The first organic solvent was ethyl acetate and ethanol, with a mass ratio of 0.69:0.31. The ceramic powder dispersing agent was ammonium polyacrylate, ammonium citrate, polyethylene glycol, and salmon oil added in a ratio of 0.1:0.3:0.4:0.2, with a total addition amount of 2% of the ceramic powder. The ratio of the ball mill and the ball mill jar was as described in the technical solution. The ball mill speed was 450 r / min, and the ball milling time was 24 h.

[0071] (2) PVB, DBP, and a second organic solvent are mixed to form a sol, which is then added to the ball mill jar described in step (1) and ball milled to obtain a silicon nitride slurry. The second organic solvent is ethyl acetate and ethanol, with a mass ratio of 0.69:0.31. The prepared sol is added after step (1). The PVB is a combination of B30H and B60H produced by Kuraray Co., Ltd. of Japan, in a ratio of 0.2:0.8, with a total addition amount of 12% of the total powder. The amount of DBP added is 95% of the total amount of PVB added. The mixture is ball milled for 24 hours.

[0072] (3) Vacuum stirring and defoaming of silicon nitride slurry and viscosity control, with viscosity controlled at 6000-6500 mpa·s and defoaming time at least 30 min.

[0073] (4) The silicon nitride slurry is fed into the casting machine for casting. The thickness of the casting is controlled at 0.30 mm. The casting speed is 0.2 m / min, the casting blade height is controlled at 0.75 mm, the material height is controlled at 25 mm, and the casting temperature is divided into 6 sections, each section is 0.8-1 m long, and the temperature of each section is 25℃, 30℃, 35℃, 40℃, 45℃ and 50℃ respectively. The drying time is 15 h.

[0074] (5) Cut the molded green body to the required size for testing, then place it in the debinding furnace for debinding, followed by testing. The debinding protective atmosphere is a mixture of nitrogen and hydrogen in a ratio of 0.85:0.15, with a gas flow rate of 1m³. 3 / h. The maximum temperature for glue removal is 500℃, the heating rate is 0.8℃ / min, and the maximum temperature is maintained for 24 hours.

[0075] Comparative Example 1 is basically the same as Example 1, except that only ammonium polyacrylate, a ceramic powder dispersant, is used, which will not be described in detail here.

[0076] Comparative Example 2 is basically the same as Example 1, except that only polyethylene glycol, a ceramic powder dispersant, is used, which will not be described in detail here.

[0077] Comparative Example 3 is basically the same as Example 1, except that the total amount of PVB in the total amount of powder is increased to 14%, which will not be described in detail here.

[0078] Comparative Example 4 is basically the same as Example 1, except that pure nitrogen is used for debinding, which will not be described in detail here.

[0079] The tensile strength of the green body and the residual carbon value after debinding of the green body were tested for each of the above embodiments and comparative examples. The test results are shown in the table below.

[0080] Test Project Tensile strength of green body (MPa) Residual carbon value (ppm) after debinding of green body Example 1 3.58 3688 Example 2 3.04 3741 Example 3 3.12 3899 Example 4 3.56 5412 Example 5 3.54 6433 Example 6 3.52 4425 Comparative Example 1 1.77 3968 Comparative Example 2 1.98 3829 Comparative Example 3 3.12 16470 Comparative Example 4 3.55 11222

[0081] Summary and analysis of results:

[0082] As can be seen from Examples 1-3, slight modifications to the proportions of the mixed ceramic powder dispersant resulted in minor fluctuations in the strength and residual carbon value of the produced green body. However, the fluctuations were within a normal and acceptable range. Furthermore, it is evident that the proportion of the mixed ceramic powder dispersant in Example 1 was the optimal choice, yielding excellent strength and residual carbon value.

[0083] As can be seen from Examples 4-6, when the debinding process parameters of silicon nitride protective atmosphere are slightly modified, the strength and residual carbon value of the produced green body also fluctuate slightly. It can be seen from the data that, under the same green body strength, the fluctuation of the debinding process parameters has a slightly greater impact on the residual carbon than the ratio of the mixed ceramic powder dispersant parameters. However, the fluctuation range is within the normal and acceptable range.

[0084] As can be seen from Comparative Example 1, the strength of silicon nitride green bodies prepared by conventionally using only ammonium polyacrylate as a ceramic powder dispersant is significantly lower than that of the preparation method proposed in this invention. This is because, under the same PVB binder system, the powder slurry has poorer dispersibility and more green body defects. Comparative Example 2, on the other hand, uses only polyethylene glycol as a dispersant, and the data shows a similar result.

[0085] As can be seen from Comparative Example 3, increasing the proportion of PVB in the total powder can indeed improve the tensile strength of silicon nitride green. When the green strength is similar to that of Example 1, its residual carbon value increases significantly, which has a significant impact on the final silicon nitride product.

[0086] As can be seen from Comparative Example 4, the protective atmosphere debinding method described in this invention does have an advantage in residual carbon value compared to debinding with pure nitrogen.

[0087] In summary, the method for preparing high-strength, low-residue silicon carbon nitride ceramic green bodies for electronic ceramics described in this invention is clearly effective.

[0088] The key design focus of this invention is to increase strength by increasing the PVB content or molecular weight of the cast slurry. A larger PVB content and higher molecular weight enhance the three-dimensional network structure of PVB within the green body. Higher molecular weight and greater PVB addition can also mitigate defects caused by uneven dispersion of silicon nitride powder, improving green body strength and mechanical properties. However, PVB, as a high-molecular-weight organic compound, has a complex structure and long branches, making it difficult to remove during debinding, especially in the HTCC field where debinding requires a protective atmosphere. Therefore, this invention improves the electrostatic repulsion effect of ammonium polyacrylate and ammonium citrate by using a reasonable ratio to coat the powder surface, significantly enhancing the effect compared to using either alone. Simultaneously, the innovative addition and reasonable combination of polyethylene glycol and salmon oil provide steric hindrance dispersion effects based on the combination of large and small molecules. The optimal ratio of these four dispersion media ensures high green body strength while maintaining low carbon content in the debinded product, addressing industry pain points and providing a new approach for the development of the HTCC industry.

[0089] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for manufacturing high-strength, low-residue silicon carbide ceramic green bodies for electronic ceramics, characterized in that: Includes the following steps: (1) Silicon nitride powder, a first organic solvent, and a ceramic powder dispersing agent are fed into a ball mill for ball milling; the silicon nitride powder includes alpha-state silicon nitride powder and beta-state crystalline silicon nitride powder, and the mass ratio of the alpha-state silicon nitride powder to the beta-state crystalline silicon nitride powder is 0.05-0.1:0.95-0.9; the ratio of the amount of ceramic powder dispersing agent added to the amount of silicon nitride powder added is 0.02:1; the ceramic powder dispersing agent is composed of ammonium polyacrylate, ammonium citrate, polyethylene glycol, and salmon oil in a mass ratio of 0.1-0.2:0.15-0.3:0.3-0.4:0.2-0.

3. (2) PVB, DBP and a second organic solvent are mixed to form a sol and added to the ball milling jar described in step (1) to continue ball milling and mixing to obtain silicon nitride slurry; (3) Vacuum stirring and defoaming and viscosity control of silicon nitride slurry. The final slurry viscosity after vacuum defoaming is 6000-6500 mpa·s, and the defoaming time is at least 30 min. (4) The silicon nitride slurry is fed into the casting machine for casting and forming of green blanks. The casting thickness is controlled to be 0.15-0.30 mm. (5) Cut the molded blank to the required size for testing, and put it into the degumming furnace for degumming and testing.

2. The method for manufacturing high-strength, low-residue silicon carbide ceramic green bodies for electronic ceramics according to claim 1, characterized in that: The particle sizes D10, D50, and D90 of the silicon nitride powder are 0.2–0.3 μm, 0.8–0.9 μm, and 1.7–1.9 μm, respectively, and the specific surface area of ​​the silicon nitride powder is 10–11 m². 2 / g, wherein the oxygen content of the silicon nitride powder is 0.5-1%.

3. The method for manufacturing high-strength, low-residue silicon carbide ceramic green bodies for electronic ceramics according to claim 1, characterized in that: In step (1), the grinding balls in the grinding jar of the ball mill are made of 99% pure alumina. The diameter of the grinding balls is 2mm, 4mm, 6mm, 8mm, 10mm and 12mm, and they are proportioned according to the closest packing ratio. The grinding balls account for 33% of the total volume of the grinding jar. After feeding, the total volume of the material plus the grinding balls does not exceed 66% of the total volume of the grinding jar. The grinding speed during the grinding process is 400 to 500 r / min and the grinding time is 16 to 24 hours.

4. The method for manufacturing high-strength, low-residue silicon carbide ceramic green bodies for electronic ceramics according to claim 1, characterized in that: In step (1), the first organic solvent is ethyl acetate and ethanol, and the mass ratio of ethyl acetate to ethanol is 0.69:0.

31.

5. The method for manufacturing high-strength, low-residue silicon carbide ceramic green bodies for electronic ceramics according to claim 1, characterized in that: In step (2), the second organic solvent is ethyl acetate and ethanol, and the mass ratio of ethyl acetate to ethanol is 0.69:0.

31.

6. The method for manufacturing high-strength, low-residue silicon carbide ceramic green bodies for electronic ceramics according to claim 1, characterized in that: The PVB used is a combination of B30H and B60H models produced by Kuraray Co., Ltd. of Japan. The ratio of PVB of model B30H to PVB of model B60H is 0.2:0.

8. The total amount of PVB added is 12% of the total powder amount. The amount of DBP added is 90% of the total PVB amount. DBP is used as a plasticizer to increase the toughness of the green body. The manufacturer is Xilong Chemical.

7. The method for manufacturing high-strength, low-residue silicon carbide ceramic green bodies for electronic ceramics according to claim 1, characterized in that: The stirring speed during the dissolution of PVB is 1000-1200 r / min, and the stirring speed after complete dissolution is 50-100 r / min. Once the bubbles are completely expelled, the prepared sol is added to the silicon nitride slurry prepared in step (1) and then the mixture is ball-milled for 24 hours.

8. The method for manufacturing high-strength, low-residue silicon carbon nitride ceramic green bodies for electronic ceramics according to claim 1, characterized in that: In step (4), the casting speed is 0.2-0.6 m / min, the casting blade height is controlled at 0.75-0.85 mm, the material height is controlled at 25-30 mm, and the casting temperature is in 6 segments, each segment is 0.8-1 m long, and the temperature of each segment is 25-30℃, 30-35℃, 35-40℃, 40-45℃, 45-50℃, and 50-55℃ respectively. The drying time is 12-15 h.

9. The method for manufacturing high-strength, low-residue silicon carbide ceramic green bodies for electronic ceramics according to claim 1, characterized in that: In step (5), the molded green blank is cut into a dumbbell shape, with the width of the thinner part in the middle being 8mm and the length of the thinner part being 80mm. The tensile strength is tested using a universal mechanical testing instrument. The molded green blank is cut into 50×50mm squares and placed in a debinding furnace for debinding. Then the carbon content is tested.

10. The method for manufacturing high-strength, low-residue silicon carbide ceramic green bodies for electronic ceramics according to claim 1, characterized in that: In step (5), the protective atmosphere for adhesive removal is a mixture of nitrogen and hydrogen, with a nitrogen-to-hydrogen ratio of 0.85–0.9:0.15–0.1 and a gas flow rate of 0.08–0.1 m³ / s. 3 / h; the maximum temperature for discharging adhesive is 450-500℃, the heating rate is 0.8℃ / min, and the maximum temperature is maintained for 24-48h.