Silicon nitride ceramic material and preparation method and application thereof

Abstract

The invention discloses a silicon nitride ceramic material and a preparation method and application thereof, and the preparation method of the silicon nitride ceramic material comprises the following steps: providing slurry which comprises a silicon-containing raw material; the silicon-containing raw material comprises silicon powder, an inhibitor and an inorganic solvent in a mass ratio of 100: (0.1-10): (10-100), and the inhibitor comprises one or more of an alcohol compound, organic acid, methyl silicone oil and a silane coupling agent; preparing a green body from the slurry; and the green body is subjected to nitriding treatment and sintering treatment in sequence. The silicon powder is used as a main source of a silicon element, and hydrogen in hydroxyl in the inhibitor is connected with oxygen in silicon dioxide formed on the surface of the silicon powder due to oxidation to form a hydrogen bond, so that the surface of the silicon powder is coated with the inhibitor to form a complex for modification, and continuous hydrolysis of the silicon powder in an inorganic solvent such as water is inhibited; and the silicon nitride ceramic material with few impurities is obtained by matching nitriding treatment and sintering treatment, so that the thermal conductivity is improved.

Description

Technical Field

[0001] This application relates to the field of ceramic materials, and particularly to a silicon nitride ceramic material, a preparation method thereof, and an application thereof. Background Art

[0002] Silicon nitride ceramic plates have excellent properties such as high strength, high hardness, high temperature resistance, and corrosion resistance, and thus have a wide range of applications in many fields such as machinery, electronics, chemical engineering, and new energy.

[0003] In the preparation of traditional silicon nitride substrates, silicon nitride powder is mainly mixed with two or more sintering aids, and organic solvents, dispersants, plasticizers, binders, etc. are added. After ball milling, a slurry with appropriate viscosity and rheology is prepared as a raw material, and then nitriding treatment and sintering treatment are carried out. However, silicon nitride powder not only has a high price but also contains a certain amount of impurities (such as oxygen with a content greater than 1%), resulting in a high oxygen content in the prepared silicon nitride ceramic plate and poor thermal conductivity of the silicon nitride ceramic plate. Summary of the Invention

[0004] Based on this, it is necessary to provide a silicon nitride ceramic material with fewer impurities and better thermal conductivity, a preparation method thereof, and an application thereof.

[0005] This application provides a preparation method of a silicon nitride ceramic material, including the following steps:

[0006] Providing a slurry, where the slurry includes a silicon-containing raw material;

[0007] Wherein the silicon-containing raw material includes silicon powder, an inhibitor, and an inorganic solvent with a mass ratio of 100:(0.1 - 10):(10 - 100), and the inhibitor includes one or more of alcohol compounds, organic acids, methyl silicone oil, and silane coupling agents;

[0008] Using the slurry to prepare a green body;

[0009] Performing nitriding treatment and sintering treatment on the green body.

[0010] In one embodiment, the inhibitor satisfies one or more of the following conditions:

[0011] (1) The alcohol compounds include one or more of ethanol, isopropanol, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, and glycerol;

[0012] (2) The organic acids include one or more of oleic acid, palmitic acid, stearic acid, citric acid, acrylic acid, and polyacrylic acid;

[0013] (3) The viscosity of the methyl silicone oil is 200 cps - 5000 cps;

[0014] (4) The silane coupling agent includes one or more of an amino silane coupling agent, an epoxy silane coupling agent, a mercapto silane coupling agent, a methacryloxy silane coupling agent, a vinyl silane coupling agent, and an amino silane coupling agent.

[0015] In one embodiment, one or more of the following conditions are satisfied:

[0016] (1) The particle size D100 of the silicon powder is 5 μm to 20 μm;

[0017] (2) The silicon-containing raw material further includes a sintering auxiliary material and an auxiliary agent, and the mass ratio of the silicon powder, the sintering auxiliary material, and the auxiliary agent is 100:(2 to 20):(5 to 55);

[0018] (3) The inorganic solvent includes water.

[0019] In one embodiment, one or two of the following conditions are satisfied:

[0020] (1) The auxiliary agent includes a dispersant, a plasticizer, a binder, and an antifoaming agent with a mass ratio of (0.3 to 7):(0.5 to 15):(5 to 30):(0.05 to 5);

[0021] (2) The sintering auxiliary material includes one or two of an alkaline earth metal compound and a rare earth compound.

[0022] In one embodiment, one or more of the following conditions are satisfied:

[0023] (1) The dispersant includes one or more of polyethylene glycol, polypropylene glycol, oleic acid, palmitic acid, citric acid, acrylic acid, polyacrylic acid, styrene maleic anhydride copolymer, and styrene maleic anhydride acrylic copolymer;

[0024] (2) The plasticizer includes one or more of glycerol, polyethylene glycol, polypropylene glycol, methyl silicone oil, and a silane coupling agent;

[0025] (3) The binder includes one or more of polyvinyl alcohol, polyvinyl butyral, polyacrylic acid, and polyurethane;

[0026] (4) The antifoaming agent includes one or more of ethanol, isopropanol, polyethylene glycol, polypropylene glycol, methyl silicone oil, and a silane coupling agent;

[0027] (5) The alkaline earth metal compound includes one or more of magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium acetate, magnesium stearate, magnesium palmitate, magnesium citrate, magnesium hydride, magnesium silicide, magnesium nitride, magnesium fluoride, and magnesium nitrate;

[0028] (6)The rare earth compound includes one or more of yttrium oxide, yttrium silicide, yttrium fluoride, yttrium chloride, yttrium nitrate, lanthanum oxide, and ytterbium oxide.

[0029] In one embodiment, the nitriding treatment satisfies one or more of the following conditions:

[0030] (1)The treatment is carried out in a nitrogen atmosphere;

[0031] (2)The treatment temperature is 1200 °C to 1500 °C;

[0032] (3)The treatment pressure is 0.01 MPa to 0.5 MPa;

[0033] (4)The treatment time is 1 h to 10 h.

[0034] In one embodiment, the sintering treatment satisfies one or more of the following conditions:

[0035] (1)The treatment temperature is 1750 °C to 1950 °C;

[0036] (2)The treatment pressure is 0.7 MPa to 5 MPa;

[0037] (3)The treatment time is 1 h to 24 h.

[0038] In one embodiment, one or two of the following conditions are satisfied:

[0039] (1)The green body is prepared by using the slurry through a tape casting method;

[0040] (2)Before the nitriding treatment, the green body further includes a debinding treatment step.

[0041] This application also provides a silicon nitride ceramic material prepared by the above preparation method.

[0042] Furthermore, this application provides the use of the above silicon nitride ceramic material in the preparation of ceramic circuit boards, heat dissipation devices, or packaging structures.

[0043] This application uses silicon powder as the main source of silicon element, and uses the hydrogen in the hydroxyl group of the inhibitor to connect with the oxygen in the silicon dioxide formed by oxidation on the surface of the silicon powder to form a hydrogen bond, so that the inhibitor is coated on the surface of the silicon powder to form a complex for modification, inhibiting the continuous hydrolysis of the silicon powder in inorganic solvents such as water. By combining the preparation methods of nitriding treatment and sintering treatment, a silicon nitride ceramic material with less impurities can be obtained, which can further improve the thermal conductivity of the silicon nitride ceramic material. Detailed Embodiments

[0044] To facilitate the understanding of the present application, the present application will be described more comprehensively below. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0046] As used herein, the alternative "and / or" includes any one of two or more related listed items, as well as any and all combinations of the related listed items. The any and all combinations include combinations of any two related listed items, any more related listed items, or all related listed items. For example, "A and / or B" includes three alternative scenarios: A, B, and "the combination of A and B".

[0047] In this document, unless otherwise stated, "one or more" means any one of the listed items or any combination of the listed items. Similarly, in other cases where "one or more" and other expressions indicating "one or more" are used, they are understood in the same way unless otherwise stated.

[0048] In this document, words such as "further", "even further", "in particular", "for example", "such as", "example", "for illustration" are used for descriptive purposes, indicating an association in the covered content between the different technical solutions before and after, but should not be construed as a limitation on the previous technical solution, nor as a limitation on the scope of protection of this document. In this document, unless otherwise stated, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0049] In this document, "optionally", "optional", "option" mean that it can be either present or absent, that is, it refers to any one of the two alternative scenarios of "present" or "absent". If the word "optional" appears multiple times in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction relationship, each "optional" is independent. In this application, descriptions such as "optionally contain" and "optionally include" mean "contain or not contain". "Optional component X" means that component X is present or absent, or means that it contains or does not contain this component X.

[0050] In this text, in "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc., the terms "first", "second", "third", "fourth", etc. are only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly specifying the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive enumerative description and should be understood not to constitute a closed limitation on quantity.

[0051] In this text, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, as well as an open technical solution including the listed features.

[0052] In this text, regarding a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the selectable numerical values within this numerical interval is considered continuous, and it includes the two numerical endpoints of this numerical interval (i.e., the minimum value and the maximum value), as well as each numerical value between these two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers within this numerical interval, it includes the two endpoint integers of this numerical range, as well as each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed in this text should be understood to include any and all sub-ranges subsumed therein. The "numerical value" in this numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. The "numerical interval" allows for a broad inclusion of numerical interval types such as a percentage interval, a ratio interval, a ratio value interval, etc.

[0053] In this text, the term "room temperature" or "normal temperature" generally refers to 4°C to 35°C, such as 20°C ± 5°C. In some embodiments of this text, "room temperature" or "normal temperature" refers to 10°C to 30°C. In some embodiments of this text, "room temperature" or "normal temperature" refers to 20°C to 30°C.

[0054] In this text, when a method process involves multiple steps, unless there are clear different descriptions in this text, the execution of these steps has no strict order limitation, and it can be executed in an order other than the described one. Moreover, any step can include multiple sub-steps or multiple stages. These sub-steps or stages do not necessarily need to be executed at the same moment, but can be executed at different moments, and their execution order does not necessarily need to be sequential, but can be executed alternately or simultaneously with other steps or a part of the sub-steps or stages of other steps.

[0055] This application provides a method for preparing a silicon nitride ceramic material, including the following steps:

[0056] Providing a slurry, the slurry including a silicon-containing raw material;

[0057] The silicon-containing raw materials include silicon powder, an inhibitor, and an inorganic solvent with a mass ratio of 100:(0.1~10):(10~100). The inhibitor includes one or more of alcohol compounds, organic acids, methyl silicone oil, and silane coupling agents.

[0058] Use the slurry to prepare a green body.

[0059] Perform nitridation treatment and sintering treatment on the green body.

[0060] In this application, by using silicon powder as the main source of silicon element, and using the hydrogen in the hydroxyl group of the inhibitor to connect with the oxygen in the silicon dioxide formed by oxidation on the surface of the silicon powder to form a hydrogen bond, the inhibitor is coated on the surface of the silicon powder to form a complex for modification, inhibiting the continuous hydrolysis of the silicon powder in inorganic solvents such as water. The preparation method combined with nitridation treatment and sintering treatment can obtain a silicon nitride ceramic material with less impurities, which can further improve the thermal conductivity of the silicon nitride ceramic material.

[0061] Furthermore, by optimizing the selection of the inhibitor and coordinating with various preparation parameters, silicon nitride plates with different performance requirements can be prepared.

[0062] Furthermore, the silicon-containing raw materials include silicon powder, an inhibitor, and an inorganic solvent with a mass ratio of 100:(0.1~5):(20~80). Further still, the silicon-containing raw materials include silicon powder, an inhibitor, and an inorganic solvent with a mass ratio of 100:(0.5~3):(30~60).

[0063] It can be understood that the preparation method of the silicon-containing raw materials includes mixing silicon powder and an inhibitor in proportion and performing a first dispersion treatment. Further, the above first dispersion treatment can be, but is not limited to, one or more processes of stirring dispersion, ball milling dispersion, planetary ball milling dispersion, sand milling dispersion, and ultrasonic dispersion, and the time of the first dispersion treatment is 10 min to 300 min. Further, the time of the first dispersion treatment is 80 min to 150 min. Specifically, the time of the first dispersion treatment can be, but is not limited to, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, or 150 min.

[0064] In a specific example, the alcohol compounds include one or more of ethanol, isopropanol, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, and glycerol. It can be understood that the molecular weights of polyethylene glycol and polypropylene glycol are independently 100 to 1000. Specifically, the molecular weights of polyethylene glycol and polypropylene glycol can be, but are not limited to, 100, 200, 300, 400, 500, 600, 700, 800, 900, or 1000 independently.

[0065] In a specific example, the organic acid includes one or more of oleic acid, palmitic acid, stearic acid, citric acid, acrylic acid, and polyacrylic acid. It can be understood that the molecular weight of polyacrylic acid is 30,000 to 250,000. Specifically, the molecular weight of polyacrylic acid can be, but is not limited to, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, 100,000, 110,000, 120,000, 130,000, 140,000, 150,000, 160,000, 170,000, 180,000, 190,000, 200,000, 210,000, 220,000, 230,000, 240,000, or 250,000.

[0066] In a specific example, the viscosity of the methyl silicone oil is 200 pcs to 5000 pcs. Specifically, the viscosity of the methyl silicone oil can be, but is not limited to, 200 pcs, 300 pcs, 400 pcs, 500 pcs, 600 pcs, 700 pcs, 800 pcs, 900 pcs, 1000 pcs, 1500 pcs, 2000 pcs, 2500 pcs, 3000 pcs, 3500 pcs, 4000 pcs, 4500 pcs, or 5000 pcs.

[0067] In a specific example, the silane coupling agent includes one or more of an amino silane coupling agent, an epoxy silane coupling agent, a mercapto silane coupling agent, a methacryloxy silane coupling agent, a vinyl silane coupling agent, and an amino silane coupling agent.

[0068] Furthermore, the amino silane coupling agent includes a secondary amino silane coupling agent. Specifically, the secondary amino silane coupling agent can be, but is not limited to, N-phenyl-3-aminopropyltrimethoxysilane. It can be understood that N-phenyl-3-aminopropyltrimethoxysilane can be, but is not limited to, Shin-Etsu KBM-573.

[0069] The epoxy group silane coupling agent includes one or both of an aliphatic epoxy group silane coupling agent and an alicyclic epoxy group silane coupling agent. Specifically, the aliphatic epoxy group silane coupling agent includes one or both of 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane. 3-Glycidoxypropyltrimethoxysilane can be, but is not limited to, Shin-Etsu KBM-403, and 3-glycidoxypropyltriethoxysilane can be, but is not limited to, Shin-Etsu KBE-403. The alicyclic epoxy group silane coupling agent includes one or both of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane. 2-(3,4-Epoxycyclohexyl)ethyltrimethoxysilane can be, but is not limited to, Shin-Etsu KBM-303, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane can be, but is not limited to, Shin-Etsu KBE-303.

[0070] The mercapto group silane coupling agent can be, but is not limited to, 3-mercaptopropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane can be, but is not limited to, Shin-Etsu KBM-803.

[0071] The methacryloxy group silane coupling agent can be one or more of 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-acryloxypropyltrimethoxysilane. 3-Methacryloxypropylmethyldimethoxysilane can be, but is not limited to, Shin-Etsu KBM-502, 3-methacryloxypropyltrimethoxysilane can be, but is not limited to, Shin-Etsu KBM-503, and 3-acryloxypropyltrimethoxysilane can be, but is not limited to, Shin-Etsu KBM5103.

[0072] The vinyl group silane coupling agent can be one or both of vinyltrimethoxysilane and vinyltriethoxysilane. Specifically, vinyltrimethoxysilane can be, but is not limited to, Shin-Etsu KBM-1003, and vinyltriethoxysilane can be, but is not limited to, Shin-Etsu KBE-1003.

[0073] The amino group silane coupling agent can be, but is not limited to, 3-chloropropyltriethoxysilane, and 3-chloropropyltriethoxysilane can be, but is not limited to, Shin-Etsu KBM-703.

[0074] Furthermore, the inorganic solvent includes water. Using water as the solvent reduces the environmental pollution caused by using organic solvents and the harm to the health of workers.

[0075] In a specific example, the silicon-containing raw material further includes sintering aids and additives, and the mass ratio of silicon powder, sintering aids, and additives is 100:(2~20):(5~55).

[0076] Further, the additives include a dispersant, a plasticizer, a binder, and an antifoaming agent with a mass ratio of (0.3~7):(0.5~15):(5~30):(0.05~5).

[0077] It can be understood that the mass ratio of silicon powder, inorganic solvent, inhibitor, sintering auxiliary, dispersant, plasticizer, binder, and antifoaming agent in the silicon-containing raw material is 100:(0.5~3):(30~60):(5~15):(0.3~7):(0.5~15):(5~30):(0.05~5). Specifically, the mass ratio of silicon powder, inorganic solvent, inhibitor, sintering auxiliary, dispersant, plasticizer, binder, and antifoaming agent in the silicon-containing raw material is 100:(0.5~3):(30~60):(5~15):(1~7):(2~10):(10~25):(0.5~4).

[0078] Specifically, the dispersant can be, but is not limited to, one or more of polyethylene glycol, polypropylene glycol, oleic acid, palmitic acid, citric acid, acrylic acid, polyacrylic acid, styrene maleic anhydride copolymer, and styrene maleic anhydride acrylic acid copolymer. The plasticizer can be, but is not limited to, one or more of glycerol, polyethylene glycol, polypropylene glycol, methyl silicone oil, and silane coupling agent. The binder can be, but is not limited to, one or more of polyvinyl alcohol, polyvinyl butyral, polyacrylic acid, and polyurethane. The antifoaming agent can be, but is not limited to, one or more of ethanol, isopropanol, polyethylene glycol, polypropylene glycol, methyl silicone oil, and silane coupling agent.

[0079] It can be understood that the silicon-containing raw material is first mixed with the sintering auxiliary and the dispersant for a second dispersion treatment, and then mixed with the plasticizer, the binder, and the antifoaming agent for a third dispersion treatment. Each of the above second dispersion treatment and third dispersion treatment independently includes one or more processes of stirring dispersion, ball milling dispersion, planetary ball milling dispersion, sand milling dispersion, and ultrasonic dispersion. The time of the second dispersion treatment and the third dispersion treatment independently includes 100 min to 800 min. The time of the second dispersion treatment and the third dispersion treatment is independently 100 min, 200 min, 300 min, 400 min, 500 min, 600 min, 620 min, 640 min, 660 min, 680 min, 700 min, 720 min, 740 min, 760 min, 780 min, or 800 min.

[0080] In a specific example, the sintering auxiliary includes one or two of alkaline earth metal compounds and rare earth compounds. The selection of the sintering auxiliary is beneficial to inhibiting the hydrolysis of silicon powder while reducing the difficulty of the silicon nitride sintering process and obtaining a silicon nitride ceramic material with better performance.

[0081] Furthermore, the alkaline earth metal compound can be, but is not limited to, one or more of magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium acetate, magnesium stearate, magnesium palmitate, magnesium citrate, magnesium hydride, magnesium silicide, magnesium silicon nitride, magnesium fluoride, and magnesium nitrate.

[0082] Furthermore, the rare earth compound can be, but is not limited to, one or more of yttrium oxide, yttrium silicide, yttrium fluoride, yttrium chloride, yttrium nitrate, lanthanum oxide, and ytterbium oxide.

[0083] In a specific example, the particle size D100 of the silicon powder is 5 μm to 20 μm. The particle size D100 of the silicon powder can be, but is not limited to, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm.

[0084] Furthermore, the particle size D50 of the silicon powder is 0.5 μm to 10 μm. The particle size D50 of the silicon powder can be, but is not limited to, 0.5 μm, 1 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm. The purity of the silicon powder is ≥99.99%, the impurities are ≤300 ppm, and the oxygen content is ≤1%.

[0085] There are overlapping parts among the above components, which can be understood as that the addition of this substance to this formula not only serves as a functional raw material with one function, but may have multiple functions. The specific dispersion treatment can be adjusted, combined, or cancelled according to the specific functions of the added specific raw materials.

[0086] In a specific example, the green body is treated in a nitrogen atmosphere during the nitriding treatment; the treatment temperature is 1200 °C to 1500 °C; the treatment pressure is 0.01 MPa to 0.5 MPa; the treatment time is 1 h to 10 h, and the heating rate is 0.3 °C / min to 15 °C / min. It can be understood that the nitriding treatment includes one or more holding temperature points.

[0087] Further, the processing temperature of the nitriding treatment can be, but is not limited to, 1200°C, 1220°C, 1240°C, 1260°C, 1280°C, 1300°C, 1320°C, 1340°C, 1360°C, 1370°C, 1380°C, 1390°C, 1400°C, 1420°C, 1440°C, 1460°C, 1480°C or 1500°C. The processing time of the nitriding treatment can be, but is not limited to, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h. The processing pressure of the nitriding treatment can be, but is not limited to, 0.01 MPa, 0.05 MPa, 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.45 MPa or 0.5 MPa.

[0088] In a specific example, the processing temperature in the sintering treatment is 1750°C to 1950°C; the processing pressure is 0.7 MPa to 5 MPa; the processing time is 1 h to 24 h, and the heating rate is 0.3°C / min to 15°C / min. It can be understood that there is one or more holding temperature points in the sintering treatment.

[0089] Further, the processing temperature in the sintering treatment can be, but is not limited to, 1750°C, 1780°C, 1800°C, 1820°C, 1830°C, 1840°C, 1850°C, 1860°C, 1880°C, 1900°C, 1910°C, 1920°C, 1930°C, 1940°C or 1950°C. The processing pressure in the sintering treatment can be, but is not limited to, 0.7 MPa, 0.9 MPa, 1 MPa, 1.2 MPa, 1.4 MPa, 1.6 MPa, 1.8 MPa, 2 MPa, 2.2 MPa, 2.4 MPa, 2.6 MPa, 2.8 MPa, 3 MPa, 3.2 MPa, 3.4 MPa, 3.6 MPa, 3.8 MPa, 4 MPa, 4.2 MPa, 4.4 MPa, 4.6 MPa, 4.8 MPa or 5 MPa. The processing time in the sintering treatment can be, but is not limited to, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h or 24 h.

[0090] In a specific example, a green body is prepared by using a slurry through the tape casting method. It can be understood that the slurry is stirred and degassed under a vacuum degree of 0.3 kPa to 300 kPa to obtain a slurry without bubbles; and the green body is prepared by tape casting. The size of the green body can be defined according to the size requirements of the required silicon nitride ceramic material. Further, the slurry is stirred and degassed under a vacuum degree of 0.3 kPa to 10 kPa.

[0091] In a specific example, the green body further includes a debinding treatment before the nitriding treatment. The temperature of the debinding treatment is 300°C to 800°C, the time of the debinding treatment is 36h to 72h, the atmosphere of the debinding treatment is air or nitrogen, and the pressure of the debinding treatment is ≤0.1 MPa.

[0092] Specifically, the temperature of the debinding treatment can be, but is not limited to, 300°C, 350°C, 400°C, 450°C, 50°C, 550°C, 600°C, 650°C, 700°C, 750°C or 800°C. The time of the debinding treatment can be, but is not limited to, 36h, 38h, 40h, 42h, 44h, 46h, 48h, 50h, 52h, 54h, 56h, 58h, 60h, 62h, 64h, 66h, 68h, 70h or 72h.

[0093] This application also provides a silicon nitride ceramic material prepared by the above preparation method.

[0094] Furthermore, this application provides the use of the above silicon nitride ceramic material in the preparation of ceramic circuit boards, heat dissipation devices or packaging structures.

[0095] The following further describes this application in detail with specific embodiments. It should be understood that these embodiments are only used to illustrate this application and not to limit the scope of this application. For the experimental methods without specific conditions in the following embodiments, the guidance given in this application is preferentially referred to, and it can also be in accordance with the experimental manuals or conventional conditions in the art, or in accordance with the conditions recommended by the manufacturer, or refer to the experimental methods known in the art.

[0096] In the following specific embodiments, for the measurement parameters of the raw material components, if there is no special description, there may be slight deviations within the weighing accuracy range. For the temperature and time parameters, acceptable deviations caused by instrument test accuracy or operation accuracy are allowed. "Normal temperature" refers to 25°C; "Normal pressure" refers to 100 KPa or 101 KPa.

[0097] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not conflict, it should be considered to be within the scope described in this specification.

[0098] The D50 of the silicon powder used is 2 to 5 μm, the D100 is 6 to 12 μm, the impurity is ≤300 ppm, and the oxygen content is ≤1%.

[0099] Example 1

[0100] Mix water, inhibitor, and silicon powder in a mass ratio of 50:1.5:100 and conduct the first dispersion treatment for 120 min to pre-treat the silicon powder and prepare a silicon-containing raw material, where the inhibitor is polyacrylic acid with a molecular weight of 80,000;

[0101] Add a dispersant and sintering auxiliary materials to the silicon-containing raw material and mix them for the second dispersion treatment for 720 min; then add a plasticizer, binder, and defoaming agent and conduct the third dispersion treatment for 600 min to mix the glue and obtain a slurry, where the mass ratio of silicon powder, dispersant, sintering auxiliary materials, plasticizer, binder, and defoaming agent is 100:5:10:6:18:1.5. The dispersant is styrene maleic anhydride copolymer, the sintering auxiliary materials are 7 parts of magnesium silicon nitride and 3 parts of yttrium oxide, the plasticizer is glycerol, the binder is polyvinyl alcohol, and the defoaming agent is methyl silicone oil.

[0102] Stir and defoam the above slurry under a vacuum degree of 2 kPa to obtain a bubble-free slurry; extrude a green tape with a thickness of 0.4 mm through a casting device, and cut the green tape to obtain a green body with the required size;

[0103] Debind the green body in a debinding furnace. The debinding treatment temperature is 600 °C, the debinding time is 70 h, and the air pressure is ≤0.1 MPa. Then transfer it to a gas pressure sintering furnace and conduct nitriding treatment for 3 h at a nitrogen pressure of 0.3 MPa and a temperature of 1370 °C. Then raise the temperature to 1840 °C and conduct sintering of silicon nitride for 6 h at a nitrogen pressure of 1 MPa to prepare a silicon nitride ceramic material.

[0104] Example 2

[0105] The difference from Example 1 lies in the selection of the inhibitor. Replace polyacrylic acid with polyethylene glycol 400.

[0106] Example 3

[0107] The difference from Example 1 lies in the selection of the inhibitor. Replace polyacrylic acid with oleic acid.

[0108] Example 4

[0109] The difference from Example 1 lies in the selection of the inhibitor. Replace polyacrylic acid with silane coupling agent KBM-503.

[0110] Example 5

[0111] The difference from Example 1 lies in the selection of the dispersant. Replace styrene maleic anhydride copolymer with the same polyacrylic acid as the inhibitor.

[0112] The inhibitor and the dispersant are the same polyacrylic acid, and the first dispersion treatment and the second dispersion treatment can be combined to simplify the process. The treatment time is 720 min.

[0113] Comparative Example 1

[0114] The difference from Example 1 lies in the processing technology, where the first dispersion treatment and the second dispersion treatment are combined and simplified.

[0115] Silicon powder, inhibitor, water, sintering auxiliary materials and dispersant were subjected to ball milling dispersion treatment for 720 min in a mass ratio of 100:1.5:50:10:5. The rest was the same as in Example 1.

[0116] Comparative Example 2

[0117] The difference from Example 1 is that no inhibitor is added.

[0118] Comparative Example 3

[0119] The difference from Example 1 lies in the selection of the inhibitor, where polyacrylic acid is replaced by ethylenediaminetetraacetic acid.

[0120] Comparative Example 4

[0121] The difference from Example 1 lies in the selection of the inhibitor, where polyacrylic acid is replaced by butyl ether.

[0122] Comparative Example 5

[0123] A binary organic solvent mixture of alcohol and toluene (weight ratio: 1:2), silicon nitride powder, sintering auxiliary materials and dispersant were subjected to ball milling dispersion treatment for 720 min in a mass ratio of 40:100:13:5. Then a plasticizer, a binder and an antifoaming agent were added for dispersion treatment for 600 min, and the mixture was mixed to obtain a slurry, where the mass ratio of silicon nitride powder, plasticizer, binder and antifoaming agent was 100:5:10:0.5, the dispersant was anhydrous castor oil, the sintering auxiliary materials were 9 parts of magnesium oxide and 4 parts of yttrium oxide, the plasticizer was DOP, the binder was polyvinyl butyral, and the antifoaming agent was methyl silicone oil.

[0124] The above slurry was stirred and defoamed under a vacuum degree of 2 kPa to obtain a slurry without bubbles; a green tape with a thickness of 0.5 mm was extruded through a casting device, and the green tape was cut into green blanks of required sizes;

[0125] The green blanks were degummed in a degreasing furnace and transferred to a gas pressure sintering furnace, and silicon nitride was sintered at a nitrogen pressure of 0.9 MPa and a temperature of 1840 °C to prepare silicon nitride ceramic materials.

[0126] Comparative Example 6

[0127] A binary organic solvent mixture of alcohol and toluene (weight ratio: 1:2), silicon powder, sintering auxiliary materials, and a dispersant are ball-milled and dispersed for 720 min at a mass ratio of 50:100:10:5. Then, a plasticizer, a binder, and an antifoaming agent are added for a second dispersion treatment for 600 min, and the mixture is mixed to obtain a slurry. The mass ratio of silicon powder, plasticizer, binder, and antifoaming agent is 100:6:18:1.5. The dispersant is anhydrous castor oil, the sintering auxiliary materials are 7 parts of magnesium oxide and 3 parts of yttrium oxide, the plasticizer is DOP, the binder is polyvinyl butyral, and the antifoaming agent is methyl silicone oil.

[0128] The above slurry is stirred and defoamed under a vacuum of 2 kPa to obtain a slurry without bubbles; a green tape with a thickness of 0.4 mm is extruded through a casting device, and the green tape is cut into green blanks of the required size;

[0129] The green blanks are degummed in a degreasing furnace and then transferred to a gas-pressure sintering furnace for nitriding treatment under a nitrogen pressure of 0.9 MPa and at a temperature of 1370 °C. Then, the temperature is raised to 1840 °C for sintering of silicon nitride to prepare silicon nitride ceramic materials.

[0130] Test Methods and Result Analysis

[0131] Oxygen content: The oxygen content of the substrate is measured using an oxygen-nitrogen-hydrogen analyzer.

[0132] Density: The density of the substrate is measured according to the standard of the national standard "GB / T25995-2010 Test Methods for Density and Apparent Porosity of Fine Ceramics".

[0133] Flexural strength: The flexural strength of the substrate is measured according to the standard of the national standard "GB / T6569-2006 Test Methods for Flexural Strength of Fine Ceramics".

[0134] Thermal conductivity: The thermal conductivity of the substrate is measured according to the standards of the national standards "GB / T39862-2021 Detection of Thermal Conductivity of High-Thermal-Conductivity Ceramics" and "GB / T22588-2008 Measurement of Thermal Diffusion Coefficient or Thermal Conductivity by Flash Method".

[0135] Toughness: The toughness of the substrate is measured according to the standard of the national standard "GB / T44304-2024 Test Methods for Room Temperature Fracture Resistance of Fine Ceramics - Indentation (IF) Method".

[0136] The properties of the silicon nitride substrates prepared in the above examples and comparative examples are summarized in Table 1 below:

[0137] Table 1

[0138]

[0139] Through the above embodiments and comparative examples, it can be shown that by selecting appropriate inhibitors, it is possible to use water as a solvent and silicon powder as a raw material to prepare high-performance and low-cost silicon nitride ceramic substrates. Examples 1 to 5 illustrate the wide range of inhibitor selection, which helps to reduce the raw material cost. Comparing Example 5 with Comparative Example 1, it can be seen that if the dispersant also has the effect of inhibiting the hydrolysis of silicon powder, the first dispersion treatment and the second dispersion treatment can be combined to simplify the preparation process. While Comparative Example 1 shows that if the dispersant does not have the effect of inhibiting the hydrolysis of silicon powder, but the first dispersion treatment and the second dispersion treatment are combined and simplified, then the inhibitor will be diluted, affecting the function of the inhibitor, resulting in slow hydrolysis of silicon powder and an increase in oxygen content, thus affecting the performance of the final silicon nitride ceramic substrate. Comparative Example 2 shows that without an inhibitor and when the dispersant does not have the effect of inhibiting the hydrolysis of silicon powder, the silicon powder will continuously hydrolyze and oxidize during the pulping process, resulting in an increase in the oxygen content of the silicon powder, thus affecting the performance of the prepared silicon nitride ceramic substrate. Comparative Examples 3 and 4 show that the wrong inhibitor is selected. Chelating agents that combine with divalent metal ions such as Mg 2+ , Ca 2+ , Mn 2+ and Fe 2+ etc. have good effects, but their binding performance with silicon dioxide is poor. When butyl ether is selected, the "R-O-R" structure of ethers is not compatible with water and will not form hydrogen bonds with "Si-OH", so methyl ethyl ketone will not attach to the surface of silicon powder to form a complex, thus having no effect of inhibiting the hydrolysis of silicon powder. At the same time, when the dispersant does not have the effect of inhibiting the hydrolysis of silicon powder, the inhibitor cannot play the role of inhibiting the hydrolysis of silicon powder, resulting in poor performance of the final silicon nitride ceramic substrate. Comparative Example 5 exemplifies the existing conventional process for preparing silicon nitride ceramic substrates and their performance. Comparative Example 6 shows that silicon nitride ceramic substrates with excellent performance can also be prepared by using the conventional ceramic substrate preparation process with silicon powder. At the same time, comparing the performance of the silicon nitride ceramic substrates prepared in Examples 1 to 5 with that of Comparative Example 5, it shows that there is little difference in the performance of the silicon nitride ceramic substrates prepared with water as a solvent and silicon powder and those prepared with organic solvents.

[0140] The above embodiments only represent several implementation manners of the present application, which are convenient for understanding the technical solution of the present application specifically and in detail, but should not be construed as a limitation on the protection scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can be made, and these all belong to the protection scope of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments based on the technical solutions provided by the present application are all within the protection scope of the appended claims of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the content of the appended claims, and the specification can be used to explain the content of the claims.

Claims

1. A method for preparing a silicon nitride ceramic material, characterized in that: The following steps are involved: providing a slurry, the slurry comprising a silicon-containing raw material; The silicon-containing raw material comprises silicon powder, an inhibitor and an inorganic solvent in a mass ratio of 100:(0.1-10):(10-100), and the inhibitor comprises one or more of an alcohol compound, an organic acid, methyl silicone oil and a silane coupling agent; preparing a green body using the slurry; The green body is subjected to nitriding treatment and sintering treatment.

2. The preparation method according to claim 1, characterized in that The inhibitor meets one or more of the following conditions: (1) The alcohol compound includes one or more of ethanol, isopropanol, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol and glycerol; (2) The organic acid includes one or more of oleic acid, palmitic acid, stearic acid, citric acid, acrylic acid and polyacrylic acid; (3) The viscosity of the methyl silicone oil is 200 cps to 5000 cps; (4) The silane coupling agent includes one or more of an aminosilane coupling agent, an epoxysilane coupling agent, a mercaptosilane coupling agent, a methacryloxysilane coupling agent, a vinylsilane coupling agent and an aminosilane coupling agent.

3. The preparation method according to claim 1, characterized in that: One or more of the following conditions are met: (1) The particle size D100 of the silicon powder is 5 μm to 20 μm; (2) The silicon-containing raw material further includes sintering auxiliary materials and auxiliary agents, and the mass ratio of the silicon powder, the sintering auxiliary materials and the auxiliary agents is 100:(2-20):(5-55); (3) The inorganic solvent includes water.

4. The preparation method according to claim 3, characterized in that: One or both of the following conditions are met: (1) The auxiliary agent includes a dispersant, a plasticizer, a binder and a defoamer in a mass ratio of (0.3-7):(0.5-15):(5-30):(0.05-5); (2) The sintering auxiliary material includes one or both of an alkaline earth metal compound and a rare earth compound.

5. The preparation method according to claim 4, characterized in that: One or more of the following conditions are met: (1) The dispersant includes one or more of polyethylene glycol, polypropylene glycol, oleic acid, palmitic acid, citric acid, acrylic acid, polyacrylic acid, styrene maleic anhydride copolymer and styrene maleic anhydride acrylic acid copolymer; (2) The plasticizer includes one or more of glycerol, polyethylene glycol, polypropylene glycol, methyl silicone oil and silane coupling agent; (3) The binder includes one or more of polyvinyl alcohol, polyvinyl butyral, polyacrylic acid and polyurethane; (4) The defoaming agent includes one or more of ethanol, isopropanol, polyethylene glycol, polypropylene glycol, methyl silicone oil and silane coupling agent; (5) The alkaline earth metal compound includes one or more of magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium acetate, magnesium stearate, magnesium palmitate, magnesium citrate, magnesium hydride, magnesium silicide, magnesium silicon nitride, magnesium fluoride and magnesium nitrate; (6) The rare earth compound includes one or more of yttrium oxide, yttrium silicide, yttrium fluoride, yttrium chloride, yttrium nitrate, lanthanum oxide and ytterbium oxide.

6. The preparation method according to claim 1, characterized in that: The nitriding treatment satisfies one or more of the following conditions: (1) Treat in a nitrogen atmosphere; (2) The processing temperature is 1200℃~1500℃; (3) The processing pressure is 0.01MPa~0.5MPa; (4) The processing time is 1h~10h.

7. The preparation method according to claim 1, characterized in that: The sintering process satisfies one or more of the following conditions: (1) The processing temperature is 1750℃~1950℃; (2) The processing pressure is 0.7MPa~5MPa; (3) The processing time is 1h~24h.

8. The preparation method according to any one of claims 1 to 7, characterized in that: One or both of the following conditions are met: (1) preparing the green body by using the slurry through a tape casting method; (2) The green body further includes a debinding step before the nitriding treatment.

9. A silicon nitride ceramic material, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 8.

10. Use of the silicon nitride ceramic material according to claim 9 in preparing a ceramic circuit board, a heat dissipation device or a packaging structure.

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