Silicon carbide composite powder, preparation method and silicon carbide ceramic materials

Abstract

This invention relates to the field of ceramic materials technology, and particularly to a silicon carbide composite powder, its preparation method, and silicon carbide ceramic materials. The preparation method of the silicon carbide composite powder provided by this invention includes the following steps: S1. Mixing silicon carbide powder and silicon powder at a specific mass ratio; S2. Performing atmospheric plasma spraying on the composite powder to obtain a liquid composite powder; S3. Quenching the liquid composite powder to obtain the silicon carbide composite powder in the quenching medium. By using atmospheric plasma spraying technology to prepare spherical silicon carbide composite powder, and utilizing the silicon solid-liquid-solid phase transformation process, silicon-coated silicon / silicon carbide spherical composite powder is prepared, effectively solving the problem of low packing density caused by the irregular shape properties of silicon carbide such as strips and angular shapes; it can effectively improve the performance of silicon carbide ceramic materials prepared by BJP.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, and in particular to a method for preparing silicon carbide composite powder, silicon carbide composite powder, and silicon carbide ceramic materials. Background Technology

[0002] Silicon carbide ceramics possess high strength, high modulus, and high thermal conductivity, making them widely used in aerospace, energy, and chemical industries. Currently, defense and industrial applications demand more complex structures from silicon carbide ceramics, such as lattice structures and topological structures, which poses a significant challenge to silicon carbide ceramic fabrication technology. Traditional fabrication methods for silicon carbide ceramics, such as isostatic pressing and slip casting, are unable to produce highly complex silicon carbide structures, necessitating the exploration of new forming processes to meet the development needs of defense and industry.

[0003] Additive manufacturing technology is a stacking manufacturing process based on the discrete-stacking principle, which involves slicing a three-dimensional model into two dimensions. This process enables the fabrication of silicon carbide ceramics with arbitrary structures and is considered the driving engine of the next industrial revolution.

[0004] Additive manufacturing technologies based on powder bed processes include selective laser sintering and binder jetting. Taking binder jetting (BJP) as an example, it is a room temperature additive manufacturing technology that uses powder as raw material. This technology selectively jets binder into a powder bed to bond the powder into a two-dimensional thin layer. By repeating the above process in three-dimensional space, a ceramic preform with a specific three-dimensional solid structure can be obtained.

[0005] Unlike slurry-based additive manufacturing technologies that add large amounts of organic matter, powder bed additive manufacturing processes have extremely low organic content, eliminating the need for degreasing and binder removal, thus significantly shortening the preparation cycle. Powder bed additive manufacturing processes, such as laser selective sintering (LSS) and BJP, face the challenge of low powder bulk density leading to poor ceramic properties after reaction sintering. Currently, spray granulation is a common method for improving the bulk density of silicon carbide powder. This method involves preparing a silicon carbide suspension solution, atomizing the solution as droplets in a drying tower, and then evaporating the water in the droplets at high temperature to obtain spherical silicon carbide particles. However, this process involves in-situ pore formation due to water evaporation, resulting in numerous capillaries within the spherical silicon carbide particles. In BJP, to prevent excessive binder overflow affecting molding accuracy, the sprayed binder content is typically only a few tens of picoliters. The numerous capillaries in the spray-granulated powder absorb most of the binder, significantly reducing the molding effect and hindering the BJP additive manufacturing process. Therefore, while ensuring the molding accuracy of BJP, exploring new methods to improve powder packing density can enable the development of high-performance silicon carbide ceramics with complex structures, which is crucial for meeting the development needs of national defense and industry.

[0006] Existing methods for preparing spherical powder generally employ spray drying, where the powder binder is an organic substance and the binder solvent is water. The water solvent evaporates completely during the drying process, resulting in numerous pores on the surface of the spherical powder, making it unsuitable for powder bed additive manufacturing technology. Plasma spraying technology is generally used primarily for coating preparation and has limited application in powder granulation. In particular, there are currently no reports on the preparation of spherical silicon carbide powder using plasma spraying technology. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a silicon carbide composite powder with high sphericity and high density prepared using atmospheric plasma spraying technology, a corresponding method for preparing high-density silicon carbide powder materials, and silicon carbide ceramic materials prepared by additive manufacturing of silicon carbide composite powder bed combined with reactive sintering.

[0008] This invention provides a method for preparing silicon carbide composite powder, the method comprising the following steps:

[0009] S1. Mix silicon carbide powder and silicon powder in a mass ratio of (40~80):(60~20) to obtain composite powder;

[0010] S2. The composite powder is subjected to atmospheric plasma spraying to obtain liquid composite powder; the liquid composite powder includes silicon in a liquid melt state and silicon carbide in a powder state; the silicon in the liquid melt state encapsulates the silicon carbide in the powder state;

[0011] S3. Quenching the liquid composite powder using a quenching medium to obtain the silicon carbide composite powder in the quenching medium.

[0012] Furthermore, the particle size range of the silicon carbide powder is 100 mesh to 2000 mesh, and the particle size range of the silicon powder is 1000 mesh to 2000 mesh; preferably, the particle size of the silicon powder is 2000 mesh.

[0013] Furthermore, the atmospheric plasma spraying includes: conveying the composite powder to the plasma spray gun via a carrier gas;

[0014] The carrier gas comprises argon and hydrogen in a volume ratio of (90~10):(10~90), wherein the argon is used to stabilize the electric arc and the hydrogen is used as a heat-conducting medium.

[0015] The power range of the plasma spray gun is 20 KW ~ 50 KW, and the spraying distance of the atmospheric plasma spraying is 20mm ~ 200mm. The spraying distance is the distance between the plasma spray gun and the quenching medium.

[0016] Furthermore, the mixing includes: wet ball milling the silicon carbide powder and the silicon powder in a ball mill jar to fully mix them; the ball milling medium for the wet ball milling is anhydrous ethanol, the grinding balls are silicon carbide balls, the ball-to-material ratio is 1~4.2, and the ball milling time is 5h~24h.

[0017] Furthermore, the quenching medium is water, oil, liquid nitrogen, carbon dioxide, or argon.

[0018] The present invention also provides a silicon carbide composite powder, which is prepared by the silicon carbide composite powder preparation method described above.

[0019] The present invention also provides a silicon carbide ceramic material, which is prepared by forming a silicon carbide preform by binder spraying or laser selective sintering of silicon carbide composite powder, followed by reaction sintering; the silicon carbide composite powder is the silicon carbide composite powder of the present invention.

[0020] Furthermore, in the process of preparing the silicon carbide preform by adhesive spray molding, the adhesive used includes a solute and a solvent. The solute is selected from at least one of vinylpyrrolidone, phenolic resin, furan resin or polyacrylic acid resin, and the solvent is selected from at least one of deionized water, anhydrous ethanol or ethylene glycol.

[0021] In the process of preparing the silicon carbide preform by adhesive spray molding, the molding thickness is set to 10μm~100μm and the scanning interval is set to 0.01mm~1mm.

[0022] Furthermore, the density of the silicon carbide preform is 1.2 g / cm³. 3 ~2.2g / cm 3 The flexural strength of the silicon carbide preform is 2MPa~14MPa.

[0023] Furthermore, the flexural strength of the silicon carbide ceramic material is 220 MPa to 450 MPa, the elastic modulus of the silicon carbide ceramic material is 270 GPa to 420 GPa, and the fracture toughness of the silicon carbide ceramic material is 1.63 MPa·m. 1 / 2 ~3.28MPa·m 1 / 2 The thermal conductivity of the silicon carbide ceramic material is 140 W / mK to 200 W / mK, and the density of the silicon carbide ceramic material is 2.85 g / cm³. 3 ~3.09g / cm 3 .

[0024] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0025] This invention utilizes atmospheric plasma spraying combined with quenching treatment to prepare spherical silicon carbide composite powder. It creatively leverages the silicon solid-liquid-solid phase transition process to prepare silicon-coated silicon / silicon carbide spherical composite powder. This not only overcomes the problem of water evaporation leading to porosity on the surface of spherical powders in existing spray granulation techniques, but also addresses the splashing problem caused by the incident flame impacting the quenching medium in existing atmospheric plasma spraying techniques. Furthermore, it effectively solves the problem of low packing density caused by the irregular shape of silicon carbide, such as its strip-like or angular forms. Moreover, the preparation method of the silicon carbide composite powder provided by this invention differs from spray granulation. Granulation using water droplets as the granulation medium results in numerous capillary pores on the surface and inside of the spherical powder due to water evaporation during the drying process of spherical droplets, which can easily lead to low BJP molding quality. This invention uses liquid-phase silicon droplets as the granulation medium. The amount of silicon evaporation during the quenching process is minimal, and there are no or very few capillary pores in the spherical composite powder. This composite powder will not interfere with the molding accuracy of BJP. Overall, the silicon carbide composite material preparation method provided by this invention can effectively improve the performance of silicon carbide ceramics prepared by BJP, and while making full use of BJP and reaction sintering processes to prepare complex structure ceramics, it endows the ceramics with excellent comprehensive properties. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the principle of the quenching process according to an embodiment of the present invention.

[0027] Figure label:

[0028] 1. Plasma spray gun 2. Si / SiC molten droplet flame 3. Baffle 4. Hole 5. Quenching medium. Detailed Implementation

[0029] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0031] This invention provides a method for preparing silicon carbide composite powder, the method comprising the following steps:

[0032] S1. Silicon carbide powder and silicon powder are mixed in a mass ratio of (40~80):(60~20) to obtain a composite powder. Silicon powder, as a binder in the silicon carbide composite powder, has a content greater than 20% to better bind the silicon carbide powder. Furthermore, in the reaction-sintered silicon carbide components prepared from the silicon carbide composite powder, controlling the silicon content in the powder to be no higher than 60% can better improve the performance of the silicon carbide components. The particle size range of the silicon carbide powder is 100 mesh to 2000 mesh. In a further preferred embodiment, the particle size range of the silicon carbide powder is 800 mesh to 1500 mesh; the particle size range of the silicon powder is 1000 mesh to 2000 mesh. More preferably, the silicon powder has a particle size of 2000 mesh; this can minimize the difficulty and time of powder sieving, while also ensuring a more suitable particle size of the composite powder after atmospheric plasma spraying and granulation; the specific powder mixing process includes: wet ball milling and fully mixing the silicon carbide powder and the silicon powder in a ball mill jar at a specific mass ratio; the ball milling medium is anhydrous ethanol, the grinding balls are silicon carbide balls, the ball-to-material ratio is 1~4.2, and the ball milling time is 5h~24h; after being fully mixed by wet ball milling, the mixture is placed in a drying oven for drying, the drying time range is 10h~18h, and the drying temperature range is 120℃~160℃.

[0033] S2. The dried composite powder is subjected to atmospheric plasma spraying to obtain liquid composite powder; the liquid composite powder includes silicon in a liquid melt state and silicon carbide in a powder state; the silicon in the liquid melt state encapsulates the silicon carbide in the powder state.

[0034] In a specific implementation, this invention creatively proposes a method for water-based spray granulation using silicon instead of water. Simultaneously, it conducts research on atmospheric plasma spraying technology, designs and controls the carrier gas composition, and adjusts the content of the heat-conducting gas. The resulting solution promotes better silicon melting and facilitates the formation of molten droplets, effectively overcoming the problem of pores on the surface of spherical powder caused by binder evaporation in existing atmospheric plasma spraying technologies. Specifically, the atmospheric plasma spraying of this invention includes: transporting the composite powder to a plasma spray gun using a carrier gas; the carrier gas includes argon and hydrogen in a volume ratio of (90~10):(10~90), where argon is used to stabilize the electric arc and hydrogen is used as a heat-conducting medium; the power range of the plasma spray gun is 20 KW~50 KW, and the spraying distance of the atmospheric plasma spraying is 20mm~200mm, where the spraying distance is the distance between the plasma spray gun and the quenching medium. By coupling the spraying power and spraying distance, the powder melting state is controlled to achieve a liquid composite powder in which silicon is in a liquid state and the morphology of silicon carbide particles remains stable. Specifically, the silicon in the liquid melt state encapsulates the silicon carbide particles in the powder state as droplets. The droplets are cooled in the air, and the cooling time is proportional to the spraying distance. The longer the cooling time, the harder the droplets are, and the less they deform when they hit the bottom of the spraying medium container, making it easier to obtain powder with high sphericity. Adjusting the spraying distance can also effectively improve the powder yield.

[0035] S3. The liquid composite powder is quenched using a quenching medium to obtain the silicon carbide composite powder. Specifically, the quenching medium is water, oil, liquid nitrogen, or other gases such as carbon dioxide and argon. This invention, while using atmospheric plasma spraying technology to prepare spherical silicon carbide composite powder, also creatively proposes a novel design for a quenching test device during the quenching process. It incorporates a perforated baffle design to ensure that the molten droplets in the spray gun are injected into the quenching medium while preventing reverse splashing, effectively overcoming the splashing problem caused by the impact of the incident flame on the quenching medium in existing technologies.

[0036] In a specific embodiment of the present invention, a silicon carbide composite powder is also provided, which is prepared by the silicon carbide composite powder preparation method described above.

[0037] In a specific embodiment of the present invention, a silicon carbide ceramic material is also provided. The silicon carbide composite powder is formed by binder spray molding to form a silicon carbide preform, and then subjected to reaction sintering to obtain the silicon carbide ceramic material. The silicon carbide composite powder is the silicon carbide composite powder of the present invention.

[0038] In a specific embodiment, during the process of preparing the silicon carbide preform by binder spray molding, the binder used includes a solute and a solvent. The solute is selected from at least one of vinylpyrrolidone, phenolic resin, furan resin, or polyacrylic acid resin, and the solvent is selected from at least one of deionized water, anhydrous ethanol, or ethylene glycol. During the process of preparing the silicon carbide preform by binder spray molding, the molding thickness is set to 10 μm to 100 μm, and the scanning interval is set to 0.01 mm to 1 mm. The density of the silicon carbide preform is 1.2 g / cm³. 3 ~2.2g / cm 3 The flexural strength of the silicon carbide preform is 2 MPa to 14 MPa. Using the silicon carbide composite material and preparation method of the present invention, the final silicon carbide ceramic material has a flexural strength of 220 MPa to 450 MPa, an elastic modulus of 270 GPa to 420 GPa, and a fracture toughness of 1.63 MPa·m. 1 / 2 ~3.28MPa·m 1 / 2 The thermal conductivity of the silicon carbide ceramic material is 140 W / mK to 200 W / mK, and the density of the silicon carbide ceramic material is 2.85 g / cm³. 3 ~3.09g / cm 3 .

[0039] The following exemplifies the preparation method of the high sphericity and high density silicon carbide composite powder of the present invention and the silicon carbide ceramic material prepared by BJP combined reaction sintering. The preparation method mainly includes the following steps:

[0040] (1) Preparation of raw material powder. Silicon carbide raw material powder is sieved using a vibrating screen. If the powder particle size is too small, sieving becomes more difficult and time-consuming; if the particle size is too large, the composite powder after atmospheric plasma spraying and granulation will have a larger particle size, increasing the gaps between powder particles and hindering the increase in bulk density. This invention preferably uses 800-1500 mesh silicon carbide powder and 1000-2000 mesh silicon powder as raw material powder. The raw material powder is mixed in a mass ratio of (40-80):(60-20) and thoroughly mixed by wet ball milling in a ball mill jar. The ball milling medium is anhydrous ethanol, the grinding balls are silicon carbide balls, the ball-to-material ratio is 1-4.2, and the ball milling time is 5-24 hours. The ball-milled mixture is then dried to obtain the composite powder.

[0041] (2) Preparation of spherical dense powder. The composite powder is transported to the plasma spray gun by a carrier gas. The main components of the carrier gas are argon and hydrogen, where argon is used to stabilize the electric arc and hydrogen is used as the heat transfer medium, with a volume ratio of (90~10):(10~90). The plasma spray gun power is 20KW~50KW, and the spraying distance is 20mm~200mm. After the composite powder is instantaneously heated by the plasma spray gun, silicon encapsulates silicon carbide particles in a molten form to form droplets. The droplets have better fluidity than angular silicon carbide particles. The droplets are then quenched to instantly condense and retain their spherical or near-spherical shape. In the quenching medium, the liquid droplets are transformed into solid spherical composite powder. The quenching medium can be water, oil, liquid nitrogen, or other gases such as carbon dioxide or argon. The volume ratio of the prepared silicon carbide composite powder to the volume of a perfect sphere with the same surface area is between 0.8 and 1, indicating high sphericity; the porosity of the prepared silicon carbide composite powder is less than 10%, indicating that it also has high density.

[0042] (3) BJP molding of silicon carbide preforms. One or more of the following are selected as the solute in the BJP binder: polyvinylpyrrolidone, phenolic resin, furan resin, and polyacrylic acid resin. One or more of the following are selected as the solvent in the BJP binder: deionized water, anhydrous ethanol, and ethylene glycol. Molding parameters: To achieve high-precision structural component fabrication, the molding thickness is 10μm~100μm, the scanning interval is 0.01mm~1mm, and BJP molding is performed according to the pre-set geometry. The density of the prepared silicon carbide preform is 1.2g / cm³. 3 ~2.2g / cm 3 The bending strength is 2MPa~14MPa.

[0043] (4) Preparation of silicon carbide ceramics by reaction sintering. The above-mentioned shaped silicon carbide preform is embedded in silicon powder and placed in a vacuum sintering furnace. In summary, the particle size of silicon powder is 5nm~73μm, the sintering temperature is 1400℃~1670℃, the holding time is 4h~21h, and after cooling to room temperature, silicon carbide ceramic composite material is obtained.

[0044] The silicon carbide ceramic composite material prepared by this invention exhibits excellent comprehensive properties, with a flexural strength of 220 MPa to 450 MPa, an elastic modulus of 270 GPa to 420 GPa, and a fracture toughness of 1.63 MPa·m. 1 / 2 ~3.28MPa·m 1 / 2 Its thermal conductivity is 140 W / m·K to 200 W / m·K, and its density is 2.75 g / cm³. 3 ~3.09g / cm 3 .

[0045] This invention employs atmospheric plasma spraying combined with quenching treatment to prepare spherical silicon carbide composite powder. It creatively utilizes the silicon solid-liquid-solid phase transition process to prepare silicon-coated silicon / silicon carbide spherical composite powder. This not only overcomes the problem of porosity on the surface of spherical powder caused by water solvent evaporation in existing spray granulation technologies, but also overcomes the splashing problem caused by the impact of the incident flame on the quenching medium in existing technologies by designing a quenching experimental device. It effectively solves the problem of low packing density caused by the irregular shape properties of silicon carbide, such as its strip-like and angular forms. Moreover, the preparation method of silicon carbide composite powder provided by this invention differs from spray granulation, which uses water droplets as the substrate. As a granulation medium, the evaporation of water during the drying process of spherical droplets creates numerous capillaries on the surface and inside of the spherical powder, easily leading to low BJP molding quality. This invention uses liquid-phase silicon droplets as the granulation medium. The amount of silicon evaporated during the quenching process is minimal, and there are no or very few capillaries in the spherical composite powder. This composite powder will not interfere with the molding accuracy of BJP. Overall, the silicon carbide composite material preparation method provided by this invention can effectively improve the performance of silicon carbide ceramics prepared by BJP, fully utilize BJP and reaction sintering processes to prepare complex structure ceramics, and endow the ceramics with excellent comprehensive properties.

[0046] The present invention will be described in detail in the following steps with reference to the embodiments. It should be understood that the following embodiments are only used to understand the present invention and do not limit the present invention.

[0047] Example 1

[0048] (1) Preparation of raw material powder. Take 1200 mesh silicon carbide powder and 2000 mesh silicon powder, mix them in a mass ratio of 59:41, and use a planetary ball mill to ball mill for 16 hours. The ball milling medium is anhydrous ethanol, the grinding ball material is silicon carbide, and the ball-to-material ratio is 3:1. Place the ball-milled powder slurry in a drying oven and dry it at 140℃ for 10 hours to obtain a uniformly mixed composite powder.

[0049] (2) Preparation of spherical dense powder. Argon and hydrogen were used as carrier gases in a volume ratio of 9:1 for atmospheric plasma spraying. The spraying power was 45KW and the spraying distance was 150mm. Quenching was performed with quenching oil to obtain spherical dense composite powder.

[0050] (3) BJP molding of silicon carbide preforms. A binder solution was prepared by mixing phenolic resin, anhydrous ethanol, and ethylene glycol in a mass ratio of 4:4:2. The printing layer thickness was adjusted to 70 μm for BJP molding to prepare silicon carbide preforms.

[0051] (4) Preparation of silicon carbide ceramics by reaction sintering. The above preform was subjected to reaction sintering densification treatment at a sintering temperature of 1650℃ for 4 hours, and then cooled to room temperature to obtain a density of 2.76 g / cm³. 3 Dense silicon carbide ceramics.

[0052] Example 2

[0053] (1) Preparation of raw material powder. Take 1500 mesh silicon carbide powder and 2000 mesh silicon powder, mix them in a mass ratio of 80:20, and use a planetary ball mill to ball mill for 20 hours. The ball milling medium is anhydrous ethanol, the grinding ball material is silicon carbide, and the ball-to-material ratio is 3:1. Place the ball-milled powder slurry in a drying oven and dry it at 140℃ for 10 hours to obtain a uniformly mixed composite powder.

[0054] (2) Preparation of spherical dense powder. Argon and hydrogen were used as carrier gases in a volume ratio of 9:1 for atmospheric plasma spraying. The spraying power was 45 kW, and the spraying distance was 100 mm. Water quenching was performed. To prevent violent water surface fluctuations or splashing caused by the high-speed flame during spraying, the design drawing for atmospheric plasma spraying is shown below. Figure 1 As shown, the Si / SiC molten droplet flame 2 is in the form of spherical droplets. After being sprayed out by the plasma spray gun 1, it comes into contact with the quenching medium 5 through the hole 4. The spherical droplets are rapidly cooled and become solid spherical powder. During this process, the spherical droplets are sprayed into the quenching medium 5. The quenching medium 5 is prone to splashing after being impacted. In order to prevent the quenching medium 5 from splashing and causing pollution or damage, the hole 4 is a high-speed incident flame. The splashed quenching medium 5 cannot escape from the hole 4 in the opposite direction of the flame injection. Therefore, by designing the baffle 3, the quenching medium 5 can be effectively blocked from splashing out of the container, ensuring the safety and environmental protection of the entire preparation process. By designing the hole 4 to reduce the impact of the jet, spherical dense silicon carbide composite powder can be obtained better after the spraying process.

[0055] (3) BJP molding of silicon carbide preforms. A binder solution was prepared by mixing phenolic resin, anhydrous ethanol, and ethylene glycol in a mass ratio of 6:2:2. The printing layer thickness was adjusted to 50 μm and BJP molding was performed to prepare silicon carbide preforms.

[0056] (4) Preparation of silicon carbide ceramics by reaction sintering. The above preform was subjected to reaction sintering densification treatment at a sintering temperature of 1650℃ for 4 hours, and then cooled to room temperature to obtain a density of 3.02 g / cm³. 3 Dense silicon carbide ceramics.

[0057] Example 3

[0058] Step (1) is the same as in Example 2.

[0059] (2) Preparation of spherical dense powder. Argon and hydrogen were used as carrier gases in a volume ratio of 8:2 for atmospheric plasma spraying. To prevent the evaporation of liquid silicon during the spraying process, the spraying power was reduced from 45KW to 35KW, while the spraying distance was increased to 200mm. This increased the cooling time of the molten droplets in the air and reduced the jet rate to decrease splashing during the quenching process, thereby improving the powder yield. Spherical dense silicon carbide composite powder was obtained after the spraying process.

[0060] (3) BJP molding of silicon carbide preforms. A binder solution was prepared by mixing phenolic resin, anhydrous ethanol, and ethylene glycol in a mass ratio of 6:2:2. The printing layer thickness was adjusted to 50 μm for BJP molding to prepare silicon carbide preforms. The preforms were then impregnated with the binder to further increase the carbon content of the preforms.

[0061] (4) Preparation of silicon carbide ceramics by reaction sintering. After degreasing and debinding the above preform, it was subjected to reaction sintering densification treatment at a temperature of 1670℃ for 2 hours, and then cooled to room temperature to obtain a density of 3.07 g / cm³. 3 The dense silicon carbide ceramic has a flexural strength of 350 MPa.

[0062] Example 4

[0063] (1) Preparation of raw material powder. Take 1300 mesh silicon carbide powder and 1800 mesh silicon powder, mix them in a mass ratio of 50:50, and use a planetary ball mill to ball mill for 16 hours. The ball milling medium is anhydrous ethanol, the grinding ball material is silicon carbide, and the ball-to-material ratio is 3:1. Place the ball-milled powder slurry in a drying oven and dry it at 140℃ for 10 hours to obtain a uniformly mixed composite powder.

[0064] (2) Preparation of spherical dense powder. Argon and hydrogen were used as carrier gases in a volume ratio of 9:1 for atmospheric plasma spraying. The spraying power was 35KW and the spraying distance was 200mm. Solid carbon dioxide was used for quenching treatment to obtain spherical dense silicon carbide composite powder.

[0065] (3) BJP molding of silicon carbide preforms. A binder solution was prepared by mixing phenolic resin, anhydrous ethanol, and ethylene glycol in a mass ratio of 4:4:2. The printing layer thickness was adjusted to 70 μm for BJP molding to prepare silicon carbide preforms.

[0066] (4) Preparation of silicon carbide ceramics by reaction sintering. The above preform was subjected to reaction sintering densification treatment at a sintering temperature of 1680℃ for 5 hours, and then cooled to room temperature to obtain a density of 2.82 g / cm³. 3 Dense silicon carbide ceramics.

[0067] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0068] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for producing a silicon carbide composite powder, characterized by, The preparation method of the silicon carbide composite powder comprises the following steps: S1. mixing silicon carbide powder and silicon powder in a mass ratio range of (40-80):(60-20) to obtain a composite powder; S2. performing atmospheric plasma spraying on the composite powder to obtain a liquid composite powder; the liquid composite powder comprises liquid melt state silicon and powder state silicon carbide; the liquid melt state silicon wraps the powder state silicon carbide; S3. performing quenching treatment on the liquid composite powder by a quenching medium to obtain the silicon carbide composite powder in the quenching medium.

2. The method of producing a silicon carbide composite powder according to claim 1, characterized by, The particle size range of the silicon carbide powder is 100-2000 mesh, and the particle size range of the silicon powder is 1000-2000 mesh.

3. The method of producing a silicon carbide composite powder according to claim 1, characterized by, The atmospheric plasma spraying comprises: delivering the composite powder to a plasma torch by a carrier gas; The carrier gas comprises argon and hydrogen in a volume ratio range of (90-10):(10-90), wherein the argon is used for stabilizing an arc, and the hydrogen is used as a heat conducting medium; The power range of the plasma torch is 20-50 KW, the spraying distance of the atmospheric plasma spraying is 20-200 mm, and the spraying distance is the distance between the plasma torch and the quenching medium.

4. The method of producing a silicon carbide composite powder according to claim 1, characterized by, The mixing comprises: wet ball milling the silicon carbide powder and the silicon powder in a ball mill tank to sufficiently mix them; the ball milling medium of the wet ball milling is anhydrous ethanol, the milling ball is a silicon carbide ball, the ball-to-material ratio is 1-4.2, and the ball milling time is 5-24 h.

5. The method of claim 1, wherein the silicon carbide composite powder is prepared by the steps of: preparing a mixture of a silicon source and a carbon source; and heating the mixture to a temperature of 1,000°C to 1,500°C in an inert gas atmosphere. The quenching medium is water, oil, liquid nitrogen, carbon dioxide or argon.

6. A silicon carbide composite powder, characterized by, The silicon carbide composite powder is prepared by the preparation method of the silicon carbide composite powder according to any one of claims 1-5.

7. A silicon carbide ceramic material, characterized by, The silicon carbide ceramic material is prepared by performing binder jetting or laser selective sintering on the silicon carbide composite powder to form a silicon carbide preform and then performing reaction sintering; the silicon carbide composite powder is the silicon carbide composite powder according to claim 6.

8. The silicon carbide ceramic material of claim 7, wherein, In the process of preparing the silicon carbide preform by the binder jetting, the binder used comprises a solute and a solvent; the solute is at least one selected from ethylene pyrrolidone, phenolic resin, furan resin or polyacrylic acid resin; and the solvent is at least one selected from deionized water, anhydrous ethanol or ethylene glycol. In the process of preparing the silicon carbide preform by the binder jetting, the forming thickness is set to 10-100 μm, and the scanning interval is set to 0.01-1 mm.

9. The silicon carbide ceramic material of claim 7, wherein, The density of the silicon carbide preform is 1.2 g / cm 3 2.2 g / cm 3 The bending strength of the silicon carbide preform is 2 MPa~14 MPa.

10. The silicon carbide ceramic material of claim 7, wherein, The bending strength of the silicon carbide ceramic material is 220 MPa to 450 MPa, the elastic modulus of the silicon carbide ceramic material is 270 GPa to 420 GPa, the fracture toughness of the silicon carbide ceramic material is 1.63 MPa·m 1 / 2 ~3.28 MPa·m 1 / 2 The thermal conductivity of the silicon carbide ceramic material is 140 W / mk to 200 W / mk, and the density of the silicon carbide ceramic material is 2.85 g / cm 3 ~3.09 g / cm 3 .

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