Complex shaped silicon carbide ceramic material and method for producing the same

Abstract

The application provides a complex-shaped silicon carbide ceramic material and a preparation method thereof. The complex-shaped silicon carbide ceramic material comprises raw materials in a proportion by weight of 75-85 parts of silicon carbide powder, 30-40 parts of anhydrous alcohol, 5-10 parts of carbon powder, 3-6 parts of resin, 2-3 parts of a dispersing agent, 0.5-0.8 parts of a curing agent, 0.5-2 parts of a binder and 110-150 parts of silicon metal particles. The preparation process comprises five steps of batching, mixing, drying and powdering, high-temperature pressure casting and high-temperature silicon infiltration sintering. The complex-shaped silicon carbide ceramic material provided by the application has excellent performance, the preparation method is simple, and the silicon carbide product can be directly sintered into a reaction sintered silicon carbide product without burying and degumming, so that the density and size precision of the product are high, and the production efficiency and product quality can be greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicon carbide ceramics, in particular to a complex shape silicon carbide ceramic material and a preparation method thereof. BACKGROUND

[0002] Reaction sintering silicon carbide has high thermal conductivity, low thermal expansion coefficient, high strength, net size sintering and other advantages, and the basic principle of its preparation process is that liquid silicon with reactivity penetrates into the carbon-containing porous ceramic green body under the action of capillary force and reacts with carbon therein to generate silicon carbide, thereby completing the densification process. In the preparation process of such ceramics, obtaining a green body that is defect-free, has uniform microstructure and good impregnability is a key problem. In the past, complex shape silicon carbide green bodies were formed by hot-pressing molding process, i.e. silicon carbide powder was mixed with paraffin and lubricant to form a wax slurry, then the wax slurry was hot-pressed to form a wax blank, and finally the silicon carbide shaped body was obtained by burying and de-waxing, and then high-temperature silicon infiltration reaction sintering was performed. A press-in molding process for silicon carbide ceramic material is provided in Chinese patent CN1182073C, i.e. taking W10 silicon carbide powder as the raw material, 80-90% by weight of the silicon carbide powder and 10-20% by weight of carbon black are mixed, and then the mixture is ball-milled, sieved and stirred with wax to form a wax slurry, which is then molded into a wax blank in a hot-pressing machine. Then the wax blank is placed in a crucible, alumina powder is used as an adsorbent, and the crucible is slowly heated in a low-temperature de-waxing furnace. When the paraffin in the blank is removed by 70-85%, the crucible is removed and cooled to room temperature, and the blank is taken out. Finally, the de-waxed silicon carbide blank and silicon chips are uniformly placed in a crucible, and the crucible is placed in a vacuum sintering furnace for sintering.

[0003] When the silicon carbide ceramic is prepared by the above process, secondary de-waxing is required, and the product needs to be buried with alumina as an adsorbent, which has many processes and a long de-waxing time. The residual buried powder on the surface after burying also affects the purity of the silicon carbide product, and void defects are also easily formed during the de-waxing process. SUMMARY

[0004] The present application provides a complex shape silicon carbide ceramic material and a preparation method thereof, to solve the problems of secondary de-waxing, many processes and poor performance of the obtained product in the prior art.

[0005] The present application provides a complex shape silicon carbide ceramic material, which comprises the following raw materials in a weight ratio of 75-85 parts of silicon carbide powder, 30-40 parts of anhydrous alcohol, 5-10 parts of carbon powder, 3-6 parts of resin, 2-3 parts of dispersing agent, 0.5-0.8 parts of curing agent, 0.5-2 parts of adhesive and 110-150 parts of metallic silicon particles.

[0006] Optionally, the silicon carbide powder comprises silicon carbide fine powder with a particle size of 20-100 μm and silicon carbide micro powder with a particle size of 0.5-2.5 μm, wherein the mass ratio of the silicon carbide fine powder to the silicon carbide micro powder is 3:(1-2).

[0007] Optionally, the silicon carbide fine powder comprises first silicon carbide fine powder with a particle size of 50-100 μm and second silicon carbide fine powder with a particle size of 20-30 μm; and the silicon carbide micro powder comprises first silicon carbide micro powder with a particle size of 2.0-2.5 μm and second silicon carbide micro powder with a particle size of 0.5-1 μm.

[0008] Optionally, the resin comprises epoxy resin and phenolic resin, and the mass ratio of the epoxy resin to the phenolic resin is 1:(0.5-2).

[0009] Optionally, the curing agent comprises 593 curing agent and urotropine curing agent, and the mass ratio of the 593 curing agent to the epoxy resin is 1:5.

[0010] Optionally, the anhydrous alcohol is anhydrous ethanol.

[0011] Optionally, the dispersing agent is tetramethylammonium hydroxide.

[0012] Optionally, the adhesive is hydroxypropyl methyl cellulose.

[0013] Optionally, the particle size of the metallic silicon particles is 3-5 mm.

[0014] The application further provides a preparation method of the complex-shaped silicon carbide ceramic material.

[0015] (1) batching: the following raw materials are weighed according to the weight fraction: 75-85 parts of silicon carbide powder, 30-40 parts of anhydrous alcohol, 5-10 parts of carbon powder, 3-6 parts of resin, 2-3 parts of dispersing agent, 0.5-0.8 parts of curing agent, 0.5-2 parts of adhesive, and 110-150 parts of metallic silicon particles;

[0016] (2) mixing: the resin, the curing agent and the anhydrous alcohol weighed in step (1) are mixed uniformly, and the mixed material and the remaining components except the metallic silicon particles are loaded into a ball mill tank for wet mixing, wherein the wet mixing time is 1.5-2.5 h and the rotating speed is 150-200 r / min;

[0017] (3) drying and powdering: the material after wet mixing in step (2) is dried, and then crushed into 30-80 mesh silicon carbide foundry sand;

[0018] (4) high-temperature die casting: the silicon carbide foundry sand prepared in step (3) is stored in a core shooting cylinder of a core shooter, a metal mold is assembled, the mold heating temperature is set to 200℃, and then the core shooter is used for die casting to obtain a silicon carbide blank;

[0019] (5) High-temperature silicon infiltration sintering: the silicon carbide blank obtained in step (4) is placed into a vacuum furnace, and then silicon particles are placed into the vacuum furnace. The vacuum furnace is heated to 600°C, and then nitrogen is filled into the vacuum furnace to heat to 1650°C for the second time. After holding for 3 hours, the sintering is completed.

[0020] The present application provides a complex-shaped silicon carbide ceramic material, which uses silicon carbide powder, anhydrous alcohol, carbon powder and resin as raw materials of the ceramic material, and adds dispersant, curing agent and adhesive as auxiliary materials. Metal silicon particles are added during sintering to co-sinter, so that the silicon carbide ceramic material with excellent performance can be obtained. The whole process is simple, and the silicon carbide product can be directly sintered without burying and degumming. The silicon carbide product has high density and high size precision, and can greatly improve production efficiency and product quality. DETAILED DESCRIPTION

[0021] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are clearly and completely described below. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work also belong to the protection scope of the present application.

[0022] The present application provides a complex-shaped silicon carbide ceramic material, which includes the following raw materials in the weight ratio: 75-85 parts of silicon carbide powder, 30-40 parts of anhydrous alcohol, 5-10 parts of carbon powder, 3-6 parts of resin, 2-3 parts of dispersant, 0.5-0.8 parts of curing agent, 0.5-2 parts of adhesive and 110-150 parts of metal silicon particles.

[0023] Further, the silicon carbide powder includes silicon carbide fine powder with a particle size of 20-100 μm and silicon carbide micro powder with a particle size of 0.5-2.5 μm, and the mass ratio of the silicon carbide fine powder to the silicon carbide micro powder is 3:(1-2). Further, the silicon carbide fine powder includes first silicon carbide fine powder with a particle size of 50-100 μm and second silicon carbide fine powder with a particle size of 20-30 μm; and the silicon carbide micro powder includes first silicon carbide micro powder with a particle size of 2.0-2.5 μm and second silicon carbide micro powder with a particle size of 0.5-1 μm. The mass ratio of the first silicon carbide fine powder to the second silicon carbide fine powder is 1:(0.5-1), and the mass ratio of the first silicon carbide micro powder to the second silicon carbide micro powder is 1:(1-1.5).

[0024] Further, the resin includes epoxy resin and phenolic resin, and the mass ratio of the epoxy resin to the phenolic resin is 1:(0.5-2).

[0025] Further, the curing agent comprises 593 curing agent and urotropine curing agent, wherein the mass ratio of the 593 curing agent to the epoxy resin is 1:5.

[0026] Further, the anhydrous alcohol is anhydrous ethanol.

[0027] Further, the dispersing agent is tetramethylammonium hydroxide.

[0028] Further, the binder is hydroxypropyl methyl cellulose.

[0029] Further, the particle size of the metallic silicon particles is between 3-5mm.

[0030] Further, the ratio of the metallic silicon particles to the total mass of the remaining components in the raw material is 1:1.

[0031] Further, the method for preparing the complex-shaped silicon carbide ceramic material comprises the following steps:

[0032] (1) batching: the following raw materials are weighed according to the weight fraction: 75-85 parts of silicon carbide powder, 30-40 parts of anhydrous alcohol, 5-10 parts of carbon powder, 3-6 parts of resin, 2-3 parts of dispersing agent, 0.5-0.8 parts of curing agent, 0.5-2 parts of binder, and 110-150 parts of metallic silicon particles;

[0033] (2) mixing: the resin, curing agent and anhydrous alcohol weighed in step (1) are mixed uniformly, and the mixed material and the remaining components except the metallic silicon particles are loaded into a ball mill tank for wet mixing, wherein the wet mixing time is 1.5-2.5h and the rotation speed is 150-200r / min;

[0034] (3) drying and powdering: the material after wet mixing in step (2) is dried, and then crushed into 30-80 mesh silicon carbide foundry sand after drying;

[0035] (4) high-temperature die casting: the silicon carbide foundry sand prepared in step (3) is stored in the core shooting cylinder of the core shooter, the metal mold is assembled, the mold heating temperature is set to 200℃, and then the core shooter is used for pressure casting to obtain a silicon carbide blank;

[0036] (5) high-temperature silicon infiltration sintering: the silicon carbide blank obtained in step (4) is placed in a vacuum furnace, and then the metallic silicon particles are placed in the vacuum furnace, heated to 600℃ in vacuum, and then nitrogen is filled into the furnace for secondary heating to 1650℃, and the sintering is completed after 3h of holding.

[0037] The application will be further described in detail in combination with specific examples.

[0038] Example 1

[0039] A complex shape silicon carbide ceramic material, comprising raw materials in the following weight ratio: 75 parts of silicon carbide powder, 30 parts of anhydrous ethanol, 5 parts of carbon powder, 3 parts of resin, 2 parts of dispersant tetramethylammonium hydroxide, 0.5 parts of curing agent, 0.5 parts of adhesive hydroxypropyl methyl cellulose, and 116 parts of metal silicon particles.

[0040] The silicon carbide powder comprises silicon carbide fine powder and silicon carbide micro powder in a mass ratio of 3:1, wherein the mass ratio of first silicon carbide fine powder to second silicon carbide fine powder in the silicon carbide fine powder is 1:0.5, and the mass ratio of first silicon carbide micro powder to second silicon carbide micro powder in the silicon carbide micro powder is 1:1.

[0041] The mass ratio of epoxy resin to phenolic resin in the resin is 1:0.5, i.e. 2 parts of epoxy resin and 1 part of phenolic resin.

[0042] The curing agent comprises 0.4 parts of 593 curing agent and 0.1 parts of urotropine curing agent.

[0043] A preparation method of a silicon carbide ceramic material for complex shapes, comprising the following steps:

[0044] (1) batching: weighing and taking the raw materials according to the above weight ratio;

[0045] (2) mixing: mixing the resin, curing agent and anhydrous alcohol weighed in step (1) uniformly, and loading the uniformly mixed material and the remaining components except for the metal silicon particles into a ball mill tank for wet mixing, wherein the wet mixing time is 1.5 h and the rotation speed is 150 r / min;

[0046] (3) drying and powdering: drying the wet mixed material in step (2), and crushing the dried material into 30-mesh silicon carbide foundry sand;

[0047] (4) high-temperature die casting: storing the prepared silicon carbide foundry sand in step (3) into a core shooting cylinder of a core shooter, loading a metal mold, setting the mold heating temperature to 200℃, and then performing die casting by the core shooter to obtain a silicon carbide blank;

[0048] (5) high-temperature silicon infiltration sintering: placing the silicon carbide blank obtained in step (4) into a vacuum furnace, and then placing metal silicon particles into the furnace, vacuum heating to 600℃, and then charging nitrogen into the furnace for secondary heating to 1650℃, and then keeping the temperature for 3 h to end the sintering.

[0049] Example 2

[0050] A silicon carbide ceramic material for complex shapes, comprising raw materials in the following weight ratio: 85 parts of silicon carbide powder, 40 parts of anhydrous ethanol, 10 parts of carbon powder, 6 parts of resin, 3 parts of dispersant tetramethylammonium hydroxide, 0.8 parts of curing agent, 2 parts of adhesive hydroxypropyl methyl cellulose, and 146.8 parts of metal silicon particles.

[0051] The silicon carbide powder comprises silicon carbide fine powder and silicon carbide micro powder in a mass ratio of 3:2, wherein the mass ratio of first silicon carbide fine powder to second silicon carbide fine powder in the silicon carbide fine powder is 1:1, and the mass ratio of first silicon carbide micro powder to second silicon carbide micro powder in the silicon carbide micro powder is 1:1.5.

[0052] The mass ratio of the epoxy resin and the phenolic resin in the resin is 1:2, that is, 2 parts of the epoxy resin and 4 parts of the phenolic resin are included.

[0053] The curing agent comprises 0.4 parts of 593 curing agent and 0.4 parts of urotropine curing agent.

[0054] A preparation method of a silicon carbide ceramic material applicable to a complex shape comprises the following steps:

[0055] (1) batching: the raw materials are weighed and taken according to the weight fractions described above;

[0056] (2) mixing: the resin, the curing agent and the anhydrous alcohol weighed in step (1) are uniformly mixed, and the uniformly mixed material and the remaining components except for the metal silicon particles are loaded into a ball mill tank for wet mixing, wherein the wet mixing time is 2.5 h and the rotating speed is 200 r / min;

[0057] (3) drying and powdering: the material after wet mixing in step (2) is dried, and then crushed into 80-mesh silicon carbide foundry sand;

[0058] (4) high-temperature die casting: the silicon carbide foundry sand prepared in step (3) is stored in a core shooting cylinder of a core shooter, a metal mold is assembled, the mold heating temperature is set to 200℃, and then the core shooter is used for pressure casting to obtain a silicon carbide blank;

[0059] (5) high-temperature silicon infiltration sintering: the silicon carbide blank obtained in step (4) is placed into a vacuum furnace, and then the metal silicon particles are placed into the vacuum furnace, the vacuum heating is performed to 600℃, nitrogen is filled into the furnace for secondary heating to 1650℃, and the sintering is ended after 3 h of heat preservation.

[0060] Example 3

[0061] A silicon carbide ceramic material applicable to a complex shape comprises the following raw materials in weight fractions: 80 parts of silicon carbide powder, 35 parts of anhydrous ethanol, 7 parts of carbon powder, 5 parts of resin, 2.5 parts of dispersant tetramethylammonium hydroxide, 0.75 parts of curing agent, 1.5 parts of adhesive hydroxypropyl methyl cellulose, and 131.75 parts of metal silicon particles.

[0062] The silicon carbide powder comprises silicon carbide fine powder and silicon carbide micro powder in a mass ratio of 3:1.5, wherein the mass ratio of first silicon carbide fine powder to second silicon carbide fine powder in the silicon carbide fine powder is 1:0.7, and the mass ratio of first silicon carbide micro powder to second silicon carbide micro powder in the silicon carbide micro powder is 1:1.3.

[0063] The mass ratio of the epoxy resin and the phenolic resin in the resin is 1:1, i.e. 2.5 parts of the epoxy resin and 2.5 parts of the phenolic resin.

[0064] The curing agent comprises 0.5 parts of the 593 curing agent and 0.25 parts of the methenamine curing agent.

[0065] A preparation method of a silicon carbide ceramic material applicable to a complex shape, comprising the following steps:

[0066] (1) batching: weighing and taking the raw materials according to the weight fractions described above;

[0067] (2) mixing: uniformly mixing the resin, the curing agent and the anhydrous alcohol weighed in step (1), and loading the uniformly mixed material and the remaining components except for the silicon metal particles into a ball mill tank for wet mixing, wherein the wet mixing time is 2 h and the rotating speed is 170 r / min;

[0068] (3) drying and powdering: drying the wet mixed material in step (2), and crushing the dried material into 50-mesh silicon carbide foundry sand;

[0069] (4) high-temperature die casting: storing the prepared silicon carbide foundry sand in step (3) into a core shooting cylinder of a core shooter, loading a metal mold, setting the mold heating temperature to 200℃, and then performing die casting by the core shooter to obtain a silicon carbide blank;

[0070] (5) high-temperature silicon infiltration sintering: placing the silicon carbide blank obtained in step (4) into a vacuum furnace, and then placing silicon metal particles into the furnace, vacuum heating to 600℃, and then charging nitrogen into the furnace for secondary heating to 1650℃, and then keeping the temperature for 3 h to end the sintering.

[0071] Comparative Example 1

[0072] The difference between Comparative Example 1 and Example 2 is only that the adhesive hydroxypropyl methyl cellulose is not used in the raw materials.

[0073] Comparative Example 2

[0074] The difference between Comparative Example 2 and Example 2 is only that the dispersant tetramethylammonium hydroxide is not used in the raw materials.

[0075] Comparative Example 3

[0076] The difference between Comparative Example 3 and Example 2 is only that the curing agent is not used.

[0077] Comparative Example 4

[0078] Comparative Example 4 differs from Example 2 only in that the resin contains only phenol-formaldehyde resin and no curing agent.

[0079] Table 1 is a table of properties of the silicon carbide bodies and complex- shaped silicon carbide ceramic materials (sintered bodies) obtained in Examples 1-3 and Comparative Examples 1-3:

[0080] Table 1

[0081]

[0082] Finally, it should be noted that the above examples are merely used to illustrate the technical solutions of the present application, and are not intended to limit the same; even though the present application has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent replacements for some or all of the technical features therein; and such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A complex shaped silicon carbide ceramic material, characterized in that, The raw materials include the following components in the following proportions by weight: silicon carbide powder 75-85 parts, anhydrous alcohol 30-40 parts, carbon powder 5-10 parts, resin 3-6 parts, dispersing agent 2-3 parts, curing agent 0.5-0.8 parts, adhesive 0.5-2 parts, and metallic silicon particles 110-150 parts; The silicon carbide powder includes silicon carbide fine powder having a particle size of 20-100 μm and silicon carbide micro powder having a particle size of 0.5-2.5 μm, wherein the mass ratio of the silicon carbide fine powder to the silicon carbide micro powder is 3:(1-2). The silicon carbide fine powder includes first silicon carbide fine powder having a particle size of 50-100 μm and second silicon carbide fine powder having a particle size of 20-30 μm. The silicon carbide micro powder includes first silicon carbide micro powder having a particle size of 2.0-2.5 μm and second silicon carbide micro powder having a particle size of 0.5-1 μm. The resin includes epoxy resin and phenolic resin, and the mass ratio of the epoxy resin to the phenolic resin is 1:(0.5-2). The method for preparing the complex-shaped silicon carbide ceramic material includes the following steps: (1) batching: the following raw materials are weighed in the following proportions by weight: silicon carbide powder 75-85 parts, anhydrous alcohol 30-40 parts, carbon powder 5-10 parts, resin 3-6 parts, dispersing agent 2-3 parts, curing agent 0.5-0.8 parts, adhesive 0.5-2 parts, and metallic silicon particles 110-150 parts; (2) mixing: the resin, curing agent and anhydrous alcohol weighed in step (1) are mixed uniformly, and the mixed material and the remaining components except for the metallic silicon particles are loaded into a ball mill tank for wet mixing, wherein the wet mixing time is 1.5-2.5 h and the rotating speed is 150-200 r / min; (3) drying and powdering: the material after wet mixing in step (2) is dried, and then crushed into 30-80 mesh silicon carbide foundry sand; (4) high-temperature die casting: the silicon carbide foundry sand prepared in step (3) is stored in a core shooting cylinder of a core shooter, a metal mold is assembled, the mold heating temperature is set to 200°C, and then the core shooter is used for die casting to obtain a silicon carbide blank; (5) high-temperature silicon infiltration sintering: the silicon carbide blank obtained in step (4) is placed into a vacuum furnace, and metallic silicon particles are placed into the furnace, the furnace is heated to 600°C in vacuum, nitrogen is filled into the furnace for secondary heating to 1650°C, and the sintering is completed after 3 h of heat preservation.

2. The complex shaped silicon carbide ceramic material according to claim 1, characterized in that The curing agent includes 593 curing agent and urotropine curing agent, and the mass ratio of the 593 curing agent to the epoxy resin is 1:

5.

3. The complex shaped silicon carbide ceramic material of claim 1, wherein, The anhydrous alcohol is anhydrous ethanol.

4. The complex shaped silicon carbide ceramic material of claim 1, wherein, The dispersing agent is tetramethylammonium hydroxide.

5. The complex shaped silicon carbide ceramic material of claim 1, wherein, The adhesive is hydroxypropyl methylcellulose.

6. The complex shaped silicon carbide ceramic material of claim 1, wherein, The particle size of the metallic silicon particles is 3-5 mm.

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