Silicon carbide ceramic material with complex shape and preparation method thereof

Abstract

The invention provides a complex-shaped silicon carbide ceramic material and a preparation method thereof, and the complex-shaped silicon carbide ceramic material comprises the following raw materials by weight: 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 dispersant, 0.5-0.8 part of a curing agent, 0.5-2 parts of an adhesive, and 110-150 parts of metal silicon particles. The preparation process comprises five steps of burdening, mixing, drying and powdering, high-temperature die casting and high-temperature siliconizing and sintering. The silicon carbide ceramic material with the complex shape is excellent in performance, simple in preparation method, free of buried sintering degumming, capable of being directly sintered into a reaction sintering silicon carbide product, high in density and high in size precision, and the production efficiency and the product quality can be greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon carbide ceramics, and particularly to a silicon carbide ceramic material with a complex shape and a preparation method thereof. Background Art

[0002] Reaction-sintered silicon carbide has the advantages of high thermal conductivity, low thermal expansion coefficient, high strength, net-size sintering, etc. The basic principle of its preparation process is that reactive liquid silicon infiltrates into a carbon-containing porous ceramic green body under the action of capillary force and reacts with the carbon therein to form silicon carbide, completing the densification process. In the preparation process of this kind of ceramic, obtaining a defect-free, microstructurally uniform and well-infiltratable green body is a key issue. In the past, to form a silicon carbide green body with a complex shape, a hot die-casting forming process was adopted. First, silicon carbide powder was mixed with paraffin and a lubricant to form a wax slurry, and then it was hot die-cast into a wax blank. After dewaxing by buried firing, a silicon carbide special-shaped blank was finally obtained, and then high-temperature silicon infiltration reaction sintering was carried out. The Chinese invention patent with the authorization announcement number CN1182073C provides a die-casting forming process for a silicon carbide ceramic material. Taking 80-90% of silicon carbide fine powder with a fineness of W10 and 10-20% of carbon black by weight percentage as the raw materials, after ball milling, sieving, and stirring with wax in sequence, it is formed into a wax blank at one time in a hot die-casting machine. Then, the wax blank is placed in a sagger, with alumina powder as an adsorbent, and put into a low-temperature dewaxing furnace to slowly raise the temperature for dewaxing. When 70% - 85% of the paraffin in the blank is discharged, the sagger is removed and cooled to room temperature, and the blank is taken out; finally, the dewaxed silicon carbide blank and silicon wafers are evenly placed in a crucible and loaded into a vacuum sintering furnace for sintering.

[0003] When preparing silicon carbide ceramics by the above process, secondary dewaxing is required, and the product needs to be buried and fired with alumina as an adsorbent. There are many processes, the dewaxing time is long, and the buried powder remaining on the surface after buried firing will also affect the purity of the silicon carbide product, and void defects are extremely likely to be formed during the dewaxing process. Summary of the Invention

[0004] The present invention provides a silicon carbide ceramic material with a complex shape and a preparation method thereof, aiming to solve the problems in the prior art that the preparation process of silicon carbide ceramics requires secondary dewaxing, has many processes, and the obtained product has poor performance.

[0005] The present invention provides a silicon carbide ceramic material with a complex shape, comprising raw materials in the following weight ratio: 75-85 parts of silicon carbide powder, 30-40 parts of absolute alcohol, 5-10 parts of carbon powder, 3-6 parts of resin, 2-3 parts of dispersant, 0.5-0.8 part of curing agent, 0.5-2 parts of binder, and 110-150 parts of metal silicon particles.

[0006] Optionally, 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, wherein the mass ratio of silicon carbide fine powder to silicon carbide micro powder is 3:(1-2).

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

[0008] Optionally, the resin includes epoxy resin and phenolic resin in a mass ratio of 1:(0.5-2).

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

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

[0011] Optionally, the dispersant is tetramethylammonium hydroxide.

[0012] Optionally, the binder is hydroxypropyl methylcellulose.

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

[0014] The present invention also provides a method for preparing a complex-shaped silicon carbide ceramic material, comprising the following steps:

[0015] (1) Ingredients: Weigh the following raw materials by weight: 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 metallic silicon particles;

[0016] (2) Mixing: The resin, curing agent and anhydrous alcohol weighed in the above step (1) are mixed evenly, and the mixed materials and the remaining components except the metal silicon particles are placed in a ball mill for wet mixing, wherein the wet mixing time is 1.5-2.5 hours and the rotation speed is 150-200 r / min;

[0017] (3) drying and powdering: drying the wet mixed material in step (2), and crushing it into 30-80 mesh silicon carbide foundry sand after drying;

[0018] (4) High temperature die casting: the silicon carbide casting sand prepared in step (3) is placed in the core shooting barrel of the core shooting machine, a metal mold is installed, the mold heating temperature is set to 200° C., and then the core shooting machine is used for die casting to obtain a silicon carbide blank;

[0019] (5) High-temperature silicon infiltration sintering: Put the silicon carbide green body obtained in step (4) into a vacuum furnace, then put in metal silicon particles, heat it in vacuum to 600 °C, and then fill the furnace with nitrogen and heat it to 1650 °C for the second time. After holding for 3 h, the sintering is completed.

[0020] The present invention provides a silicon carbide ceramic material with a complex shape. Using silicon carbide powder, absolute alcohol, carbon powder, and resin as raw materials for the ceramic material, and adding a dispersant, a curing agent, and an adhesive as auxiliary materials, and adding metal silicon particles during sintering for co-sintering, a silicon carbide ceramic material with excellent performance can be obtained. Moreover, the entire process is simple, without the need for buried firing and debinding, and can directly fire reaction-sintered silicon carbide products, which have high density and high dimensional accuracy, and can greatly improve production efficiency and product quality. Specific embodiments

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts also belong to the scope of protection of the present invention.

[0022] The present invention provides a silicon carbide ceramic material with a complex shape, including the following raw materials in parts by weight: 75 - 85 parts of silicon carbide powder, 30 - 40 parts of absolute 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 between 20 - 100 μm and silicon carbide micropowder with a particle size between 0.5 - 2.5 μm, and the mass ratio of the silicon carbide fine powder to the silicon carbide micropowder is 3:(1 - 2). Further, the silicon carbide fine powder includes first silicon carbide fine powder with a particle size between 50 - 100 μm and second silicon carbide fine powder with a particle size between 20 - 30 μm; the silicon carbide micropowder includes first silicon carbide micropowder with a particle size between 2.0 - 2.5 μm and second silicon carbide micropowder with a particle size between 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 micropowder to the second silicon carbide micropowder is 1:(1 - 1.5).

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

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

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

[0027] Furthermore, the dispersant is tetramethylammonium hydroxide.

[0028] Furthermore, the binder is hydroxypropyl methylcellulose.

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

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

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

[0032] (1) Ingredients: Weigh the following raw materials by weight: 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 metallic silicon particles;

[0033] (2) Mixing: The resin, curing agent and anhydrous alcohol weighed in step (1) are mixed uniformly, and the uniformly mixed materials and the remaining components except the metal silicon particles are placed in a ball mill for wet mixing, wherein the wet mixing time is 1.5-2.5 hours and the rotation speed is 150-200 r / min;

[0034] (3) drying and powdering: drying the wet mixed material in step (2), and crushing it into 30-80 mesh silicon carbide foundry sand after drying;

[0035] (4) High temperature die casting: the silicon carbide casting sand prepared in step (3) is placed in the core shooting barrel of the core shooting machine, a metal mold is installed, the mold heating temperature is set to 200° C., and then the core shooting machine is used for die casting to obtain a silicon carbide blank;

[0036] (5) High-temperature siliconization sintering: The silicon carbide blank obtained in step (4) is placed in a vacuum furnace, and then metallic silicon particles are added, and vacuum heated to 600°C. Nitrogen is then filled into the furnace and heated to 1650°C for a second time. The sintering is terminated after keeping the temperature for 3 hours.

[0037] The present invention is further described in detail below in conjunction with specific embodiments.

[0038] Example 1

[0039] A silicon carbide ceramic material with a complex shape, comprising raw materials in the following weight ratio: 75 parts of silicon carbide powder, 30 parts of absolute ethanol, 5 parts of carbon powder, 3 parts of resin, 2 parts of dispersant tetramethylammonium hydroxide, 0.5 part of curing agent, 0.5 part of binder hydroxypropyl methylcellulose, and 116 parts of metallic silicon particles.

[0040] The silicon carbide powder includes silicon carbide fine powder and silicon carbide micropowder with a mass ratio of 3:1. Among them, the mass ratio of the first silicon carbide fine powder to the second silicon carbide fine powder in the silicon carbide fine powder is 1:0.5, and the mass ratio of the first silicon carbide micropowder to the second silicon carbide micropowder in the silicon carbide micropowder is 1:1.

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

[0042] The curing agent includes 0.4 part of 593 curing agent and 0.1 part of hexamethylenetetramine curing agent.

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

[0044] (1) Weighing and batching: Weigh and take the raw materials according to the above weight ratio.

[0045] (2) Mixing: Mix the resin, curing agent and absolute ethanol weighed in step (1) evenly, and put the evenly mixed material and the remaining components except the metallic silicon particles into a ball mill tank for wet mixing. The wet mixing time is 1.5 h and the rotation speed is 150 r / min.

[0046] (3) Drying and powder making: Dry the material after wet mixing in step (2), and crush it into 30-mesh silicon carbide foundry sand after drying.

[0047] (4) High-temperature die casting: Put the silicon carbide foundry sand prepared in step (3) into the core shooting cylinder of a core shooter, install the metal mold, set the mold heating temperature at 200 °C, and then carry out die casting by the core shooter to obtain a silicon carbide blank.

[0048] (5) High-temperature silicon infiltration sintering: Put the silicon carbide blank obtained in step (4) into a vacuum furnace, then put in metallic silicon particles, heat it in vacuum to 600 °C, and then fill the furnace with nitrogen and heat it again to 1650 °C. After holding for 3 h, the sintering is completed.

[0049] Example 2

[0050] A silicon carbide ceramic material that can be used for complex shapes, comprising raw materials in the following weight ratio: 85 parts of silicon carbide powder, 40 parts of absolute ethanol, 10 parts of carbon powder, 6 parts of resin, 3 parts of dispersant tetramethylammonium hydroxide, 0.8 part of curing agent, 2 parts of binder hydroxypropyl methylcellulose, and 146.8 parts of metallic silicon particles.

[0051] The silicon carbide powder includes silicon carbide fine powder and silicon carbide micropowder with a mass ratio of 3:2. Among them, the mass ratio of the first silicon carbide fine powder to the second silicon carbide fine powder in the silicon carbide fine powder is 1:1, and the mass ratio of the first silicon carbide micropowder to the second silicon carbide micropowder in the silicon carbide micropowder is 1:1.5.

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

[0053] The curing agent includes 0.4 part of 593 curing agent and 0.4 part of hexamine curing agent.

[0054] A preparation method of a silicon carbide ceramic material that can be used for complex shapes includes the following steps:

[0055] (1) Weighing ingredients: Weigh and take the raw materials according to the above weight parts.

[0056] (2) Mixing: Mix the resin, curing agent and absolute ethanol weighed in step (1) evenly, and put the evenly mixed material and the remaining components except the metal silicon particles into a ball mill tank for wet mixing, where the wet mixing time is 2.5 h and the rotation speed is 200 r / min.

[0057] (3) Drying and powder making: Dry the material after wet mixing in step (2), and crush it into 80-mesh silicon carbide foundry sand after drying.

[0058] (4) High-temperature die casting: Put the silicon carbide foundry sand prepared in step (3) into the core shooting cylinder of a core shooter, install the metal mold, set the mold heating temperature at 200 °C, and then perform die casting by the core shooter to obtain a silicon carbide blank.

[0059] (5) High-temperature silicon infiltration sintering: Put the silicon carbide blank obtained in step (4) into a vacuum furnace, then put in metal silicon particles, heat it in vacuum to 600 °C, and then fill the furnace with nitrogen and heat it again to 1650 °C, and end the sintering after holding for 3 h.

[0060] Example 3

[0061] A silicon carbide ceramic material that can be used for complex shapes includes the following raw materials with weight part ratios: 80 parts of silicon carbide powder, 35 parts of absolute ethanol, 7 parts of carbon powder, 5 parts of resin, 2.5 parts of dispersant tetramethylammonium hydroxide, 0.75 part of curing agent, 1.5 parts of binder hydroxypropyl methylcellulose, and 131.75 parts of metal silicon particles.

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

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

[0064] The curing agent includes 0.5 part of 593 curing agent and 0.25 part of hexamethylenetetramine curing agent.

[0065] A preparation method of a silicon carbide ceramic material that can be used for complex shapes includes the following steps:

[0066] (1) Weighing materials: Weigh and take materials according to the above-mentioned parts by weight of the raw materials;

[0067] (2) Mixing: Mix the resin, curing agent and absolute ethanol weighed in step (1) evenly, and put the evenly mixed material and the remaining components except the metal silicon particles into a ball mill tank for wet mixing, where the wet mixing time is 2 h and the rotation speed is 170 r / min;

[0068] (3) Drying and powder making: Dry the material after wet mixing in step (2), and crush it into 50-mesh silicon carbide foundry sand after drying;

[0069] (4) High-temperature die casting: Put the silicon carbide foundry sand prepared in step (3) into the core shooting barrel of a core shooter, install the metal mold, set the mold heating temperature at 200 °C, and then perform die casting by the core shooter to obtain a silicon carbide green body;

[0070] (5) High-temperature silicon infiltration sintering: Put the silicon carbide green body obtained in step (4) into a vacuum furnace, then put in metal silicon particles, heat it in vacuum to 600 °C, and then fill the furnace with nitrogen and heat it to 1650 °C for the second time, and end the sintering after holding for 3 h.

[0071] Comparative Example 1

[0072] The difference between Comparative Example 1 and Example 2 is only that the binder hydroxypropyl methylcellulose 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] The difference between Comparative Example 4 and Example 2 is only that the resin only contains phenolic resin and no curing agent is used.

[0079] Table 1 shows the performance indexes of the silicon carbide green bodies and the complex-shaped silicon carbide ceramic materials (sintered bodies) obtained in Examples 1-3 and Comparative Examples 1-3 as shown in Table 1:

[0080] Table 1

[0081]

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these 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 invention.

Claims

1. A complex-shaped silicon carbide ceramic material, characterized in that: The invention comprises raw materials in the following weight proportions: 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.

2. The complex-shaped silicon carbide ceramic material according to claim 1, characterized in that: 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).

3. The complex-shaped silicon carbide ceramic material according to claim 2, characterized in that: The silicon carbide fine powder includes a first silicon carbide fine powder having a particle size between 50 and 100 μm and a second silicon carbide fine powder having a particle size between 20 and 30 μm; The silicon carbide micropowder includes a first silicon carbide micropowder with a particle size between 2.0 and 2.5 μm and a second silicon carbide micropowder with a particle size between 0.5 and 1 μm.

4. The complex-shaped silicon carbide ceramic material according to claim 1, characterized in that: The resin comprises epoxy resin and phenolic resin, and the mass ratio thereof is 1:(0.5-2).

5. The complex-shaped silicon carbide ceramic material according to claim 4, characterized in that: The curing agent includes 593 curing agent and urotropine curing agent, wherein the mass ratio of the 593 curing agent to the epoxy resin is 1:

5.

6. The complex-shaped silicon carbide ceramic material according to claim 1, characterized in that: The anhydrous alcohol is anhydrous ethanol.

7. The complex-shaped silicon carbide ceramic material according to claim 1, characterized in that: The dispersant is tetramethylammonium hydroxide.

8. The complex-shaped silicon carbide ceramic material according to claim 1, characterized in that: The binder is hydroxypropyl methylcellulose.

9. The complex-shaped silicon carbide ceramic material according to claim 1, characterized in that: The particle size of the metal silicon particles is between 3 and 5 mm.

10. A method for preparing a complex-shaped silicon carbide ceramic material according to any one of claims 1 to 9, characterized in that: The steps include: (1) Ingredients: Weigh the following raw materials by weight: 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, 0.2-0.6 parts of curing agent, 0.5-2 parts of adhesive, and 100-200 parts of metallic silicon particles; (2) Mixing: The resin, curing agent and anhydrous alcohol weighed in the above step (1) are mixed evenly, and the mixed materials and the remaining components except the metal silicon particles are placed in a ball mill for wet mixing, wherein the wet mixing time is 1.5-2.5 hours and the rotation speed is 150-200 r / min; (3) drying and powdering: drying the wet mixed material in step (2), and crushing it into 30-80 mesh silicon carbide foundry sand after drying; (4) High temperature die casting: the silicon carbide casting sand prepared in step (3) is placed in the core shooting barrel of the core shooting machine, a metal mold is installed, the mold heating temperature is set to 200° C., and then the core shooting machine is used for die casting to obtain a silicon carbide blank; (5) High-temperature siliconization sintering: The silicon carbide blank obtained in step (4) is placed in a vacuum furnace, and then metallic silicon particles are added, and vacuum heated to 600°C. Nitrogen is then filled into the furnace and heated to 1650°C for a second time. The sintering is terminated after keeping the temperature for 3 hours.

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