A silicon carbide outer coating based on carbon / carbon composite material for silicon and preparation method thereof

Abstract

The present invention discloses a silicon carbide outer coating based on a carbon / carbon composite material for silicon and a preparation method thereof. The silicon carbide of the present invention does not react with silicon. After the carbon / carbon composite material thermal field component is treated with the silicon carbide outer coating, the silicon erosion rate can be greatly reduced, and the oxidation resistance can be improved, thereby extending the service life of the product. In addition, its dense structure can avoid silicon agglomeration, reduce the cleaning frequency during the production process, and the manufacturing process is simple.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicon carbide outer coatings, and relates to a silicon carbide outer coating of a carbon / carbon composite material, and specifically relates to a silicon carbide outer coating based on a carbon / carbon composite material for silicon and a preparation method thereof. Background Art

[0002] The manufacturing of semiconductor silicon single crystals in the photovoltaic industry mostly adopts the Czochralski method (CZ method for short). During the process of pulling single crystal silicon rods, the temperature in the furnace is as high as 1550℃. Carbon / carbon composite materials (carbon-carbon composite materials) have the characteristics of low thermal expansion coefficient, low density, ablation resistance, corrosion resistance, stable friction coefficient, good thermal and electrical conductivity, high strength, high modulus, etc. In addition, this material has the characteristic that the mechanical properties do not decrease but increase with the increase of temperature, and is widely used in aviation, aerospace and civil industry. Therefore, the insulation system and heating system of the single crystal furnace thermal field are usually made of carbon / carbon composite materials.

[0003] However, many of the above properties of carbon / carbon composite materials can only be maintained under inert atmosphere or under conditions below 450°C, otherwise oxidation weight loss will significantly reduce the mechanical properties of carbon / carbon composite materials, thereby limiting their wide application as high-temperature refractory materials in oxidizing atmospheres. At the same time, the thermal insulation system and heating system of the single crystal furnace of carbon / carbon composite materials, after being eroded by silicon vapor, will react with silicon and carbon at high temperatures to generate corresponding stresses. After long-term use, the thermal field parts will experience cracks, powder and slag, silicon adhesion and agglomeration, and other undesirable phenomena, and it is impossible to ensure that the silicon liquid in the crucible has a suitable temperature gradient along the radial direction and the silicon rod being pulled and the silicon liquid in the crucible along the axial direction, thereby ensuring the production quality of single crystal silicon rods.

[0004] Therefore, how to use new materials and new solutions to improve the service life of carbon / carbon composite thermal field components, reduce production and maintenance costs, improve silicon corrosion resistance, oxidation resistance, and protect the matrix is ​​a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] In view of the problems that the carbon / carbon composite thermal field parts for silicon in the prior art have cracks, powder and slag, silicon adhesion and agglomeration, and the existing silicon carbide coating is complicated to manufacture and has a high manufacturing cost, the present invention provides a silicon carbide outer coating based on the carbon / carbon composite material for silicon and a preparation method thereof. The silicon carbide of the present invention does not react with silicon, and the carbon / carbon composite thermal field parts can greatly reduce the rate of silicon erosion and improve the anti-oxidation ability after being treated with the silicon carbide outer coating, thereby extending the service life of the product, and its dense structure can avoid silicon agglomeration, reduce the frequency of cleaning during the production process, and have a simple manufacturing process.

[0006] The purpose of the present invention is to provide a silicon carbide outer coating to solve the problems of cracks, powder and slag falling, silicon adhesion and agglomeration in silicon carbon-carbon composite thermal field parts, extend the service life and reduce the cleaning frequency.

[0007] The purpose of the present invention is achieved through the following technical solutions: A silicon carbide outer coating based on a carbon / carbon composite material for silicon, comprising: a carbon / carbon composite material substrate, a pyrolytic carbon coating, and a SiC sintered coating; The pyrolytic carbon coating is located on the carbon / carbon composite material substrate, and the SiC sintered coating is located on the pyrolytic carbon coating; The thickness of the carbon / carbon composite material substrate is not limited; The thickness of the pyrolytic carbon coating is 10 μm-20 μm; The thickness of the SiC sintered coating is 60 μm-80 μm; The carbon / carbon composite material substrate is a material obtained by densification of a carbon fiber preform or a short fiber molded carbon / carbon composite material. The density of the carbon / carbon composite material substrate is ≥1.3g / cm 3 ; The pyrolytic carbon coating is prepared by vapor deposition; The SiC sintered coating is sintered by special ceramic slurry; The silicon carbide outer coating based on the carbon / carbon composite material for silicon has the following performance indicators: Surface density: 248g / m 2 -252g / m 2 , silicon carbide content>95%, with good thermal conductivity, thermal stability, oxidation resistance and chemical corrosion resistance.

[0008] Furthermore, the carbon / carbon composite material substrate is selected from plates, tubes or other special-shaped parts.

[0009] Furthermore, the carbon / carbon composite material has a density of ≥1.3 g / cm after densification treatment. 3 , and the density is uniform, its surface needs to be polished clean with sandpaper less than 60 mesh and maintain a certain roughness.

[0010] Furthermore, the pyrolytic carbon coating is prepared by placing a carbon / carbon composite material substrate into a chemical vapor deposition furnace, slowly heating it to a deposition temperature of 950°C-1200°C, introducing hydrocarbon gas and diluent gas for chemical vapor deposition for 20h-35h, and the deposition thickness on the substrate surface is <20μm.

[0011] The SiC sintered coating is uniformly coated on the surface of the carbon / carbon composite material substrate. The SiC sintered coating is coated on the carbon / carbon substrate after chemical deposition. The pyrolytic carbon coating does not cause the carbon / carbon substrate to be completely closed. After the surface is dried and solidified, it is placed in a vacuum sintering furnace for sintering.

[0012] Furthermore, the SiC sintered coating, and its preparation method, comprises the following steps: ① Prepare silicone resin, high-purity silicon powder, silicon carbide powder, additives, and sintering stabilizer in a mass ratio of 20:30:40:2:8; the proportion of each component of the SiC sintering coating will be adjusted accordingly for products with different requirements; The organic silicone resin is one of methyl silicone resin and methyl phenyl silicone resin; the particle size of the high-purity silicon powder is 200-300 mesh; the particle size of the silicon carbide powder is 200-300 mesh; the auxiliary agent includes but is not limited to a dispersant, etc., the dispersant is a polymer organic dispersant, a thixotropic agent, etc., and the sintering stabilizer is a mixture of two or more of boron carbide, molybdenum carbide, titanium silicon carbide, etc. in any proportion; ② Disperse high-purity silicon powder and silicon carbide powder in silicone resin and add additives; ③ Carry out vacuum sintering at a temperature of 1750°C.

[0013] The present invention also relates to a method for preparing the above-mentioned silicon carbide outer coating based on the carbon / carbon composite material for silicon, comprising the following steps: 1) Grind the surface of the carbon / carbon composite material substrate to a rough state using sandpaper with a mesh size less than 60, and then clean the surface; 2) Place the carbon / carbon composite material substrate treated in the above step into a chemical vapor deposition furnace, slowly heat it to a deposition temperature of 950°C-1200°C, introduce hydrocarbon gas and diluent gas for chemical vapor deposition for 20h-35h, and deposit a thickness of less than 20μm on the surface of the substrate, so that a uniform pyrolytic carbon coating is formed on its surface; 3) Prepare silicone resin, high-purity silicon powder, silicon carbide powder, additives, and sintering stabilizer, mix them in a mass ratio of 20:30:40:2:8, and evenly apply them on the surface of the pyrolytic carbon coating of the carbon / carbon composite material substrate obtained in the previous step. After the surface is dried and cured, put it into a vacuum sintering furnace for sintering at a sintering temperature of 1750°C to obtain a SiC sintered coating.

[0014] Compared with the prior art, the present invention has the following advantages: 1. The silicon carbide outer coating based on the carbon / carbon composite material for silicon described in the present invention can be used to repair carbon / carbon composite thermal field components that are not cracked but severely silicon-corroded, thereby extending the service life of the thermal field components. The operation is simple and the process cycle for preparing the silicon carbide outer coating is short. It is a coating material that reduces costs and increases efficiency.

[0015] 2. The silicon carbide outer coating based on the carbon / carbon composite material for silicon described in the present invention can significantly reduce the silicon erosion rate when the carbon / carbon composite material is used in a single crystal furnace, improve the oxidation resistance, and its dense structure can avoid silicon agglomeration, reduce the cleaning frequency during the production process, and has a simple manufacturing process.

[0016] 3. The method for preparing a silicon carbide outer coating based on a carbon / carbon composite material for silicon described in the present invention has low production cost and simple and quick production steps. At the same time, the prepared silicon carbide outer coating can extend the service life of carbon-carbon parts, reduce the production and maintenance costs of carbon-carbon parts, improve silicon corrosion resistance, oxidation resistance, protect the substrate, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of the silicon carbide outer coating based on the carbon / carbon composite material for silicon in Example 1 of the present invention; Figure 2 1 is a graph of the carbon / carbon composite material after the outer coating of the silicon carbide based carbon / carbon composite material for silicon in Example 1 of the present invention with and without coating (left: the carbon / carbon composite material after coating; right: the carbon / carbon composite material without coating); Figure 3 These are pictures of a carbon / carbon composite thermal field component repaired before and after repair using the silicon carbide outer coating based on the carbon / carbon composite material for silicon in Example 1 of the present invention (left: a carbon / carbon composite thermal field component with severe silicon corrosion; right: a carbon / carbon composite thermal field component after repair). DETAILED DESCRIPTION

[0018] The present invention is described in detail below with reference to the accompanying drawings and examples. It should be noted that the embodiments and drawings are only used for illustrative description of the present invention and do not limit the protection scope of the present invention.

[0019] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0020] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0021] Embodiment 1: A silicon carbide outer coating based on a carbon / carbon composite material for silicon, comprising: a carbon / carbon composite material substrate, a pyrolytic carbon coating, and a SiC sintered coating; The pyrolytic carbon coating is located on the carbon / carbon composite material substrate, and the SiC sintered coating is located on the pyrolytic carbon coating; The thickness of the carbon / carbon composite material substrate is not limited; the carbon / carbon composite material substrate is a material obtained by densification of a carbon fiber preform or a short fiber molded carbon / carbon composite material, and the density of the carbon / carbon composite material substrate is ≥1.3g / cm 3 ; The thickness of the pyrolytic carbon coating is 10 μm; the pyrolytic carbon coating is prepared by a vapor deposition method; The thickness of the SiC sintered coating is 60 μm; the SiC sintered coating is sintered by special ceramic slurry; The above-mentioned method for preparing a silicon carbide outer coating based on a carbon / carbon composite material for silicon comprises the following steps: 1) Grind the surface of the carbon / carbon composite material substrate to a rough state with sandpaper less than 60 mesh, and then clean the surface; 2) Place the carbon / carbon composite material substrate treated in the above step into a chemical vapor deposition furnace, slowly heat it to the deposition temperature of 950°C, introduce hydrocarbon gas and diluent gas for chemical vapor deposition for 35 hours, and deposit a thickness of less than 20 μm on the surface of the substrate, so that a uniform pyrolytic carbon coating is formed on its surface; 3) Prepare silicone resin, high-purity silicon powder, silicon carbide powder, additives, and sintering stabilizer, mix them in a mass ratio of 20:30:40:2:8, and evenly apply them on the surface of the pyrolytic carbon coating of the carbon / carbon composite material substrate obtained in the previous step. After the surface is dried and cured, put it into a vacuum sintering furnace for sintering at a sintering temperature of 1750°C to obtain a SiC sintered coating.

[0022] A silicon carbide outer coating based on a carbon / carbon composite material for silicon is prepared with the following performance indicators: Surface density: 248g / m 2 , silicon carbide content>95%, with good thermal conductivity, thermal stability, oxidation resistance and chemical corrosion resistance.

[0023] Figure 1 is a schematic structural diagram of a silicon carbide outer coating based on a carbon / carbon composite material for silicon in Example 1; Figure 2 1 is a carbon / carbon composite material after the outer coating of the carbon / carbon composite material for silicon based on silicon in the coated and uncoated Example 1, wherein the left side: the carbon / carbon composite material after coating; the right side: the uncoated carbon / carbon composite material; through Figure 2It can be seen that after coating, the rate of silicon erosion can be greatly reduced, the anti-oxidation ability can be improved, thereby extending the service life of the product, and its dense structure can avoid silicon agglomeration; Figure 3 The figure is a picture of the carbon / carbon composite thermal field component repaired before and after the repair using the silicon carbide outer coating based on the carbon / carbon composite material for silicon in Example 1, wherein the left side: the carbon / carbon composite thermal field component with severe silicon corrosion; the right side: the carbon / carbon composite thermal field component after repair; through Figure 3 It can be seen that the repaired material still has the technical indicators of single crystal furnace pulling, and it can still be guaranteed to be used for more than 6 months, achieving the effect of repairing scrap materials and reducing costs and increasing efficiency.

[0024] Embodiment 2: A silicon carbide outer coating based on a carbon / carbon composite material for silicon, comprising: a carbon / carbon composite material substrate, a pyrolytic carbon coating, and a SiC sintered coating; The pyrolytic carbon coating is located on the carbon / carbon composite material substrate, and the SiC sintered coating is located on the pyrolytic carbon coating; The thickness of the carbon / carbon composite material substrate is not limited; the carbon / carbon composite material substrate is a material obtained by densification of a carbon fiber preform or a short fiber molded carbon / carbon composite material, and the density of the carbon / carbon composite material substrate is ≥1.3g / cm 3 ; The thickness of the pyrolytic carbon coating is 20 μm; the pyrolytic carbon coating is prepared by a vapor deposition method; The thickness of the SiC sintered coating is 70 μm; the SiC sintered coating is sintered by special ceramic slurry; The above-mentioned method for preparing a silicon carbide outer coating based on a carbon / carbon composite material for silicon comprises the following steps: 1) Grind the surface of the carbon / carbon composite material substrate to a rough state with sandpaper less than 60 mesh, and then clean the surface; 2) Place the carbon / carbon composite material substrate treated in the above step into a chemical vapor deposition furnace, slowly heat it to the deposition temperature of 1200°C, introduce hydrocarbon gas and diluent gas for chemical vapor deposition for 20 hours, and deposit a thickness of less than 20 μm on the surface of the substrate, so that a uniform pyrolytic carbon coating is formed on its surface; 3) Prepare silicone resin, high-purity silicon powder, silicon carbide powder, additives, and sintering stabilizer, mix them in a mass ratio of 20:30:40:2:8, and evenly apply them on the surface of the pyrolytic carbon coating of the carbon / carbon composite material substrate obtained in the previous step. After the surface is dried and cured, put it into a vacuum sintering furnace for sintering at a sintering temperature of 1750°C to obtain a SiC sintered coating.

[0025] A silicon carbide outer coating based on a carbon / carbon composite material for silicon is prepared with the following performance indicators: Surface density: 250g / m 2 , silicon carbide content> 96%, with good thermal conductivity, thermal stability, oxidation resistance and chemical corrosion resistance.

[0026] Embodiment 3: A silicon carbide outer coating based on a carbon / carbon composite material for silicon, comprising: a carbon / carbon composite material substrate, a pyrolytic carbon coating, and a SiC sintered coating; The pyrolytic carbon coating is located on the carbon / carbon composite material substrate, and the SiC sintered coating is located on the pyrolytic carbon coating; The thickness of the carbon / carbon composite material substrate is not limited; the carbon / carbon composite material substrate is a material obtained by densification of a carbon fiber preform or a short fiber molded carbon / carbon composite material, and the density of the carbon / carbon composite material substrate is ≥1.3g / cm 3 ; The thickness of the pyrolytic carbon coating is 15 μm; the pyrolytic carbon coating is prepared by a vapor deposition method; The thickness of the SiC sintered coating is 80 μm; the SiC sintered coating is sintered by special ceramic slurry; The above-mentioned method for preparing a silicon carbide outer coating based on a carbon / carbon composite material for silicon comprises the following steps: 1) Grind the surface of the carbon / carbon composite material substrate to a rough state with sandpaper less than 60 mesh, and then clean the surface; 2) Place the carbon / carbon composite material substrate treated in the above step into a chemical vapor deposition furnace, slowly heat it to the deposition temperature of 1100°C, introduce hydrocarbon gas and diluent gas for chemical vapor deposition for 30 hours, and deposit a thickness of less than 20 μm on the surface of the substrate, so that a uniform pyrolytic carbon coating is formed on its surface; 3) Prepare silicone resin, high-purity silicon powder, silicon carbide powder, additives, and sintering stabilizer, mix them in a mass ratio of 20:30:40:2:8, and evenly apply them on the surface of the pyrolytic carbon coating of the carbon / carbon composite material substrate obtained in the previous step. After the surface is dried and cured, put it into a vacuum sintering furnace for sintering at a sintering temperature of 1750°C to obtain a SiC sintered coating.

[0027] A silicon carbide outer coating based on a carbon / carbon composite material for silicon is prepared with the following performance indicators: Surface density: 252g / m 2 , silicon carbide content> 96%, with good thermal conductivity, thermal stability, oxidation resistance and chemical corrosion resistance.

[0028] Comparative Example: The difference between the comparative example and Example 1 is that the coating is prepared in a different manner; 1) The surface of the densified carbon / carbon composite material product is polished to a rough state with sandpaper less than 60 mesh to clean the surface; 2) Place the carbon / carbon composite substrate in a chemical vapor deposition furnace and slowly heat it to the deposition temperature of 1050°C. 2 Chemical vapor deposition is carried out with a diluent gas for 35 hours, and the deposition thickness on the substrate surface is less than 100 μm, so that a uniform SiC coating is formed on the surface; The obtained coating is a micron coating, the surface density and uniformity are difficult to guarantee, and it is easy to cause fiber strength attenuation. Its production cost is high and the process is complicated.

[0029] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, improvements and polishing made without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A silicon carbide outer coating based on a carbon / carbon composite material for silicon, characterized in that: include: Carbon / carbon composite substrates, pyrolytic carbon coatings, SiC sintered coatings; The pyrolytic carbon coating is located on the carbon / carbon composite material substrate, and the SiC sintered coating is located on the pyrolytic carbon coating; The thickness of the carbon / carbon composite material substrate is not limited; The thickness of the pyrolytic carbon coating is 10 μm-20 μm; The thickness of the SiC sintered coating is 60 μm-80 μm; The carbon / carbon composite material substrate is a material obtained by densification of a carbon fiber preform or a short fiber molded carbon / carbon composite material. The density of the carbon / carbon composite material substrate is ≥1.3g / cm 3 ; The pyrolytic carbon coating is prepared by vapor deposition; The SiC sintered coating is sintered by special ceramic slurry; The silicon carbide outer coating based on the carbon / carbon composite material for silicon has the following performance indicators: Surface density: 248g / m 2 -252g / m 2 , silicon carbide content>95%, with good thermal conductivity, thermal stability, oxidation resistance and chemical corrosion resistance.

2. A silicon carbide outer coating based on a carbon / carbon composite material for silicon as claimed in claim 1, characterized in that: The carbon / carbon composite material substrate is selected from plates, tubes or other special-shaped parts.

3. The silicon carbide outer coating based on the carbon / carbon composite material for silicon according to claim 1, characterized in that: The carbon / carbon composite material has a density of ≥1.3 g / cm after densification treatment. 3 , and the density is uniform, and its surface is polished cleanly with sandpaper less than 60 mesh, and the roughness is maintained.

4. The silicon carbide outer coating based on the carbon / carbon composite material for silicon according to claim 1, characterized in that: The pyrolytic carbon coating is prepared by placing a carbon / carbon composite material substrate into a chemical vapor deposition furnace, slowly heating it to a deposition temperature of 950°C-1200°C, introducing hydrocarbon gas and diluent gas for chemical vapor deposition for 20h-35h, and depositing a thickness of less than 20μm on the substrate surface; The SiC sintered coating is uniformly coated on the surface of the carbon / carbon composite material substrate. The SiC sintered coating is coated on the carbon / carbon substrate after chemical deposition. The pyrolytic carbon coating does not cause the carbon / carbon substrate to be completely closed. After the surface is dried and solidified, it is placed in a vacuum sintering furnace for sintering.

5. The silicon carbide outer coating based on the carbon / carbon composite material for silicon according to claim 1, characterized in that: The SiC sintered coating and its preparation method include the following steps: ① Prepare silicone resin, high-purity silicon powder, silicon carbide powder, additives, and sintering stabilizer in a mass ratio of 20:30:40:2:8; the proportion of each component of the SiC sintering coating will be adjusted accordingly for products with different requirements; The organic silicon resin is one of methyl silicone resin and methyl phenyl silicone resin; the particle size of the high-purity silicon powder is 200-300 mesh; the particle size of the silicon carbide powder is 200-300 mesh; the auxiliary agent is a dispersant selected from a polymer organic dispersant; the sintering stabilizer is a mixture of two or more of boron carbide, molybdenum carbide, titanium silicon carbide in any proportion; ② Disperse high-purity silicon powder and silicon carbide powder in silicone resin and add additives; ③ Carry out vacuum sintering at a temperature of 1750°C.

6. A method for preparing a silicon carbide outer coating based on a carbon / carbon composite material for silicon according to any one of claims 1 to 5, characterized in that: The following steps are involved: 1) Grind the surface of the carbon / carbon composite material substrate to a rough state with sandpaper less than 60 mesh, and then clean the surface; 2) Place the carbon / carbon composite material substrate treated in the above step into a chemical vapor deposition furnace, slowly heat it to a deposition temperature of 950°C-1200°C, introduce hydrocarbon gas and diluent gas for chemical vapor deposition for 20h-35h, and deposit a thickness of less than 20μm on the surface of the substrate, so that a uniform pyrolytic carbon coating is formed on its surface; 3) Prepare silicone resin, high-purity silicon powder, silicon carbide powder, additives, and sintering stabilizer, mix them in a mass ratio of 20:30:40:2:8, and evenly apply them on the surface of the pyrolytic carbon coating of the carbon / carbon composite material substrate obtained in the previous step. After the surface is dried and cured, put it into a vacuum sintering furnace for sintering at a sintering temperature of 1750°C to obtain a SiC sintered coating.

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