A material and method for removing molten metal silicon from a sintering device for reactive silicon carbide

Abstract

The present invention relates to the field of surface treatment of silicon carbide ceramics after sintering, and in particular to a material for removing molten metal silicon from a sintering device for reactive silicon carbide, which comprises the following components in parts by weight: 70 to 100 parts by weight of carbon powder; 0 to 10 parts by weight of a binder; 0 to 10 parts by weight of boron nitride; and 0 to 10 parts by weight of a solvent; wherein, in the process of removing the molten metal silicon from the material for removing molten metal silicon from a sintering device for reactive silicon carbide, the amount of carbon powder added is 2 times or more of the weight of the molten metal silicon. The present invention provides a material for removing molten metal silicon from a sintering device for reactive silicon carbide, which is used to remove molten metal silicon in a sintering device, thereby ensuring the repeated use of the sintering device and improving the quality of silicon carbide reaction sintered products.

Description

Technical Field

[0001] The invention relates to the field of surface treatment of silicon carbide ceramics after sintering, and in particular to a material and method for removing molten metal silicon from a sintering device for reactive silicon carbide. Background Art

[0002] Silicon carbide ceramic materials have the characteristics of wear resistance, high strength, thermal shock resistance, high hardness, oxidation resistance and chemical corrosion resistance. They are widely used in kiln tools, aerospace, semiconductors, photovoltaics and other fields. Among them, reaction sintering to prepare silicon carbide ceramic materials has the advantages of simple sintering equipment, low sintering temperature and low production cost compared to solid phase sintering to prepare silicon carbide ceramic materials. At the same time, the sintered products hardly shrink, so reaction sintered silicon carbide ceramics have obvious advantages in sintering some products with complex structures.

[0003] The sintering device used in reaction sintering of silicon carbide is used to place the silicon carbide blank. With repeated use of the sintering device or due to excessive silicon addition during sintering, molten metal silicon is easily accumulated in the sintering device and is difficult to remove. Since the bottom plate of the sintering device must have a certain degree of flatness to prevent the silicon carbide blank from being distorted and tilted when placed, otherwise it is easy to cause deformation of the sintered product. Therefore, the metal silicon adhering to the bottom plate of the sintering device must be effectively removed to ensure the repeated use of the sintering device.

[0004] At present, mechanical removal is generally used to remove the metallic silicon on the surface of the reaction sintering support device, that is, manual grinding is performed using tools such as angle grinders and sandpaper, or the support device is immersed in a strong alkaline solution such as sodium hydroxide to allow the metallic silicon to react with the strong alkali, thereby achieving the effect of removing the metallic silicon; however, these methods are not only time-consuming, labor-intensive and material-consuming, but also extremely unsafe. Summary of the invention

[0005] Based on the above problems, the present invention provides a material for removing molten metallic silicon from a firing device for reactive silicon carbide, which is used to remove the molten metallic silicon in the firing device, thereby ensuring the repeated use of the firing device and improving the quality of silicon carbide reactive sintered products; and provides a method for removing molten metallic silicon from a firing device for reactive silicon carbide. The method is safe, reliable, fast and efficient, and can also reduce the production cost of removing molten metallic silicon.

[0006] A first aspect of the present invention provides a material for removing molten metal silicon from a reactive silicon carbide support device, comprising the following components in parts by weight:

[0007] 70 to 100 parts by weight of carbon powder;

[0008] 0 to 10 parts by weight of binder;

[0009] Boron nitride 0 to 10 parts by weight;

[0010] Solvent 0 to 10 parts by weight;

[0011] Among them, in the process of removing the molten metal silicon by the reactive silicon carbide sintering device, the amount of carbon powder added is 2 times or more of the weight of the molten metal silicon.

[0012] A second aspect of the present invention provides a method for removing molten metallic silicon from a reactive silicon carbide support device, comprising the following steps:

[0013] S1. Mix the components of the material for removing molten metal silicon from the reactive silicon carbide using the sintering device described in the first aspect of the present invention evenly, and stir for 0 h to 6 h;

[0014] S2, covering or coating the material obtained in step S1 on the surface of the sintering device to which the molten metal silicon is adhered;

[0015] S3, placing the sintering device obtained in step S2 into a vacuum reaction chamber, heating it to 1400° C. to 1700° C., and keeping it at that temperature for 0.5 h to 5 h;

[0016] S4, subjecting the sintering device obtained in step S3 to a cooling treatment to generate powdered silicon carbide, which is then self-detached to obtain a sintering device for removing molten metal silicon;

[0017] Wherein, in step S1, the amount of carbon powder added is 2 times or more of the weight of the molten metal silicon.

[0018] Through the above technical solution, the present invention has at least the following beneficial effects compared with the prior art:

[0019] The material for removing molten metallic silicon from a reactive silicon carbide support device provided by the present invention utilizes the characteristic that carbon powder at high temperature reacts with molten metallic silicon to generate powdered silicon carbide, and an excess of carbon powder is added to the removal material. The generated silicon carbide is simple and easy to remove, thereby being able to quickly remove the molten metallic silicon adhering to the surface of the support device, and also ensuring the repeated use of the support device, thereby improving the quality of the silicon carbide reaction sintered product. In addition, the method for removing molten metallic silicon from a reactive silicon carbide support device provided by the present invention uses a sintering method to remove molten metallic silicon, which is safer, more reliable, faster and more efficient, and can also reduce the production cost of removing molten metallic silicon.

[0020] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of a reactive silicon carbide sintering device before removing molten metal silicon according to an embodiment of the present invention.

[0022] Figure 2 A schematic diagram of a reactive silicon carbide sintering device after removing molten metal silicon according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0024] Reaction sintering is a process of preparing silicon carbide by mixing α-SiC and carbon powder in a certain proportion and then forming a silicon carbide blank. When sintering at high temperature (1500-1800℃), metal silicon is placed on the silicon carbide blank, and the carbon powder in the silicon carbide blank is heated to react with liquid Si or gas phase Si to generate β-SiC, filling the pores in the blank to prepare dense silicon carbide ceramics. This method has a low sintering temperature and can produce complex products, but 8% to 20% of free silicon still remains in the blank. During the reaction sintering process, the amount of silicon added is calculated based on the carbon content in the blank, but there will inevitably be silicon residues in the ceramic after sintering, and the volatilization of gas phase Si during the sintering process will also cause Si loss. Therefore, 1.2 to 2 times the theoretical amount of silicon required is usually added during the sintering process. The excess molten metal silicon after sintering will remain in the graphite sintering device, and inevitably some metal silicon will stick to the sintering device, which is difficult to remove. Moreover, with the repeated use of the sintering device, or due to excessive silicon addition during sintering, metallic silicon will accumulate in the sintering device, making it more difficult to remove; Figure 1 The figure shows the schematic diagram of the reaction silicon carbide before the molten metal silicon is removed by the sintering device. Figure 1 Figure (a) shows the situation where molten metal silicon is bonded to a square sample. At this time, the residual molten metal silicon will make it impossible to remove the sample smoothly, affecting the subsequent use of the sintering device. Figure 1It can be seen from Figures (b) and (c) that after the sample is mechanically removed, black molten metal silicon still remains on the surface of the graphite support device, and it is uneven. Since the bottom plate of the support device must have a certain degree of flatness to prevent it from being distorted and tilted when placing the silicon carbide blank, otherwise it will cause deformation of the sintered product. Therefore, the molten metal silicon adhering to the bottom plate of the support device must be removed cleanly to ensure that the support device can be used repeatedly and the quality of the sintered product can be guaranteed.

[0025] Therefore, based on the above problems, the first aspect of the present invention provides a material for removing molten metal silicon from a reactive silicon carbide support device, which comprises the following components in parts by weight:

[0026] 70 to 100 parts by weight of carbon powder;

[0027] 0 to 10 parts by weight of binder;

[0028] Boron nitride 0 to 10 parts by weight;

[0029] Solvent 0 to 10 parts by weight;

[0030] Among them, in the process of removing the molten metal silicon from the sintering device for reactive silicon carbide, the amount of carbon powder added is 2 times or more of the weight of the molten metal silicon. It should be noted that the weight content of the molten metal silicon attached to the surface of the sintering device for reactive silicon carbide can be obtained by measuring the weight difference of the sticky molten metal silicon before and after the reaction of the sintering device for reactive silicon carbide, and the amount of carbon powder added needs to ensure that its weight is 2 times or more of the weight of the molten metal silicon, that is, to ensure that the carbon powder is excessive.

[0031] The material for removing molten metal silicon from the reactive silicon carbide sintering device provided by the present invention is added with an excess amount of carbon powder relative to the molten metal silicon. The carbon powder reacts with the molten metal silicon to generate silicon carbide powder. The silicon carbide powder has a loose structure and can quickly detach from the sintering device, thereby quickly removing the molten metal silicon adhering to the surface of the sintering device, ensuring the repeated use of the sintering device and improving the quality of the silicon carbide reactive sintering products. Moreover, the removal material of the present invention is different from the removal material using a strong alkaline solution. It utilizes the characteristic that carbon powder at high temperature will react with molten metal silicon to generate powdered silicon carbide. It can quickly remove the molten metal silicon adhering to the surface, and will not cause damage to the sintering device due to the addition of the strong alkaline solution, further extending the service life of the sintering device.

[0032] In the present invention, the weight content of the carbon powder in the component can be 70 parts by weight to 100 parts by weight. Exemplarily, the weight content of the carbon powder can be 70 parts by weight, 71 parts by weight, 72 parts by weight, 73 parts by weight, 74 parts by weight, 75 parts by weight, 76 parts by weight, 77 parts by weight, 78 parts by weight, 79 parts by weight, 80 parts by weight, 81 parts by weight, 82 parts by weight, 83 parts by weight, 84 parts by weight, 85 parts by weight, 86 parts by weight, 87 parts by weight, 88 parts by weight, 89 parts by weight, 90 parts by weight, 91 parts by weight, 92 parts by weight, 93 parts by weight, 94 parts by weight, 95 parts by weight, 96 parts by weight, 97 parts by weight, 98 parts by weight, 99 parts by weight, 100 parts by weight. On the premise of ensuring that the weight content of the carbon powder added to the material component is 2 times or more of the weight of the molten metal silicon, the weight content of the carbon powder in the component can be 70 parts by weight to 100 parts by weight.

[0033] In a preferred embodiment, the weight content of the carbon powder in the component may be 80 parts by weight to 90 parts by weight.

[0034] In the present invention, the weight content of the binder in the component can be 0 to 10 parts by weight. Exemplarily, the weight content of the binder can be 0 parts by weight, 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, and 10 parts by weight. The binder in the component plays a role in closely contacting the carbon powder with the molten metal silicon, especially for the outer wall of the support device and other locations that are not easy to contact with the ingredients, more binder needs to be added. However, the binder may not be added to the component, because on a flat support plate, the carbon powder can directly contact the molten metal silicon on the surface of the support plate, and a reaction can occur directly under high temperature. However, the addition of the binder helps to increase the degree of contact between the carbon powder and the molten metal silicon. Therefore, the removal effect of the molten metal silicon can be further improved by adjusting the weight content of the binder in the component to be within a suitable range.

[0035] In a preferred embodiment, the weight content of the binder in the component may be 3 parts by weight to 8 parts by weight.

[0036] In the present invention, the weight content of the boron nitride in the component can be 0 to 10 parts by weight. Exemplarily, the weight content of the boron nitride can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts by weight. Adding boron nitride to the component of the removed material can prevent the contact between the molten metal silicon and the graphite support device to a certain extent. This is because in the process of reacting to generate silicon carbide, boron nitride will adhere to the surface of the generated molten metal silicon, avoiding the contact between the molten metal silicon and the support device, thereby preventing the molten metal silicon from sticking and further improving the removal effect of the molten metal silicon.

[0037] In a preferred embodiment, the weight content of the boron nitride in the component may be 1 part by weight to 5 parts by weight.

[0038] In the present invention, the weight content of the solvent in the component can be 0 to 10 parts by weight. Exemplarily, the weight content of the solvent can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts by weight. The solvent in the component plays a role in fully mixing the binder and the carbon powder. The more fully the binder and the carbon powder are mixed, the better the coating effect of the removed material, the higher the contact area with the molten metal silicon, and the better the removal effect of the molten metal silicon for the complex structure of the support device; however, for the removal of the molten metal silicon on the surface of the flat support plate, the solvent may not be added, because the binder may not be added to the component at this time, so there is no need for solvent to mix the materials, and the excess carbon powder can also play the role of removing the molten metal silicon at high temperature.

[0039] In a preferred embodiment, the weight content of the solvent in the components may be 5 parts by weight to 10 parts by weight.

[0040] Furthermore, in the process of removing the molten metal silicon from the material of the reactive silicon carbide sintering device, the amount of carbon powder added is 2 to 5 times the weight of the molten metal silicon. Specifically, the mass of the molten metal silicon in the reacting silicon carbide supporting device is first measured by calculating the weight difference before and after the reacting silicon carbide sticky molten metal silicon, and then the mass content of the carbon powder in the material is adjusted according to the mass of the molten metal silicon, so that the amount of the carbon powder added is 2 to 5 times the weight of the molten metal silicon. By adjusting the weight ratio of carbon powder to molten metal silicon in this way, the structure of the generated silicon carbide powder can be further improved, making its structure looser and able to automatically fall off from the surface of the supporting device, thereby achieving the purpose of quickly removing the molten metal silicon sticking to the surface of the supporting device; however, the amount of the carbon powder added should not be too much. For example, when the amount of the carbon powder added is more than 5 times the weight of the molten metal silicon (not including 5 times), the amount of carbon powder added is excessive, which will lead to waste of raw materials, increase process costs, and is not suitable for wide application; therefore, it is best to control the amount of carbon powder added within an appropriate range.

[0041] Furthermore, boron nitride can prevent the contact between molten metal silicon and the graphite burning device to a certain extent, but too much weight content of boron nitride will lead to waste of raw materials, increase process costs, and cause residual components of boron nitride after high-temperature treatment to easily appear on the surface of the graphite burning device. Therefore, in the present invention, based on the total weight of the material used to remove molten metal silicon by the burning device for reactive silicon carbide, the mass ratio of the carbon powder to the boron nitride is (20-40): 1. By controlling the mass ratio of carbon powder to boron nitride, the boron nitride content in the appropriate range can be better matched, thereby improving the removal effect of molten metal silicon. Exemplarily, the mass ratio of the carbon powder to the boron nitride can be 20:1, 21:1, 22:1, 23:1, 24:1, 25:1, 26:1, 27:1, 28:1, 29:1, 30:1, 31:1, 32:1, 33:1, 34:1, 35:1, 36:1, 37:1, 38:1, 39:1, 40:1.

[0042] In a preferred embodiment, based on the total weight of the material removed from the molten metal silicon by the reactive silicon carbide sintering device, the mass ratio of the carbon powder to the boron nitride is (25-35):1.

[0043] In a specific embodiment, the carbon powder includes at least one of graphite powder, carbon black, and petroleum coke.

[0044] In a specific embodiment, the binder includes at least one of phenolic resin, epoxy resin, polyvinyl alcohol, carboxymethyl cellulose, and dextrin.

[0045] In a specific embodiment, the solvent includes at least one of distilled water and ethanol.

[0046] In the present invention, the carbon powder includes graphite powder, carbon black and petroleum coke.

[0047] In a specific embodiment, based on the total weight of the carbon powder, the weight percentage of the graphite powder is 40wt% to 50wt%, for example, 40wt%, 41wt%, 42wt%, 43wt%, 44wt%, 45wt%, 46wt%, 47wt%, 48wt%, 49wt%, 50wt%; the weight percentage of the carbon black is 30wt% to 35wt%, for example, 30wt%, 31wt%, 32wt%, 33wt%, 34wt%, 35wt%; the weight percentage of the petroleum coke is 20wt% to 25wt%, for example, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%.

[0048] The carbon powder of the present invention can include three components: graphite powder, carbon black and petroleum coke at the same time, and when these three components are contained at the same time, it is easier to quickly remove the molten metal silicon on the surface of the burning device. This is because petroleum coke will melt to a dense state as the temperature rises during the removal of the molten metal silicon, and the excess free silicon is not easy to flow out during the high-temperature reaction, making the generated silicon carbide easier to separate from the burning device with a higher temperature, thereby improving the separation efficiency of silicon carbide; however, the proportion of petroleum coke should not be too high, because the particle size of petroleum coke is generally about 0.15mm, which is much larger than the actual particle size range of graphite powder and carbon black. When mixed with a binder, the contact degree between the carbon powder mixture of the present invention and the burning device will decrease, reducing the reaction efficiency of carbon powder and molten metal silicon at high temperature, so it is necessary to add a certain amount of graphite powder and carbon black to mix with petroleum coke, which can further improve the reaction effect of removing molten metal silicon, and can also avoid the outflow of excess free silicon, accelerate the separation of silicon carbide from the burning device, and improve the separation efficiency.

[0049] A second aspect of the present invention provides a method for removing molten metallic silicon from a reactive silicon carbide support device, comprising the following steps:

[0050] S1. Mix the carbon powder, the binder, the boron nitride and the solvent in the material for removing molten metal silicon from the reactive silicon carbide sintering device according to the first aspect of the present invention in the above proportions, and stir for 0 h to 6 h (for example, 0 h, 1 h, 2 h, 3 h, 4 h, 5 h or 6 h);

[0051] S2, covering or coating the material obtained in step S1 on the surface of the sintering device to which the molten metal silicon is adhered;

[0052] S3, placing the sintering device obtained in step S2 into a vacuum reaction chamber, heating it to 1400° C. to 1700° C. (for example, 1400° C., 1450° C., 1500° C., 1550° C., 1600° C., 1650° C. or 1700° C.), and keeping it warm for 0.5 h to 5 h (for example, 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h or 5 h);

[0053] S4, subjecting the sintering device obtained in step S3 to a cooling treatment to generate powdered silicon carbide, which is then self-detached to obtain a sintering device for removing molten metal silicon;

[0054] Wherein, in step S1, the amount of carbon powder added is 2 times or more of the weight of the molten metal silicon.

[0055] The method for removing molten metallic silicon from a reactive silicon carbide support device provided by the present invention is different from general mechanical removal and removal by caustic soda immersion. The method of generating silicon carbide powder by sintering reaction is safer and more reliable. In addition, the method can uniformly remove the support device, and the removal is cleaner and more efficient. The process does not require human participation or preparation of a strong alkaline solution, and can also effectively reduce the production cost of removing molten metallic silicon.

[0056] According to the method for removing molten metal silicon from a sintering device for reactive silicon carbide of the present invention, in step S1, the amount of carbon powder added is 2 to 5 times the weight of the molten metal silicon. In a preferred embodiment, the amount of carbon powder added is 2.5 to 4 times the weight of the molten metal silicon.

[0057] According to the method for removing molten metallic silicon from a supporting device for reactive silicon carbide of the present invention, in step S2, the material obtained in step S1 is covered or coated on the surface of the supporting device to which the molten metallic silicon is adhered; in the actual operation process, it is necessary to ensure that a sufficient amount of material is removed from the surface of the supporting device to which the molten metallic silicon is attached, so in a specific embodiment, the coating thickness of the material for removing molten metallic silicon from the supporting device for reactive silicon carbide is 1 mm to 40 mm, for example, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm.

[0058] In a preferred embodiment, the coating thickness of the material removed from the molten metal silicon by the reactive silicon carbide sintering device is 5 to 30 mm.

[0059] According to the method for removing molten metal silicon from a sintering device for reactive silicon carbide of the present invention, the heating rate of the heat treatment is 10°C / min to 30°C / min; illustratively, the heating rate of the heat treatment can be 10°C / min, 15°C / min, 20°C / min, 25°C / min, and 30°C / min. The heating rate during the heating treatment will affect the reaction rate of the carbon powder and the molten metal silicon in the mixed material, so the heating rate should not be too low and needs to be greater than 10°C / min, but the heating rate should not be too high either, because if the heating rate of the sintering device is too high, some free silicon will escape, and the reaction cannot be thorough, so that a small amount of silicon still remains on the surface of the sintering device. In a preferred embodiment, the heating rate of the heat treatment is 15 / min to 25°C / min.

[0060] According to the method for removing molten metal silicon with a sintering device for reactive silicon carbide of the present invention, the temperature rise range during the heating process can be 1500°C to 1650°C; exemplary, the temperature can be 1500°C, 1510°C, 1520°C, 1530°C, 1540°C, 1550°C, 1560°C, 1570°C, 1580°C, 1590°C, 1600°C, 1610°C, 1620°C, 1630°C, 1640°C, 1650°C. Within this temperature range, the molten metal silicon can react better with the carbon powder in the mixture to generate easily removable silicon carbide.

[0061] The present invention will be described in further detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0062] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0063] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] In the following examples, unless otherwise specified, all components used were commercially available analytically pure. 1 part by weight represents 1 g.

[0065] Example 1

[0066] It is used to remove the molten metal silicon remaining on the surface of the sintering device for reactive silicon carbide, wherein the weight content of the molten metal silicon remaining on the surface of the sintering device is about 20 to 30 parts by weight according to calculation. The specific removal steps are as follows:

[0067] (1) 100 parts by weight of petroleum coke is taken to cover or coat the area on the surface of the graphite support device where the molten metal silicon is adhered, so that the coating thickness on the surface of the graphite support device is 30 mm;

[0068] (2) Place the graphite support device coated with the removal material in a vacuum sintering furnace and heat it at a heating rate of 30°C / min, keep it at 1500°C for 5 hours, cool it down and take it out of the furnace.

[0069] After the furnace is taken out, the area of ​​the graphite support device that was originally adhered to the molten metal silicon produces powdery green silicon carbide, such as Figure 2 As shown in Figure (a), after brushing with a brush, the surface of the graphite support device is restored to a smooth surface, and the molten metal silicon has been basically removed. Figure 2 As shown in Figure (b).

[0070] Example 2

[0071] It is used to remove the molten metal silicon remaining on the surface of the sintering device for reactive silicon carbide, wherein the weight content of the molten metal silicon remaining on the surface of the sintering device is about 20 to 30 parts by weight according to calculation. The specific removal steps are as follows:

[0072] (1) According to the above weight parts, 75 parts by weight of carbon black, 10 parts by weight of epoxy resin, 5 parts by weight of boron nitride and 10 parts by weight of distilled water were mixed and stirred for 4 hours;

[0073] (2) Covering or coating the mixed material on the area on the surface of the graphite support device where the molten metal silicon is adhered, so that the coating thickness on the surface of the graphite support device is 20 mm;

[0074] (3) Place the graphite support device coated with the removal material in a vacuum sintering furnace and heat it at a heating rate of 20°C / min. Maintain the temperature at 1600°C for 3 hours. Then cool it down and take it out of the furnace.

[0075] After being taken out of the furnace, the area of ​​the graphite support device that was originally stuck with molten metal silicon produced powdery green silicon carbide. After being brushed off with a brush, the surface of the graphite support device returned to being smooth, and the molten metal silicon was basically removed.

[0076] Example 3

[0077] It is used to remove the molten metal silicon remaining on the surface of the sintering device for reactive silicon carbide, wherein the weight content of the molten metal silicon remaining on the surface of the sintering device is about 20 to 30 parts by weight according to calculation. The specific removal steps are as follows:

[0078] (1) Take 85 parts by weight of graphite powder, 2 parts by weight of polyvinyl alcohol, 3 parts by weight of dextrin, 5 parts by weight of phenolic resin, and 5 parts by weight of distilled water according to the above weight parts, stir and mix, and stir for 2 hours;

[0079] (2) Covering or coating the mixed material on the area on the surface of the graphite support device where the molten metal silicon is adhered, so that the coating thickness on the surface of the graphite support device is 10 mm;

[0080] (3) Place the graphite support device coated with the removal material in a vacuum sintering furnace and heat it at a heating rate of 10°C / min. Maintain the temperature at 1700°C for 0.5h, cool it down and take it out of the furnace.

[0081] After being taken out of the furnace, the area of ​​the graphite support device that was originally stuck with molten metal silicon produced powdery green silicon carbide. After being brushed off with a brush, the surface of the graphite support device returned to being smooth, and the molten metal silicon was basically removed.

[0082] Example 4

[0083] It is used to remove the molten metal silicon remaining on the surface of the sintering device for reactive silicon carbide, wherein the weight content of the molten metal silicon remaining on the surface of the sintering device is about 20 to 30 parts by weight according to calculation. The specific removal steps are as follows:

[0084] (1) 50 parts by weight of graphite powder, 35 parts by weight of carbon black and 25 parts by weight of petroleum coke are mixed evenly and then covered or coated on the area on the surface of the graphite support device where the molten metal silicon is adhered, so that the coating thickness on the surface of the graphite support device is 15 mm;

[0085] (2) Place the graphite support device coated with the removal material in a vacuum sintering furnace and heat it at a heating rate of 30°C / min, keep it at 1500°C for 5 hours, cool it down and take it out of the furnace.

[0086] After being taken out of the furnace, the area of ​​the graphite support device that was originally adhered to the molten metal silicon produced powdered green silicon carbide; after brushing it with a brush, the surface of the graphite support device returned to being smooth, and the molten metal silicon was basically removed.

[0087] Comparative Example 1

[0088] This comparative example was carried out with reference to Example 1, the only difference being that the weight content of petroleum coke was changed to 35 parts by weight.

[0089] After being taken out of the furnace, the area of ​​the graphite support device that was originally adhered to the molten metal silicon produced a small amount of powdered green silicon carbide. After brushing it off with a brush, molten metal silicon still remained on the surface of the graphite support device, and the surface was uneven.

[0090] Comparative Example 2

[0091] This comparative example was carried out with reference to Example 2, the only difference being that the weight content of carbon black was changed to 35 parts by weight.

[0092] After being taken out of the furnace, the area of ​​the graphite support device that was originally adhered to the molten metal silicon produced a small amount of powdered green silicon carbide. After brushing it off with a brush, molten metal silicon still remained on the surface of the graphite support device, and the surface was uneven.

[0093] Comparative Example 3

[0094] This comparative example was carried out with reference to Example 3, the only difference being that the weight content of the graphite powder was changed to 35 parts by weight.

[0095] After being taken out of the furnace, the area of ​​the graphite support device that was originally adhered to the molten metal silicon produced a small amount of powdered green silicon carbide. After brushing it off with a brush, molten metal silicon still remained on the surface of the graphite support device, and the surface was uneven.

[0096] From the analysis of the results of the above embodiments and comparative examples, it can be seen that the material for removing molten metallic silicon by the support burning device for reactive silicon carbide provided by the present invention utilizes the characteristic that carbon powder at high temperature will react with molten metallic silicon to generate powdered silicon carbide, and an excess of carbon powder is added to the removal material. The generated silicon carbide is simple and easy to remove, thereby being able to quickly remove the molten metallic silicon sticking to the surface of the support burning device, and also ensuring the repeated use of the support burning device, thereby improving the quality of the silicon carbide reaction sintered product; and the method for removing molten metallic silicon by the support burning device for reactive silicon carbide provided by the present invention uses a sintering method to remove molten metallic silicon, which is safer, more reliable, faster and more efficient, and can also reduce the production cost of removing molten metallic silicon.

[0097] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A material for removing molten metal silicon from a reactive silicon carbide sintering device, characterized in that: In parts by weight, it includes the following components: 70 to 100 parts by weight of carbon powder; 0 to 10 parts by weight of binder; Boron nitride 0 to 10 parts by weight; Solvent 0 to 10 parts by weight; Among them, in the process of removing the molten metal silicon by the reactive silicon carbide sintering device, the amount of carbon powder added is 2 times or more of the weight of the molten metal silicon.

2. The material for removing molten metal silicon from the reactive silicon carbide sintering device according to claim 1, characterized in that: In parts by weight, it includes the following components: 80 to 90 parts by weight of carbon powder; 3 to 8 parts by weight of binder; 1 to 5 parts by weight of boron nitride; 5 to 10 parts by weight of solvent.

3. The material for removing molten metal silicon from the reactive silicon carbide sintering device according to claim 1, characterized in that: In the process of removing the molten metal silicon from the material of the reactive silicon carbide sintering device, the amount of carbon powder added is 2 to 5 times the weight of the molten metal silicon, preferably 2.5 to 4 times.

4. The material for removing molten metal silicon from the reactive silicon carbide sintering device according to claim 1, characterized in that: Based on the total weight of the material removed from the molten metal silicon by the reactive silicon carbide sintering device, the mass ratio of the carbon powder to the boron nitride is (20-40):1; preferably (25-35):

1.

5. The material for removing molten metal silicon from the reactive silicon carbide sintering device according to claim 1, characterized in that: The carbon powder includes at least one of graphite powder, carbon black and petroleum coke; And / or, the binder includes at least one of phenolic resin, epoxy resin, polyvinyl alcohol, carboxymethyl cellulose, and dextrin; And / or, the solvent includes at least one of distilled water and ethanol.

6. The material for removing molten metal silicon from the reactive silicon carbide sintering device according to claim 5, characterized in that: The carbon powder includes graphite powder, carbon black and petroleum coke; Preferably, based on the total weight of the carbon powder, the weight percentage of the graphite powder is 40wt% to 50wt%, the weight percentage of the carbon black is 30wt% to 35wt%, and the weight percentage of the petroleum coke is 20wt% to 25wt%.

7. A method for removing molten metal silicon from a reactive silicon carbide sintering device, characterized in that: The following steps are involved: S1. Mix the carbon powder, the binder, the boron nitride and the solvent in the material for removing molten metal silicon from the reactive silicon carbide sintering device according to any one of claims 1 to 6 in the above proportions and stir for 0 h to 6 h; S2, covering or coating the material obtained in step S1 on the surface of the sintering device to which the molten metal silicon is adhered; S3, placing the sintering device obtained in step S2 into a vacuum reaction chamber, heating it to 1400° C. to 1700° C., and keeping it at that temperature for 0.5 h to 5 h; S4, subjecting the sintering device obtained in step S3 to a cooling treatment to generate powdered silicon carbide, which is then self-detached to obtain a sintering device for removing molten metal silicon; Wherein, in step S1, the amount of carbon powder added is 2 times or more of the weight of the molten metal silicon.

8. The method for removing molten metal silicon by using a sintering device for reactive silicon carbide according to claim 7, characterized in that: In step S1, the amount of carbon powder added is 2 to 5 times the weight of the molten metal silicon; preferably 2.5 to 4 times; And / or, the coating thickness of the material removed from the molten metal silicon by the reactive silicon carbide sintering device is 1 mm to 40 mm, preferably 5 mm to 30 mm.

9. The method for removing molten metal silicon by using a sintering device for reactive silicon carbide according to claim 7, characterized in that: The heating rate of the heating treatment is 10°C / min to 30°C / min, preferably 15°C / min to 25°C / min.

10. The method for removing molten metal silicon by using a sintering device for reactive silicon carbide according to claim 7, characterized in that: In the heat treatment, the temperature is raised to 1500°C to 1650°C.

Images