A process for depositing silicon carbide coating on graphite surface

Abstract

The present invention relates to the field of silicon carbide technology and discloses a process for depositing a silicon carbide coating on the surface of a graphite part, comprising the following steps: Step 1: Using ultrasound to clean the surface of the graphite part to ensure that it is free of impurities; Step 2: Mixing silicon carbide, white corundum powder, aluminum oxide powder, ceramic powder, chromium oxide, green powder, spodumene, and oil sludge in proportion; Step 3: Adding a sodium hydroxide aqueous solution to the mixture and stirring and mixing; Step 4: Adding silica sol to the mixture to which the sodium hydroxide aqueous solution has been added and stirring and mixing; Step 5: Evenly coating the stirred coating on the surface of the graphite part to form a coating; Step 6: Allowing the coated graphite part to dry naturally in the shade. This process for depositing a silicon carbide coating on the surface of a graphite part increases the heat resistance of the coating by adding ceramic powder to the formula, making the coating more stable, thereby achieving the beneficial effect of improving the silicon carbide coating formula process so that the surface of the graphite part can be directly coated.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon carbide, in particular to a process for depositing a silicon carbide coating on the surface of a graphite part. Background Art

[0002] Silicon carbide coating on graphite surface is a dense, high-temperature resistant and anti-oxidation ceramic coating made on the graphite surface. Its main component is silicon carbide material, which can effectively solve the problem of graphite oxidation at high temperatures above 500°C. There are two processes for silicon carbide coating on graphite surface. One is to use special equipment to make silicon carbide coating. The produced silicon carbide coating has a uniform thickness of 0.1-0.3mm, high bonding strength, and does not require high-temperature strengthening; the second process is to use KN1000 silicon carbide coating to make a layer of silicon carbide coating with a thickness of 0.5-1mm on the graphite surface; the above two methods produce silicon carbide coating on graphite surface.

[0003] A search of the Chinese publication number (CN 112225585 B) has revealed a process for depositing a silicon carbide coating on the surface of a graphite part. The process comprises the following steps: removing impurities from the surface of the graphite part, spray cleaning, deposition reaction, and cooling the graphite part. A storage platform is provided in a reactor, a liquid collecting assembly and a spray assembly that can be covered on the storage platform are provided on the storage platform, a cooling assembly connected to the liquid collecting assembly is provided around the spray assembly, and under the action of a switching device, the spray assembly and the cooling assembly alternately work independently under the guidance of the switching device, so that impurity removal and surface deposition on the graphite part are completed in the same reactor. This solves the technical problem in the prior art that the deposition on the surface of the graphite part needs to be carried out in two workstations, which causes the surface of the graphite part to be easily worn during the transfer process, thereby affecting the deposition effect.

[0004] The above-mentioned technical solution only improves the deposition of graphite parts, but not the silicon carbide coating. Conventional silicon carbide coating is still used. Conventional silicon carbide coating cannot withstand the high-temperature processing of graphite at temperatures of 500 degrees and above. Therefore, once the graphite workpiece is subjected to high-temperature work, it will still oxidize. The current mainstream method is still to use special equipment to make silicon carbide coating, rather than direct coating. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In response to the shortcomings of the existing technology, the present invention provides a process for depositing silicon carbide coating on the surface of graphite parts. It has an improved silicon carbide coating formula process and can directly coat the surface of graphite parts. The improved silicon carbide coating has the advantages of being more heat-resistant, not easy to deform at high temperatures, and more stable, thereby solving the problems of the above-mentioned technology.

[0007] (2) Technical solution

[0008] To achieve the above object, the present invention provides the following technical solution: a process for depositing a silicon carbide coating on a graphite part surface, comprising the following steps:

[0009] Step 1: Use ultrasonic waves to clean the surface of the graphite parts to ensure there are no impurities;

[0010] Step 2: mixing silicon carbide, white corundum powder, aluminum oxide powder, ceramic powder, chromium oxide, green powder, spodumene and oil sludge in proportion;

[0011] Step 3: adding sodium hydroxide aqueous solution to the mixture and stirring and mixing;

[0012] Step 4: adding silica sol to the mixture to which the sodium hydroxide aqueous solution has been added and mixing and stirring;

[0013] Step 5: The stirred coating is evenly applied to the surface of the graphite part to form a coating;

[0014] Step 6: Allow the coated graphite parts to dry naturally in the shade.

[0015] Preferably, the ratio of silicon carbide, white corundum powder, alumina powder, ceramic powder, chromium oxide, green powder, spodumene and oil sludge is 30-45% of silicon carbide, 3-6% of white corundum powder, 2-5% of alumina powder, 6-10% of ceramic powder, 3-7% of chromium oxide, 4-6% of green powder, 2-5% of spodumene and 5-15% of oil sludge.

[0016] Through the above technical solution, ceramic powder is added to the formula to increase the heat resistance of the coating, and the thermal insulation properties of ceramics are used to cool the internal graphite parts to avoid being affected by high temperatures. At the same time, oil sludge is added and the high-temperature solidification properties of oil sludge are used to harden the coating on the surface of the graphite parts in a high-temperature environment to protect them and make the coating more stable.

[0017] Preferably, the sodium hydroxide aqueous solution ratio range is 10-16% of the sodium hydroxide aqueous solution.

[0018] According to the above technical solution, the powder is blended by using sodium hydroxide aqueous solution as fusion water.

[0019] Preferably, the silica sol ratio in step 4 is in the range of 8-12%.

[0020] Through the above technical solution, the powder and the sodium hydroxide aqueous solution are blended through silica sol to make them sticky and quick-drying.

[0021] Preferably, the coating formula is 35% silicon carbide, 5% white corundum powder, 5% alumina powder, 6% ceramic powder, 4% chromium oxide, 5% green powder, 5% spodumene, 7% oil sludge, 16% sodium hydroxide aqueous solution and 12% silica sol.

[0022] Preferably, the coating formula is 30% silicon carbide, 3% white corundum powder, 5% alumina powder, 9% ceramic powder, 6% chromium oxide, 5% green powder, 3% spodumene, 12% oil sludge, 16% sodium hydroxide aqueous solution and 11% silica sol.

[0023] Preferably, the coating formula is 40% silicon carbide, 3% white corundum powder, 2% alumina powder, 10% ceramic powder, 3% chromium oxide, 5% green powder, 2% spodumene, 15% oil sludge, 15% sodium hydroxide aqueous solution and 10% silica sol.

[0024] Preferably, the coating formula is 45% silicon carbide, 5% white corundum powder, 5% alumina powder, 6% ceramic powder, 3% chromium oxide, 6% green powder, 2% spodumene, 5% oil sludge, 11% sodium hydroxide aqueous solution and 12% silica sol.

[0025] Preferably, the coating formula is 38% silicon carbide, 3% white corundum powder, 2% alumina powder, 7% ceramic powder, 7% chromium oxide, 4% green powder, 2% spodumene, 15% oil sludge, 12% sodium hydroxide aqueous solution and 10% silica sol.

[0026] Preferably, the coating formula is 30% silicon carbide, 5% white corundum powder, 5% alumina powder, 10% ceramic powder, 4% chromium oxide, 6% green powder, 5% spodumene, 15% oil sludge, 11% sodium hydroxide aqueous solution and 9% silica sol.

[0027] Compared with the prior art, the present invention provides a process for depositing silicon carbide coating on the surface of graphite parts, which has the following beneficial effects:

[0028] 1. The process of depositing silicon carbide coating on the surface of graphite parts increases the heat resistance of the coating by adding ceramic powder to the formula, and uses the thermal insulation properties of ceramics to cool the internal graphite parts to avoid being affected by high temperatures. At the same time, oil sludge is added and its high-temperature solidification property is used to harden the coating on the surface of the graphite parts in a high-temperature environment to protect them and make the coating more stable. This achieves the beneficial effect of improving the silicon carbide coating formula process to directly coat the surface of graphite parts.

[0029] 2. The process of depositing silicon carbide coating on the surface of graphite parts increases the heat resistance of the coating by adding ceramic powder to the formula, and uses the thermal insulation properties of ceramics to cool the internal graphite parts to avoid being affected by high temperatures. The improved silicon carbide coating has the beneficial effects of being more heat-resistant, less prone to deformation at high temperatures, and more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making creative efforts are within the scope of protection of the present invention.

[0032] See also Figure 1 A process for depositing a silicon carbide coating on a graphite part surface comprises the following steps:

[0033] Step 1: Use ultrasonic waves to clean the surface of the graphite parts to ensure there are no impurities;

[0034] Step 2: mixing silicon carbide, white corundum powder, aluminum oxide powder, ceramic powder, chromium oxide, green powder, spodumene and oil sludge in proportion;

[0035] Step 3: adding sodium hydroxide aqueous solution to the mixture and stirring and mixing;

[0036] Step 4: adding silica sol to the mixture to which the sodium hydroxide aqueous solution has been added and mixing and stirring;

[0037] Step 5: The stirred coating is evenly applied to the surface of the graphite part to form a coating;

[0038] Step 6: Allow the coated graphite parts to dry naturally in the shade.

[0039] Specifically, the ratio of silicon carbide, white corundum powder, alumina powder, ceramic powder, chromium oxide, green powder, spodumene and oil sludge is 30-45% of silicon carbide, 3-6% of white corundum powder, 2-5% of alumina powder, 6-10% of ceramic powder, 3-7% of chromium oxide, 4-6% of green powder, 2-5% of spodumene and 5-15% of oil sludge.

[0040] The advantage is that by adding ceramic powder to the formula, the heat resistance of the coating is increased, and the thermal insulation properties of ceramics are used to cool the internal graphite parts to avoid being affected by high temperatures. At the same time, oil sludge is added and the high-temperature solidification properties of oil sludge are used to harden the coating on the surface of the graphite parts in a high-temperature environment to protect them and make the coating more stable.

[0041] Specifically, the sodium hydroxide aqueous solution ratio range is 10-16% of the sodium hydroxide aqueous solution.

[0042] The advantage is that the powder can be tempered by using the sodium hydroxide aqueous solution as the melting water.

[0043] Specifically, the silica sol ratio in step 4 is in the range of 8-12%.

[0044] The advantage is that the powder is mixed with a sodium hydroxide aqueous solution through silica sol to make it sticky and quick-drying.

[0045] Example 1

[0046] The coating formula is 35% silicon carbide, 5% white corundum micropowder, 5% aluminum oxide micropowder, 6% ceramic powder, 4% chromium oxide, 5% green micropowder, 5% spodumene, 7% oil sludge, 16% sodium hydroxide aqueous solution and 12% silica sol.

[0047] Example 2

[0048] The coating formula is 30% silicon carbide, 3% white corundum powder, 5% aluminum oxide powder, 9% ceramic powder, 6% chromium oxide, 5% green powder, 3% spodumene, 12% oil sludge, 16% sodium hydroxide aqueous solution and 11% silica sol.

[0049] Example 3

[0050] The coating formula is 40% silicon carbide, 3% white corundum powder, 2% aluminum oxide powder, 10% ceramic powder, 3% chromium oxide, 5% green powder, 2% spodumene, 15% oil sludge, 15% sodium hydroxide aqueous solution and 10% silica sol.

[0051] Example 4

[0052] The coating formula is 45% silicon carbide, 5% white corundum micropowder, 5% aluminum oxide micropowder, 6% ceramic powder, 3% chromium oxide, 6% green micropowder, 2% spodumene, 5% oil sludge, 11% sodium hydroxide aqueous solution and 12% silica sol.

[0053] Example 5

[0054] The coating formula is 38% silicon carbide, 3% white corundum powder, 2% aluminum oxide powder, 7% ceramic powder, 7% chromium oxide, 4% green powder, 2% spodumene, 15% oil sludge, 12% sodium hydroxide aqueous solution and 10% silica sol.

[0055] Example 6

[0056] The coating formula is 30% silicon carbide, 5% white corundum micropowder, 5% aluminum oxide micropowder, 10% ceramic powder, 4% chromium oxide, 6% green micropowder, 5% spodumene, 15% oil sludge, 11% sodium hydroxide aqueous solution and 9% silica sol.

[0057] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A process for depositing silicon carbide coating on the surface of a graphite part, characterized in that: The following steps are involved: Step 1: Use ultrasonic waves to clean the surface of the graphite parts to ensure there are no impurities; Step 2: mixing silicon carbide, white corundum powder, aluminum oxide powder, ceramic powder, chromium oxide, green powder, spodumene and oil sludge in proportion; Step 3: adding sodium hydroxide aqueous solution to the mixture and stirring and mixing; Step 4: adding silica sol to the mixture to which the sodium hydroxide aqueous solution has been added and mixing and stirring; Step 5: The stirred coating is evenly applied to the surface of the graphite part to form a coating; Step 6: The coated graphite parts are naturally dried in the shade; The ratio of the silicon carbide, white corundum powder, aluminum oxide powder, ceramic powder, chromium oxide, green powder, spodumene and oil sludge is 30-45% of silicon carbide, 3-6% of white corundum powder, 2-5% of aluminum oxide powder, 6-10% of ceramic powder, 3-7% of chromium oxide, 4-6% of green powder, 2-5% of spodumene and 5-15% of oil sludge; the ratio of the sodium hydroxide aqueous solution is 10-16% of the sodium hydroxide aqueous solution; and the ratio of the silica sol in step 4 is 8-12% of the silica sol.

2. The process for depositing a silicon carbide coating on a graphite part according to claim 1, wherein: The coating formula is 35% silicon carbide, 5% white corundum micropowder, 5% aluminum oxide micropowder, 6% ceramic powder, 4% chromium oxide, 5% green micropowder, 5% spodumene, 7% oil sludge, 16% sodium hydroxide aqueous solution and 12% silica sol.

3. The process for depositing silicon carbide coating on the surface of a graphite part according to claim 1, characterized in that: The coating formula is 30% silicon carbide, 3% white corundum powder, 5% aluminum oxide powder, 9% ceramic powder, 6% chromium oxide, 5% green powder, 3% spodumene, 12% oil sludge, 16% sodium hydroxide aqueous solution and 11% silica sol.

4. The process for depositing a silicon carbide coating on a graphite part according to claim 1, wherein: The coating formula is 45% silicon carbide, 5% white corundum micropowder, 5% aluminum oxide micropowder, 6% ceramic powder, 3% chromium oxide, 6% green micropowder, 2% spodumene, 5% oil sludge, 11% sodium hydroxide aqueous solution and 12% silica sol.

5. The process for depositing silicon carbide coating on the surface of a graphite part according to claim 1, characterized in that: The coating formula is 38% silicon carbide, 3% white corundum powder, 2% aluminum oxide powder, 7% ceramic powder, 7% chromium oxide, 4% green powder, 2% spodumene, 15% oil sludge, 12% sodium hydroxide aqueous solution and 10% silica sol.

6. The process for depositing silicon carbide coating on the surface of a graphite part according to claim 1, characterized in that: The coating formula is 30% silicon carbide, 5% white corundum micropowder, 5% aluminum oxide micropowder, 10% ceramic powder, 4% chromium oxide, 6% green micropowder, 5% spodumene, 15% oil sludge, 11% sodium hydroxide aqueous solution and 9% silica sol.

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