A method for preparing a double-layer tantalum carbide coating and a graphite component

Abstract

This invention relates to the field of semiconductor technology, and particularly to a method for preparing a double-layer tantalum carbide coating and a graphite component. The method involves forming a first tantalum carbide coating that is loose and porous. This allows the significant thermal stress within the sintered first tantalum carbide coating to be released through its porous structure, resulting in better bonding between the first tantalum carbide coating and the graphite component, preventing the first tantalum carbide coating from detaching from the graphite substrate surface. The second tantalum carbide coating formed on the surface of the first tantalum carbide coating is a dense coating. Since both the second and first tantalum carbide coatings are made of tantalum carbide, their thermal stresses are not significantly different, making it easier for the first and second tantalum carbide coatings to bond tightly together. This results in a denser double-layer coating, making the resulting graphite component with the double coating more durable.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a method for preparing a double-layer tantalum carbide coating and a graphite component. Background Technology

[0002] With the continuous development of high-frequency communication equipment and power devices, third-generation SiC semiconductors are emerging in fields such as satellite communication, 5G networks, rail transportation, and high-voltage power grids due to their superior performance. Currently, most companies use the PVT method to prepare SiC single crystals. However, this method corrodes graphite components during the preparation of silicon carbide single crystals, resulting in a high defect density in the prepared SiC single crystals, which cannot meet the requirements for use in power devices under higher voltage environments.

[0003] The dense TaC coating can effectively protect the graphite substrate from corrosion during silicon carbide crystal growth, thus avoiding defects in the grown silicon carbide crystals caused by the corrosion of the graphite substrate. However, during the sintering process, due to the large difference in the coefficients of thermal expansion between the graphite substrate and the TaC coating, the sintered tantalum carbide coating contains significant thermal stress. This thermal stress cannot be released, resulting in poor bonding strength between the tantalum carbide coating and the graphite substrate. Consequently, the tantalum carbide coating peels off from the surface of the graphite substrate and from sharp areas such as chamfers and right angles. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a method for preparing a double-layer tantalum carbide coating and a graphite component.

[0005] To achieve the above objectives, the present invention provides a method for preparing a double-layer tantalum carbide coating, comprising:

[0006] Provides a first suspension containing oxygen / tantalum elements;

[0007] Provides a silicon / carbon / tantalum composite phase material and a first second suspension containing tantalum powder;

[0008] The first suspension is coated onto the surface of the graphite component and cured to form a first pre-coating layer;

[0009] The second suspension is coated onto the surface of the first pre-coating layer and cured to form the second pre-coating layer;

[0010] A graphite component with a first pre-coating and a second pre-coating is sintered. The first pre-coating forms a first tantalum carbide coating, and the second pre-coating forms a second tantalum carbide coating, ultimately obtaining a graphite component with a double-layer tantalum carbide coating. The first tantalum carbide coating has a loose and porous structure. The thermal stress inside the first tantalum carbide coating after sintering is released through the loose and porous structure, which allows the first tantalum carbide coating to better bond with the graphite component. The second tantalum carbide coating located on the surface of the first tantalum carbide coating has a dense structure, making the obtained double coating more dense.

[0011] Optionally, the oxygen- or tantalum-containing material includes Ta. x O y C. One or more of tantalum ethoxide and tantalum oxide; the ratio of the amount of oxygen to tantalum in the oxygen / tantalum element-containing substance is in the range of 1:1 to 5.

[0012] Optionally, the molar ratio of tantalum, silicon, and carbon in the silicon / carbon / tantalum composite phase is in the range of 1–3:1–8:1.

[0013] Optionally, the preparation steps of the silicon / carbon / tantalum composite phase material include:

[0014] Provide a second type of powder containing tantalum, silicon, or carbon powder;

[0015] The second tantalum-containing powder, the silicon-containing powder, and the carbon powder are mixed uniformly.

[0016] The mixed second tantalum-containing powder, the silicon-containing powder, and the carbon powder are sintered to form a primary silicon / carbon / tantalum composite phase material.

[0017] The primary silicon / carbon / tantalum composite phase material is crushed, and the primary silicon / carbon / tantalum composite phase material with a particle size within a set range is selected as the silicon / carbon / tantalum composite phase material.

[0018] Optionally, the second tantalum-containing powder includes tantalum-based and tantalum-based oxygen-containing compounds.

[0019] Optionally, the molar ratio of tantalum to silicon in the second tantalum-containing powder and the silicon-containing powder is in the range of 1 to 5.

[0020] Optionally, the thickness of the first tantalum carbide coating is greater than the thickness of the second tantalum carbide coating, the thickness of the first tantalum carbide coating is in the range of 20 μm to 40 μm, the thickness of the second tantalum carbide coating is in the range of 10 μm to 20 μm, and the porosity of the loose porous structure of the first tantalum carbide coating is in the range of 30% to 50%.

[0021] Optionally, it also includes machining the graphite parts to a predetermined size using a machine gap of 0.4 mm or more.

[0022] This invention also provides a method for preparing a double-layer tantalum carbide coating, comprising:

[0023] Provides a first suspension containing oxygen / tantalum elements;

[0024] Provides a silicon / carbon / tantalum composite phase material and a first second suspension containing tantalum powder;

[0025] The first suspension is coated onto the surface of the graphite component and cured to form a first pre-coating layer;

[0026] The graphite component with the first pre-coating is sintered to form a first tantalum carbide coating.

[0027] The second suspension is coated onto the surface of the first tantalum carbide coating and cured to form a second pre-coating;

[0028] The graphite component with the second pre-coating is sintered, and the second pre-coating forms a second tantalum carbide coating, finally obtaining a graphite component with a double-layer tantalum carbide coating. The first tantalum carbide coating has a loose and porous structure. The thermal stress inside the first tantalum carbide coating after sintering is released through the loose and porous structure, which makes the first tantalum carbide coating better bonded to the graphite component. The second tantalum carbide coating located on the surface of the first tantalum carbide coating has a dense structure, making the obtained double coating more dense.

[0029] The present invention also provides a graphite component, which is obtained by the above-described method for preparing a tantalum carbide coating.

[0030] In summary, the advantages and beneficial effects of the present invention are as follows:

[0031] This invention provides a method for preparing a double-layer tantalum carbide coating and a graphite component. The method for preparing the double-layer tantalum carbide coating includes: coating a first suspension and a second suspension onto the surface of a graphite component, curing them to form a first pre-coating and a second pre-coating; and sintering the first pre-coating and the second pre-coating sequentially cured on the surface of the graphite component to form a first tantalum carbide coating and a second tantalum carbide coating, ultimately obtaining a graphite component with a double-layer tantalum carbide coating. The first tantalum carbide coating has a loose, porous structure, which releases internal thermal stress, allowing for better bonding between the first tantalum carbide coating and the graphite component. This results in a better bond between the final double-layer tantalum carbide coating and the graphite component, avoiding the significant difference in thermal expansion coefficients between the graphite substrate and the first tantalum carbide coating. The large thermal stress within the sintered first tantalum carbide coating could cause it to detach, leading to the final double-layer tantalum carbide coating peeling off the graphite component surface. A second tantalum carbide coating is then formed on the surface of the first tantalum carbide coating. This second tantalum carbide coating is dense. Since both the second and first tantalum carbide coatings are made of tantalum carbide, the thermal stress difference between them is not significant. This makes it easier for the first and second tantalum carbide coatings to bond tightly without peeling off due to large thermal stress differences. This results in a denser double-layer coating, making the resulting graphite component with the double coating more durable. Attached Figure Description

[0032] Figure 1 A schematic flowchart illustrating a method for preparing a double-layer tantalum carbide coating according to an embodiment of the present invention;

[0033] Figure 2 This is a schematic flowchart illustrating another method for preparing a double-layer tantalum carbide coating according to an embodiment of the present invention. Detailed Implementation

[0034] To facilitate understanding by those skilled in the art, the present invention will be further described in detail below with reference to specific embodiments.

[0035] This invention provides a method for preparing a double-layer tantalum carbide coating, such as... Figure 1 As shown, it includes:

[0036] Step S10: Provide a first suspension containing oxygen / tantalum elements;

[0037] Step S20: Provide a silicon / carbon / tantalum composite phase material and a first second suspension containing tantalum powder;

[0038] Step S30: The first suspension is coated onto the surface of the graphite component and cured to form a first pre-coating layer;

[0039] Step S40: The second suspension is coated onto the surface of the first pre-coating layer and cured to form the second pre-coating layer;

[0040] In step S50, the graphite component with the first pre-coating and the second pre-coating is sintered. The first pre-coating forms a first tantalum carbide coating, and the second pre-coating forms a second tantalum carbide coating, ultimately obtaining a graphite component with a double-layer tantalum carbide coating. The first tantalum carbide coating has a loose and porous structure. The thermal stress inside the first tantalum carbide coating after sintering is released through the loose and porous structure, which allows the first tantalum carbide coating to better bond with the graphite component. The second tantalum carbide coating located on the surface of the first tantalum carbide coating has a dense structure, making the obtained double coating more dense.

[0041] Specifically, step S10 is performed to provide a first suspension containing oxygen / tantalum elements.

[0042] In this embodiment of the invention, the ratio of the amount of oxygen to tantalum in the oxygen-containing / tantalum element material ranges from 1:1 to 5.

[0043] In this embodiment of the invention, the oxygen-containing / tantalum element is Ta. x O y C. One or more of tantalum ethoxide and tantalum oxide.

[0044] In this embodiment of the invention, the mass range of the oxygen / tantalum element material is 0.5 mol to 5 mol.

[0045] In this embodiment of the invention, the oxygen-containing / tantalum element material is in powder form. Since the powdered oxygen-containing / tantalum element material has small particles, it is easy to prepare a uniformly distributed first suspension.

[0046] In this embodiment of the invention, the first suspension further includes a first binder and a first organic solvent, which facilitates subsequent first uniform mixing and coating of the first suspension onto the surface of the graphite component.

[0047] In this embodiment of the invention, the first binder accounts for 0.1% to 1% of the total amount of the first suspension, and the first organic solvent accounts for 50% to 80% of the total amount of the first suspension.

[0048] In this embodiment of the invention, the first adhesive is gum arabic. In other embodiments, the first adhesive is epoxy resin, PVA (polyvinyl alcohol), PVB (polyvinyl butyral), or other suitable materials.

[0049] In this embodiment of the invention, the mass fraction of the first adhesive ranges from 0.01% to 0.1%.

[0050] In this embodiment of the invention, the first organic solvent is ethanol. In other embodiments, the first organic solvent is ethylene glycol, acetone, or other suitable substances.

[0051] In this embodiment of the invention, the preparation step of the first suspension includes:

[0052] Step S11: Provide an oxygen / tantalum element substance;

[0053] Step S12: Provide a first adhesive and a first organic solvent;

[0054] Step S13: After uniformly mixing the oxygen-containing / tantalum element material, the first binder, and the first organic solvent, the first suspension is obtained.

[0055] In this embodiment of the invention, the preparation step of the first suspension further includes adding a first grinding ball during the first uniform mixing process to shorten the time of the first uniform mixing.

[0056] In this embodiment of the invention, the first grinding bead is a zirconia ball, and the first grinding bead is selected with two particle sizes of 3 mm and 5 mm, and the ratio of the two particle sizes of the first grinding bead is in the range of 1:2 to 3.

[0057] In this embodiment of the invention, the time range for the first uniform mixing is 1h to 10h.

[0058] Step S20 is performed to provide a silicon / carbon / tantalum composite phase material and a first second suspension containing tantalum powder.

[0059] In this embodiment of the invention, the ratio of the amounts of tantalum, silicon, and carbon in the silicon / carbon / tantalum composite phase is in the range of 1–3:1–8:1.

[0060] In this embodiment of the invention, the amount of the silicon / carbon / tantalum composite phase material ranges from 1 mol to 10 mol.

[0061] In this embodiment of the invention, the first tantalum-containing powder is one or more of tantalum powder, tantalum oxide powder, and tantalum chloride powder.

[0062] The first tantalum powder provides tantalum element for the subsequent sintering process of the graphite component with the first pre-coating and the second pre-coating. The tantalum element fuses with the crystal bonds of the carbon element in the graphite component, and finally forms a tantalum carbide coating on the surface of the graphite component. Due to the fusion of the crystal bonds of the tantalum element and the carbon element in the graphite component, the tantalum carbide coating is tightly bonded to the graphite crucible, and the formed tantalum carbide coating is dense and not easy to fall off.

[0063] In this embodiment of the invention, the mass range of the tantalum-containing powder is 1g to 20g.

[0064] In this embodiment of the invention, the second suspension further includes a second binder and a second organic solvent, wherein the second binder accounts for 0.1% to 1% of the total amount of the first suspension, and the second organic solvent accounts for 50% to 80% of the total amount of the first suspension.

[0065] In this embodiment of the invention, the second adhesive is gum arabic. In other embodiments, the second adhesive is epoxy resin, phenolic resin, PVA (polyvinyl alcohol), PVB (polyvinyl butyral), or other suitable materials.

[0066] In this embodiment of the invention, the second organic solvent is ethanol. In other embodiments, the second organic solvent is ethylene glycol, acetone, or other suitable substances.

[0067] In this embodiment of the invention, the preparation step of the second suspension includes:

[0068] Step S21: Provide silicon / carbon / tantalum composite phase material and tantalum-containing powder;

[0069] Step S22: Provide an organic binder and an organic solvent;

[0070] Step S23: After the silicon / carbon / tantalum composite phase material, the tantalum-containing powder, the organic linker, and the organic solvent are mixed uniformly for the second time, the second suspension is obtained.

[0071] In this embodiment of the invention, the preparation step of the second suspension further includes adding a second grinding ball during the second uniform mixing process to shorten the time of the second uniform mixing.

[0072] In this embodiment of the invention, the second grinding bead is a zirconia ball, and the second grinding bead is selected with two particle sizes of 3 mm and 5 mm, and the ratio of the two particle sizes of the first grinding bead is in the range of 1:2 to 3.

[0073] In this embodiment of the invention, the time range for the second uniform mixing is 1h to 10h.

[0074] In this embodiment of the invention, the preparation steps of the silicon / carbon / tantalum composite phase material include:

[0075] Step S211: Provide a second tantalum-containing powder, a silicon-containing powder, and carbon powder;

[0076] In this embodiment of the invention, the second tantalum-containing powder is tantalum-based powder and tantalum-oxygenated compound. Specifically, in this invention, the second tantalum-containing powder is tantalum powder and tantalum oxide powder.

[0077] In this embodiment of the invention, the molar ratio of tantalum to silicon in the second tantalum-containing powder and the silicon-containing powder is in the range of 1 to 5.

[0078] In this embodiment of the invention, the amount of the second tantalum-containing powder ranges from 0.5 mol to 1.0 mol.

[0079] In this embodiment of the invention, the silicon-containing powder is SiO2 powder; in other embodiments, the silicon-containing powder is silicon powder, SiC powder, or other suitable silicon-containing material.

[0080] In this embodiment of the invention, the amount of silicon powder ranges from 0.2 mol to 1 mol, and the amount of carbon powder ranges from 0.01 mol to 0.05 mol.

[0081] Step S212: The second tantalum-containing powder, the silicon-containing powder, and the carbon powder are uniformly mixed.

[0082] In this embodiment of the invention, the second tantalum-containing powder, the silicon-containing powder, and the carbon powder are placed in a crucible, and the second tantalum-containing powder, the silicon-containing powder, and the carbon powder are mixed by vibration using a vibrator. The vibration mixing time range is 10 min to 30 min, wherein the crucible is a silicon carbide crucible.

[0083] Step S213: The mixed second tantalum-containing powder, the silicon-containing powder, and the carbon powder are sintered to form a primary silicon / carbon / tantalum composite phase material;

[0084] In this embodiment of the invention, the mixed second tantalum-containing powder, the silicon-containing powder, and the carbon powder are placed in a vacuum sintering furnace for sintering. During the sintering process, an argon-hydrogen mixed gas is introduced, wherein the hydrogen gas accounts for 5% of the argon-hydrogen mixed gas. The sintering temperature range for the mixed second tantalum-containing powder, the silicon-containing powder, and the carbon powder is 1000℃ to 1800℃. The sintering time range for the mixed second tantalum-containing powder, the silicon-containing powder, and the carbon powder is 1h to 5h.

[0085] Step S214: The primary silicon / carbon / tantalum composite phase material is crushed, and the primary silicon / carbon / tantalum composite phase material with a particle size within a set range is screened as silicon / carbon / tantalum composite phase material.

[0086] In this embodiment of the invention, the particle size of the silicon / carbon / tantalum composite phase material is set in the range of 1 μm to 3 μm.

[0087] After sintering, the second tantalum-containing powder, the silicon-containing powder, and the carbon powder form a mixture of SiC and TaC, which have high melting points. x Ta x Si y One or more of these silicon / carbon / tantalum composite phases make the subsequently prepared second tantalum carbide coating more dense.

[0088] Step S30 is performed to coat the first suspension onto the surface of the graphite component and cure it to form a first pre-coating.

[0089] In this embodiment of the invention, the temperature range for solidifying the first suspension on the surface of the graphite component is 50°C to 100°C, and the time range for solidifying the first suspension on the surface of the graphite component is 10 min to 30 min.

[0090] The thickness of the first pre-coating layer ranges from 50 μm to 300 μm.

[0091] In one embodiment of the invention, the first suspension is applied to the surface of the graphite component by brushing. In other embodiments, the first suspension is applied to the surface of the graphite component by spraying or dipping.

[0092] Step S40 is performed to coat the second suspension onto the surface of the first pre-coating layer and cure it to form the second pre-coating layer.

[0093] In this embodiment of the invention, the temperature range for curing the second suspension onto the first pre-coating surface is 50°C to 100°C, and the time range for curing the first suspension onto the first pre-coating surface is 1 hour to 10 hours.

[0094] In this embodiment of the invention, the thickness of the second pre-coating layer ranges from 10 μm to 100 μm.

[0095] In one embodiment of the invention, the second suspension is applied to the surface of the first pre-coating layer by brushing. In other embodiments, the second suspension is applied to the surface of the first pre-coating layer by spraying or dipping.

[0096] In step S50, the graphite component with the first pre-coating and the second pre-coating is sintered. The first pre-coating forms a first tantalum carbide coating, and the second pre-coating forms a second tantalum carbide coating, ultimately obtaining a graphite component with a double-layer tantalum carbide coating. The first tantalum carbide coating has a loose and porous structure. The thermal stress inside the first tantalum carbide coating after sintering is released through the loose and porous structure, which allows the first tantalum carbide coating to better bond with the graphite component. The second tantalum carbide coating located on the surface of the first tantalum carbide coating has a dense structure, making the obtained double coating more dense.

[0097] In this embodiment of the invention, the thickness of the first tantalum carbide coating is greater than the thickness of the second tantalum carbide coating, the thickness of the first tantalum carbide coating is in the range of 20 μm to 40 μm, and the thickness of the second tantalum carbide coating is in the range of 10 μm to 20 μm.

[0098] The thickness of the first tantalum carbide coating is greater than that of the second tantalum carbide coating to prevent the second tantalum carbide coating from being too thick and having fluidity, which would block the pores of the porous first tantalum carbide coating and affect the release of thermal stress during the sintering process of the first and second pre-coatings.

[0099] In this embodiment of the invention, the loose porous structure of the first tantalum carbide coating has a uniform porosity, which ranges from 30% to 50%. This avoids incomplete stress release between the graphite substrate and the first tantalum carbide coating during sintering due to excessively small porosity. It also avoids breakage at the connection between voids caused by excessively large voids. The cracks formed by the cracks extend from the surface of the graphite component to the outermost surface of the second tantalum carbide coating, causing corrosion of the graphite component from the cracks, thus further protecting the graphite component. At the same time, it also increases the bonding strength between the first tantalum carbide coating and the surface of the graphite component.

[0100] In this embodiment of the invention, the method further includes: processing the graphite component to a specific size using a machine gap of 0.4 mm or more, increasing the contact area between the graphite substrate and the first tantalum carbide coating and the second tantalum carbide coating, slowing down the flow of the first suspension and the second suspension after coating the graphite component, avoiding the problem of poor coating thickness uniformity caused by the chamfers and sharp edges of conventional graphite components, and improving the bonding strength between the first tantalum carbide coating and the second tantalum carbide coating and the graphite substrate.

[0101] This invention also provides a method for preparing a double-layer tantalum carbide coating, such as... Figure 2 As shown, it includes:

[0102] Step S100: Provide a first suspension containing oxygen / tantalum elements;

[0103] Step S200: Provide a silicon / carbon / tantalum composite phase material and a first second suspension containing tantalum powder;

[0104] Step S300: The first suspension is coated onto the surface of the graphite component and cured to form a first pre-coating layer;

[0105] Step S400: Sinter the graphite component with the first pre-coating to form a first tantalum carbide coating.

[0106] Step S500: The second suspension is coated onto the surface of the first tantalum carbide coating and cured to form a second pre-coating.

[0107] In step S600, the graphite component with the second pre-coating is sintered, and the second pre-coating forms a second tantalum carbide coating, ultimately obtaining a graphite component with a double-layer tantalum carbide coating. The first tantalum carbide coating has a loose and porous structure, and the thermal stress inside the sintered first tantalum carbide coating is released through the loose and porous structure, which allows the first tantalum carbide coating to better bond with the graphite component. The second tantalum carbide coating located on the surface of the first tantalum carbide coating has a dense structure, making the obtained double coating more dense.

[0108] This invention also provides a graphite component, which is obtained using the above-described method for preparing a tantalum carbide coating.

[0109] Finally, it should be noted that any modification or equivalent substitution of some or all of the technical features based on the device structure and the technical solutions of the embodiments of the present invention, without departing from the corresponding technical solutions of the present invention, shall fall within the patent scope of the device structure and the embodiments of the present invention.

Claims

1. A method for preparing a double-layer tantalum carbide coating, characterized in that, include: Provides a first suspension containing oxygen / tantalum elements; Provides a silicon / carbon / tantalum composite phase material and a first second suspension containing tantalum powder; The first suspension is coated onto the surface of the graphite component and cured to form a first pre-coating layer; The second suspension is coated onto the surface of the first pre-coating layer and cured to form the second pre-coating layer; A graphite component with a first pre-coating and a second pre-coating is sintered. The first pre-coating forms a first tantalum carbide coating, and the second pre-coating forms a second tantalum carbide coating, ultimately obtaining a graphite component with a double-layer tantalum carbide coating. The first tantalum carbide coating has a loose and porous structure. The thermal stress inside the first tantalum carbide coating after sintering is released through the loose and porous structure, which allows the first tantalum carbide coating to better bond with the graphite component. The second tantalum carbide coating located on the surface of the first tantalum carbide coating has a dense structure, making the obtained double coating more dense.

2. The method for preparing a double-layer tantalum carbide coating as described in claim 1, characterized in that, The oxygen- or tantalum-containing material includes Ta. x O y C. One or more of tantalum ethoxide and tantalum oxide; the ratio of the amount of oxygen to tantalum in the oxygen / tantalum element-containing substance is in the range of 1:1 to 5.

3. The method for preparing a double-layer tantalum carbide coating as described in claim 1, characterized in that, The molar ratio of tantalum, silicon, and carbon in the silicon / carbon / tantalum composite phase ranges from 1 to 3:1 to 8:

1.

4. The method for preparing a double-layer tantalum carbide coating as described in claim 1, characterized in that, The preparation steps of the silicon / carbon / tantalum composite phase material include: Provide a second type of powder containing tantalum, silicon, or carbon powder; The second tantalum-containing powder, the silicon-containing powder, and the carbon powder are mixed uniformly. The mixed second tantalum-containing powder, the silicon-containing powder, and the carbon powder are sintered to form a primary silicon / carbon / tantalum composite phase material. The primary silicon / carbon / tantalum composite phase material is crushed, and the primary silicon / carbon / tantalum composite phase material with a particle size within a set range is selected as the silicon / carbon / tantalum composite phase material.

5. The method for preparing a double-layer tantalum carbide coating as described in claim 4, characterized in that, The second tantalum-containing powder includes tantalum-based and tantalum-containing oxygen compounds.

6. The method for preparing a double-layer tantalum carbide coating as described in claim 4, characterized in that, The molar ratio of tantalum to silicon in the second tantalum-containing powder and the silicon-containing powder ranges from 1 to 5.

7. The method for preparing a double-layer tantalum carbide coating as described in claim 1, characterized in that, The thickness of the first tantalum carbide coating is greater than the thickness of the second tantalum carbide coating. The thickness of the first tantalum carbide coating ranges from 20 μm to 40 μm, and the thickness of the second tantalum carbide coating ranges from 10 μm to 20 μm. The porosity of the loose porous structure of the first tantalum carbide coating ranges from 30% to 50%.

8. The method for preparing a double-layer tantalum carbide coating as described in claim 1, characterized in that, Also includes: The graphite parts are machined to the predetermined size using a machine gap of 0.4mm or more.

9. A method for preparing a double-layer tantalum carbide coating, characterized in that, include: Provides a first suspension containing oxygen / tantalum elements; Provides a silicon / carbon / tantalum composite phase material and a first second suspension containing tantalum powder; The first suspension is coated onto the surface of the graphite component and cured to form a first pre-coating layer; The graphite component with the first pre-coating is sintered to form a first tantalum carbide coating. The second suspension is coated onto the surface of the first tantalum carbide coating and cured to form a second pre-coating; The graphite component with the second pre-coating is sintered, and the second pre-coating forms a second tantalum carbide coating, ultimately obtaining a graphite component with a double-layer tantalum carbide coating. The first tantalum carbide coating has a loose and porous structure. The thermal stress inside the first tantalum carbide coating after sintering is released through the loose and porous structure, which makes the first tantalum carbide coating better bonded to the graphite component. The second tantalum carbide coating located on the surface of the first tantalum carbide coating has a dense structure, which makes the obtained double coating more dense.

10. A graphite component, characterized in that, The tantalum carbide coating is obtained by any one of the preparation methods described in claims 1 to 9.

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