Method for forming a tantalum carbide coating and the tantalum carbide coating thereof

Abstract

A method for forming a tantalum carbide coating is disclosed to address the problems of excessive porosity and insufficient adhesion in tantalum carbide coatings formed by conventional atmospheric plasma spraying processes. The method includes: heating tantalum carbide powder to remove oxides from its surface; melting and depositing the treated tantalum carbide powder onto the surface of a workpiece using atmospheric plasma spraying to form a tantalum carbide coating; subjecting the tantalum carbide coating to a carburizing treatment, whereby a carbon-containing compound acts on the tantalum carbide coating to allow carbon elements in the carbon-containing compound to diffuse into the surface layer of the tantalum carbide coating; the carbon content of the surface layer of the tantalum carbide coating after the carburizing treatment is less than 20 wt%. This achieves the effects of improving the adhesion of the tantalum carbide coating and reducing its porosity. The invention further includes a tantalum carbide coating obtained by the aforementioned method.

Claims

1. A method for forming a tantalum carbide coating, comprising: heating a tantalum carbide powder to remove oxides contained on the surface of the tantalum carbide powder to obtain a treated tantalum carbide powder; melting and depositing the treated tantalum carbide powder onto the surface of a workpiece by atmospheric plasma spraying to form a tantalum carbide coating; and performing a carburizing treatment on the tantalum carbide coating, wherein the carburizing treatment involves acting a carbon-containing compound on the tantalum carbide coating to allow carbon elements in the carbon-containing compound to diffuse into a surface layer of the tantalum carbide coating; wherein the carbon content of the surface layer of the tantalum carbide coating after carburizing treatment is less than 20 wt%.

2. The method for forming the tantalum carbide coating as claimed in claim 1, wherein, The carburization depth of the surface layer of the tantalum carbide coating after carburization treatment is 3 to 10 µm.

3. The method for forming the tantalum carbide coating as described in claim 1, wherein, The carburizing process is carried out in a mixed atmosphere containing methane, hydrogen, and argon at 900–1100°C.

4. The method for forming the tantalum carbide coating as described in claim 3, wherein, The mixed atmosphere containing methane, hydrogen and argon consists of 0.5 to 2 vol% methane, 2 to 5 vol% hydrogen and the balance argon.

5. The method for forming the tantalum carbide coating as claimed in claim 1, wherein, The carburizing process takes 10 to 50 minutes.

6. The method for forming the tantalum carbide coating as claimed in claim 1, wherein, The tantalum carbide powder is heated to remove oxides from its surface. This process is carried out in a mixed atmosphere containing hydrogen and an inert gas, wherein the mixed atmosphere contains 1 to 4 vol% hydrogen.

7. The method for forming the tantalum carbide coating as claimed in claim 1, wherein, The oxygen content of the tantalum carbide powder after this treatment is less than 0.5 wt%.

8. The method for forming the tantalum carbide coating as claimed in claim 1, wherein, The oxygen content of the treated tantalum carbide powder is 0.15–0.45 wt%.

9. A tantalum carbide coating, obtained by the forming method of any one of claims 1 to 8.

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