How to prepare CVD TaC coating?

CVD TaC coating is an important high-temperature structural material with high strength, corrosion resistance and good chemical stability. Its melting point is as high as 3880℃, and it is one of the highest temperature-resistant compounds. It has excellent high-temperature mechanical properties, high-speed airflow erosion resistance, ablation resistance, and good chemical and mechanical compatibility with graphite and carbon/carbon composite materials.

Therefore, in the MOCVD epitaxial process of GaNLEDs and Sic power devices, CVD TaC coating has excellent acid and alkali resistance to H2, HC1, and NH3, which can completely protect the graphite matrix material and purify the growth environment.

CVD TaC coating is still stable above 2000℃, and CVD TaC coating begins to decompose at 1200-1400℃, which will also greatly improve the integrity of the graphite matrix. Large institutions all use CVD to prepare CVD TaC coating on graphite substrates, and will further enhance the production capacity of CVD TaC coating to meet the needs of SiC power devices and GaNLEDS epitaxial equipment.

The preparation process of CVD TaC coating generally uses high-density graphite as the substrate material, and prepares defect-free CVD TaC coating on the graphite surface by CVD method.

The realization process of CVD method to prepare CVD TaC coating is as follows: the solid tantalum source placed in the vaporization chamber sublimates into gas at a certain temperature, and is transported out of the vaporization chamber by a certain flow rate of Ar carrier gas. At a certain temperature, the gaseous tantalum source meets and mixes with hydrogen to undergo a reduction reaction. Finally, the reduced tantalum element is deposited on the surface of the graphite substrate in the deposition chamber, and a carbonization reaction occurs at a certain temperature.

The process parameters such as vaporization temperature, gas flow rate, and deposition temperature in the process of CVD TaC coating play a very important role in the formation of CVD TaC coating.

CVD TaC coating with mixed orientation was prepared by isothermal chemical vapor deposition at 1800°C using a TaCl5–H2–Ar–C3H6 system.

Figure 1 shows the configuration of the chemical vapor deposition (CVD) reactor and the associated gas delivery system for TaC deposition.

Figure 2 shows the surface morphology of the CVD TaC coating at different magnifications, showing the density of the coating and the morphology of the grains.

Figure 3 shows the surface morphology of the CVD TaC coating after ablation in the central area, including blurred grain boundaries and fluid molten oxides formed on the surface.

Figure 4 shows the XRD patterns of the CVD TaC coating in different areas after ablation, analyzing the phase composition of the ablation products, which are mainly β-Ta2O5 and α-Ta2O5.