Abstract
The poor oxidation resistance of tantalum-tungsten alloy at high temperatures limits its development as an ideal candidate for thermal components in aerospace. In this study, a composite coating including an internal TaSi2-WSi2 layer and an external ZrB2-MoSi2-ZrSi2 layer was prepared on the surface of Ta10W alloy by combining slurry sintering and halide activated pack cementation (HAPC). The composite coating has a dense structure, and the coating samples remains intact after oxidation at 1500°C for 6 hours, while the unprotected substrate oxidizes to powder within 3 minutes. The coated samples also withstood more than 300 shock heating cycles from room temperature to 1500°C. Its notable resistance to high-temperature oxidation was ascribed to the development of a compact and uniform SiO2 oxide layer containing oxide crystals comprising ZrSiO4, ZrO2, and Ta2O5 during the oxidation process, which effectively mitigated the diffusion of oxygen into the interior of the coating.
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