Enhancing TZM alloy's resistance to high-temperature oxidation with cold-sprayed Ni-based MMC coating

Molybdenum-titanium-zirconium (TZM) alloy, renowned for its high refractory properties, has limited applications in open atmospheres because of its low resistance to oxidation at elevated temperatures. In this study, Ni-Al 2 O 3 cold spray coating was employed to create a protective layer on the TZM to protect against high-temperature oxidation. The microstructure, microhardness, and oxidation performance of the Ni-based MMC coating were investigated at various temperatures up to 1000 °C. The MMC coating's microstructure consisted of Al 2 O 3 particles randomly distributed within the nickel matrix, resulting from the CS coating, which is a solid-state deposition method. In the oxidation tests of TZM at temperatures of 750 and 1000 °C, it was observed that there was a significant mass loss because of the generation and evaporation of the MoO 3 phase. It was determined that the Ni-based MMC coating on TZM significantly reduced mass loss by preventing molybdenum from coming into contact with oxygen. Following the 1000 °C oxidation test, the XRD examination revealed the presence of MoO 2 and MoO 3 phases on the surfaces of TZM, while NiO and NiMoO 4 phases were identified on the surfaces of the MMC coating. It was determined that the NiMoO 4 phase formed at the end of the MoO 3 vapor on the TZM side surfaces, while the NiO phases developed in the MMC coating layer through a chemical reaction.