Preparation of iridium‑hafnium intermetallic compound coatings in molten salts

Abstract

A uniform and continuous iridium‑hafnium diffusion coating was fabricated using the metalliding process in a molten salt of LiF-HfF4 at relatively low temperatures to improve the oxidation resistance of pure iridium under extreme operating conditions. The phase composition and morphology of the diffusion coatings prepared at different temperatures from 950 to 1200 °C were determined by X-ray diffraction and scanning electron microscopy coupled with energy dispersive X-ray microanalysis, respectively. The results show that the diffusion coating consists of HfIr3, HfIr and Hf2Ir intermetallic compounds. With an increase in temperature, the thickness of the coating increased significantly. This shows that metalliding is a promising method for the preparation of uniform iridium‑hafnium diffusion coatings.