Influence of Al2O3 mass fractions on microstructure, oxidation resistance and friction–wear behaviors of CoCrAlYTaSi coatings

Abstract

CoCrAlYTaSi coatings with different Al2O3 mass fractions were fabricated on Ti–6Al–4V alloy using a laser cladding (LC). The effects of Al2O3 mass fractions on the microstructure, oxidation resistance and friction–wear performance of obtained coatings were investigated, and the wear mechanisms were also discussed. The results show that the hardness of CoCrAlYTaSi coating increases with the increase of Al2O3 mass fractions, the dendritic structure with the Al2O3 mass fraction of 15% is compactly refined. The diffusion barrier layer of Al2O3 contains Y oxide precipitate, which reduces the oxidation rate and the movement of Ta. The total mass gain per unit area of CoCrAlYTaSi coating with the Al2O3 mass fractions of 15, 30 and 45% is 33.96, 29.82, and 26.27 mg •cm−2, respectively, the oxidation resistance with the Al2O3 mass fraction of 15% is the best among the three kinds of coatings. The average coefficients of friction (COFs) of CoCrAlYTaSi coatings with the Al2O3 mass fractions of 0, 15, 30 and 45% are 1.12, 0.17, 0.23, and 0.35, respectively, and the corresponding wear rates of are 1.59 × 10−4, 1.02 × 10−4, 0.54 × 10−4, and 0.3 × 10−4 mm3 N−1•m−1, respectively, the wear mechanism is abrasive wear and micro–cutting.