Joining of arc sprayed coating to substrate by compound casting

Abstract

Compound casting was used to achieve the joining of arc sprayed coating to substrate. A layer of coating was deposited on the core by arc spraying, and then molten metal was poured into the mould to achieve the combination between substrate and coating. After solidification, the microstructure, chemical compositions and phase constitutions at the interface were analysed. The results show that in the case of casting aluminium or A356 melt around the aluminium coating, metallurgical bonding is formed at the interface after the oxide layer on the surface of coating is broken. There is no continuous metallic transition at the interface of Al coating/Al (Al/Al), while a transition from substrate to coating is formed at the interface of Al coating/A356 (Al/A356). Two diffusion layers are formed at the interface of Al coating/AZ91 (Al/AZ91), and the layers beside the substrate and coating are composed of Al₁₂Mg₁₇+δ (Mg) and Al₃Mg₂ respectively.