Deposition characteristics of Al–12Si alloy coating fabricated by cold spraying with relatively large powder particles

In this paper, the microstructure, microhardness and adhesive strength of Al–12Si coating produced by cold spraying were investigated. It is found that a thick, dense and well bonded Al–12Si coating could be produced by cold spraying with a relatively large powder through the control of spray conditions. The critical velocity for large Al–12Si particles was lower than that of small Al–12Si particles. The as-deposited Al–12Si coating had the same crystal structure as Al–12Si powder. The localized interface melting occurred resulting from both the adiabatic shearing upon impact and the thermal effect of hot gas. Some fine Si particles precipitated in a-Al matrix because of the thermal effect of hot gas during coating deposition. The dispersed Si particles in Al–12Si coating improved the coating microhardness