Al-rich hard coatings on Al alloy by low-pressure plasma spraying

In order to improve the wear resistance of an Al alloy surface, a low-pressure plasma spray coating has been carried out on an A6063 Al alloy substrate plate by using rapidly-solidified Al alloy powders of Al-50 wt% Si, Al-17 wt% Si-15 wt% Fe and Al-50 wt% Fe alloys. A dense layer with high hardness of HV 200-240 and HV 450-530 was obtained at Al-50 Si and Al-17 Si-15 Fe powders, respectively. The abrasive wear resistance of these coatings was improved by two and three times compared to that of A6063. Much higher hardness, HV 700-850 in the coatings was obtained with Al-50 Fe powder, but porosity and cracking occurred in the layer. These defects prevented an improvement of the abrasive wear resistance of the coatings compared to those of Al-50 Si and Al-17 Si-15 Fe powders.