Effects of Heat-Treatment on Corrosion Resistance of Cu-Al Composite Coating Prepared by Low Pressure Cold Spraying

Cu-Al composite coatings were prepared on the surface of 45 steel substrate by low pressure cold spraying, and then the coatings were heat-treated at different temperatures. Static indentation method and scanning electron microscopy (SEM) were used to characterize the micro-hardness and micro-morphology of the coating before and after heat-treatment. The corrosion resistance of the coating before and after heat-treatment was studied by corrosion immersion test and copper accelerated acetate spray test (CASS). The results show that when the heat-treatment temperature was 450 ℃, the elements of copper and aluminum in coatings were obviously diffused, and the coating had good mechanical properties and corrosion resistance, whose porosity and corrosion rate were 0.44% and 0.55 g/(m²·h), respectively,and corrosion resistance reached the sixth grade standard. Heat-treatment can reduce the internal porosity of the coating, and the dense structure of the coating and the corrosion products on the surface of the coating can well block corrosive media, thereby providing long-term effective protection for the substrate.