Effect of Heat Treatment on Microstructure and Properties of Cold Sprayed Iron Coating

Cold spraying has great potentials in deposition of a majority of metallic coatings and metal–ceramic composites for many industry applications. In this study, iron coatings were deposited on aluminum substrates and the effect of post–spray heat treatment on the coating microstructure and microhardness was examined. The results showe that the as–sprayed Fe coating presents a relatively dense inner structure but a relatively porous top layer. Some large open pores were present on the coating surface due to the influence of in–flight particle surface oxidation which was observed as the bright spray jet during spraying. The microstructure of the annealed Fe coating changed little, but the coating microhardness was decreased significantly. The intermetallics of 10μm thickness were formed between the Fe coating and Al substrate.