Deposition of copper based composite coating using novel explosive spray coating method

Abstract

Micron sized Copper powder is sprayed on steel substrates with the help of a novel explosive spray coating set up developed in the laboratory by burning a pyrotechnic powder mixture (Barium nitrate + Al) in the gun barrel in a controlled manner. A thick Cu-based composite coating is developed on the pre-treated and pre-heated low carbon steels. Different characterisation methods such as XRD, FESEM, Microhardness tests, scratch test etc. are adopted to characterise the deposited coating. A major presence of Cu is noticed near the top surface of the coating. The coating is monolithic in nature with pores, cracks, and amorphous phases present in it. The average hardness of the coating is found to be high due to the presence of hard phases such as BaAl2O4, Fe3N, AlN, etc. in it. The adhesion strength of the coating is found to be remarkably high due to the strong mechanical anchorage offered by the substrate asperities towards the coating material and the inter-diffusion of materials between the coating and the substrate at the interface zone.