Characterizations of cold-sprayed Nickel–Alumina composite coating with relatively large Nickel-coated Alumina powder

Previous studies have shown that the fabrication of metal matrix composites (MMCs) by cold spraying is effective and promising. When light materials, such as SiC and Al2O3, were used as reinforcements, it was diffcuclt to obtain a high volume fraction of hard phase in the composite just through the simple powder mixture. Therefore, in this study, a Ni-coated Al2O3 powder, which was produced through hydrothermal hydrogen reduction method, was employed aiming at increasing the volume fraction of ceramic particles in the deposited composite coating. It was found that a dense Ni–Al2O3 composite coating could be deposited with the Ni-coated Al2O3 powder under the present spray conditions. X-ray diffraction analysis indicated that the composite coating had the same phase structures as the feedstock. The volume fraction of Al2O3 in the composite was about 29 ± 6 vol.%, which is less than that in the feedstock (nominal: 40–45 vol.%) due to the rebound of some Al2O3 particulates upon kinetic impacting. The microhardness of the composite coating was about 173 ± 33Hv0.2.