AbstractThe influence of atmosphere, current, voltage, and powder feed rate on the microstructure of air plasma sprayed Cu-Ni-In coatings has been investigated. The effect of substrate pretreatment by blasting with alumina grit on substrate-coating bonding was also studied. Air blasting with alumina at appropriate pressures produced surface roughness that enhanced bonding by allowing particles of Cu-Ni-In powder contacting the substrate surface to bond by a combination of mechanical interlocking, solidification forces, diffusion, and micro welding. Blasting also caused alumina particles to become embedded in the surface, causing local contamination. A logarithmic relationship was found between the kinetic energy of microthe alumina particles and substrate weight loss during blasting. Substrate-coating lap shear bond strength was found to increase with increasing alumina particle size in the range studied (24-220 mesh) and to reach a maximum at the air pressure corresponding to maximal surface roughness. Spraying parameters found to give optimal microstructural properties and microstructures are given.