In cold spraying, various issues affect the mechanical properties of the coatings. Adhesion strength is usually considered to be the most crucial mechanical property. The aim of this study was to investigate the adhesion strength of cold sprayed copper and nickel chromium alloy coatings. The focus was especially in studying the influence of powders, substrates and heat treatments on adhesion strength. Three different copper and three nickel-20%chromium powders were tested. The substrate materials were carbon steel and copper. Furthermore, effect of substrate pre-treatment to the adhesion strength of the cold sprayed copper coatings was investigated. The influences of the powders and the substrates on the cold sprayed coatings were dependent on the materials. Adhesion strength of the cold sprayed Cu coatings was significantly higher on the Cu substrate than on the steel substrate. Moreover, heat treatment improved the adhesion strengths with increasing annealing temperature.

Cold spraying is quite a new process, which is an effective method to deposit dense and pure coatings. The aim of this study was to investigate microstructures and mechanical properties (hardness and adhesion) of the cold sprayed coatings. The coating materials were aluminium, copper, nickel and zinc. The substrate materials were carbon steel and copper. Influence of heat treatments on mechanical properties was studied, especially different heat treatment times and temperatures. The hardness of the cold sprayed coatings was higher than that thermally sprayed coatings and bulk materials. During heat treatment, the hardness of the cold sprayed coatings decreased and the ductility increased. Corrosion resistance of cold sprayed coatings was also studied. The corrosion resistance was tested with salt spray (fog) testing and open cell potential measurements. The corrosion tests showed some through-porosity but some parts of the cold sprayed coatings appeared to be fully dense, which showed their potential for corrosion protection.

Cold spraying is a novel coating method in which coating is formed by mechanical deformation of sprayed metal particles. This heavy deformation causes structures, which need recrystallization heat-treatment in order to gain back the materials natural deformability. Aluminum, copper, nickel and Ni-20%Cr were cold sprayed and heat-treated at several temperatures. Coatings were sprayed using nitrogen as process gas. Substrate material was carbon steel. Heat-treatment temperatures were chosen from near room temperature to below coating materials melting temperature. As-sprayed and heat-treated coatings were characterized in microstructure, hardness, phase structure and electrical resistivity. It was found that 200ºC was enough to increase electric conductivity to 87% of pure copper. By heat treatment ductility was able to be increased and hardness subsequently decreased.