Microstructure, mechanical and tribological properties of cold sprayed Cu[sbnd]W coatings

Abstract

This paper presents the results of the investigation of the microstructure and properties of copper‑tungsten coatings with different compositions on aluminum alloy substrates. Coatings were obtained by cold spray method using powder mixtures as feedstock. The effect of the powder mixture composition on the deposition efficiency and the tungsten content in the coating have been studied. X-ray diffraction analysis was used to investigate the phase composition and to reveal the peculiarities of changes in the crystalline structure of copper and tungsten particles after cold spraying in relation to the coating composition. Using the method of instrumental indentation on cross-sections of the coatings mechanical properties were measured. It was shown that increasing of tungsten content in the coatings contributes to increasing the microhardness and Young's modulus of the coatings. The mapping images showed that all coatings were characterized by non-uniformity of mechanical properties over the cross-section. The bonding strength of coatings significantly increases with increasing tungsten content in the feedstock. CuW coatings are characterized by lower specific wear rate values and higher coefficients of friction under dry sliding wear conditions in a ball-on-flat mode compared to pure copper coating.