The effect of the standoff distance on the microstructure and mechanical properties of cold sprayed Cr3C2-25(Ni20Cr) coatings

In this study, coatings were obtained by spraying two Cr3C2-25(Ni20Cr) powders, possessing different morphology and grain size distributions, on an Al 7075 alloy substrate at various standoff distances. The applied powders and process parameters allowed to produce deposits characterised by a compact microstructure and negligible porosity. Depending on the used powder, the obtained coatings showed variations in surface roughness and how the Cr3C2 particles were incorporated into the Ni20Cr matrix. The standoff distance significantly affected the coatings microstructure, mechanical properties, and deposition efficiency. The coatings obtained at a standoff distance of 50 mm were characterised by the highest hardness and amount of incorporated Cr3C2 particles. In turn, coatings sprayed at the distance of 30 mm possessed the highest microhardness and Young modulus, as well as lowest surface roughness.