Microstructure and properties of Cu–Cr coatings deposited by cold spraying

Abstract

Cold spraying is used to deposit coatings on a copper substrate with mixed Cu–Cr composite powders. The morphology evolution of Cu and Cr phase during cold spray is studied. And the mechanical properties of Cu–Cr coating is researched. Results indicate that ductile copper shows heavy plastic deformation, brittle chromium shows some crack and even break during cold spraying. Cold sprayed coatings show a good adhesion with substrate and a homogeneous distribution of Cr particles in the microstructure. The Cr contents of coatings are 13.06%–16.01% which obviously reduce compared to feedstock (45.00%) due to the high hardness and poor deformation. The hardness of Cu–Cr coatings is 145.7 Hv. Copper further deform during the wear process while chromium show evidence of brittle fracture. The dominant wear mechanism for the Cu–Cr coatings is plastic deformation and delamination. The electrical conductivity of pure Cu coatings and Cu–Cr coatings are 73.28% and 53.49% IACS, respectively. Cu–Cr coatings have similar hardness and electrical conductivity as of Cu75Cr25 alloy ingots (VIM). The results indicate that cold spray technique provides an effective approach to manufacture uniform and dense Cu–Cr coatings with accepted physical and mechanical properties.