On the PEO treatment of cold sprayed 7075 aluminum alloy and its effects on mechanical, corrosion and dry sliding wear performances thereof

Abstract

The plasma electrolytic oxidation (PEO) process was used to deposit an alumina coating on a cold sprayed 7075 aluminum alloy to improve the surface properties. The phase compositions, microstructures, basic mechanical properties, as well as the corrosion and the dry sliding wear resistance of cold sprayed 7075 aluminum alloy before and after PEO treatment, were investigated. The results show that a single-layered dense alumina coating with a thickness of ~15–20 μm and hardness of 1353 HV0.01 is realizable on the cold sprayed 7075 aluminum alloy by PEO treatment aided by an aluminate electrolyte. The corrosion current density and wear rate of the alumina PEO coating were 6.27 × 10−7 A/cm2 and 1.22 × 10−6 mm3/N·m respectively, which were three and two orders of magnitude lower compared to the uncoated rolled 7075 aluminum alloy (T6) substrate, thus highlighting the excellent wear and corrosion resistance of the PEO treated cold sprayed Al alloy surface.