Abstract
- Nickel–rhenium (Ni–Re) alloy coatings were electroplated from Watts-type electrolytes. The influences of deposition variables on the appearance quality, chemical composition, the partial deposition current density, and the Faradaic efficiency (FE) were optimized, simultaneously microstructure, phases, roughness, optical, microhardness and abrasion resistance of the coatings were investigated. The optimal deposition variables were current density of 5 mA cm–2, pH of 5.5 and bath temperature of 60–70°C. Ni-rich alloy coatings with the FE as high as 99.5% and Re-content as high as 43 wt % were obtained. A bright Ni80Re20 coating with a low surface roughness of 9.17 ± 1.79 nm was obtained under the optimal deposition variables. The fcc-Ni(Re) and hcp-Re phases co-existed in Ni80Re20 coating. The Specular Component Include (SCI) value for the reflectivity of Ni80Re20 coating was 42.9 ± 0.7%. The surface quality, microhardness and abrasion resistance of the alloy coating by the addition of 20 at % Re was improved.