Effect of rhenium on corrosion behavior of electrodeposited Co-Cu alloy coating at room temperature and high temperature

Abstract

Rhenium (Re) is a high-performance refractory metal. Adding rhenium to the alloy can significantly improve the overall performance of the alloy. This paper proposes a simple way to prepare rhenium alloy coatings. The microstructure and XRD results show that the addition of rhenium has a certain effect on the alloy coating. Co-Cu-Re alloy coating had a corrosion current density of 3.2 10−6 (A/cm2) in a solution of 3.5% NaCl, which was 3.4 times lower than that of the mild steel substrate and 2.4 times lower than that of the Co-Cu alloy coating. The charge transfer resistance (Rct) is 4512 (Ω·cm2), which is 6 times larger than that of the mild steel substrate and 1.1 times larger than that of the Co-Cu alloy coating. The electrochemical test results show that the addition of rhenium element can enhance the corrosion resistance of the alloy coating. In the high-temperature oxidation experiment, the oxidation rate constant of the rhenium-containing coating was calculated to be the smallest compared with the mild steel substrate and the Co-Cu alloy coating, and it was observed that the addition of rhenium can effectively inhibit the interdiffusion of elements, indicating that the rhenium-containing coating has stronger high-temperature oxidation resistance. Finally, through the XPS characterization of the alloy coating, the mechanism by which rhenium protects the alloy coating in a high-temperature environment is explained. The addition of rhenium has a broader significance in improving the overall performance of the alloy coating, and will promote its wide application in various fields.