Oxidation and Adhesion of Decorative Nickel-Chromium Plating on Ferritic Stainless Steel

Decorative Ni-Cr plating on ferritic stainless steel was exposed to pure carbon dioxide (CO2) at 200 and 300 degrees C for 180 hours under continuous and cyclic oxidation tests. After oxidation test, weight changes of samples exposed to CO2 were found to be less than that of samples exposed to air. However, weight changes were dependent on temperature and oxidation conditions. Heat-quench test was operated at temperature of 200-500 degrees C for determining adhesion behavior of decorative Ni-Cr plating. From the heat-quench test, it revealed that adhesion ability between Ni-Cr plating layer and substrate increased with thickness of Ni pre-plating layer at temperature of 200 and 300 degrees C. But, at temperature above 300 degrees C, the adhesion ability increased with surface roughness of substrate before coating. In order to achieve important properties of decorative Ni-Cr plating, i.e., oxidation resistance, beautiful appearance and good adhesion, surface of substrate was necessarily prepared under medium roughness and then it was pre-plated with the thickest Ni layer before Cr coating was applied.