Effect of MoO2 and TiO2 on electrodeposition and properties of chromium coating

The process of chromium electroplating from a low-concentrated (120 g l−1 CrO3) bath with additive Limeda Ch-3 and fine-dispersion suspensions of molybdenum dioxide (MoO2) and titanium dioxide (TiO2) particles has been studied. The effects of these fine-dispersion particles, capable of co-deposition with chromium matrix, on certain characteristics of the coating have been considered in this work. A lower rate of the formation of composite Cr–MoO2 and Cr–TiO2 compared with that of Cr coating is supposed to be related to the adsorptive capacity of MoO2 and TiO2 and desorption of their hydrides from the electrode surface. It has been shown that high-dispersed particles of MoO2 may be used to reduce hydrogenation of the substrate. Moreover, MoO2, as well as TiO2 particles, have an effect on such coating properties as hardness, ductility, internal stresses and a high-temperature resistance.