Effect of Current Density on Microstructure and Microhardness of Iron Coatings Electroplated at Low Temperature

Fe coatings were prepared by direct current electroplating at a low temperature and current density.The morphology,metallographic structure and composition of as-prepared Fe coatings were analyzed with a scanning electron microscope and a metallographic microscope,while their microhardness was measured with a microhardness meter so as to investigate the effect of current density on the microstructure and microhardness of the coatings.Results indicate that as-prepared Fe coatings appear to be black and contain net-like strip structure.The microhardness measured at the net-like strip structure is lower than that measured at intact coating surfaces.Besides,the microhardness of Fe coatings increases with increasing current density,but the size and amount of cracks rise therewith.Moreover,Fe coating obtained at a lower current density consists of single pure Fe phase;the net-like stripes are not co-electrodeposited structure but oxidation-induced micro-cracks.