Influence of process parameters on crack formation in direct current and pulse reversal plated hard chromium

It has for a long time been known that crack free chromium coatings can be obtained by pulse reversal plating, but it has only much later been understood that reoxidation of hydrogen from the surface during the anodic periods is essential for obtaining crack free deposits. In this paper, it is shown that a specific anodic charge depending on the charge of the previous cathodic pulse is needed to obtain a crack free coating and that residual stress in the coating will be less at more frequent current reversals. Furthermore, too large an anodic charge will result in redissolution of chromium and thereby decrease the current efficiency.