In a last step the roll will be dipped into a chromic acid bath to cover the metal by chromium coating. By applying a DC-voltage (anode +, roll -) the chromium ions are deposited on the roll surface. With this layer of some microns the ground – EDT – and/or Superfinish – structures can be frozen thus increasing roll lifetime. The abrasive wear from the strip on the rolls during rolling will be reduced and the thermal conductivity enhanced.
micro cracks of a textured chrome-plated surface
micro cracks etched, 500x magnified