CHROMIUM PLATED ALUMINUM SUBSTRATE AND ITS PRODUCTION

摘要

PURPOSE:To obtain an Al substrate having superior corrosion resistance and especially suitable for a memory disk by forming a crack-free Cr layer by electroplating on the modified surface of Al or an Al alloy as a base material. CONSTITUTION:The surface of Al or an Al alloy as a base material is modified so that it can be electroplates with Cr. The base material is then immersed in an electrolytic Cr bath contg. 200-600g/l (expressed in terms of CrO3)Cr<6+>, 0.5-8g/l SO4<2-> and 0-5g/l F<-> and/or fluoride ion and electroplating is carried out at 55-75 deg.C and 10-90A/dm<2> current density to form a crack-free Cr layer on the surface of the base material.