Electropolishing of metals in alcoholic solution of sulphuric acid

Abstract

The potentiodynamic polarization curves of iron, nickel, cobalt, molybdenum, copper and iron-nickel and cobalt-nickel alloys were measured in the polishing solution of 1M H 2SO 4 in CH 3OH. The above mentioned metals and alloys may be divided into three groups: metals and alloys with high dissolution rate in the active state in which the polishing follows immediately behind the active dissolution region (Fe, Co and Ni-Fe and NiCo alloys with a low nickel content), metals and alloys with low passivating current density that become passive at first and the polishing takes place behind the region of localized corrosion (nickel and NiFe and NiCo alloys with a high nickel content) are metals that are polished in the transpassive region (molybdenum).