Electrochemical iron-chromium alloying of carbon steel surface using alternating pulsed electrolysis

Abstract

Alternating pulsed electrolysis was investigated for the surface modification of carbon steel substrates with carbon contents of 0.2 mass%, 0.6 mass% and 0.8 mass%, This process involves the anodic periodic dissolution of substrates to provide ferrous or ferric ions near the substrate as an electroactive component to form the objective alloy during subsequent cathodic times. The carbon steel substrates dissolved heterogeneously since the substrates had nonuniform texture composed of ferrite, cementite, and pearlite. Although the heterogeneous dissolution tended to provide a rough surface of the iron-chromium alloy layers, which resulted in poor adhesion of the layers, relatively flat and smooth alloy layers were obtained by reducing the amount of dissolved iron during each anodic pulse. Pits and defects that were originally recognized on the carbon steel substrate were gradually filled in and covered with iron-chromium alloy by the pulsed electrolysis. © 2008 The Japan Institute of Metals.