Electrodeposition of High-bright Hard Cr-C Layers on Steel Plate Cold-rolled Commercial from Trivalent Chromium/Organic Additives/Highly Concentrated Conductive Salt Aqueous Baths

Abstract

To prepare Cr-C alloy layers having high current efficiency, high Vickers hardness, and high brightness in electrodeposition on commercial cold-rolled steel plate, this study examined additives put into electrodeposition baths. From a Cr₂ （SO₄）₃/（NH₄）₂SO₄ aqueous bath containing oxalic acid and CrCl₃/highly concentrated CaCl₂/H₃BO₃ aqueous bath containing glycine, Cr-C alloy layers having high current efficiency, high Vickers hardness, and high brightness were formed. With the optimized bath compositions, the Cr-C alloy layers were produced with high current efficiency, high Vickers hardness, and high brightness. The highest current efficiency of 31.8% was obtained in a 0.4 mol kg^－1 glycine/0.75 mol kg^－1 CrCl₃/4.68 mol kg^－1 CaCl₂/0.49 mol kg^－1 H₃BO₃ bath. The Cr-C layers mainly comprised Cr₃C₂ and Cr₇C₃ alloys.