Electroplating of titanium on iron by galvanic contact deposition in NaCl–TiCl2 molten salt

摘要

A commercial titanium coating method is not available with the exception of physical vapor deposition or titanium cladding which are a very expensive processes. However, it is very attractive to coat the surface of steel with a thin titanium layer for improving its corrosion resistance against salt water or acids. This paper describes a method for electroplating a thin titanium layer on an iron surface by galvanic contact deposition in which pure titanium and an iron electrode are immersed into a molten salt (NaCl–TiCl₂) at high temperature; both electrodes are connected through an external circuit. By immersing iron in the molten salt for 10?h at 1200?K, we obtained a flat and thin layer of titanium–iron alloy on iron. The thickness and composition of this layer were 50±10?μm and Ti—15–16?mol% Fe, respectively. The corrosion resistance of this titanium-rich alloy layer is expected to be greater than that of steel. Galvanic contact deposition is a very simple method in which iron and titanium electrodes are just immersed into molten salts without the use of an external power source. Thus, the capability of the method presently proposed could be suggested so as to improve the corrosion resistance of steel, particularly from the practical process point of view.