A procedure for preparing titanium alloys is described. The procedure includes activation in a solution of chromic and hydrofluoric acids and perferentially dissolves the baser phase of the titanium alloys. Titanium alloys can then be plated, obtaining good adhesion. Adhesion ranges from 70-120 N/mm2.
Only during chromium plating, titanium alloys absorb an excessive amount of hydrogen, but interposing a 20 μm thick nickel barrier inhibits hydrogen pickup. Fatigue loss of plated titanium alloys can be improved by shot peening to about the same level as measured for unmachined, unplated specimens.
Nickel or electroless nickel plating on titanium alloys exposed to temperatures above 450°C give rise to the formation of hard layers of intermetallic phases caused by diffusion of nickel into titanium. Chromium-titanium diffusion reaction starts above 750°C.