A variety of electrochemical processes make use of platinum plated titanium electrodes. Before an adherent coating can be deposited onto the titanium, however, the tenacious oxide layer must first be removed, this being especially important if the thickness of the platinum deposit is to be greater than 2 to 3 micrometres, as is generally required for industrial use.

In a recent article M. Pushpavanam and S. R. Natarajan of the Central Electrochemical Research Institute, Karaikudi, India, describe experiments carried out to identify a titanium pretreatment procedure that would facilitate the direct electrodeposition of platinum from a dinitrosulphato platinous acid (DNS) system at pH 2–3 (Met. Finish., 1994, 92, (6), 85–87, 157).

Eight different etchant compositions were considered in the experimental programme and their performance assessed in terms of deposit appearance and adhesion, performance under corrosion conditions and the initial substrate metal weight loss. Adherent platinum coatings up to 8 micrometres thick, with good corrosion resistance, were produced by direct deposition after the titanium substrate had been treated in a solution of sodium fluoride, hydrochloric acid and acetic acid; the optimised conditions being identified in the article.