Electrodes and methods of making same

Abstract

Abstract A surface region of a body of titanium or a titanium -base alloy of similar anodic polarization properties is coated with a fine scale mixture of a relatively insoluble metal and a more easily soluble metal and the latter is subsequently dissolved out thus forming an electrode having a large surface area. As described the insoluble metal is one of the Group VIII platinum group metals or an alloy consisting of such metals and the soluble metal is copper, silver, nickel or tin. The fine scale mixture may be formed by successively electro-plating with the insoluble and soluble metals and heating to cause them to interdiffuse e.g. by plating titanium with platinum from an alkaline bath containing sodium hexahydroxy platinate, optionally heating, e.g. at 780 DEG C., to bond the plating to the base, then electro-plating with copper and heating to 400 to 800 DEG C. The soluble metal e.g. copper may then be removed by chemical etching in nitric acid or anodic etching in sulphuric acid. The resulting electrode has a reduced over-voltage when used as anodes e.g. in the electrolysis of sodium chloride solution. Reference is made to effecting coating by dipping, chemical reduction, or vapour deposition, or pack treatment in metal powder, and to co-deposition of the insoluble and soluble metals prior to electro-plating the titanium may be etched in HCl and scrubbed with abrasive powder.

Inventors

• 👤 Joseph Bernard Cotton
• 👤 Peter Charles Steele Hayfield

Bibliographic Details