ES361889A1 - Electrodes for electrochemical processes - Google Patents

Abstract

An electrode, which may be used as an anode in a Hg cathode cell for the electrolysis of brine, comprises a support material in the form of a "valve metal" carrying on at least a part of its surface a layer of an "operative electrode material" in combination with an "inorganic glaze". "Valve metal" means Ti, Zr, Nb, Ta, W or an alloy comprising more than 50% by weight of one of these metals. "Operative electrode material" means an electroconducting material which is active in transferring electrons to or from the ions of an electrolyte and which is resistant to electrochemical attack. The material may be a platinum metal (i.e. Pt, Rh, Ir, Ru, Os, Pd or an alloy of two or more of these metals) and/or oxides thereof. "Inorganic glaze" means an inorganic oxide or a combination of such oxides which has been laid down by solidification in the vitreous condition from the molten state. The electrode may be made by depositing on the valve metal a coating of the operative electrode material, applying over the coating a layer of an inorganic glazing composition and melting the glaze. Alternatively, both the operative electrode material and the glazing composition may be deposited in a single step from a suspension containing particles thereof. The glaze may comprise silica, titania and zirconia. The glaze may be produced by coating the electrode with an aqueous sodium silicate solution optionally containing titania and then firing the coating. In an example, Ti was etched in oxalic acid coated with Ru by painting on a mixture containing ruthenium chloride, isopropyi alcohol and, as reducing agent, linalool and then heating at 300 C. in air to dry the Ru coated Ti was then heated in air at 450 C. to oxidize at least the outermost part of the Ru layer glass enamelling slip was applied and melted by heating at 590 C. The slip consisted of PbO, B 2 O 3 , SiO 2 , CdO, Na 2 O, kaolin and H 2 O.