Abstract: A ceramic/metal composite material comprises a surface ceramic coating comprising an oxidized alloy of copper stabilized by being in solid solution with nickel oxide or manganese oxide on a substrate which is an oxidation resistant alloy essentially devoid of copper or any metal which oxidizes more readily than copper. The composite is made by oxidizing a copper-based alloy on a substrate and simultaneously oxidizing the substrate surface to form an oxygen-barrier interface, for example a chromium oxide layer formed on an alloy of chrominum with nickel, iron and/or cobalt. The composite may be used as anode substrate for a cerium oxyfluoride coating used in aluminum electrowinning.

Abstract: A non-consumable anode of the type comprising an oxide ceramic coating on a metal substrate, for molten salt electrolysis, namely the electrowinning of metals such as aluminum, has an electronically-conductive oxygen barrier layer between the oxide ceramic coating and the substrate, the oxygen barrier layer containing chromium oxide. Usually, the oxygen barrier layer is a surface film integral with a chromium-containing alloy substrate, comprising 10 to 30% by weight of chromium, 55 to 90% of nickel, cobalt and/or iron and up to 15% of aluminum, titanium, zirconium, yttrium, hafnium or niobium. The ceramic oxide coating may comprise copper oxide in solid solution with at least one further oxide; nickel ferrite; copper oxide and nickel ferrite; doped, non-stoichiometric or partially substituted spinels; or rare earth metal oxides or oxyfluorides.