Abstract: An electrode adapted for chromium plating from trivalent chromium baths which comprises a conductive base, an electrode material layer comprising iridium oxide formed thereon, and a porous layer formed on the surface of the electrode material layer. The porous can comprise an oxide containing at least one element selected from the group consisting of silicon, molybdenum, titanium, tantalum, zirconium, and tungsten. Use of this electrode for chromium plating reduces the oxidation of trivalent chromium into hexavalent chromium.

Abstract: A chromium plating method using a plating bath comprising trivalent chromium and an electrode which is an anode comprising an electrode substrate of titanium, tantalum, zirconium, niobium or an alloy thereof, coated with an electrode catalyst comprising at least iridium oxide and, optionally, at least one of titanium, tantalum, niobium, zirconium, tin, antimony, ruthenium, platinum, cobalt, molybdenum, tungsten or an oxide thereof. The anode may be placed directly in the chromium plating bath or may be placed in an anode chamber partitioned from the chromium plating bath with an ion-exchange membrane. The chromium plating method may be a barrel plating method.

Abstract: There are described an anode, a process for producing the same, an apparatus for electrolytic chromium plating, and a method for electrolytic chromium plating, using such anode, wherein the anode comprises an electrically conductive substrate comprising a valve metal or an alloy thereof, a first intermediate layer formed on the sustrate and comprising an oxide of tin, a second intermediate layer formed on the first intermediate layer and comprising either (1) platinum metal and an oxide of tin, or (2) platinum metal, an oxide of tin, and iridium oxide, and a surface layer formed on the second intermediate layer and comprising either (1) platinum metal and an oxide of tin, or (2) platinum metal, an oxide of tin, and iridium oxide, the composition of said surface layer being different form that of said second intermediate layer.

Abstract: A method for the electrolytic pin plating of a steel plate using an insoluble anode, said anode being an insoluble electrode comprising a corrosion-resistant metal substrate having provided thereon a coating containing a platinum group metal or an oxide thereof, said anode being enclosed with a diaphragm.

Abstract: A method for the electrolytic pickling or degreasing of a steel plate in an aqueous solution having an electrode disposed therein, wherein an insoluble electrode or a ferrite electrode is used as the electrode, said insoluble electrode comprising an electrically conductive substrate having provided thereon directly or through an intermediate layer, an electrode coating containing a platinum group metal or an oxide thereof.

Abstract: A titanium composite material is disclosed which comprises a titanium or titanium alloy substrate, a base layer formed thereon of a calcium phosphate compound resulting from calcination of a hydrochloric or nitric acid aqueous solution of the calcium phosphate compound, and a covering layer thereon of a calcium phosphate compound formed by sintering a suspension of the calcium phosphate compound applied to the base layer. The composite material is useful as a biological implant. It is produced by activating the surface of the substrate, forming the base layer by calcining the solution coated on the substrate and then forming the covering layer by sintering the suspension coated on the base layer. The covering layer may be hydrothermally treated to increase its crystallinity.

Abstract: A process for recovering sulfuric acid from an aqueous sulfuric acid solution containing ferrous sulfate is disclosed, which comprises electrolyzing the aqueous sulfuric acid solution containing ferrous sulfate to thereby oxidize ferrous ion dissolved in the solution to ferric ion, and then removing the ferric ion by solvent extraction using a solvent and an extractant.

Abstract: An electrode for electrolysis is disclosed, comprising an electrode substrate made of a conductive metal having provided thereon an intermediate layer and a coating of an electrode active substance, in which an intermediate layer is formed by tin-plating and is composed of a tin and/or tin oxide. The electrode exhibits high resistance to passivation and excellent durability, and is particularly suitable for use in electrolysis accompanied by oxygen generation and for organic electrolysis.

Abstract: A method of electrolytically treating metals with an a.c. current or alternating pulsive current using an electrode comprising a metal substrate having a coating that comprises an oxide of ruthenium, iridium or rhodium as a counter electrode.

Abstract: A titanium composite material is disclosed which comprises a titanium or titanium alloy substrate, a base layer formed thereon of a calcium phosphate compound resulting from calcination of a hydrochloric or nitric acid aqueous solution of the calcium phosphate compound, and a covering layer thereon of a calcium phosphate compound formed by sintering a suspension of the calcium phosphate compound applied to the base layer. The composite material is useful as a biological implant. It is produced by activating the surface of the substrate, forming the base layer by calcining the solution coated on the substrate and then forming the covering layer by sintering the suspension coated on the base layer. The covering layer may be hydrothermally treated to increase its crystallinity.

Abstract: A process for producing a calcium phosphate compound coated composite material is disclosed, wherein a coating layer of a calcium phosphate compound is formed on the surface of a metal substrate by coating the surface of said metal substrate with an aqueous solution of nitric acid having hydroxyapatite dissolved therein, and then firing said coated substrate at a temperature of 300.degree. C. or more. The composite material is useful as implants (e.g., artificial bones, dentures, and dental roots) and cements therefor.

Abstract: An electrode for electrolysis which comprises an electrode substrate made of a conductive metal having thereon a coating of an electrode active substance is disclosed, in which a first intermediate layer comprising at least one compound of rare earth element and a second intermediate layer containing at least one of base metals and base metal oxides are provided between said electrode substrate and electrode active substance coating. The electrode exhibits high resistance to passivation and excellent durability, and is particularly suitable for use in electrolysis accompanied by oxygen generation and for organic electrolysis.

Abstract: A method for the manufacture of an electrode by a thermal treatment of a liquid composition containing an electrode component metal, where the electrode is produced in a high yield and high ratio of retention of the component metal, in which a liquid composition containing an electrode component metal and an organic compound as a ligand capable of forming a complex with a metal ion of the electrode component metal is heat treated.