GB1373150A - Chromium oxide coating of electrically conducting surfaces and composition therefor - Google Patents

Abstract

1373150 Electro-depositing lubricating chromium oxide film M & T CHEMICALS Inc 15 June 1972 [30 June 1971] 28095/72 Heading C7B A lubricating, abrasion resistant film containing 0.1-100 mg/m<SP>2</SP> of a water-soluble surfactant occluded in trivalent chromium oxide is electrodeposited on an article having an electrically conductive surface, e.g. metal sheet or strip or metal-clad plastics, from an aqueous bath containing hexavalent chromium and at least one water-soluble surfactant. The hexavalent chromium may be added as chromic acid, all or part of which is replaced by sodium, potassium or lanthanum (di)chromate, strontium chromate or magnesium dichromate, in a concentration of from 1 to 100 g/l calculated as trivalent chromium oxide. The surfactant may be in a concentration of 0.05 to 20 g/l and comprise at least one organic sulphonic acid containing 6 to 30 C atoms, Na and K salt thereof, and mixed Na and K salt of organic di- and trisulphonic acid: e.g. Na dodecyldiphenylether disulphonate, hexylbenzene sulphonate, octylsulphonate and perfluoroethylcyclohexyl sulphonic acid. The bath may also contain, as catalyst anions, sulphate, chloride, fluoride, fluosilicate, fluoborate, fluoaluminate, fluotitanate or fluozirconate; and, as neutralizer and/ or buffer, phosphate, borate or carboxylate. The article may be of Fe, steel, brass, bronze, Cu, Zn, Al, Mg, Ni, Cr, Sn, Pb, or alloys thereof, or as can stock, e.g. steel plated with Zn, Sn or Cr; as metal-clad plastics, A-B-S, acetal, acrylic, alkyd, alkyl, amine, cellulosic, chlorinated polyether, epoxy, furane, fluorocarbon, isocyanate (urethane), polyamide (nylon), phenoxide, phenolic, polyester, polycarbonate, polyethylene, silicone, polystyrene, polyvinyl resins (or copolymers thereof) may be used.