AQUEOUS SOLUTION FOR BLACKENING CHEMICAL CONVERSION COATING OF ZINC OR ZINC ALLOY SURFACE AND METHOD OF FORMING BLACKENED ANTI-CORROSION COATING FILM USING THE AQUEOUS SOLUTION FOR THE CHEMICAL CONVERSION COATING

• Main Authors: ENDO YASUHIKO, WATANABE SHUNJIRO
• Format: Patent
• Language: English
• Published: 07.07.2011
• Subjects: ADHESIVES; APPLYING LIQUIDS OR OTHER FLUENT MATERIALS TO SURFACES, IN GENERAL; CHEMICAL PAINT OR INK REMOVERS; CHEMISTRY; COATING COMPOSITIONS, e.g. PAINTS, VARNISHES ORLACQUERS; CORRECTING FLUIDS; DYES; FILLING PASTES; INKS; LAYERED PRODUCTS; LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT ORNON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM; METALLURGY; MISCELLANEOUS APPLICATIONS OF MATERIALS; MISCELLANEOUS COMPOSITIONS; NATURAL RESINS; PAINTS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; PERFORMING OPERATIONS; POLISHES; PROCESSES FOR APPLYING LIQUIDS OR OTHER FLUENT MATERIALS TOSURFACES, IN GENERAL; SPRAYING OR ATOMISING IN GENERAL; TRANSPORTING; USE OF MATERIALS THEREFOR; WOODSTAINS

The present invention provides a chromium-free surface treating method capable of treating a surface of a metallic member having a surface of zinc or zinc alloy so as to provide good blackness and rust inhibitive performance, and an aqueous solution for chemical conversion coating that can be applied to the treatment method. The aqueous solution contains neither trivalent or hexavalent chromium ion, and contains 5-20 g of phosphate ions per liter, 0.1-3 g of divalent iron ions per liter, 1-10 g of divalent manganese ions per liter, and 1-3 g of nitrate ions per liter. The aqueous solution has a pH of 1-3. A black coating film of Fe3O4 is formed by immersing the metallic member in the aqueous solution, then a conversion coating film of cerium oxide is formed thereon, and then a siliceous coating film is formed thereon.