| 摘要 |
PURPOSE:To prevent the generation of rust by bonding zinc particles with trivalent chromium compound to form a coat, forming the coat having a thickness more than a specified value on the surface of a back metal and adhering a pad onto the coat through adhesives. CONSTITUTION:A mixed treatment liquid of chromic acid and zinc particles 4 is applied to the surface of an iron back metal 1 by brushing, dipping or the like, treated by heating in a baking furnace at 300-330 deg.C to reduce sexivalent chromium to trivalent chromium, and the surface of the back metal 1 and the surfaces of the zinc particles 4 are coated with trivalent chromium compound 3 to interpose between the particles 4 and form a coat 2 integral therewith. The thickness of the coat 2 is more than 5mu in consideration of rust preventive capability. Accordingly, the controlled self-sacrifice protection of the zinc particles 4, the passive state of the back metal surface caused by chromic acid, barrier action of trivalent chromium compound are effected doubly or trebly to produce strong rust-preventive capability. |
