| 摘要 |
PURPOSE:To enable to completely carry out the plating to a prearranged part by preliminarily forming an oxalate film to a part not requiring the plating of a steel product by an aqueous oxalic acid solution. CONSTITUTION:An aqueous oxalic acid solution or an aqueous solution based on oxalic acid is coated on an unplated surface of a steel product and an oxalate film is formed by chemical formation. Said film is formed in an amount of about 1- 50g/m<2> in a film weight. Subsequently, the oxalate film formed steel product is heated in an oxidation furnace or a nonoxidation furnace and introduced into a reduction furnace to activate and purify a surface to be plated and, thereafter, immersed in a plating bath or flux treatment is applied to said surface to be plated and, after drying in a drying furnace, immersed in the plating bath to uniformly applying the plating only on said surface to be plated. Said plating inhibiting film can be easily removed by wet brushing or the like. Further, to said aqueous oxalic acid solution, as an activator, for example, hydrochloric acid or the like can be added and, as an oxidation promotor, for example, thiosulfate or the like can be added therewith and it is possible to add Mg, Ca or the like. |
