| 摘要 |
PURPOSE:To improve remarkably the corrosion resistance of an alloyed galvanized steel plate by electroplating a small amt. of zinc on the surface of said steel plate then forming a chromate film thereon. CONSTITUTION:Many cracks or craters exist on the surface of an alloyed galvanized steel plate and said surface has low corrosion resistance; therefore, the surface is electroplated thereon with zinc and is thereafter subjected to a chromating treatment. The zinc is electroplated on said surface to 0.01-0.2mu thickness equivalent to the amt. to be consumed in the succeeding stage, i.e., a chromating treatment. A chromated film is formed at 60-150mg/m<2> in terms of Cr on the zinc electroplated layer by the chromating treatment. The chromated film is formed to the inside of the cracks and craters existing on the alloyed galvanized surface, whereby the corrosion resistance is remarkably improved. |
