| 摘要 |
PURPOSE:To improve corrosion resistance of blank steel under various corrosive circumstances by forming a film of zinc plating on the surface of blank steel and forming a ductized film on the film. CONSTITUTION:The surface of blank steel 1 is cleaned by degreasing, washing with water, pickling etc. Then, a zincplating film 2 is formed by generally known method. After forming the film 2, it is washed with water and dried, and ductile processing is performed. That is, it is immersed in aqueous dispersion containing metallic zinc particles, chromic acid anhydride, organic solvent etc. It is then baked to form a ductized film 3 on the film 2. One coat and one bake are sufficient for the film 3. However, two coats and two bakes are made if necessary. By this way, defective parts of the film 3 are filled up with corrosion product of the film 2, and supply of electrolyte and oxygen to the blank steel 1 is lessened. Thus, corrosion protecting effect is improved. |
