| 摘要 |
PURPOSE:To prevent defective plating by pretreating sintered metal with nonaqueous solution, and then treating the surface of the sintered metal to form a protective film on its surface. CONSTITUTION:Sintered metal made of Nd-Fe-B permanent magnet is pretreated with nonaqueous solution. The pretreatment includes the step of activating it with inorganic acid of nonaqueous solution using mixture liquid of organic solvent such as alkyl alcohol, etc., strong acid of nitric acid, etc., metal having lower ionization tendency than that of base material of the sintered metal, and salt with the strong acid. Then, a protective film is formed on the pretreated surface by a method such as electric nickel-plating, etc. Thus, the film having excellent adhesive properties, corrosion resistance and external appearance can be formed. |
