| 摘要 |
<p>A method for treating a metal surface with zinc phosphate of this invention can treat an iron-based surface, a zinc-based surface, an aluminum-based surface as well as a metal surface having two kinds or more of these surfaces with the same zinc phosphate treating solution, and even if treating times increases, the method makes it possible to form a coating film having superior adhesion and high corrosion resistance under a stable condition, and also, it prevents a precipitate formed by a metal ion eluted from a metal surface to be treated, especially, by an aluminum ion. A complex fluoride compound contained in said zinc phosphate treating solution of coming in contact with a metal surface is added so that a concentration ( unit: g/l ) converted into at least one of a hexafluorosilicic acid group ( SiF6<2><-> ) and a tetrafluoroboric acid group ( BF4 <-> ), with an aluminum ion concentration ( unit: g/l ) contained in said treating solution, is satisfactory for the following equation (I). <MATH> d</p> |
