Metal displacement solution, method for surface treatment of aluminum or aluminum alloy

Abstract

The present invention aims to provide a metal displacement solution that can provide good adhesion to a plating film (metal film), and a method for surface treatment of aluminum or an aluminum alloy using the metal displacement solution. Included is a metal displacement solution which contains a zinc compound, a nickel compound, a germanium compound, and a fluorine compound.

1 . A metal displacement solution, comprising:
 at least one zinc compound;   at least one nickel compound;   at least one germanium compound; and   at least one fluorine compound.   
     
     
         2 . The metal displacement solution according to  claim 1 ,
 wherein the metal displacement solution contains the zinc compound in an amount corresponding to a zinc concentration of 0.2 to 5.0 g/L.   
     
     
         3 . The metal displacement solution according to  claim 1 ,
 wherein the metal displacement solution contains the nickel compound in an amount corresponding to a nickel concentration of 0.2 to 10 g/L.   
     
     
         4 . The metal displacement solution according to  claim 1 ,
 wherein the metal displacement solution contains the germanium compound in an amount corresponding to a germanium concentration of 0.2 to 5.0 g/L.   
     
     
         5 . The metal displacement solution according to  claim 1 ,
 wherein the metal displacement solution contains the fluorine compound in an amount corresponding to a fluorine concentration of 5.0 to 50 g/L.   
     
     
         6 . The metal displacement solution according to  claim 1 ,
 wherein the metal displacement solution has a ratio of zinc concentration to germanium concentration of 1:5 to 5:1.   
     
     
         7 . The metal displacement solution according to  claim 1 ,
 wherein the metal displacement solution has a pH of 4.0 to 6.5.   
     
     
         8 . The metal displacement solution according to  claim 1 ,
 wherein the metal displacement solution is for treating aluminum or an aluminum alloy.   
     
     
         9 . A method for surface treatment of aluminum or an aluminum alloy, the method comprising:
 bringing a workpiece having aluminum or an aluminum alloy on its surface into contact with the metal displacement solution according to  claim 1  to remove an oxide film on the aluminum or aluminum alloy and displace the aluminum with the metals in the metal displacement solution to form a displacement metal film containing the metals on the surface of the workpiece.   
     
     
         10 . The method for surface treatment of aluminum or an aluminum alloy according to  claim 9 ,
 wherein the method comprises, after forming the displacement metal film, forming a plating film on a surface of the displacement metal film.