Plating method for aluminum alloy material

Abstract

There is provided a method of applying plating to an aluminum alloy material, which comprises a step of cathodic acid electrolysis as a pretreatment for the plating for removing insoluble matters from the aluminum alloy generated in a previous alkaline-etching step.

1 . A method of applying plating to an aluminum alloy material, which comprises a step of cathodic acid electrolysis as a pretreatment for the plating for removing insoluble matters in the aluminum alloy generated in a previous alkaline-etching step.  
   
   
       2 . The method according to  claim 1 , wherein the cathodic acid electrolysis is performed in a solution of ferric sulfate with the aluminum alloy material being employed as a cathode.  
   
   
       3 . The method according to  claim 1 , wherein the aluminum alloy material is a cylinder for an internal combustion engine wherein the plating is applied to a sliding surface of piston of the cylinder.  
   
   
       4 . The method of  claim 3  wherein the iron plating is applied to the sliding surface of the piston.  
   
   
       5 . A cylinder for an internal combustion engine, which is featured in that a sliding surface of piston thereof is applied with an iron plating according to the method claimed in  claim 3 .  
   
   
       6 . A method of applying plating to an aluminum alloy material, which comprises the steps of: 
 degreasing the aluminum alloy material;    subjecting the degreased aluminum alloy material to an alkali-etching treatment;    subjecting the alkali-etched aluminum alloy material to cathodic acid electrolysis;    subjecting the electrolyzed aluminum alloy material to an anodic oxidation treatment; and    applying plating to the anodically oxidized aluminum alloy material.    
   
   
       7 . The method according to  claim 6 , wherein the cathodic acid electrolysis is performed in a solution of ferric sulfate with the aluminum alloy material being employed as a cathode.  
   
   
       8 . The method according to  claim 6 , wherein the aluminum alloy material is a cylinder for an internal combustion engine wherein the plating is applied to a sliding surface of a piston of the cylinder.  
   
   
       9 . The method of  claim 8  wherein the iron plating is applied to the sliding surface of the piston.  
   
   
       10 . A cylinder for an internal combustion engine, which is featured in that a sliding surface of piston thereof is applied with an iron plating according to the method claimed in  claim 8.