Electroplating method for magnesium and magnesium alloy

Abstract

An electroplating method for magnesium and magnesium alloys, comprising: providing a magnesium or magnesium alloy substrate and pre-treating it to be cleaned; roughening the surface of the substrate; activating the surface of the substrate; chemically plating the substrate to form a nickel coating on its surface; and electroplating the substrate to form, in order, a first nickel coating, a copper coating, a second nickel coating, and a chromium coating on the chemically produced nickel coating.

1 . An electroplating method for magnesium and magnesium alloys, comprising:
 providing a magnesium or magnesium alloy substrate and pre-treating it to be cleaned;   roughening the surface of the substrate;   activating the surface of the substrate;   chemically plating the substrate to form a nickel coating on its surface; and   electroplating the substrate to form, in order, a first nickel coating, a copper coating, a second nickel coating, and a chromium coating on the chemically produced nickel coating.   
   
   
       2 . The electroplating method as claimed in  claim 1 , wherein roughening the surface of the substrate is carried out by dipping the substrate in a roughening solution containing pyrophosphate in a mass concentration of about 350-450 g/L and sodium carbonate in a mass concentration of about 50-100 g/L for about 10-30 minutes at about 55-65° C. 
   
   
       3 . The electroplating method as claimed in  claim 1 , wherein activating the surface of the substrate is carried out by dipping the substrate in an activating solution containing hydrofluoric acid in a concentration by volume of about 150-300 ml/L for about 1-5 minutes at about 30-40° C. 
   
   
       4 . The electroplating method as claimed in  claim 1 , wherein chemically plating the substrate is carried out by immersing the substrate in a solution containing sodium hypophosphite in a mass concentration of about 10-30 g/L and basic nickel carbonate in a mass concentration of about 20-50 g/L for about 20-60 minutes at about 70-90° C. 
   
   
       5 . The electroplating method as claimed in  claim 1 , wherein electroplating the substrate to form the first nickel coating is carried out in a first electrolyte containing a nickel sulphate component in a mass concentration of about 240-300 g/L, a nickel chloride component in a mass concentration of about 30-50 g/L, and a boric acid component in a mass concentration of about 30-50 g/L at about 50-55° C.; the electric current density through the first electrolyte is about 1-4 A/dm 2 ; and the electroplating lasts for about 4-10 minutes. 
   
   
       6 . The electroplating method as claimed in  claim 1 , wherein electroplating the substrate to form the copper coating is carried out in a second electrolyte containing a copper sulphate component in a mass concentration of about 180-220 g/L, and a sulfuric acid component in a mass concentration of about 40-80 g/L at about 20-25° C.; the electric current density through the second electrolyte is about 1-3 A/dm 2 ; and the electroplating lasts for about 5-30 minutes. 
   
   
       7 . The electroplating method as claimed in  claim 5 , wherein electroplating the substrate to form the second nickel coating is carried out in substantially the same way as was the forming the first nickel coating. 
   
   
       8 . The electroplating method as claimed in  claim 1 , wherein electroplating the substrate to form the chromium coating is carried out in a third electrolyte containing a chromium sulphate component in a mass concentration of about 240-300 g/L, and a boric acid component in a mass concentration of about 70-90 g/L at about 30-50° C.; the electric current density through the third electrolyte is about 1-15 A/dm 2 ; and the electroplating lasts for about 1-15 minutes. 
   
   
       9 . The electroplating method as claimed in  claim 8 , wherein the substrate is subjected to neutralization treatment after the electroplating process in a neutralization solution including a sulfuric acid component in a concentration by volume of about 20-50 ml/L, and an oxydol component in a concentration by volume of about 50-100 ml/L for about 1-3 minutes at about 20-30° C. 
   
   
       10 . The electroplating method as claimed in  claim 1 , wherein pre-treating the substrate includes degreasing and cleaning the substrate.