Method of surface treating metal and metal surface treated thereby

Abstract

It is an object of the present invention to provide a method of metal surface treatment and a surface treated metal thereby, which has excellent corrosion resistance and can form a coat having high corrosion resistance on metal substrates such as iron, zinc, aluminum and magnesium. A method of metal surface treatment comprising the step of forming a chemical conversion coat on the surface of a metal article to be treated by a chemical conversion treatment reaction by a chemical conversion treatment agent containing a zirconium-containing compound and a fluorine-containing compound, wherein said chemical conversion treatment reaction is conducted through cathodic electrolysis treatment.

1 . A method of metal surface treatment comprising 
 the step of forming a chemical conversion coat on the surface of a metal article to be treated by a chemical conversion treatment reaction by a chemical conversion treatment agent containing a zirconium-containing compound and a fluorine-containing compound,    wherein said chemical conversion treatment reaction is conducted through cathodic electrolysis treatment.    
     
     
         2 . The method of metal surface treatment according to  claim 1 , 
 wherein the cathodic electrolysis treatment is conducted in conditions that the concentration of the zirconium-containing compound in the chemical conversion treatment agent is adjusted to 10 to 100000 ppm on the zirconium metal equivalent basis, a ratio of weight as the total zirconium metal to weight of the total fluorine (amount of zirconium/amount of fluorine) is adjusted to within 0.2 to 1.0 and a pH of the chemical conversion treatment agent is adjusted to within 1 to 6.    
     
     
         3 . The method of metal surface treatment according to  claim 1  or  2 , 
 wherein the cathodic electrolysis treatment is conducted in conditions of voltage of 0.1 to 40 V and current density of 0.1 to 30 A/dm 2 .  
 
     
     
         4 . The method of metal surface treatment according to any of  claim 1  or  2 , 
 wherein the metal article to be treated is at least one species selected from the group consisting of an aluminum-based substrate, a zinc-based substrate, an iron-based substrate, and a magnesium-based substrate.  
 
     
     
         5 . A surface treated metal having a chemical conversion coat attained by the method of metal surface treatment according to  claim 1  or  2 .