Method for sealing pores

Abstract

A method for sealing pores includes: providing an object which includes a substrate formed of a metal or alloy of the metal, and a passivation layer formed on the substrate, the passivation layer being formed of metal oxide and having a plurality of pores; immersing the object as a cathode and an anode in a solution containing metal cations and anions; providing an electric current between the anode and the object with an electric current density across the object being less than 0.5 A/dm 2 , such that the metal cations and anions in the solution undergo a redox reaction on the passivation layer; and sealing the pores of the passivation layer with a metallic compound formed by the redox reaction of the metal cations and the anions in the solution.

1 . A method for sealing pores comprising:
 providing an object which includes a substrate formed of a metal or alloy of the metal, and a passivation layer formed on the substrate, the passivation layer being formed of metal oxide and having a plurality of pores;   immersing the object as a cathode and an anode in a solution containing metal cations and anions;   providing an electric current between the anode and the object with an electric current density across the object being between 0.02 A/dm 2  and 0.06 A/dm 2 ; and   sealing the pores of the passivation layer with a metallic compound formed by reaction of the metal cations and the anions in the solution.   
     
     
         2 . (canceled) 
     
     
         3 . The method as claimed in  claim 1 , wherein the metal cations in the solution is selected from the group consisting of nickel ions, chromium ions, and zirconium ions. 
     
     
         4 . The method as claimed in  claim 1 , wherein the anions in the solution is at least one selected from the group consisting of acetate ions, fluoride ions, and sulfate ions. 
     
     
         5 . The method as claimed in  claim 1 , wherein the solution has a pH value ranging between 3 and 7. 
     
     
         6 . The method as claimed in  claim 1 , wherein the solution has a temperature that is controlled between 60° C. and 96° C. 
     
     
         7 . The method as claimed in  claim 1 , wherein the anode is at least one selected from the group consisting of a carbon anode, a stainless steel anode, an aluminum anode, and a lead anode. 
     
     
         8 . The method as claimed in  claim 1 , wherein the metal of the substrate is at least one selected from the group consisting of aluminum, magnesium and titanium. 
     
     
         9 . The method as claimed in  claim 1 , wherein the object further includes a dye dispersed in the passivation layer.