Chemical conversion bath replenishment method

Abstract

The purpose of the present invention is to provide a method for replenishing an aluminum metal chemical conversion bath, the method being capable of maintaining the corrosion resistance and coating film adhesiveness of the chemical conversion coating formed even if the aluminum metal chemical conversion bath is used continuously. Provided is a method for replenishing an aluminum metal chemical conversion bath with a replenishing agent, wherein the replenishing agent comprises a zirconium salt and/or a titanium salt and an effective fluoride, and the replenishing agent is supplied so that the ratio F/Al of the fluorine ion concentration (mg/L) with respect to the aluminum ion concentration (mg/L) in the aluminum metal chemical conversion bath is 1.8-4.5.

1 . A method for replenishing an aluminum metal chemical conversion bath with a replenishing agent,
 wherein the replenishing agent comprises a zirconium salt and/or a titanium salt, and an effective fluoride, and   wherein the replenishing agent is supplied so that the ratio F/Al of the fluorine ion concentration (mg/L) with respect to the aluminum ion concentration (mg/L) in the aluminum metal chemical conversion bath is 1.8 to 4.5.   
     
     
         2 . The method according to  claim 1  for replenishing an aluminum metal chemical conversion bath, wherein the replenishing agent further comprises at least one kind selected from the group consisting of phosphoric acid, phosphorous acid and hydrogen peroxide. 
     
     
         3 . The method according to  claim 1  for replenishing an aluminum metal chemical conversion bath, wherein the aluminum metal chemical conversion bath comprises a zirconium salt and/or a titanium salt; an effective fluoride; at least one kind selected from the group consisting of phosphoric acid, condensed phosphoric acid and salts thereof; and at least one kind selected from the group consisting of phosphorous acid, hypophosphoric acid and salts thereof. 
     
     
         4 . The method according to  claim 1  for replenishing an aluminum metal chemical conversion bath, wherein the replenishing agent is supplied such that the chemical conversion bath has a pH in a prescribed range so as to give the F/Al ranging from 1.8 to 4.5. 
     
     
         5 . The method according to  claim 1  for replenishing an aluminum metal chemical conversion bath, wherein the replenishing agent is supplied such that the chemical conversion bath has an electric conductivity in a prescribed range so as to give the F/Al ranging from 1.8 to 4.5. 
     
     
         6 . The method according to  claim 1  for replenishing an aluminum metal chemical conversion bath, wherein a treatment target of the aluminum metal chemical conversion bath is an aluminum beverage can.