Anodizing process, with low environmental impact, for a woodpiece of aluminum or aluminum alloys

Abstract

The process for anodizing a workpiece of aluminum or aluminum alloys provides for the use of the workpiece as the anode of an electrolytic cell in the presence of an aqueous acid solution which contains from 10 to 200 g sulfuric acid and from 5 to 200 g L(+)-tartaric acid.

What is claimed is:  
     
         1 . Process for anodizing a workpiece of aluminium or aluminium alloys, which provides for the use of the workpiece as the anode of an electrolytic cell in the presence of an aqueous acid solution, 
 wherein the aqueous acid solution contains from 10 to 200 g sulphuric acid and from 5 to 200 g L(+)-tartaric acid.    
     
     
         2 . Process according to  claim 1 , wherein the aqueous acid solution contains from 20 to 80 g sulphuric acid and from 30 to 120 g L(+)-tartaric acid per liter of solution.  
     
     
         3 . Process according to either of the preceding claims, wherein the solution is maintained, during the anodizing treatment, at a temperature of between ambient temperature and 120° C., and preferably between 25 and 35° C.  
     
     
         4 . Process according to  claim 1 , wherein the electrolytic cell is subjected to a voltage of between 1 and 120 V, and preferably of between 10 and 30 V.  
     
     
         5 . Process according to  claim 1 , wherein it has a duration of between 5 and 120 minutes, and preferably of between 5 and 30 minutes.  
     
     
         6 . Process according to  claim 1 , wherein it is preceded by a cleaning, deoxidizing and rinsing treatment for the workpiece to be anodized.  
     
     
         7 . Process according to  claim 1 , wherein it is followed by a rinsing and sealing treatment for the anodized workpiece.