The quality of Aluminum Affect to Anodizing result

The condition that can’t be avoided to make a best result of anodizing aluminum is the purity of aluminum metal. The purity of aluminum is an important factor in electropolishing of the aluminum metal. An appreciable increase in reflectivity can achieved only in amount of admixtures is much less satisfactory. Very often polishing becomes impossible because of the non-uniform dissolution of the surface of the anode.

This factor renders difficult the polishing of aluminum alloys, especially those containing silicon. For the treatment of castings of an aluminum alloy containing 5 per cent silicon, an electrolyte comprising 13 per cent hydro-fluoroboric acid and 52 percent glycerin is recommended. The solution is used at 25 oC with a current density of 200 amp./sq.ft., the time of polishing being 10 minutes. During polishing the solution is stirred. Bath chemicals and conditioning are very dependent on the purpose of anodizing process.