Hard Coating Treatment of Aluminum and Aluminum Alloys Processing and Performance Requirements
This specification establishes the engineering requirements for producing a hard coating on aluminum and aluminum alloys and the properties of such coating. This process has been used typically to increase, by the formation of a dense aluminum oxide, surface hardness and resistance to abrasion and corrosion of aluminum and aluminum-alloy parts containing, in general, less than 5% copper or 8% silicon or a total of 8% of both, but usage is not limited to such applications. Alloys with higher silicon content can be coated satisfactorily with proper precautions in processing. Careful consideration should be given when using this process on highly-stressed parts because of the resultant marked lowering of fatigue performance and on parts with sharp corners and edges where chipping may result.