ציפוי אנודיזציה על גבי משטח מצופה ליישום בפריטים תעופתיים

מהנדס ניצן פוקס, חיל האוויר

Aluminum alloys are favored for structural parts in aircrafts, thanks to their low density and high corrosion resistance. In order to extend the work-life of a part, and to lower the chance of failure caused by corrosion, an anodic plating is applied. The oxide film created in the process provides superior protection compared to chromatic-conversion, another common plating for Aluminum.

The main disadvantage of the oxide film is that in order to repair a local defect in the film (pits, erosion, etc. ) one must first remove the film entirely. Removal of the oxide film removes some of the Aluminum beneath it, thinning the part. After several repair cycles, the dimensions of the part no longer meet the manufacturer's criteria and must be rejected. That can be problematic when no spare parts are available, or when trying to lower maintenance costs.

The IAF's Materials Division has developed a different method: Reapply an anodic plating on an existing one. A series of tests were conducted in accordance with aerospace specifications. The new film resembles the original one and demonstrates fine corrosion resistance properties. These results open the way for the repair of anodic plating without thinning the part.  At present, a 2 years validation of this process is performed by periodic inspections on serving parts.

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