Review of alternatives to chromate for corrosion protection of aluminum aerospace alloys

The advent of chromate replacements for aluminum alloys began in the late 1970s. As regulations became increasingly stricter, commercial, academic and government facilities have relied on a collaborative effort to come up with novel innovations for the corrosion protection of aerospace aluminum alloys. More elaborate coatings formulations have failed to produce the level of protection that chromates provide, therefore researchers have moved to more advanced technologies for improved protection. Some of the newer alternatives include low temperature cationic plasma deposition, sol-gel and ceramer coatings, various inorganic and organic inhibitors and conducting polymers including some based on double helical structures. Although ultimate protection has not been achieved by one single technique, it is believed that a combination of the most promising alternatives will provide the desired protection.