Observations on chromate conversion coatings from a sol–gel perspective

Chromate conversion coatings (CCCs) have been applied to aluminum substrates for many years to improve corrosion resistance and paint adhesion. In recent years the so-called sol–gel chemistry based coating systems have been examined as possible replacements for CCCs on aluminum. A mechanism is proposed for the formation of CCC on aluminum that is consistent with sol–gel chemistry principles. The conclusions illustrate important considerations for developing non-CCCs for aluminum.