Thermal degradation of a Mg-Rich primer on AA 2024-T3

摘要

The effectiveness of chromate-based coatings at mitigating the corrosion associated with aluminium alloys has resulted in these coating being the prototype for the protection of aluminium aircraft structures (1,2). The United States Air Force have used pigments based on zinc chromate, zinc tetroxy chromate and strontium chromate to inhibit the corrosion of AA 2024-T3 structures (3). An environmental limitation is associated with the use of the chromate-based coatings due to the leaching of the soluble chromate from the polymeric binder. The toxic nature of chromates (4,5) has led to the introduction of Federal regulations by the United States government into the use of chromate-based pigments (6). The corrosion protection afforded by chromate-based pigments is due to the passivating of the aluminium surface. Inhibitors that similarly passivate the aluminium surface have been proposed and include vanadates, phosphates, molybdates, borates and silicates (1,7,8,9).