Protection of AA 6061 alloy from combined environmental corrosion for aerospace applications

The recent trend in aerospace industry is to develop coatings for protecting aerospace materials from various combinations of environments. One such combination is protection of aluminium alloy 6061 from combined environments of marine and high temperature. Present study pertains to development of polymeric coating with aluminium metal phosphate with appropriate fillers to withstand 500°C with a thermal gradient of 400°C for duration of 2 minutes. Various pre-treatments of the base metal have been carried out and adhesion, thermal resistance, potentio-dynamic polarization and impedance tests are conducted to establish thermal and corrosion resistance of the developed coating. Additives of zirconium oxide, silica and some organic fibers in the coating have been optimized to 30% to achieve maximum adhesion strength. Significant increase in thermal and corrosion resistance of base metal has been achieved with present coating system for 6061 Al-alloy.