Electrodeposition of aromatic bis-silanes for pretreatment of aluminum alloys
Abstract-It has been demonstrated that electrodeposition of silanes provides films exhibiting better corrosion resistance than other methods of silane-coating deposition, including dip coating and spray coating. Bis-silanes have been shown to form highly-hydrophobic, non-porous films. In this paper, the corrosion-resistance performance of aromatic bis-silane films on 6011 and 2024-T3 aluminum alloys is discussed. The silane films formed have been found to be protective against pitting and uniform corrosion for 1000h of salt-fog exposure. The silane film has been found to provide good adhesion to a commercial primer, making it a potential candidate for replacement of conventional chromate conversion coating pretreatment in protective coating systems. A mechanism is proposed for the bonding of the silane film to the oxide substrate as well as to the primer.