Electrochemically assisted silanization treatment of an aluminum alloy under oxygen pressure for corrosion protection

A silane film was prepared on an aluminum alloy through electrochemically assisted deposition under different oxygen pressure levels. Surface morphology observation and corrosion resistance evaluation of the silanized aluminum alloy showed that silane film deposition was enhanced by exerting oxygen pressure during the electrochemically assisted silanization (EAS). The coverage degree and corrosion resistance of the silane film prepared under oxygen pressure increased compared with those of the silane film prepared by dipping or electrochemically assisted deposition without oxygen pressure. These phenomena were explained by the increased OH- ion generation rate under oxygen pressure due to the facilitated oxygen diffusion and by the fact that the OH- ions not only can accelerate the condensation reaction of the silanols but also increase the amount of hydroxyl groups on the surface of the Al alloy, consequently improving the formation of the silane film.