Study of the corrosion resistance of modified chromate film obtained from low chromate concentration solutions

Conventional chromate films obtained from low chromate concentration solutions are not able to reach the standard of neutral salt spray test, herein they were modified by adding titanium with four valence into chromate solutions. Morphology, composition and structure of the obtained chromate film were studied by measurement of polarized electric resistance and neutral salt spray test, with result that corrosion resistance of the chromate film was greatly improved with the addition of titanium (IV) which attributes to the formation of titanium dioxide and titanyl sulfate in chromate films and their corrosion products. The existence of titanium dioxide and titanyl sulfate reduces the corrosion of zinc deposits.