Corrosion Behaviour of Room Temperature Cured Polysilazane-Derived Silica Coatings on Al 5086

Silica coatings from polysilazane precursors were prepared to protect aluminium substrates from corrosion. Polysilazane can be converted to silica by simple exposition to air or basic vapours and the properties of the synthesized film make this precursor a valuable choice to obtain solid, crack-free, highly adhesive and protective coatings. The optimal deposition, obtained at 15 cm min-1 of dip-coating withdrawal speed, 20% PHPS precursor in n-butyl ether, 24 hours of exposition to 10% ammonia vapours and 6 days of ageing in air, manages to slow down the corrosion process by three orders of magnitude, therefore providing a longer lasting commodity. Specimens have been characterized by IR and XPS spectroscopy, AFM imaging and electrochemical studies.