Sol-gel deposition of ZrO2 films in air and in oxygen-free atmospheres for chemical protection of 304 stainless steel : A comparative corrosion study

ZrO2 coatings for corrosion protection were deposited on 304 stainless steel by sol-gel method using zirconium propoxide as precursor and densified in air and in oxygen-free (argon or nitrogen) atmospheres. XRD and IR data of the films were practically independent of the atmosphere used in the densification step showing that the ceramic oxide is properly formed from the precursor. The corrosion behavior of the stainless steel substrate was studied by potentiodynamic polarization curves in the absence and the presence of ZrO2 coatings prepared in air, argon or nitrogen. The coatings extended the lifetime of the material by a factor of almost eight in a very aggressive environment, independently of the preparation procedure. The possibility of depositing pure or mixed oxide films by sol-gel methods in the absence of additional oxygen will allow the preparation of specific coatings onto oxygen-reactive substrates.