Deposição de filmes protetores finos de SiO2 pelo método sol-gel sobre aço inoxidável 316L

Abstract

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Thin SiO2 films were deposited on 316L stainless steel sheets by a sol-gel method using Si(OC2H5)4 as precursor, absolute ethanol, glacial acetic acid and water as solvents and the application of ultra-sound radiation. After heating up to 800°C in air, the properties of the densified coatings were studied by X-ray Diffraction and FTIR Reflection Spectroscopy. The chemical protection of these coatings against thermal oxidation of the steel in air was determined by weight-gain measurements. Potentiodynamic polarization curves at 1 mV s(-1) in aqueous 15 % H2SO4 solutions at different temperatures were used to analyze the protection of the coatings against acid corrosion of the steel. In both cases, the SiO2 films proved to be very efficient protectors against corrosion. Calculations based on the measured corrosion rate in acid solutions showed that the life-time of the substrate can be increased by a factor of 3 to 5.