Protective properties of composite oxide coatings deposited by sol-gel method

In this work, we compare the protective properties, morphology, and adhesion of unary and composite, sandwich Al 2 O 3 –TiO 2 coatings deposited on X5CrNi18-9 austenitic stainless steel using the sol-gel method. It is found that the type and sequence of the films in investigated composite sandwich coatings have essential influence on their properties. The best protective properties exhibit coatings in which Al 2 O 3 film is directly on the substrate surface. The best adhesion is revealed in coatings in which TiO 2 film is directly on the steel surface. It is found that composite oxide sol-gel coatings improve the resistance of stainless steel better then unary coatings both in the range of electrochemical and high-temperature corrosion. This improvement can result from mutual influence of titania and alumina films by delay of their crystallization process.