Abstract
Ceramic coatings are widely used to protect metals against oxidation at high temperatures. In order to obtain ceramic layers with strong metal substrate adhesion, an original method has been developed. It involves pretreatment of the metal surface to form a functional conversion coating, characterised by strong interfacial adhesion with the substrate and by a particular morphology. Its particular texture allows the cathodic deposition of alumina and/or zirconia during electrolysis of aluminium and/or zirconium salt solutions. After heating, the coating presents a continuous composition gradient with refractory compounds at the surface. This electrochemical method offers a relatively easy way to establish coating composition and enables the preparation of a mixed ceramic layer. Results for Al2O3-ZrO2 coating preparation are presented. The electrochemical behaviour and chemical composition are analysed. Electrolytic bath composition, electrochemical parameters, and coating composition are correlated.
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