Hydrothermal treatment of sputtered Al-Zr and Al-Ti coatings was performed in an autoclave. Electron microscopy of generated conversion layers revealed dual layered boehmite films. Needle morphology at top, and thin compact oxide at interface with metal substrate was observed. X-ray energy dispersive, and photoelectron spectroscopy revealed enrichment of Zr or Ti in compact oxide, and oxidation of Zr, Ti and Al. Potentiodynamic polarization showed decrease in passive current densities due to treatment. Treated Zr containing surfaces showed lower corrosion current density when compared to those containing Ti. The observed electrochemical properties are correlated with microstructure and composition of conversion layers.
- Programområde 4: Mineralske råstoffer