Microstructure and corrosion performance of steam-based conversion coatings produced in the presence of TiO₂ particles on aluminium alloys

The steam-based conversion coatings containing TiO₂ particles were prepared using a two-step process comprising of spin coating of particles onto an aluminium substrate followed by a high-pressure steam treatment. Process has resulted in the formation of aluminium oxide layer (~1.3 μm thick) embedded with TiO₂ particles. The electrochemical measurements show the beneficial effect of TiO₂ particles in the oxide layer by exhibiting lowest anodic and cathodic activities, and reduced pit depth. The presence of TiO₂ particles shifts the corrosion potential values to positive side (noble side) when compared to the coatings without TiO₂ particles, while the shift in the pitting potential was a function of the steam treatment time and degree of particle incorporation into the oxide.