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

• Steam treatment in the presence of TiO2 created a 1.3 μm thick oxide layer.
• Steam treatment resulted in the incorporation of TiO2 particles into the oxide layer.
• Incorporated TiO2 improved the corrosion resistance of steam-based oxide films.

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.