Improving wear and corrosion protection of AISI 304 stainless steel by Al2O3-TiO2 hybrid coating via sol-gel process.

Al₂O₃, TiO_2, and Al₂O₃-TiO₂ coatings were deposited on AISI 304 stainless steel plates by the sol–gel dipping technique, and the effects of the coating composition on microstructure, wear, and corrosion characteristics were examined. Tribological features were determined by ball-on-disc sliding tests against an Al₂O₃ ball under a 10 N load, while corrosion properties were evaluated by potentiodynamic polarisation tests performed in 3.5% wt. NaCl solution. γ-Al₂O₃, α-Al₂O_3, and rutile phases were detected in the hybrid coatings. The highest coating thickness was obtained in single Al₂O₃ film and decreased with an increasing amount of TiO₂ nanoparticles. The single Al₂O₃ layer had both the highest wear resistance and the lowest corrosion resistance. Although TiO₂ addition caused an increase in the wear rate, it improved the corrosion resistance of the coating by filling the voids in the Al₂O₃ film. The Al₂O₃-TiO₂ hybrid film with a relative ratio of 6:1 as a candidate for the wear- and corrosion-resistant coating decreased wear and corrosion losses of the 304 substrates by 83% and 97%, respectively. [ABSTRACT FROM AUTHOR]