Development and characterization of sol–gel silica–alumina composite coatings on AISI 316L for implant applications

Sol–gel alumina coatings were deposited on medical grade stainless steel (AISI 316L) with an intermediate layer of silica by dip-coating method. The coatings obtained were homogeneous, crack-free and consisted of low crystalline γ-Al2O3 along with some boehmite phase. EDAX revealed the presence of only Al in the film. The corrosion performance of alumina-coated stainless steel was evaluated by electrochemical polarization, open-circuit potential measurement and chronoamperometry in Ringerʹs solution. Coating has shown to enhance the pitting potential of AISI 316L by ∼ 470 mV and reduced passive current ≤ 10− 9 A cm− 2. The formation of thermodynamically stable silica–alumina interface was proposed to account for enhanced corrosion protection behaviour of the coating.