Interface-dominated TiO2 nanotube-stearic acid coating beyond additive effects for corrosion protection

In aqueous environments, constructing hydrophobic interfaces represents one strategy for corrosion protection. Such interfaces reduce corrosion rates by isolating aqueous solutions from contact through low-surface-energy interface design. However, current hydrophobic interfaces rely on low-surface-energy modifications, facing failure due to insufficient coating adhesion. This study employs a composite coating formed by in-situ grown TiO2 nanotube arrays and stearic acid, investigating the corrosion protection capability and failure mechanisms of this composite structure. Simultaneously, under identical stearic acid loading conditions, the TiO2 nanotube array-stearic acid composite coating demonstrates superior corrosion protection compared to pure titanium surfaces loaded with stearic acid. SVET results indicate that the active corrosion centers of TiO2 nanotubes are located internally. An innovative ohmic circuit model is proposed to explain the mechanism behind the beyond additive effect. The results demonstrate that the TiO2 nanotube-stearic acid composite coating synergistically enhances corrosion protection through stearic acid filling within the TiO2 nanotube array. This work confirms the application potential of filling TiO2 nanotube arrays with hydrophobic agents for corrosion-protective coatings and provides insights for designing coating interfaces with ordered array structures.