Towards remarkable corrosion protection by synergizing PANI with plasma-electrolyzed inorganic layer

Abstract

Notwithstanding the increasing interest in the enhancement of the corrosion properties of active metallic materials, the role of organic corrosion barrier remains insufficiently understood with respect to the formation of structural microdefects in the inorganic layer and the decrease in the corrosion rate. The present work proposed the mechanism by which an organic polymer would improve the barrier properties of the defective TiO₂ coating as an inorganic layer and thereby, improve corrosion protection. This protection mechanism enhances the hydrophobicity of the TiO₂ surface because of the notable homogeneity of the organic polymer polyaniline (PANI). The adsorption of PANI on the surface of the TiO₂ coating was verified using SEM and EDAX. The electrochemical performance was enhanced remarkably because of the integral synergy between TiO₂ and PANI in the composite, which could be controlled by adjusting the number of deposition cycles. In addition, the novel protection mechanism of this hybrid layer was based on the counter anions stored within PANI. These were released as active corrosion inhibitors upon the onset of a severe chemical attack on the TiO₂ layer or metal substrate. Thus, these composites reduced the diffusion of metal ions and prevented the penetration of corrosive ions, thereby yielding a remarkable corrosion resistance.