In-situ synthesis and excellent corrosion performance of strontium hydroxyphosphate/polyaniline composite with wrapped structure

Abstract

In the process of preventing corrosion in metal equipment or alloys, controlling electron transfer at the metal/electrolyte interface is essential to reduce the corrosion rate. In this study, cetyl-trimethyl ammonium bromide was employed as a template agent to facilitate the in-situ polymerization of aniline monomers in the presence of strontium hydroxyphosphate (Sr₅(PO₄)₃OH) particles. This resulted in the formation of a wrapped structure of Sr₅(PO₄)₃OH/polyaniline (Sr-HAP/PANI) composite through SrN coordination bonds. This structure hinders electron transport and increases the difficulty of corrosive ion diffusion, thus enhancing the anticorrosive properties of phosphate-based epoxy coatings. Furthermore, the composition of the coating surface was improved in terms of dispersion and hydrophobicity, which synergistically inhibits the infiltration of corrosive ions. The anticorrosion mechanism of the Sr-HAP/PANI composite was thoroughly investigated, revealing that the microcapacitance effect, electron transfer delay effect, and multilayer barrier effect work together to promote the anticorrosion performance of the composite coating. After 72 h of immersion in a 3.5 wt% NaCl solution, the total impedance value of the Sr-HAP/PANI coating increased to twice that of the epoxy resin. Overall, this paper presents a new environmentally safe organic/inorganic anticorrosion material with a promising potential in the field of corrosion inhibition.