An insight on the corrosive performance of acrylic-epoxy based coatings: the significance of its electrochemical impedance evaluations

Since few decades, researchers have continuously devoted significant efforts to develop coatings as an alternative approach to protect corrosion. Herein, a series of coatings containing various ratios of acrylic and epoxy resins were developed to investigate the corrosion protection on mild steel substrates. In addition, 1 wt% polydimethylsiloxane (PDMS) solution was incorporated as a modifier to enhance the corrosion protection performance and the hydrophobicity of the coatings. The chemical structures and thermal stability of the fabricated coatings were evaluated by the Fourier-Transform Infrared Spectroscopy (FTIR) and Thermogravimetric (TGA) analysis respectively. Furthermore, via the utilization of ultraviolet-visible (UV-Vis) spectroscopy and water contact angle (WCA) instrument, the degree of transparency and surface wettability of the coating samples were investigated. Electrochemical impedance spectroscopy (EIS) was employed to evaluate the corrosion protection performance of the coatings. Among all the coating samples, the EIS results revealed that the T1, T5, and T7 coating samples containing higher ratios of acrylic resin exhibited pronounced impedance modulus ( Z 0.01 H z ) values exceeding 10 10 Ω cm 2 throughout 60 days of exposure to the corrosive medium, 3.5 wt% NaCl solution. Moreover, this finding was supported by the breakpoint frequency measurement which showed that the T1 and T5 coating samples performed at a full capacitive region even after 60 days of immersion. From this investigation, it was concluded that the T5 coating sample exhibited optimum results, thus enhancing the overall corrosion protection performance.