Fabrication on designing of a macromolecular epoxy resin as anti-corrosive coating material for electrocatalytically deposited cadmium on 15CDV6 steel in 3% NaCl solution

Present study deliberates for the surface treatment of15CDV6 steel using electrolytic cadmium and its corrosion resistance behavior by a macromolecular epoxy coating (DGEBA-DAA) using computational and experimental techniques. Electrochemical results demonstrated that presence of the cadmium enhances the interfacial adhesion behavior of the DGEBA-DAA and same conclusion was reinforced through the computational studies carried out by means of density functional theory (DFT) and molecular dynamic (MD) simulations methods. EIS studies conducted at several time intervals varying from 1 h to 180 days showed that increase in immersion time results into the corresponding decrease in the corrosion resistance behavior of DGEBA-DAA coating as significant decrease in the values of charge transfer resistance (R_ct) and polarization resistance (R_p) were observed on increasing the immersion time. DGEBA-DAA coating showed the highest R_ct and R_p values of 6.61 kΩ cm² and 13.52 kΩ cm², respectively after 1 h immersion time whereas the lowest R_ct and R_p values of 1.07 kΩ cm² and 1.80 kΩ cm² were obsrved after 180 days immersion. Scanning electron microscopy (SEM) analysis coupled with energy dispersive spectroscopy (EDS) showed that increase in the immersion of 15CDV6 steel in electrolyte decreases the corrosion resistance of the DGEBA-DAA coating through the development, deepening and broadening of the micro-pores. DFT study indicated that DGEBA-DAA interacts through charge transfer (donor-acceptor) interactions in which polar functional groups act as sites for the interactions (adsorption). Outcomes of MD simulations studies depicted that DGEBA-DAA, adsorbed on the cadmium (Cd) surface using its flat or nearly flat orientation thereby acts as effective anti-corrosive coating material. Results of EIS, SEM-EDS, DFT and MDS analyses were in good agreement.