Effect of graphene oxide wrapped functional silicon carbide on structural, surface protection, water repellent, and mechanical properties of epoxy matrix for automotive structural components

This study is aimed to develop novel nanocomposites with enhanced structural, mechanical and electrochemical properties for automotive applications. Polymeric coatings have been widely used in the automobile industry for the corrosion protection of metallic materials. The (3-aminopropyl)trimethoxysilane (APTMS) functionalized SiC was encapsulated by graphene oxide (GO) as an effective nanofiller in the epoxy matrix (EP). The protective performance of epoxy coating on mild steel in the presence of different concentrations of graphene oxide wrapped silicon carbide nanoparticles was evaluated in seawater by electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM). The optimum percentage of graphene oxide embedded SiC nanoparticles in the epoxy matrix was found to be 2.0 wt% in which the coating has the least agglomeration and appropriate corrosion resistance. The EIS measurements showed an enhanced coating resistance of EP-GO/APTMS-SiC nanocomposite (6498.17 kΏ.cm2) after 720 h immersion in seawater compared to EP-SiC (1124.95 kΏ.cm2) and plain epoxy (1.21 kΏ.cm2) coatings. It was found that the coating resistance of the EP-GO/APTMS-SiC nanocomposite coating was around 31% higher than that of the EP matrix. SECM measurements confirmed that the least dissipation of ferrous ions were observed at the crack of the EP-GO/APTMS-SiC nanocomposite coated steel specimen (1.6 I/nA) due to the improved resistance for anodic dissipation of the coated substrate. FE-SEM/EDX examined that Si was reinforced in the degradation products which formed an excellent passive layer at the coating/steel interface. The results showed that the newly developed EP-GO/APTMS-SiC nanocomposite coating possessed superior corrosion protection and enhanced hydrophobic behaviors (WCA: 131º). Therefore, it was concluded that the EP-GO/APTMS-SiC coatings on mild steel displayed superior surface protection, water repellent, and mechanical behaviors in the marine environment for long periods of exposure. Thus, EP-GO/APTMS-SiC coatings on mild steel can be used in industrial and marine applications.