Novel multilayer structural epoxy composite coating containing graphene oxide and silanized chromium carbide for the protection of steel structures

Abstract

Nanocomposite coatings have been extensively used in the manufacture of automotive components to protect against corrosion of steel structures. The (3-mercaptopropyl) tris[2-(2-methoxyethoxy) ethoxy] silane (MPTMEES) functionalized Cr₃C₂ was encapsulated with graphene oxide (GO) as an efficient nanofiller in the epoxy matrix (EP). The silanized chromium carbide wrapped in graphene oxide was tested by SEM/EDX and TGA. Electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) were used to study the protective performance of epoxy coating on steel in the presence of varying weight percentages of graphene oxide wrapped silanized chromium carbide in seawater. After 1 h of immersion, the coating resistance of EP-MPTMEES/Cr₃C₂ was determined to be over 43% higher than that of pure matrix. After 240 h in seawater, EIS tests revealed that EP-GO/MPTMEES-Cr₃C₂ nanocomposite coatings had a higher coating resistance (6340 kΩ.cm²) than ordinary epoxy (1.2 kΩ.cm²) coatings. Because of the coated substrate’s improved resistance to anodic dissipation, the least dissipation of ferrous ions was found at the crack of the EP-GO/MPTMEES-Cr₃C₂ nanocomposite coated steel specimen (1.5 I/nA). The silanized Cr₃C₂ was reinforced in the degradation products, forming an excellent passive layer at the coating/steel contact, according to FE-SEM/EDX analysis. The newly developed EP-GO/MPTMEES-Cr₃C₂ nanocomposite coating had improved corrosion protection and enhanced hydrophobic characteristics (WCA: 146°), according to the findings. The epoxy matrix with graphene oxide wrapped silanized chromium carbide demonstrated improved adhesive capabilities.