RETRACTED: Flame Retardant and Anticorrosion Behavior of Multifunctional Epoxy Nanocomposite Coatings Containing Graphitic Carbon Nitride/Silanized HfO<sub>2</sub> Nanofillers for the Protection of Steel Surface in Automobile Industry
Joseph Raj Xavier, S. P. Vinodhini, B. Ramesh, Raja Beryl J
Abstract
With the help of (3-trimethoxysilylpropyl) diethylenetriamine (TMSPETA), hafnium(IV) oxide (HfO 2 ), an inorganic nanofiller, was modified. The resulting TMSPETA/HfO 2 was then encased in graphitic carbon nitride (GCN) and placed within a pure epoxy resin (EP). The protective behavior of mild steel coated with epoxy in the presence of various concentrations of GCN/TMSPETA-HfO 2 was studied using electrochemical methods in seawater environment. It was found that the addition of 0.6 wt % of GCN/TMSPETA-HfO 2 to the epoxy resin produced maximum resistance. Hence, the optimum concentration of 0.6 wt % was utilized for further investigation. The PHRR and THR values for the GCN/TMSPETA-HfO 2 significantly decreased by 73% and 57%, respectively, as compared to pure EP, showing that the material is more flame retardant. The results of salt spray tests showed that the inclusion of GCN/TMSPETA-HfO 2 in the epoxy matrix enhanced the corrosion protection performance and reduced water absorption. EIS measurements showed that the epoxy-GCN/TMSPETA-HfO 2 had increased coating resistance of 6.42E9 Ω·cm 2 even after 320 h of exposure to seawater. According to SECM investigations, the coated steel with EP-GCN/TMSPETA-HfO 2 nanocomposite has the lowest ferrous ion dissipation (1.0 I/nA). FE-SEM/EDX investigation revealed that silanized GCN was enhanced in the degradation products, resulting in a durable inert nanolayered covering. The newly created EP-GCN/TMSPETA-HfO 2 coating was incredibly water-resistant, with a WCA of 165°. The TMSPETA-HfO 2 wrapped in GCN has demonstrated strong adhesion and hardness in the epoxy substrate as well as good mechanical properties. An increased adhesive strength (19.1 MPa) was achieved for mild steel coated with EP-GCN/TMSPETA-HfO 2 prior to being immersed in seawater. As a result, the coating has greater adhesive strength and can hold up even after a prolonged immersion. In light of this, the EP-GCN/TMSPETA-HfO 2 nanocomposite may be used as a coating component in the automotive industry.