Flame Retardant and Anticorrosion Behavior of Multifunctional Epoxy Nanocomposite Coatings Containing Graphitic Carbon Nitride/Silanized HfO_2 Nanofillers for the Protection of Steel Surface in Automobile Industry

摘要

With the help of (3-trimethoxysilylpropyl) diethylenetriamine(TMSPETA), hafnium(IV) oxide (HfO_2), aninorganic nanofiller, was modified. The resulting TMSPETA/HfO_2 was then encased in graphitic carbon nitride (GCN) andplaced within a pure epoxy resin (EP). The protective behavior ofmild steel coated with epoxy in the presence of variousconcentrations of GCN/TMSPETA-HfO_2 was studied usingelectrochemical methods in seawater environment. It was foundthat the addition of 0.6 wt of GCN/TMSPETA-HfO_2 to theepoxy resin produced maximum resistance. Hence, the optimumconcentration of 0.6 wt was utilized for further investigation. ThePHRR and THR values for the GCN/TMSPETA-HfO_2 significantlydecreased by 73 and 57, respectively, as compared topure 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. EISmeasurements showed that the epoxy-GCN/TMSPETA-HfO_2 had increased coating resistance of 6.42E9 Ω·cm~2 even after 320 h ofexposure to seawater. According to SECM investigations, the coated steel with EP-GCN/TMSPETA-HfO_2 nanocomposite has thelowest ferrous ion dissipation (1.0 I/nA). FE-SEM/EDX investigation revealed that silanized GCN was enhanced in the degradationproducts, resulting in a durable inert nanolayered covering. The newly created EP-GCN/TMSPETA-HfO_2 coating was incrediblywater-resistant, with a WCA of 165°. The TMSPETA-HfO_2 wrapped in GCN has demonstrated strong adhesion and hardness in theepoxy substrate as well as good mechanical properties. An increased adhesive strength (19.1 Mpa) was achieved for mild steel coatedwith EP-GCN/TMSPETA-HfO_2 prior to being immersed in seawater. As a result, the coating has greater adhesive strength and canhold up even after a prolonged immersion. In light of this, the EP-GCN/TMSPETA-HfO_2 nanocomposite may be used as a coatingcomponent in the automotive industry.