Mechanical, thermal, and surface properties of fusion-bonded epoxy nanocomposite coatings

Epoxy coatings have generally been used in applications that require the surfaces to be protected against corrosion. However, their use in demanding applications wherein the contacting surfaces are required to be protected against wear and tear has been limited due to their inferior mechanical and thermal properties. To overcome this challenge, epoxy composite coatings came into being, wherein the epoxy resin is reinforced with different fillers. However, due to the availability of a large variety of fillers, the selection of a suitable filler and the amount to be used in the epoxy resin for the best properties still remains a challenge. Hence, the focus of this research is to compare the performance of five different fillers, viz. carbon nanotubes (CNTs), graphene (GO), alumina (Al₂O₃), titanium dioxide (TiO₂), and ceria (CeO₂) in enhancing the mechanical, thermal, and surface properties of epoxy coatings. The five fillers selected covered the spectrum of carbon based, ceramic, and metallic oxide fillers. Different loadings (0.5, 1.5, and 3 wt%) of each of the fillers were used to fabricate fusion-bonded epoxy composite coatings on mild steel coupons using an electrostatic spray gun. The effect of these fillers was evaluated on the hardness, thermal conductivity, and water contact angle of the epoxy composite coatings. It was observed from the results that 0.5 wt% of Al₂O₃ was found to be the best-performing filler among all the fillers in terms of higher hardness and 3 wt% of Al₂O₃ was best in terms of thermal conductivity as compared to the pristine epoxy coatings and other epoxy composite coatings.