Study on the impact of hybridization of spherical fillers with size differences and sheet fillers on the thermal conductivity and anticorrosive performance of composite coatings

Abstract The improvement of anti‐corrosion performance and enhancement of functionality in anti‐corrosion coatings are essential. Boron nitride (BN), as a two‐dimensional thermal conductive filler, is incorporated into composite coatings to provide corrosion resistance and thermal conductivity. The combination of BN with zero‐dimensional filler alumina (Al 2 O 3 ) proves to be an effective method for enhancing the thermal conductivity of composite coatings. In this study, micro alumina (Micro‐Al 2 O 3 ) and/or nano alumina (Nano‐Al 2 O 3 ) were combined with BN to be integrated into waterborne epoxy resin (WER), resulting in different composite coatings (BN@Micro‐Al 2 O 3 /WER, BN@Nano‐Al 2 O 3 /WER, and BN@Micro‐Al 2 O 3 /Nano‐Al 2 O 3 /WER). The influence of different hybrid modes of two‐dimensional and zero‐dimensional thermal conductive fillers on corrosion resistance and thermal conductivity was discussed. The composite coating BN@Micro‐Al 2 O 3 /Nano‐Al 2 O 3 /WER exhibits the highest thermal conductivity at 0.789 W/mK with a filler loading of 30 wt% BN, 4 wt% Micro‐Al 2 O 3 , and 6 wt% Nano‐Al 2 O 3 . Meanwhile, the composite coating BN@Nano‐Al 2 O 3 demonstrates superior anti‐corrosion performance at a filler loading of 20 wt% BN and 10 wt% Nano‐Al 2 O 3 . After immersion in a 28‐day period in a NaCl solution with a concentration of 3.5%, the impedance modulus remains above 10 9 Ω·cm 2 , while corrosion current density is measured at 7.3367 × 10 −8 A/cm 2 . The hybrid mode involving two‐dimensional and zero‐dimensional thermal conductive fillers can effectively improve the composite coatings' corrosion resistance and thermal conductivity. There are variations in the optimal hybrid methods for incorporating two‐dimensional and zero‐dimensional thermal conductive fillers to enhance anti‐corrosion and heat conduction effectiveness of coatings. Highlights The properties of coating is improved by the incorporation of BN and Al 2 O 3 . The prepared coating performs good thermal conductivity. The synergy of BN and Al 2 O 3 can improve thermal conductivity significantly. The obtained coating performs good corrosion resistance. The synergy of BN and Al 2 O 3 can also improve anti‐corrosion effectively.