Effects of h-BN content and silane functionalization on thermal conductivity and corrosion resistance of h-BN/EPN coating

The effects of h-BN and silane functionalization on h-BN/EPN coating are investigated. Herein, kinds of 3-aminopropyltriethoxysilane (APTES, KH-550)-functionalized-h-BNNs (A-BNNS)/epoxy phenolic resin (EPN) coating are prepared. XRD results show that the silanization treatment does not affect the organization of A-BNNS. XPS and TEM results indicate that the number of silane molecules on the surface of A-BNNS increases with APTES addition. SEM results show that the A-BNNS filler is uniformly dispersed in the coating, but the porosity increases. TC, heating infrared thermal and EIS results all present a trend of increasing first and then decreasing, with the enhancement of silane functionalization. In a positive effect, the silanol molecules enhance the crosslink density of the coating, which improves the thermal conductivity and corrosion resistance of the coating. However, on the negative side, as the degree of silane increases, the silane film with low thermal conductivity on the surface of A-BNNS thickens. Meanwhile, the increase in filler content significantly shortens the transmission distance of phonons between fillers and improves phonon transmission efficiency, thus enhancing the thermal conductivity of the coating. Nevertheless, as the A-BNNS content increases, the total amount of defects between the filler and resin interface also increases, and the hydrophilicity of A-BNNS increases, which would lead to a rapid decrease in the corrosion resistance of the coating. As a result, when the initial ratio between h-BNNs and APTES is 1:3 and 15 wt% A-BNNS is added, the best comprehensive coating performance can be obtained, i.e., and the TC of the coating reaches 0.64 W/m·K while the impedance modulus at 0.05 Hz is 1.12 × 1010 Ω·cm2. This work provides an important guidance for the exploitation of heat exchanger coatings with excellent TC and corrosion resistance.