A composite epoxy coating with a newly synthetic BN@SiO2 filler and its improvement on the durability of cement-based materials

Abstract

In order to improve the durability of cement-based materials, a composite epoxy coating with a newly synthetic BN@SiO2 filler was developed using nanosilica (SiO2) and hexagonal boron-nitride (h-BN). In this study, the BN@SiO2 was synthesized through grafting SiO2 nanoparticles onto surface of h-BN, while the BN@SiO2 were verified by using Fourier transform infrared (FTIR) spectrum, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and transmission electron microscopy (TEM). Results showed that, the BN@SiO2 as a filler can outperform the SiO2 and h-BN for improving the thermostability and waterproofing performance of the coating. Three composite coatings prepared by SiO2, h-BN and developed BN@SiO2 can effectively prevent mortar from carbonation and chloride attack, but the coating with BN@SiO2 filler has more effectively performance than that with SiO2 and h-BN fillers. After the mortar sample covered with BN@SiO2 coating undergoes 180 days of chloride attack and 28 days of carbonization, its chloride penetration and carbonization depths were reduced by 50% and 64% compared to pure coating, respectively. In general, optimizing the properties of the filler can significantly enhance the barrier properties of coatings, which is beneficial for improving the durability of cement-based materials.