A study on superhydrophobic coating in anti-icing of glass/ porcelain insulator

摘要

This paper focuses on the preparation of a superhydrophobic coating on glass/porcelain insulators which possess anti-icing property below freezing temperature. Inspired by lotus-effect, the fabrication of a superhydrophobic coating has two steps: the first step is to construct a hierarchical SiO2 coating on the substrate surface, and the second step is the chemical modification of the SiO2 coating with lH,lH,2H,2H-Perfluorodecyltriethoxysilane (PDTS). The precursor for the hierarchical SiO2 coating is a suspension of SiO2 sol particles and dispersible SiO2 powder particles. According to the TEM testing, SiO2 sol particles prepared by sol-gel method has an average particle size about 2-5 nm, while the size of the dispersible SiO2 particles is ca. 20 nm. The precursor was sprayed on glass/porcelain insulators, and then dried at ambient condition, finally heat-treated at 773 K for 2 h. The morphology of the superhydrophobic coating was characterized by TEM and AFM, and experimental results indicated that the coating featured [hierarchical structure consisting of both large bumps with micron-sized height (0.8-urn) and tiny papillae with the size about 30 nm] micron-sized roughness (0.8 um) combined with nano-sized roughness (about 2 nm). Moreover, the scratch test showed that the coating tightly adhered to the surface of the glass/porcelain insulators. The superhydrophobic property of the coating was examined by a contact angle measurement, and the results demonstrated that the static water contact angle is high up to 163.6°, and the sliding angle is 1.4°. The superhydrophobic property of the coating was also confirmed by the outdoor tests in winter, and it was found that the superhydrophobic coating had the function in anti-icing, based on which the anti-icing mechanism underlying was discussed in terms of the interaction between impacting droplets and superhydrophobic surface.