A novel thermal insulation and anticorrosion coating based on silica aerogel modification for mild steel: Experimental and theoretical studies

We synthesized PA-SiO 2 gel nanoparticles using sol-gel method by modifying silica aerogel with phytic acid (PA) and 2-(3-epoxycyclohexane) ethyl trimethoxysilane (Si186). By introducing the PA-SiO 2 gel nanoparticles into waterborne epoxy (WEP) coating, the PA-SiO 2 gel1.0 %/WEP coating exhibits excellent corrosion resistance. This is mainly attributed to the strong complexation of PA with metal ions and the physical barrier effect of SiO 2 gel as a filler. In this case, the PA-SiO 2 gel nano-filler not only fills the defects and pores in the WEP coating, but also acts as a physical barrier to extend the invasion of corrosive substances. In addition, the strong complexation of PA with metal ions forms a protective film of a dense complex on the metal surface to prevent further corrosion. Meanwhile, the interface interaction between the coating and metal is enhanced, and its mechanical properties are improved. The electrochemical impedance spectroscopy (EIS) results show that the impedance modulus of PA-SiO 2 gel1.0 %/WEP coating (1.53×10 9 Ω·cm 2 ) is three orders of magnitude higher than that of pure WEP coating (9.33×10 6 Ω·cm 2 ) at 0.01 Hz after immersion in 3.5 wt% NaCl solution for 30 days. The Tales test results show that the corrosion inhibition efficiency is 99.9 % higher than that of pure WEP coating.