A simplified preparation of silica aerogel/epoxy composite coating based on rice husk ash for enhancing corrosion resistance

Using rice husk ash as silicon source to prepare silica aerogels is one of the most possible ways to realize high value utilization of husk ash. However, the applications of rice husk ash-based silica aerogels (HSAs) using the conventional procedure (without incorporating special materials or processes) are limited due to their relatively inferior properties compared to silica aerogel prepared from conventional silicon sources. Therefore, it is necessary to explore new application areas where HSA can be competent. In this study, HSAs were prepared using a simple conventional protocol and utilized as fillers to enhance the corrosion resistance of epoxy coating. The results showed that the optimal HSA had a specific surface area of 470.3 m 2 /g and a water contact angle of 158.5°. The HSA/epoxy composite can be prepared simply using a magnetic stiran. When the addition amount is 6%, the coating has the best corrosion resistance. The protection efficiency remaining at 91.4%, after 20 days of immersion in a 3.5% NaCl solution, which was 48.7% for pure epoxy coating. The polarization resistance value was 7591.7% higher compared to pure epoxy coating. This performance was better than that reported for some conventional fillers in the literature. Besides the similar effect as other fillers, it is possible that the HSA may have trapped O 2 and Cl − , preventing them from contacting directly with the metal. Graphical abstract