Interaction of fumed silica with epoxy resin
Blank epoxy coating (EC) and fumed silica epoxy composite coatings (SECCs) reinforced with different loading levels of nano- (7 nm) and micro (0.2-0.3 μm) silica were successfully prepared using ultrasonic technique. SEM analysis revealed a uniform dispersion of nano- and micro-silica fillers in the epoxy matrix up to 3 wt.% loading. It is found that ultrasonication results in permanent chemical bonding between epoxy resin and silica particles as investigated by FT-IR spectroscopy and DSC. Quantitative FTIR generally reveals that nano-silica shows more participation in chemical bonding to epoxy than micro-silica.
Use of nano-silica leads to improved corrosion resistance
Coated steel panels with either EC or SECCs were evaluated with regard to surface wettability, corrosion resistance, thermal stability and mechanical properties. Micro-silica treated coatings show enhanced hydrophobicity in contrast to nano-silica samples as revealed by contact angle measurements. Results of salt spray test and thermogravimetric analysis indicate that the addition of nano-silica show improved corrosion resistance and thermal stability of the epoxy coating compared to micro-silica. The mechanical properties namely scratch hardness, adhesion, impact strength and abrasion resistance were also improved in the same manner.
The study is published in: Progress in Organic Coatings Volume 129, April 2019, Pages 1-9.