Corrosion and wear resistance behavior of nano-silica epoxy composite coatings

• Silica nano particles were prepared from silicon alkoxide in alcoholic solution.
• TGA/DTA analysis shows that the composite coating is stable up to 577 K.
• TEM study shows the particle size of silica is 50–70 nm and the composite is 200 nm.
• Nano silica coating shows better wear resistance than microsilica coating.
• Nano silica composite coating performs well in salt spray and EIS in NaCl solution.

Recent developments made in the synthesis of nano-materials have demonstrated their contribution in the field of protective coatings. Sol–gel method is the simple and elegant technique for the preparation of nanosilica particles. The nano-silica composites were prepared by mixing the epoxy compounds and polyamide hardener and characterized by using X-ray powder diffraction (XRD), thermal analysis (TGA and DTA), FT-IR spectroscopic technique and SEM analysis. The size of the nano particles was confirmed by transmission electron microscopy (TEM). Mechanical properties of the nano-silica epoxy composites were determined by ASTM method. The wear index data of the nano-silica incorporated epoxy composite were found to be 32 mg/1000 cycles. Corrosion performance was evaluated by salt spray test and electrochemical impedance measurements. The nano-silica epoxy composite coatings withstood 720 h in salt spray test, whereas the micro silica coatings withstood up to 650 h. Electrochemical impedance spectroscopy results of the nano-silica epoxy composite coatings showed a resistance of 2.36 × 106 Ω cm2 after 30 days of immersion in 3% NaCl solution, whereas micro silica incorporated coatings showed a resistance of 5.41 × 104 Ω cm2 under similar conditions.