Effect of SiO₂ concentration on the mechanical and anticorrosive properties of the hybrid PMMA/SiO₂ coating synthesized in situ by sol-gel process.

Abstract

Anti-corrosive evaluation of a hybrid polymethylmethacrylate (PMMA) with silica particles (SiO2) is presented, the hybrid (PMMA-SiO2) was synthetized in situ by sol-gel process. The SiO2 particles were embedded into to matrix PMMA at different concentrations. The hybrid structure of the coatings was characterized and observed with Fourier Transform Infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The deposition of the hybrid in aluminum 7075-T6 (Al7075) substrates was made with the blade coating technique, measuring wet and dry film thickness. For the preparation of the hybrid, PMMA was used without any type of curing, which allowed us to save resources. All tests were performed according to American Society for Testing and Materials (ASTM international) standards. The incorporation of SiO2 to concentrations significantly improved the mechanical and anti-corrosive results. PMMA-SiO2 coating, once deposited on the surface of Al7075 plates, has been tested inside a salt fog chamber (CNS) operated under accelerated conditions. They were improved up to 920 h its corrosion resistance. The abrasion tests had an increase of 50%, its hardness up to 4H and the wear index improved by 50% compared with the hybrids with minor SiO2 concentration, which shows that a higher concentration of SiO2 particles has a higher performance of the coating.