Nanoscratch profiles of hybrid films based on (3-glycidoxypropyl) trimethoxysilane and modified with tetraethoxysilane

Silsesquioxanes (SSO) derived from the hydrolytic condensation of (3-glycidoxypropyl)trimethoxysilane (GPMS) and tetraethoxysilane (TEOS) were prepared by the sol-gel process. Hardness H and elastic modulus E of the SSO films modified with 5, 10, 15, 20, 25 and 30 wt-%TEOS contents were measured by the continuous stiffness measurement technique and the brittle index H/E for the films was calculated from the results. The nanoscratch testing was carried out to study the influence of the different TEOS contents of the coatings on the scratch-testing profiles, including the pre-scan, scratch-scan and post-scan profiles. The film containing 20 wt-%TEOS was found to have the best elastoplastic behaviour and scratch resistance, based on considerations including the baseline of the pre-scan profile, the depth of the scratch, the abrupt change in the scratching curve and the fluctuation and recovering characteristic for the post-scan profile.