Fabrication and adhesive properties of thin organosilane films coated on low carbon steel substrates

We investigated the fabrication and adhesive properties of thin organosilane films coated on the surface of low carbon steel substrates by curing γ-glycidoxypropyltrimethoxysilane (γ-GPS) solutions hydrolyzed in different solvents. This method appears to be a promising alternative treatment for the chromium and phosphate mainly due to its excellent corrosion protection and adhesion properties to organic coatings and a non-toxic pretreatment. In this work the elemental distribution in γ-GPS films coated on low carbon steel substrates was analyzed by an energy dispersive X-ray spectrometer (EDX), and the effect of curing temperature and solution concentration on the chemical structures of this silane was also carried out with reflection–absorption infrared (RAIR) spectroscopy. We systematically investigated the processing variables regarding adhesive strength of the film, including hydrolysis solvents, hydrolysis time, solution concentration and curing temperature. Compared with other experimental conditions, the present results provided a consistent demonstration that γ-GPS films exhibited improved adhesive strength to metal substrates in case of using DI water/methanol mixture as hydrolysis solvent, hydrolysis time of 48 h, solution concentration of 10%, curing temperature of 150 °C and curing time of 1 h. The fracture mode of γ-GPS films varied with different deposition parameters.