Study On The Preparation And Anticorrosion Of The Epoxy/SiO₂ Hybrid Materials

The Epoxy/TEOS, Epoxy/GPTMS and Epoxy/GPTMS-TEOS hybrid materials were prepared by the two-step method based on the precursors of tetraethoxysilane (TEOS), (3-glycidoxypropyl)trimethoxysilane(GPTMS). The samples were characterized by modern test methods.Scanning electron microscopy (SEM) showed that the inorganic moieties existed in the form of nano-spheres within the epoxy matrix, when the organosilcon precursor was aged for one day. The hybrids with inorganic precursors aging for more than 15 days showed no phase separation.Fourier transformed infrared spectrum (FTIR) showed that there were no chemical but hydrogen bonds between inorganic Si-O-Si network and epoxy matrix in Epoxy/TEOS hybrid materials. There were covalent bonds between inorganic moieties and the organic matrix in the Epoxy/GPTMS and Epoxy/GPTMS-TEOS hybrid materials, because the epoxide group of GPTMS could connect epoxy matrix with covalent bonds as a result of the curing agent.TG-DSC showed the thermostability of hybrid materials were greatly improved, because the strong Si-O-Si network restricted the epoxy polymer chains and the bond energy of Si-0 was bigger than that of C-C. In the same conditions, Epoxy/GPTMS and Epoxy/GPTMS-TEOS hybrid materials were superior to Epoxy/TEOS hybrid material because of the covalent bonds between the Si-O-Si network and epoxy matrix.Tafel polarization plots of organic-inorganic hybrid coatings on carbon steel in 3.5wt% sodium chloride solution were obtained. The results show that zero current potential (Ecorr) of the hybrid coatings increased and the corrosion current (Icorr) decreased. The results from electrochemical impedance spectrum (EIS) indicated that Epoxy/GPTMS hybrid coating was a coating with big coating resistance and small capacitance. The corrosion resistance was found to increase by 80% after Epoxy/GPTMS hybrid coating was doped 5wt% PANi/SiO2 inhibitor.