The influence of PBO coating on room temperature mechanic properties of heat-treated quartz fiber-reinforced methyl silicon resin composites. I. Flexural properties

In the present work, PBO was coated on the quartz fiber by the liquid method to improve the room temperature flexural properties of the heat-treated quartz fiber/methyl silicon resin composites. The atomic force microscopy (AFM) images indicated that the PBO coating on the surface of quartz fiber is uniform; the Weibull distribution was used to evaluate the single filament tensile strength of the purchased and PBO-coated quartz fiber before and after 500 °C treated for 30 min. The results indicated that the single filament tensile strength of PBO-coated quartz fiber before high temperature treated is lower than the purchased fiber, while after 500 °C treated for 30 min the single filament tensile strength of PBO-coated quartz fiber is higher than the purchased fiber because of the higher thermo-stability of the PBO coating. After 500 °C treated for 30 min, the room temperature flexural strength of PBO-coated fiber-reinforced composites is about 50 MPa, 100% higher than the untreated fiber composites. The mechanism of the crack propagation in the purchased and PBO-coated fiber-reinforced composites is studied through scanning electronic microscopy (SEM). The results indicated that PBO coating inhibit the reaction between quartz fiber and methyl silicon resin, thus avoiding the fiber fracture caused by the crack of the resin.