Fabrication and mechanical properties of SiO2 matrix composites reinforced by carbon nanotube

Carbon nanotubes (CNTs) and SiO2 glass powder were mixed by ultrasonication in ethanol solution. CNT–SiO2 composites with improved mechanical properties were fabricated by hot pressure sintering in 1300 °C 25 MPa, N2 atmosphere). Effects of CNTs content on the relative density and mechanical properties were investigated. The bending strength and fracture toughness of the 5vol.%CNT–SiO2 composite, compared with the monolithic SiO2, were enhanced 65 and 100%, respectively. The main reinforcing mechanisms include CNTs pulling-out, crack deflxion, bridging and CNTs rupture. The defects and aligning direction of CNTs in the matrix are also the affecting factors on the mechanical properties of composites as prepared.