Mechanical properties and microstructure of 2.5D (shallow straight-joint) quartz fibers-reinforced silica composites by silicasol-infiltration-sintering

2.5D (shallow straight-joint) quartz fibers-reinforced silica composites were successfully prepared by silicasol-infiltration-sintering method. The composites were sintered at 450 °C and the density of the composite was up to 1.70 g/cm3 after 11 infiltration-sintering cycles. The characteristics of 2.5D (shallow straight-joint) structure were determined. Flexural strength and shear strength of the composites were investigated along the warp and weft directions. The undulation of warp yarns could reduce the mechanical properties of the composites along warp direction. The flexural and shear stress-deflection curves exhibited mostly nonlinear behavior. The failure was not catastrophic. Some fibers pull-out indicated that the composite exhibited a certain degree of toughness. Microstructural observations revealed that the interface strength between the fiber and the matrix was weak for the relatively low sintering temperature of 450 °C.