Mechanical properties and microstructure of 2.5D (shallow bend-joint) quartzf/silica composites by silicasol-infiltration-sintering

Abstract

Silica composites (2.5D quartz fibers-reinforced) were prepared by the silicasol-infiltration-sintering method. The fiber volume fraction was 50.5%. The composites were sintered in a temperature range of 400∼450°C. Mechanical properties of the composites were determined by pc-controlled electronic universal testing machines. The microstructure of the composite was observed by scanning electron microscopy (SEM). The density of the composite was 1.77 g/cm3. The flexural strength and the shear strength of the composites were 50.35 MPa and 22.41 MPa, respectively. The stress-deflection curves exhibited mostly nonlinear behavior; the failure was not catastrophic. Some fibers pull-out indicated that the composite had part toughness. However, abundant fibers fractured in the same plane revealed that the composite presented serious brittleness. The fracture mechanism of the composite was a mixture of ductile and brittle modes.

Keywords

• fracture mechanism
• interface
• mechanical properties
• microstructure
• 2.5d quartzf/silica composites