Effects of volume fraction of short-cut quartz fibers on mechanical and thermal properties of SiO2f/SiO2 composites

Abstract

SiO_2f/SiO₂ composites were prepared by compression molding and sintering using short-cut quartz fibers as reinforcement. The effects of fiber volume fraction (15%∼35%) on bulk density, apparent porosity, and mechanical and thermal properties of the composites were investigated. The results indicated that the samples with 25% fiber volume fraction had the best comprehensive performance, with an apparent porosity and compressive strength of 36% and 46.3 MPa, respectively. The flexural strength of the samples was 13.9 MPa, which represented a 90% increase compared to the samples without fibers. It was attributed to the occurrence of fiber debonding and fiber pull-out in the porous matrix. Meanwhile, the residual strength ratio of the samples after 20 thermal shocks was 74.8%. In addition, the average coefficient of thermal expansion was 0.95 × 10^− 6/℃ at 300 ℃∼700 ℃ and the thermal conductivity was 0.388 W·m^− 1·K^− 1 at 800 °C. This approach can satisfy the requirements of low cost, fast preparation of SiO_2f/SiO₂ composites, which offers the prospect of its application in the integration of load-bearing and thermal insulation.