Effect of temperature on the mechanical behavior of mullite fibrous ceramics with a 3D skeleton structure prepared by molding method

Abstract

Fibrous ceramics with the mullite fibers as the matrix and silicon resin as the binder was fabricated by a molding method. The effect of sintering temperature, especially 1500°C, on the properties of the products, such as porosity, microstructure, mechanical behavior and fracture mechanism, were investigated. This fibrous ceramics exhibited low densities (0.425–0.441g/cm3), high porosities (81.6–82.3%), low thermal conductivities (0.083–0.089W/mK), relatively high compressive strength (1.21–1.58MPa), and high rebound-resilience ratios (70–85%), which made it a promising high-temperature insulation materials. When the sintering temperature increased above 1300°C, the fracture behavior of the products was mainly attributed to the fibers break and the binders fracture. As the sintering temperature increased to 1500°C, the grains in the mullite fibers grew up, and the strength of fibers decreased, finally leading to the degradation of the sample mechanical performance. What's important, the compressive strength of the products sintered at 1500°C was 1.36MPa and the elastic strain could reach 3.2%, which means that the products can still be put to use in the high-temperature fields.