Geometrically tailored 3D spacer woven fabrics for reinforcing rigid/flexible silica aerogels: mechanisms and properties

Abstract

Silica aerogels feature ultra-low thermal conductivity and ultra-lightweight characteristics, but their inherent fragility and poor mechanical performance severely restrict structural applications. This study addresses this challenge by employing three-dimensional spacer woven glass fiber fabric (GF-3D-SF) to reinforce both rigid (TEOS-based) and flexible (MTMS-based) silica aerogel matrices. The effects of fabric geometric parameters (spacer density and height) on the microstructure, mechanical properties, and thermal insulation performance of the composites were systematically investigated. Results reveal two distinct reinforcement mechanisms tailored to matrix stiffness. For rigid TEOS-based composites, strong interfacial bonding enables effective stress transfer and fiber bridging, significantly enhancing compressive/flexural strength with increased density. However, higher spacer height induces Euler buckling and thus degrades structural stability. For flexible MTMS-based composites, although weak interfacial bonding limits strength enhancement, the inherent elasticity of the matrix endows the composites with exceptional elastic recovery and cyclic fatigue resistance, which is complemented by the structural support of the 3D spacer fabric. Thermal conductivity increases with spacer density but decreases with spacer height. This work clarifies the synergy between matrix properties and fabric architecture, establishing a geometry-mediated design strategy for fabricating aerogel composites with tailored multifunctional properties.