Preparation, performance and underlying mechanisms of single and mixed sols in thermal insulation fiber composites

Abstract

Inorganic fiber-based insulation materials are widely utilized in high-temperature industrial applications, aerospace, and energy systems due to their excellent thermal stability, low density, and tailorable microstructural characteristics. However, achieving an optimal balance between room-temperature mechanical integrity and high-temperature insulation performance remains a critical challenge, particularly when selecting suitable binder systems. In this study, inorganic fiber-based insulation boards were fabricated via mechanical compression molding to systematically evaluate the effects of silica sol and alumina sol as binders on material properties. The influence of mixed sol ratios (alumina/silica) on the structural and functional performance of the fiberboards was further investigated. The results demonstrate that fiberboards prepared with alumina sol exhibit significantly enhanced physical properties at room temperature, with compressive strength increases ranging from 74.6% to 331.0% compared to those using silica sol. Conversely, the alumina-based boards show reduced high-temperature stability and thermal insulation performance. By employing mixed sol systems, the complementary advantages of both binders can be partially integrated. With increasing alumina sol content in the hybrid system, the microstructure and overall performance progressively approach those of the pure alumina system. Accordingly, this study establishes that tailoring the type and proportion of composite sol enables directional property design for fiberboards, thereby providing a viable strategy to meet specific application requirements across diverse thermal environments.

Graphical abstract