Lower thermal conductivity and outstanding compressive strength of oxide fiber porous ceramics

Abstract

The development of reusable large-area thermal insulation materials for re-entry vehicles faces challenges such as uneven density distribution and low mechanical strength in domestic research. To address these issues, this study innovatively optimizes binder selection (aluminum sol vs. silica sol) and process control (compression rates of 10–30%) to enhance the performance of oxide fiber porous ceramics. By systematically investigating the microstructure-mechanical property relationship, the ceramics exhibited ultralow density (0.39 g/cm³), reduced thermal conductivity (.0985 W/(m·K)), and significantly improved compressive strength (1.03 MPa). Oxide fiber porous ceramics were prepared by gel casting using silica sol and aluminum sol as adhesives and quartz fiber as fiber skeleton. During the preparation, the fiber arrangement and adhesive content in the wet embryo were controlled by extrusion, and their properties and morphology were characterized. The density of the ceramics increased with the compression amount. The thermal conductivity of the material showed a trend of first increasing and then decreasing. Using aluminum sol as a binder could effectively improve the compressive strength of the ceramics. The ceramics achieve ultralow density and minimized thermal conductivity, demonstrating a breakthrough in balancing mechanical and thermal performance for aerospace applications.