Lightweight Y2O3 stabilized ZrO2 (YSZ) fiber porous ceramics with ultra-low thermal conductivity

Fiber porous ceramics have numerous applications in protecting structural parts from melting due to combustion gases in aircraft engines. Although these materials have been utilized for decades, considerable research continues to focus on their further optimization, particularly in enhancing high-temperature resistance, lowering thermal conductivity , and improving compressive strength . In this work, the three-dimensional Y 2 O 3 -stabilized ZrO 2 (YSZ) fiber porous ceramics were fabricated by adding silica-boron sol (SBS) as an inorganic binder to the YSZ fiber substrate followed by a pressureless sintering process. During this process, a borosilicate glass phase was developed at the intersections of the fibers, helping enhance the thermal stability and improve mechanical properties. The three-dimensional YSZ fiber porous ceramics were characterized by ultra-low thermal conductivity (0.054–0.065 W·m −1 ·K −1 ), enhanced compressive strength (144.82–238.81 kPa), high open porosity (88.64–91.67 %) and extremely low bulk density (0.41–0.53 g·cm −3 ). When the SBS content in the YSZ fiber porous ceramics was 25 wt%, the sample achieved optimal overall performance, with a low bulk density of 0.44 g·cm −3 , thermal conductivity of 0.058 W·m −1 ·K −1 and the compressive strength of 201.26 kPa. The research provides critical insights for preparation and engineering applications of YSZ fiber porous ceramics in aircraft engine thermal protection systems.