In-situ mullite whisker-segmented pore structures in Al2O3-SiC-C castables and influence on thermal conductivity

Aiming to improve thermal insulation and minimize heat dissipation in high-temperature industrial applications, this study fabricated mullite whisker-reinforced Al 2 O 3 -SiC-C (ASC) castables via in-situ whisker growth. Using boehmite as a pore-forming agent, AlF 3 as a catalyst, and silica sol as a binder, the composites were synthesized and characterized for mechanical properties, thermal conductivity, oxidation resistance, and slag resistance. Finite element simulations (160 μm and 10 mm models) analyzed whisker-induced pore refinement effects on heat transfer. After sintering at 1450 °C, in-situ grown mullite whiskers partitioned large pores into smaller ones, refined pore structures, and introduced abundant solid-gas interfaces. These deflected heat flux, increased path tortuosity, and elevated interfacial thermal resistance, reducing 800 °C thermal conductivity by 20.9% compared to the control sample. The material retained good mechanical strength, oxidation resistance, and slag penetration resistance. This work offers new insights for designing high-performance castables combining superior insulation with robust high-temperature performance.