Synthesis and properties of porous alumina ceramics with inter-locked plate-like structure through the tert-butyl alcohol-based gel-casting method

Porous alumina ceramics with inter-locked plate-like structure were successfully fabricated by the tert-butyl alcohol-based gel-casting method. The effects of Al/Si mole ratio on the structure and properties of the obtained products were investigated. The formation process of the inter-locked structure was analyzed. The products fabricated with the one-step method, in which the growth of plate-like alumina and the formation of the inter-locked structure were combined together, exhibited a high porosity of 76.21%, a compressive strength of 0.525 MPa and a low thermal conductivity of 0.495 W/mK, while the products fabricated by the two-step method after sintered at 1500 °C using the grinded powders after 700 °C heat-treatment as the starting materials possessed a relatively high compressive strength of 4.80 MPa. The obtained porous alumina ceramics were promising flexible insulant materials for the application in high-temperature field. •Porous alumina ceramics with inter-locked plate-like structure were fabricated.•The inter-locked topaz is the template for the inter-locked plate-like structure.•Gel-casting method provides the skeleton for the growth of the platelets.•The porosity of the obtained porous ceramics is high, up to 76.21%.•Ceramics possess a low thermal conductivity of 0.495 W/mK and good elasticity.