Novel design of elongated mullite reinforced highly porous alumina ceramics using carbonized rice husk as pore-forming agent.

A facile strategy for the fabrication of elongated mullite reinforced porous alumina ceramics (PACs) using carbonized rice husk (CRH) as pore-forming agent and silica source is reported for the first time. A large amount of elongated mullite is synthesized in pores due to the reaction of amorphous silica in CRH skeleton and alumina ceramic powder. Elongated mullite acts as the bridges between pore walls, enhancing the compressive strength of PACs. Furthermore, secondary pores from the intersection of elongated mullite is favor of decreasing of the thermal conductivity. High performance PAC with porosity of 74.3% has been fabricated by employing 25 wt% CRH, which possesses relatively low thermal conductivity of 0.189 W/(m•K) and ultra-high compressive strength of 45 MPa. Its comprehensive performance is much better than that of existing ceramic materials. Our findings present a facile, eco-friendly and effective approach to fabricate high performance PACs as the high-temperature thermal insulation materials. [ABSTRACT FROM AUTHOR]