Structure and Physicomechanical Properties of Porous Ceramic Based on Al2O3 Prepared Using a Filtration Combustion Method

Abstract

Atechnological approach is proposed making it possible to prepare highly porous ceramic based on Al₂O₃ using a method of filtration combustion (FC). The method is based on an exothermic oxidation reaction (in an FC regime) of aluminum powder PAP-2 particles mixed with spherulites of commercial alumina (type 1 material) or kaolin fibers (type 2 material). Depending on the volume faction of PAP-2 open porosity for sintered type 1 material is from 38 to 50%, and ultimate strength in bending is from 10 to 50 MPa. Good material thermal shock resistance, evaluated from the relative loss of crack resistance after thermal cycling by a regime of heating to 850°C and cooling in an air stream (18°C), comprises 12 – 15% and is unchanged after five successive thermal cycles. Material of type 2 is an ultra-lightweight heat insulator with density of 0.25 – 0.50 g/cm³. The bearing strength is 0.10 – 0.15 MPa, and thermal conductivity in the range 20 to 1000°C is 0.06 – 0.17 W/(m·K).