Processing and thermomechanical evaluation of fibre-reinforced alumina filters

Impregnation of polymeric foams with ceramic suspensions has been widely em ployed in industry to fabricate ceramic filters of various shapes and contr olled pore size at a reduced processing cost. Ceramic filters find applicat ion in cast metal industry to remove the undesired impurities from the melt , leading to products of higher quality. This paper reports a complete stud y on the fabrication of fibre-reinforced alumina filters. Rheological measu rements of ceramic suspensions showed that the slip adherence on polymer su bstrate was largely improved when thickening agent was incorporated into th e compositions, as a result of the increase in pseudoplasticity and in visc osity. Thermomechanical evaluation of the filters produced with fibre addit ion revealed that the fibre reinforcement improved the mechanical performan ce and reduced the damage by applied thermal stresses. Strengthening and to ughening of the ceramic matrix has been explained based on the fibre proper ties, fibre-matrix interface strength and thermal expansion mismatch that m ay occur in mixed systems. (C) 1999 Kluwer Academic Publishers.