Employing miniaturized test methods to determine high-temperature strength of carbon-bonded alumina

Abstract

The Brazilian disc test (BDT) and the ball-on-three-ball (B3B) test, both adapted for utilizing miniaturized specimens, are used to characterize the strength of ceramic filter materials made from carbon-bonded alumina (Al₂O₃-C) at temperatures up to 1500 °C. Conventionally manufactured Al₂O₃-C and environmentally friendly coal tar pitch-free variations of filter materials are investigated. To determine the fracture stresses and the Weibull distribution of the material’s strength, finite element models and the maximum likelihood method are used. Scanning electron microscopy of fracture surfaces gives insight into the microstructure of tested samples. The material strength of the pitch-free Al₂O₃-C was found to be inferior to the conventional alternative. The volume-related Weibull stress distributions revealed that the uniaxial strength of the conventional filter materials exhibited an increasing trend as temperature increased, which was contrary to the biaxial strength.