Mechanical Properties of Alumina Particulate and Platelet-Reinforced Glass Composites with a Crystalline Phase at the Interface

Abstract

Alumina particulate and platelet-reinforced glass matrix composites with an anorthite phase precipitated at the interface were fabricated by hot pressing. In order to evaluate the mechanical properties of the materials, four-point bending tests in air and in vacuum, and indentation fracture tests in air were performed. The acoustic emission (AE) signals of the alumina particulate glass composite were measured during bending tests in air. The relative density and the elastic modulus of the samples sintered by hot pressing were higher than those of the samples sintered under atmospheric pressure. The bending strength of the samples with larger amount of precipitated phase decreased compared with that of the samples without precipitation both for tests in air and in vacuum due to coarse precipitation but there was a monotonic increase of fracture toughness because of the interfacial precipitation. SEM observation of the crack paths indicated that the crack propagated through the precipitated phase. The results of AE location were related to the bending strength behavior of the particulate samples.