Determination of residual stresses in three-layer alumina composites using an indentation technique

Abstract

The distribution of residual stresses in three-layer reaction bonded alumina (RBAO) composites with 17.5 vol % zirconia in the inner layer and 40 vol % mullite in the outer layers was determined by an indentation technique. It could be shown that the outer layers are subject to a residual compressive stress while the inner layer is under a tensile stress. With increasing outer layer thickness, the residual compressive stress decreases, and the residual tensile stress increases. Compressive stresses up to 550 MPa were measured in this study. It was found that the residual stresses are not uniform throughout the layers. The magnitude of the stresses decreases with increasing distance from the interfaces. This is attributed to creep during cooling from the sintering temperature.