Neutron Diffraction Studies of Residual Stresses in Functionally Graded Alumina/Zirconia Ceramics

Abstract

Graded Al2O3/Y-ZrO2 ceramics are developed to receive a construction material combining favourable properties of both constituent components, alumina (low wear rate, high hardness) and zirconia (high strength and toughness). The high performance of this material can be reached by optimising the internal residual stress distribution resulting mainly from phase specific stresses after cooling from the sintering temperature. For this purpose, non-destructive neutron diffraction mapping of residual stresses has been employed. However, the application of the conventional method does not provide straightforward results on macroscopic residual stresses. This experimental technique uses the crystal lattice plane as a built in microscopic strain gauge and the measured quantities are then lattice strains detected in each constituent phase separately. Based on these experimental resources, the paper proposes a procedure of separation of the residual macroscopic stress from phase specific stresses. The application of the presented method is demonstrated on functionally graded materials (FGM) prepared by electrophoretic deposition (EPD).