Residual Stress Measurements of Alumina-Zirconia Ceramics by Time-of-Flight Neutron Diffraction

Abstract

Abstract. Neutron strain scanning and Rietveld analysis were used to study the residual stresses in Al 2 O 3 /Y-TZP ceramic composites fabricated by different green processing techniques (a novel tape casting and conventional slip casting) and with different zirconia content. The results show that the residual stresses in zirconia particulates are tensile and the ones in alumina matrix are compressive, with almost flat through-thickness residual stress profiles in all bulk samples. The residual stresses for both phases were mainly dependent on the zirconia content, irrespective of the measurement direction and the fabrication process. IntroductionAlumina-zirconia ceramics have received considerable attention in both engineering and academic fields due to their improved mechanical properties when compared with pure alumina ceramics [1][2][3][4]. It has been proposed that the residual stresses due to thermal and elastic mismatches between alumina and zirconia could contribute to toughening and enhance the structural performance of these ceramic composites [5,6].Numerous works have been done on residual stresses analysis in Al 2 O 3 -ZrO 2 composites [6-10] and a wide range of results were obtained depending on fabrication routes, composition design and measurement techniques. In this study Al 2 O 3 /Y-TZP (alumina/tetragonal ZrO 2 stabilized with 3 mol% Y 2 O 3 ) composites were investigated. Samples were prepared by a novel tape casting route [11,12] for stacking green ceramic tapes made from high solid content of water-based slurries at room temperature and using low pressures. The conventional slip casting [13] was taken as reference for comparison. The effect of the Y-TZP content on the Al 2 O 3 /Y-TZP composites was also studied.Time-of-flight (TOF) neutron diffraction and Rietveld analysis have been applied for the nondestructive determination of the residual stresses in Al 2 O 3 /Y-TZP bulk samples. Through-thickness residual stress profiles corresponding to both phases, i.e. alumina and zirconia, were obtained, and compared to available data in the literature and to estimations by theoretical models. The effects of Y-TZP content and the new processing method on the microstructure and residual stresses of the ceramic composites were established.