Estimation of thickness of hydrothermal degraded layer in 3Y-TZP by x-ray diffraction

Abstract

A method is present for estimating the thickness of monoclinic layer formed by hydrothermal degradation of zirconia doped with 3 mol % of yttria (3Y-TZP) by means of X-ray diffraction at different incidence angles. The method is based on: a) determining the monoclinic concentration in the degraded layer by X-ray diffraction at angles for which the beam penetration depth is smaller than the layer thickness; b) calculating and using the ratio between intensities of the same main tetragonal peak in the degraded and in the as sintered specimens at angles for which the contribution of the same tetragonal peak form the layer and from the underneath non-degraded material are significant. In order to compare with experimental results, 3Y-TZP has been subjected to degradation in an autoclave at temperatures of 131ºC in water vapour at a pressure of 0.2MPa. The method may be useful when the thickness of the degraded layer is in the range between a few hundred nanometres and a few microns.