Effects of surface-finishing condition and annealing on transformation sensitivity of a 3 mol.% Y 2O 3 stabilized tetragonal zirconia surface under interaction of lubricant

Abstract

Transformation behavior of a 3 mol.% Y 2O 3 stabilized tetragonal zirconia (3Y-TZP) surface is affected by not only stresses but also environmental conditions. In this paper, effects of surface-finishing conditions such as grinding and lapping and annealing after them on transformation sensitivity of a 3Y-TZP surface in hot oil are evaluated by tetragonal phase content, calculated from X-ray diffraction patterns. The depth of transformed layer of the specimens, which have been held in oil at 473 K, is also measured by a microscopic examination of cross-sections. The work-affected layer of the worked surface is evaluated by the value of IP T(002)/IP T(200) where IP T(002) and IP T(200) are the intensities of the tetragonal phase peaks T(002) and T(200) at 2θ≅35° in an X-ray diffraction pattern, respectively. When the value of IP T(002)/IP T(200) of the worked surface is larger than that of the sintered one, as in the surfaces ground by #200 and #400 diamond wheels, the following annealing at ∗ about 1473 K is effective at improving resistibility of surfaces to phase transformation in hot oil. The annealed specimen, however, whose work-affected layer is removed by lapping prior to the annealing treatment, shows the same transformation sensitivity as the sintered one. It is also shown that the compressive residual stress has a significant effect towards increasing the resistibility of surfaces to phase transformation.