Strength of Yttria-Stabilised Zirconia with Near-Surface Grinding Residual Stresses

摘要

The residual stresses induced by grinding in tetragonal zirconia polycrystals stabilised with 2.5% molar yttria (Y-TZP) have been investigated. Two Y-TZP microstructures have been analysed; one consists of very fine tetragonal grains, whereas the other exhibits a coarser duplex structure of cubic and tetragonal grains. It is shown that indentation cracks after grinding are always shorter than in the annealed condition and this effect is much larger for the coarse duplex microstructure. It is also found that biaxial flexure strength of ground specimens increases with respect to that in the annealed condition, in spite of the large number of surface defects induced by machining. These findings are analysed by Raman spectroscopy as well as by X-ray diffraction and related to changes in the near surface microstructure induced by grinding. The results are discussed within a fracture mechanics framework.