Nucleation and growth of environment-induced monoclinic phase in yttria-TZP ceramics

The transformation of tetragonal zirconia polycrystallines (TZP) to the monoclinic phase at the microscopic level is studied. Standard femoral heads that had been produced from powder containing yttria by cold isostatically pressing, pressureless sintering and hot pressing to give a high density of 6.1 Mg m-3. The volume fraction of the monoclinic phase produced by the aging treatment was determined by X-ray diffraction. Raman spectroscopy was also performed. Scanning light interferometry data were obtained from three sites close to the polar and equatorial positions and the number of monoclinic peaks determined and the diameter of the largest monoclinic region measured.