ULTRAFINE-GRAINED DENSE MONOCLINIC AND TETRAGONAL ZIRCONIA

Nanoparticles of ZrO2 with diameters ranging from 4 to 8 nm were synth esized by gas condensation. As-prepared n-ZrO2 particles have a monocl inic and a high-pressure tetragonal structure depending on size. Pure ZrO2 was sintered to full density under vacuum at 0.4T(m) within the m onoclinic phase field. Final grain sizes in theoretically dense pellet s are below 60 nm. By sintering below the monoclinic-tetragonal transi tion temperature, microcracking was completely avoided. Tetragonal ZrO 2 stabilized with 3 mol% Y2O3 was prepared by interdiffusion of nanopa rticles and sintered to near-theoretical density.