Toughened RE-TZP ceramics obtained by HPHT process

Yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) presents unique combinations of properties such as high fracture toughness, chemical stability and biocompatibility. These characteristics are responsible for great potential for application as structural components. This material is usually obtained by solid-state sintering, at temperatures around 1500–1600 °C. The objective of this work is the development and characterization of ZrO2-based ceramics, obtained by high-pressure, high-temperature (HPHT) sintering. As an alternative stabilizer of tetragonal ZrO2 phase, the use of a mixed yttrium–rare earth oxide, designated as RE2O3, is proposed. ZrO2–6 wt.% RE2O3 powders were compacted and sintered at temperatures between 1100 and 1400 °C, using high pressures (4 or 5 GPa) and low sintering times (1–5 min). The sintered bodies were characterized by relative density, X-ray diffraction, and scanning electron microscopy. Hardness and fracture toughness were the mechanical properties evaluated. The best results were obtained in samples sintered at 1200 °C–4 GPa for 1 min, which presented hardness of 545 kgf/mm2, fracture toughness 10.7 MPa m1/2, with relative density about 98% of the theoretical density and 97.3% of tetragonal phase.