Hydrothermal ageing study on two step sintered 3Y-TZP ceramic

Abstract

In this study, Hydrothermal ageing resistance of two step sintered 3 mol. % Yittria stabilized tetragonal zirconia polycrystalline (3Y-TZP) ceramic was analysed. 3Y-TZP ceramic powder was die pressed followed by cold isostatic pressing. Then the compacts were sintered by using Two-Step Sintering (TSS) technique. The first step sintering involved, heating the samples to a temperature (T1) at a heating rate of 10˚C/min and holding the samples at this temperature for one minute then the samples were cooled to second step sintering temperature (T2) at a cooling rate 10˚C/min and held at that temperature for two hours. Samples were sintered using tube furnace for nine different sintering profiles.The Hydrothermal ageing process was carried out in an autoclave with superheated water steam at 180˚C and 10 bar for different period of time to assess the ageing resistance of 3Y-TZP ceramics. The ageing process was held for 2h, 7h, 15h, 23h, 48h, 72h, 96h and 144h. The phase analysis of the sintered samples was recorded by X-ray Diffraction (XRD). The sample sintered with first step sintering temperature 1450°C and below did not exhibited any phase transformation even after 100 hours of ageing. Samples sintered at 1500⁰C are more responsive to hydrothermal ageing. Our study reveals that 1450°C would be the best first step sintering temperature to get better hydrothermal ageing resistance.