Y-TZP ceramics has outstanding mechanical properties and has been used for many engineering applications. However, amajor drawback of this ceramic is the undesirable ageing-induced tetragonal to monoclinic phase transformation resulting inproperties deterioration when exposed to steam environment. In the present work, the effect of sintering temperatures (1200to 1500 oC) on mechanical properties, microstructure and low temperature ageing behaviour of the sintered Y-TZP sampleswere investigated. The sintered bodies were characterized to determine the bulk density, Young's modulus, Vickers hardnessand fracture toughness. The sintered samples were exposed to superheated steam at 180 oC/10 bar vapor pressure and theextent of monoclinic phase development were measured at selected intervals. It was found that the relative density and Young'smodulus of the sintered samples increased with sintering temperature and attained a maximum value of 99% and 211 MPa,respectively at 1400 oC. On the other hand, maximum Vickers hardness and fracture toughness of 14.4 GPa and 5.07 MPam1/2respectively, was measured at 1350 oC. X-ray diffraction studies indicated that after 24 h of ageing, no traces of monoclinicphase was found in the Y-TZP having an average grain size of below 0.3 µm. The study found that sintering at 1350-1400 oCwas optimum to produce sintered bodies having good ageing resistant without sacrificing the mechanical properties.

Keywords: 3Y-TZP, Mechanical properties, Low-temperature degradation, Average grain size