Mechanical properties of pressure-less sintered zirconia-magnesium aluminum silicate glass composite

摘要

The main objective of the present study was to develop a high-strength machinable ceramic based on zirconia (ZrO _2) and magnesium aluminum silicate (Mg _3Al _2Si _6O _(18); MAS) glass system through pressure-less sintering. Pressure-less sintering of ZrO _2, _3 mol% yttria-stabilized (YSZ) was carried out at 1450°C in air, using 10 wt% MAS glass as a sintering additive. The influence of glass on the microstructure and mechanical properties of the composite was investigated. The presence of glass into the ZrO _2 matrix was substantiated using scanning electron microscopy (SEM). X-ray diffractometry (XRD) revealed no crystalline phases other than tetragonal ZrO _2. The flexural strength of the composite was found to be ～30% higher than YSZ. The apparent crack resistance was determined by Vickers microindentations carried out at different loads ranging from 9.8 to 196 N. The apparent crack length on the surface at each load was found to be decreased (6-21%) in YSZ and the corresponding crack-resistance values increased by about 5-20%. Both YSZ and composite showed rising trend in crack-resistance values as the indentation load was increased. Improved properties of composite sample were attributed to the formation of a relatively larger process zone surrounding the crack, crack-arrest behavior due to the localized compressive stresses, and the crack-bridging phenomena.