Sintering Behaviour and Mechanical Properties
of Alumina Doped Zirconia (3YSZ)

Abstract

Zirconia as a structural material has gained the wide industrial and technological research interest attributed to the low temperature densification behaviour combined with the improved mechanical properties. Numerous studies have reported that the dopant Al2O3 in ZrO2 matrix is of particular interest that ascribed to the improved densification rates coupled with the mechanical properties in terms of strength, fracture toughness without compromising hardness. However, the mechanical performance of Al2O3 doped ZrO2 ceramics typically depend on the
microstructure evaluation in terms of density and grain growth behaviour which varies as a function of temperature, time, and Al2O3 concentration. Moreover, few comprehensive studies are available on the sintering behaviour and mechanical properties of Al2O3 doped ZrO2 ceramics where the dopant concentration level is above 1000 ppm but the property correlations with the dopant concentration are rather limited. Therefore, the present work is aimed to
investigate the influence of Al2O3 dopant concentration (0 – 1600 ppm) on densification behaviour, grain growth kinetics, and mechanical performance of ZrO2 ceramics in the sintering temperature range of 1350°C - 1550°C for a period of 2, 6, and 10 hours. The experimental results revealed that concentration of dopant Al2O3 has played a decisive role
on the development of ZrO2 ceramics with the desired microstructural features. High dense fine grained Al2O3 doped ZrO2 ceramics of relative sintered density (~99.6%) and grain size (~250 nm) have been obtained at an optimum dopant concentration level of 1000 ppm at 1350°C for 6 h. Grain growth has been observed to be increased with the increase of sintering temperature, time, and independent of Al2O3 concentration. Grain growth kinetics of 1000 ppm
Al2O3 doped ZrO2 ceramics has been found to follow cubic law and the activation energy was 608 ± 12 kJ/mol. The mechanical properties of optimum Al2O3 (~1000 ppm) doped ZrO2 ceramics have been found to be hardness (~12.9 GPa), fracture toughness (~4.1 MPa. m1/2) and diametric tensile strength (~286 MPa), respectively. The present investigation unfolds the fact that the doping of Al2O3 at a concentration level above 1000 ppm is not feasible in order to obtain high dense fined grained ZrO2 ceramic with improved mechanical response for structural applications.