Influence of silica content on the stabilization of tetragonal zirconia for biomedical applications

Abstract

Tetragonal phase of Zirconia (ZrO 2 ) attracts more attention when referring to the phase development compared to the monoclinic and cubic phase. Tetragonal phase offers many favorable features such as high chemical and wear resistance, high fracture toughness and hardness. However, tetragonal ZrO 2 is not stable at room temperature, make it having issues in cooling process. The difficulty to maintain tetragonal phase at room temperature was assisted by the reversible process of ZrO 2 . This reversible process that happened at tetragonal to monoclinic phase transition, caused the monoclinic phase alone are presented after cooling process. The transformation of tetragonal to monoclinic is accompanied by the increase in volume, in which can lead to the propagation of cracks. Thus, ZrO 2 ceramic became a brittle material instead of their high fracture toughness and hardness. Silica (SiO 2 ) was introduced as the dopant component to overcome this transformation-induced cracking when ZrO 2 was sintered above 800 °C. An attempt was made in this work to investigate the effect of calcination temperature and SiO 2 concentrations toward ZrO 2 stabilisation by using sol-gel method. The phase transformation of ZrO 2 and its morphology were characterized via X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). From the XRD analyses, it was determined that SiO 2 with 0.5 M concentration has played a crucial role in the stabilisation of tetragonal ZrO 2 . However, both monoclinic and cubic were found when the concentration of SiO 2 is lower than 0.5M.