Effect of Adding MgO on Microstructure of Zirconia Toughened Alumina (ZTA) Composite for Medical Applications

Abstract

Zirconia toughened alumina (Biolox delta) is a new-generation ceramic with four times the strength of alumina alone, used in artificial joints. The composite ZTA, consisting of 82 wt. %Al2O3, 17 wt. % ZrO2, 0.5 wt. % Cr2O3, and 0.5 wt. % SrO, was made using the sol-gel process, starting with salts. To investigate the effects of MgO on the ZTA microstructure, two concentrations (0.25 and 0.5 wt. %) of MgO were added to biolox during gelation to study the ZTA microstructure. Powders were sintered in the air for 2 hrs. at 1450 ºC. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray analysis (EDX) were used to characterize sintering powders. ZTA + xMgO structural characteristics differ from pure ZTA's. According to XRD calculations, grainsize decreased from 41.82 nm to 31.88 and 26.83 nm with increasing MgO concentration, but the specific surface area (SSA) increased from 40.63 to 54.79 m2/gm while crystallization improved. SEM examination shows the composite has a homogeneous dispersion of shaped particles. The EDX test shows the composite's homogeneous element distribution. ZTA+ xMgO powders were more antibacterial than ZTA powders. MgO inhibits bacterial activity and grain formation in ZTA composite during sintering, which makes it a good choice for medical applications, mainly artificial joints.