Synthesis and characterisation of nano powders for production of zirconia toughened alumina bioceramic implant materials

Zirconia toughened alumina (ZTA) is a very important bio ceramic implant material with excellent biocompatibility as an inert bone substitute material for orthopedic applications and also for dental implants. In this study, alumina (Al2O3) and yttria stabilised zirconia (YSZ) nano powders in soft agglomerate form were synthesised by co-precipitation method. Aluminium nitrate {Al(NO3)3•9H2O}, zirconium oxynitrate {ZrO(NO3)2•xH2O} and yttrium nitrate hexahydrate {Y(NO3)36H2O} were dissolved in distilled water. NaOH solution was added as precipitant. The solution was turned into gel by mixing on hot plate magnetic stirrer at ambient temperature. In this way, Al2O3 and YSZ nano powders were synthesised together to produce the ZTA bioceramic implant material. The crystal structure, morphology and other physical properties of synthesised nano powders were investigated and characterised by scanning electron microscope (SEM) and X-ray diffraction (XRD). The composition ratio of ZrO2/Al2O3 and co-precipitation conditions had significant effect on the synthesised powder morphology and particle size and distribution in final product. The powders have a different morphology like formless and spherical and have the particle size distribution in the range of 100-900 nm. The final products have a very high relative sinter density about 91%, a small particle size of < 2 µm and homogeneity of particle and porosity distribution in microstructure.