Bio-Ceramics Case

High pure Alumina (Al2O3) bio-ceramics are been developed as an alternate to surgical metal alloys for hip joints as well as tooth implants as it is hard and bio-inert component. However the sintering temperature is very high as pure Al2O3 has higher melting point. The addition of other ceramic oxides can improve the sintering behaviour of these components. In the present study the effect of minor additions of ceramic oxides: TiO2, CaO, and Bentonite (Al2O3.4SiO2.H2O) on microstructure, compaction, sintering behaviour of Al2O3, as well as their effect on physical and mechanical properties were studied in detail. A predetermined ratio of powder particles were subjected manual blending using mortar and pestles. The green compacts were made using two methods: 1.compaction and 2.slip casting. The compaction was carried out at 1.6 tonnes using a a die made of low alloy steel. The slip casting is carried out using PVA as a binder. The green compacts were dried at 1100C for 12 hours. The temperature was gradually raised in the stages of 250, 500, 1050˚C. The sintering temperature and phase transformation characteristics of the material were studied using phase diagram. The properties of the samples were evaluated once again after sintering at 10500C. The characteristics of green compacts as well as pre-sintered products were been evaluated using various techniques. Subsequently selected samples were subjected to sintering in a muffle furnace at atmospheric condition.

The powder particles characterized before compaction and sintering showed particle size in the range of 75 to 150 microns for Al2O3, 1 to 5 µm TiO2 microns for 50 to 75 µm for CaO. The morphology of the powder particles was found to be spherical. The microstructural features of green compacts showed uniform distribution throughout the samples. However after sintering two phases: an Al2O3 rich phase and TiO2-CaO phase were observed in the microstructure. By using phase diagrams it was confirmed that