Effect of MgO on the physical, mechanical and microstructural properties of ZTA-TiO2 composites

Ceramic composites of alumina (Al2O3), 3 mol% yittria stabilized zirconia (ZrO2), Magnesia (MgO) and Titania (TiO2) were produced and different physical and mechanical properties were characterized. This multi component toughened Al2O3 was also characterized by observing XRD and SEM. The weight percentages of ZrO2 (15 wt%) and TiO2 (0.5 wt%) were constant where the amount of MgO varied from 0 to 1.5 wt%. The batch compositions were properly weighed, dried, mixed with polyvinyle alcohol binder, again dried and pressed into 10 mm diameter shaped samples by uniaxial pressure of 160 MPa. The prepared green samples were sintered at 1450 degrees C, 1520 degrees C and 1590 degrees C for 5 h under pressureless condition. The effect of MgO addition and variation of sintering temperature was observed on the density, porosity, hardness, fracture toughness and diametral tensile strength of the sintered pellets. Hardness and fracture toughness were calculated by indentation technique. SEM and XRD were used to characterize the microstructure and phases present in the sintered ceramic composites. Results show that, the addition of MgO upto 1% influences all the physical and mechanical properties to improve, where further addition of MgO shows no fruitful effect. From the phase analysis and rietveld analysis one extra phase of spinel (MgAl2O4) founded when MgO added more than 0.5%. The perfect sintering temperature was found 1520 degrees C. Further increasing the sintering temperature causes structural imperfection of the composites and the physical and mechanical properties diminished at the sintering temperature at about 1600 degrees C.