The effect of niobium oxide (Nb2O5) on the sintering behavior of composite Al2O3-ZrO2

In this research, the effect of adding niobium oxide to the microstructure and stability of the zirconia phase in the sintering sample obtained from an alumina-zirconia composite following mechanical milling. To this end, alumina and zirconia powders were used as the raw materials and niobium oxide powder was used as additive. All of the alumina-zirconia composites contained an invariant zirconia content equal to 10 weight percent, and 1 weight percent of niobium oxide was added to composite samples. Composite powders were subjected to axial pressure in tablet casts. Afterwards, samples were exposed to sintering for two hours in a thermal furnace at a temperature of 1300 to 1500 . X-ray diffraction was used to identify phases, and microstructures were examined through the SEM (scanning electron microscope) method. Examination and experiment results indicated that niobium oxide considerably influenced sintering density, and increased density up to 3.75 g/cm3. On the other hand, the size of background particles increased to 2.19 microns after sintering and the tetragonal phases decreased. In this research, the effect of this oxide on the sintering mechanism of the alumina-zirconia composite and stability of the zirconia tetragonal phase were discussed and analyzed.