Toughening and strengthening of Nb2O5 doped zirconia/alumina (ZTA) composites

The aim of this research is to investigate the characteristics and mechanical properties of Nb2O5 doped zirconia-toughened-alumina composites. Samples of partially stabilized-zirconia toughened alumina (ZTA) with the addition of 5 vol.% ZrO2 doped with Nb2O5 in amounts of 0.2, 0.4 and 0.6 vol.% were prepared by sol-gel technique. The powders of each composition were uniaxially pressed into discs and rectangular bars, and then pressureless sintered at 1500° up to 1650 °C for 1 h. The phase constitution and microstructures of the as sintered ceramic composites were characterized by using an X-ray diffractometer and a scanning electron microscope respectively. The mechanical properties of the ceramic composites were evaluated through Vickers hardness, flexural strength and fracture toughness tests. It was found that increasing the Nb2O5 concentration had a strong effect on the densification behavior, microstructure and mechanical properties of the ZTA composites.