The Role of Nb2Zr6O17 Phase on the Hardness and Fracture Toughness of ZTA/Nb2O5 by Cold Isostatic Pressing

Abstract

The microstructure and mechanical properties of zirconia toughened alumina (ZTA) ceramic added with niobia (Nb2O5) through cold isostatic pressing (CIP) method was investigated. The amount of Nb2O5 is varied from 0 wt.% to 7 wt.%. The phase composition of the sintered bodies was analyzed with an x-ray diffractometer, while their microstructure was observed with a scanning electron microscope. It is found that up to 3 wt.% of Nb2O5 addition, the secondary phase of Nb2Zr6O17 presence as square shape particles confirm by SEM and EDX. The addition of 3 wt.% showed the highest Vickers hardness value with 1600HV. It was observed that, further addition of Nb2O5 (> 3 wt.% ) deteriorates the Vickers hardness of ZTA. While the fracture toughness value increased at 3 wt.% until 5 wt.% of Nb2O5 addition (6.71 MPa · √m and 6.80 MPa · √m respectively). It was also found that the value for bulk density increased and porosity decreased with the increasing of Nb2O5 addition.