Effect of niobium oxide (Nb₂O₅) addition to the physical and mechanical properties of cold isostatic press zirconia toughened alumina (ZTA) was investigated. Various amount of Nb₂O₅ (0 - 7 wt.%) were added into ZTA separately through solid state method. The influences of Nb₂O₅ addition were investigated on the structural, microstructural and mechanical properties of ZTA ceramics. XRD analysis identified the presence of t-ZrO2, m-ZrO2 and Nb2Zr6O17 phase in this system. The presence of Nb2Zr6O17 phase found to deteriorate the properties of ZTA ceramic, which is related to the solubility limit of Nb₂O₅. The optimum value was achieve at 1 wt.% Nb₂O₅, which gives the highest value for Vickers hardness (1840 HV), fracture toughness (8.60 MPa.m1/2) and flexural strength (351 MPa). The lower porosity results in the enhancement of the mechanical properties. Dense body was obtained via CIP method with the relative density achieve 99.8% to the theoretical density. The crack associated from indentation technique related with the increasing of fracture toughness value due to the presence of crack deflection. The phase transformation (t → m) also occurs in this system and resulted in improvement for fracture toughness and flexural strength. The obtained values indicated that Nb₂O₅ found to improve the physical and mechanical properties of ZTA ceramic. Thus, the high strength and toughness of ZTA ceramic can be produced.
