HfO2 doped 3Y-TZP on mechanical properties and low temperature degradation (LTD)

The mechanical properties and ageing resistance of 0.5-10 mol% HfO2 doped 3Y-TZP have been investigated. All samples were sintered at 1500 degrees C-2 h and characterized by density testing. Samples with polished surfaces were submitted to X-Ray diffraction (XRD) and microstructure testing and then cut into standards for 3-point bending testing. Group 2 was characterized by Vickers hardness and fracture toughness. Group 3 was accelerated ageing procession in autoclave condition containing at 134 degrees C and 0.2 MPa 10 h up to 40 h, and then detected by transmission electron microscopy (TEM) analysis. All sintered specimens presented nearly full densification. The grain size of 3Y0.5Hf-TZP was smaller than that of undoped 3Y-TZP after sintering. 3Y0.5Hf-TZP enhanced the bending strength by 34.6% compared to 3Y-TZP. The ageing kinetic parameter (n similar to (0.66-1.64)) was related to the grain size and the ageing time from the onset of the transition until the transition reaches saturation.