The sintering curves for the standard cycle (FIGURE ), i.e. a dwell time at 1450°C for 15 min with a pressure of 40 MPa, show relatively little difference between samples without glass phase. In presence of a glass phase, the densification rate peak seems more pronounced around 1300°C (i.e. for a time of 500 s in FIGURE ), and when both zirconia and a glass phase are present (AP ng -Zm and AP ng -Zt), densification starts slightly earlier than for other samples.