Fast firing of 3 mol% yttria-stabilized zirconia: On the effect of heating rate on sintering

The impact of rapid heating on sintering is currently getting a growing scientific interest. Previous results have shown that when considering 90 nm-sized 3 mol% yttria-stabilized zirconia (3YSZ) powder the heating rate effect on densification is not detectable, whereas it is huge when using finer powder (approximate to 20 nm, specific surface area, SSA = 30-60 m2 g-1). Herein, we investigate the fast firing of approximate to 40 nm 3YSZ powder (SSA = 16 m2 g-1) and compare it with conventional sintering. The results show that the heating rate has a modest effect on the final density with improvements always below 2%-3% in terms of relative density. The relatively good match between fast firing and the densification behavior predicted by the master sintering curves agrees with the observed microstructural evolution, where fast-firing provides only a modest effect on the pore size. Finally, it is shown that the heating rate does not impact the dynamics of closed pore formation. Combined FEM simulation and master sintering curve (MSC) method were used to identify the heating rate effect on sintering. The results show that when considering 40 nm 3YSZ powder the MSC provides a modest underestimation of the density achieved by fast firing. Coherently, the microstructure poorly depends on the thermal history. image