By focusing, for example, on yttria

By focusing, for example, on yttria powder as the starting powder, it appears that most of the time, the densification capacity is studied as a function of the time, or the temperature, or more generally the sintering cycle but only for a given morphology. Spheres are often chosen, because they are well known to be a good morphology for sintering. Akinc4 proposes pertinent study of monosized spherical yttria powders sintered respectively at 1500, 1600 and 1700 ◦C for 7 to 720 mn to reach density of 98–99%. Rhodes5 shows that the effects of agglomeration size of fine yttria stabilized zirconia limit the green density and also limit final sintering stage to 95%. He also proposes a method6 to retard grain growth to get a pore-free ceramic of La2O3–Y2O3 leading to 100% theoretical density by heating until 2170 ◦C. Full density is related to high sintering temperatures most of the time.