The Effect of Particle Shape on Sintering Behavior and Compressive Strength of Porous Alumina

Alumina particles with different shapes, such as sphere, rod, and disk, were examined for the sintering behavior and compressive strength of partially sintered porous alumina. While both the spherical and disk-like particles were packed well to the relative density of 61.2-62.3%, the packing density of rod-like particles was only 33.5%. The sintering rate of alumina particles increased in the order of disk < rod < sphere. The compressive strength of sintered porous alumina was higher for the spherical particles than for the rod-like and disk-like particles. The uniform distribution of the applied load over many developed grain boundaries contributed to the increase in the compressive strength for the spherical particles. The applied load concentrated on a few grain boundaries of rod-like or disk-like particles, caused fracture at a low compressive stress.