Grain growth enhancement in alumina during hot isostatic pressing

Pore closure in spark plasma sintered alumina studied by variable energy positrons

“…Since no significant compact shrinkage is observed in the samples sintered at high heating rate, therefore the only way to close the open pores in these samples is to break down their interconnection with the free sample surface through a grain growth process at low sintering temperature. It is known that grain growth at low sintering temperature occur through Ostwald ripening or surface diffusion mechanism [2] and it can be enhanced by the excess formation of point defects at grain surface similarly as reported during high heating rate of hot isostatic pressing of alumina [21].…”

Transparent polycrystalline alumina using spark plasma sintering: Effect of Mg, Y and La doping

“…Taking into consideration the fact that higher applied pressures lead to an enhanced grain growth above a critical temperature, 30 the addition of dopants seems to increase this temperature. The enhanced grain growth for pure alumina under increased pressure has also been reported for HIP sintered samples 31 and is known to be dependent on the sintering temperature, the density of the ceramic to be sintered. The critical values of these parameters can be influenced by the doping strategies 31,32 as we have also observed here.…”

Effects of heating rate on microstructure and transparency of spark-plasma-sintered alumina

“…Large DC current for rapid heating is considered to assist the defect formation owing to high-temperature plasma generated on particle surfaces, and the deformation-induced defect is well known to induce dynamic grain growth. 13,14 The defect produced by both heating and deformation may therefore accelerate the grain growth during SPS processing.…”