Effect of rapid heating on densification and grain growth in hot pressed alumina

Compact bodies of alpha-alumina with an average particle size of 0.22 mu m were hot-pressed at heating rates of 5 and 500 degrees C/min. A specimen wi th a relative density of 99.5% was obtained with adopting a heating rate of 500 degrees C/min up to 1310 degrees C, for a holding time of 2 min under a uniaxial pressure of 50 MPa. The average grain size was 1.5 mu m. Both de nsification and grain growth were enhanced by rapid heating. A rationale fo r this result was given under the assumption that an increase in defect con centration in the alumina grains was produced by rapid heating.