Densification and grain growth in pulse electric current sintering of alumina

Pulse electric current sintering (PECS) method was used to sinter an ultrafine and high purity α-Al2O3 powder. The powder compact was either slowly heated (50 °C/min) or rapidly heated (300 °C/min) to temperatures ranging between 1000 and 1400 °C and then rapidly cooled down without holding. The densification and grain growth behaviors at different stages of the PECS process were investigated. At the earlier stages, fast heating greatly promoted the formation of necking between particles and enhanced both densification and grain growth; at the late stage, faster heating resulted in smaller grain sizes.