Pressure‐assisted flash sintering of ZnO ceramics

Abstract

Implementing pressure‐assisted flash sintering of ZnO powder without pretreatment by a new experimental configuration is presented. Rapid and energy‐concentrated heating of electrode‐sample‐electrode area by induction heating allows preheating and flash sintering of loose‐pack powder in the die with pressure assistance. Using an insulated die enables the current to flow through the sample during flash sintering. ZnO ceramics with a relative density of 95.1% can be achieved in less than 3 min. The whole process includes 104 s of preheating by a low‐power induction heating device and 30 s of flash sintering assisted by a pressure of 26 MPa using the pulsed direct current (DC). The process characteristics of pressure‐assisted flash sintering using the pulsed DC are discussed. The effect of pressure on densification and grain size is analyzed in detail, and some potential mechanisms are provided.

Use of partial discharges measurements and video recordings to investigate the influence of relative humidity on zinc oxide subjected to high electric fields

“…Flash sintering relies on applying an electric field during the heat treatment, in order to reduce significantly sintering temperatures and times [6][7][8]. Successful densification of ZnO was first demonstrated for an electric field applied at relatively high temperature [8][9][10][11][12][13][14] but recent works report that flash sintering of ZnO can also occur at room temperature [15][16][17][18][19]. This property opens up remarkable prospects in terms of energy savings.…”