Densification behaviour and microstructural development in undoped yttria prepared by flash-sintering

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• 作者：Hidehiro Yoshida ; Yoshio Sakka ; Takahisa Yamamoto ; Jean-Marie Lebrun ; Rishi Raj
• 关键词：Yttria ; Flash-sintering ; Electron microscopy ; Diffusion
• 刊名：Journal of the European Ceramic Society
• 出版年：April, 2014
• 年：2014
• 卷：34
• 期：4
• 页码：991-1000
• 全文大小：3272 K

文摘

Conventional sintering of undoped Y₂O₃ requires temperatures above 1400 掳C for a few hours. We show that it can be sintered nearly instantaneously to nearly full density at furnace temperature of 1133 掳C under a DC applied field of 500 V/cm. At 1000 V/cm sintering occurs at 985 掳C. The FLASH event, when sintering occurs abruptly, is preceded by gradually accelerated field-assisted sintering (FAST). This hybrid behaviour differs from earlier work on yttria-stabilized zirconia where all shrinkage occurred in the flash mode. The microstructure of flash-sintered specimens indicated that densification was accompanied by rapid grain growth. The single-phase nature of flash-sintered Y₂O₃ was confirmed by high-resolution transmission electron microscopy. The non-linear rise in conductivity accompanying the flash led to Joule heating. It is postulated that densification and grain growth were enhanced by accelerated solid-state diffusion, resulting from both Joule heating and the generation of defects under the applied field.