(K0.5Na0.5)NbO3 세라믹스의 초기 분말 입도 분포가 소결체의 미세구 조에 미치는 영향

초록

In this study, the effect of the initial particle size distribution (PSD) of (K0.5Na0.5)NbO3 powders on the microstructure of sintered ceramics was investigated. (K0.5Na0.5)NbO3 powders with uni-, bi-, tri-, and quad-modal PSDs were obtained through a planetary ball-mill. For the specimens sintered at 1080°C, the growth of abnormal grains was promoted from the powders exhibiting quad- and tri-modal PSDs with a high content of large parti cles, resulting in a microstructure in which huge abnormal grains were predominant. However, as the number of peaks in PSD and the overall particle size decreased, the abnormal grain growth was suppressed and the grain growth of small particles started, resulting in a microstructure with a uniform grain size. For the specimens sin tered at 1100°C, huge abnormal grains were not observed due to the decrease in the critical driving force for 2D nucleation even when powders with quad- and tri-modal PSDs were used. It was confirmed that when powder with unimodal PSD was used, a uniform microstructure that was not significantly affected by the sintering tem perature could be obtained. The results of this study demonstrate that the microstructure of (K0.5Na0.5)NbO3- based ceramics can be controlled by controlling the particle size of the initial powder.

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