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Examination of techniques for synthesizing highly efficiency thermoelectric material NaCo2O4.

高效热电材料NaCo2O4合成技术的检验。

基本信息

批准号：
14550686
负责人：
SHIMOZAKI Toshitada
金额：
$ 1.86万
依托单位：
Kyusyu Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14550686/
关键词：
NaCo2O4 correlated electron oxide Thermoelectric Material Plasma sintering method Pressing method at air Melt method orientationing of crystal 緻密化固相反応法低荷重化加熱法ホットプレス法ゼーベック係数電気伝導度 NaCo204 熱電変換材料粉末焼結法配向性結晶粒成長

项目摘要

Synthesizing techniques for highly efficiency thermoelectric material NaCo2O4 have been examined. Usual sintering method, hot press method, plasma-sintering method, pressing method at air, melt solidification method were tried. Appropriate amount of Na2Co3 and Co oxide powder were mixed and grind in a boll mill by using methanol. The mixed powder was dried and sintered at 880℃ for 12h or 24 h. The precursor was again grind in the boll mill to make powder. Then the powder was sintered by various techniques. One is hot pressed at various temperatures for various anneal times. One is shaped to 5 mm x 6mm x 20mm size in a pressed mold. The specimens were sintered in a temperature range from 880〜1000℃ for various anneal times. Some of the specimens were pressed in an air atmosphere under 10kgf/cm^2 to make porous specimen to precise specimen. Some of powder is sintered in a plasma sintering machine in the temperature range 700〜850℃ for 5 min〜15min. Some of specimens with 5 mm x 6mm x 20mm i … More n size were heated up to 1100℃ and they were melted and slowly cooled to 950℃.Synthesizing techniques for highly efficiency thermoelectric material NaCo2O4 have been examined. Usual sintering method, hot press method, plasma-sintering method, pressing method at air, melt solidification method were tried. Appropriate amount of Na2Co3 and Co oxide powder were mixed and grind in a boll mill by using methanol. The mixed powder was dried and sintered at 880℃ for 12h or 24 h. The precursor was again grind in the boll mill to make powder. Then the powder was sintered by various techniques. One is hot pressed at various temperatures for various anneal times. One is shaped to 5 mm x 6mm x 20mm size in a pressed mold. The specimens were sintered in a temperature range from 880〜1000℃ for various anneal times. Some of the specimens were pressed in an air atmosphere under 10kgf/cm^2 to make porous specimen to precise specimen. Some of powder is sintered in a plasma sintering machine in the temperature range 700〜850℃ for 5 min〜15min. Some of specimens with 5 mm x 6mm x 20mm in size were heated up to 1100℃ and they were melted and slowly cooled to 950℃.We could not make porous specimen to precise specimen by any other method such as hot press method, plasma sintering method and melt and solidification method excepting by pressing them at air atmosphere. However, thermoelectric properties of these precise specimens are not so much better than that made from by usual sintering method. They are only 20% better than the usual sintering method. The reasons were expected that Na atoms evaporated from specimens or excess Na atoms were absorbed from Na2Co3 powder, which were put around the specimen to prevent the evaporation of Na atoms. Consequently, the most important problem is how to control the Na concentration at the best condition. Less

研究了高效热电材料NaCo_2O_4的合成工艺。试验了真空烧结法、热压法、等离子烧结法、常压压制法、熔体凝固法等。将适量的Na 2Co 3和Co氧化物粉末混合并在球磨机中通过使用甲醇研磨。将混合粉末干燥并在880℃下烧结12 h或24 h。将前体再次在球磨机中研磨以制备粉末。然后通过各种技术烧结粉末。其中一个在不同温度下热压不同的退火时间。一种是在压制模具中成型为5 mm x 6 mm x 20 mm的尺寸。试样在880 ~ 1000℃范围内进行了不同退火时间的烧结。在空气气氛中以10 kgf/cm ^2的压力对部分试样进行压制，以使多孔试样成为精密试样。部分粉末在等离子烧结机中在700 - 850℃温度范围内烧结5 min-15 min。一些5 mm x 6 mm x 20 mm i的样本 ...更多信息 n粒度的混合物加热至1100℃，熔融后缓慢冷却至950℃，研究了高效热电材料NaCo_2O_4的合成工艺。试验了真空烧结法、热压法、等离子烧结法、常压压制法、熔体凝固法等。将适量的Na 2Co 3和Co氧化物粉末混合并在球磨机中通过使用甲醇研磨。将混合粉末干燥并在880℃下烧结12 h或24 h。将前体再次在球磨机中研磨以制备粉末。然后通过各种技术烧结粉末。一种是在不同温度下热压不同退火时间。一种是在压制模具中成型为5 mm x 6 mm x 20 mm的尺寸。试样在880 ~ 1000℃范围内进行了不同退火时间的烧结。在空气气氛中以10 kgf/cm ^2的压力对部分试样进行压制，以使多孔试样成为精密试样。部分粉末在等离子烧结机中在700 - 850℃温度范围内烧结5 min-15 min。将尺寸为5 mm × 6 mm × 20 mm的试样加热到1100℃后熔化，然后缓慢冷却到950℃，除了在空气气氛中压制外，其它任何方法如热压法、等离子烧结法和熔化凝固法都不能将多孔试样制成精密试样。然而，这些精密试样的热电性能并不比普通烧结法制备的试样好多少。它们只比通常的烧结方法好20%。其原因可能是Na原子从试样中蒸发或过量的Na原子从Na 2Co 3粉末中被吸收，这些粉末被放置在试样周围以防止Na原子的蒸发。因此，如何将钠离子浓度控制在最佳条件下是最重要的问题。少