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

探讨了高效热电材料NaCo2O4的合成技术，尝试了普通烧结法、热压法、等离子烧结法、空气压制法、熔融凝固法等，将适量的Na2Co3和Co氧化物粉体混合并研磨。将混合粉末用甲醇干燥并在880℃下烧结12h或24h，将前体再次在球磨机中研磨。然后将粉末通过各种技术进行烧结，在不同的温度下进行不同的退火时间。将样品在压制模具中成型为 5 毫米 x 6 毫米 x 20 毫米的尺寸。 880〜1000℃不同的退火时间，一些样品在10kgf/cm^2的空气气氛中压制，以将多孔样品制成精密样品。在等离子烧结机中，在700〜850℃的温度范围内烧结5分钟〜15分钟，将一些尺寸为5mm x 6mm x 20mm的样品加热至1100℃，然后将其熔化并缓慢冷却至950℃。 ℃.研究了高效热电材料NaCo2O4的合成技术，包括普通烧结法、热压法、尝试了等离子烧结法、空气压制法、熔融凝固法，将适量的Na2Co3和Co氧化物粉末混合并用甲醇在球磨机中研磨，将混合粉末在880℃下干燥并烧结12h或24。 h.将前体再次在球磨机中研磨以制成粉末，然后通过各种技术对粉末进行不同的退火时间的热压。在压制模具中将样品制成5毫米×6毫米×20毫米的尺寸，在880〜1000℃的温度范围内进行不同的退火时间，并将一些样品在10kgf/cm^2的空气气氛中压制以形成多孔。将部分粉末在等离子烧结机中在700〜850℃的温度范围内烧结5分钟〜15分钟。将尺寸为 5 mm x 6mm x 20mm 的样品加热至 1100℃，然后熔化并缓慢冷却至 950℃。我们无法通过热压法、等离子烧结法等任何其他方法将多孔样品制成精密样品。然而，这些精密样品的热电性能并不比通常的烧结方法好多少。比通常的烧结方法好20％，预计原因是Na原子从样品中蒸发或过量的Na原子被Na2Co3粉末吸收，这些粉末被放置在样品周围以防止测试中的Na原子蒸发。如何将Na浓度控制在最佳状态。