放电等离子体烧结(SPS)制备多晶La0.4Pr0.6B6块体及其发射性能研究

doi:10.3724/SP.J.1077.2010.00743

无机材料学报 ›› 2010, Vol. 25 ›› Issue (7): 743-747.DOI: 10.3724/SP.J.1077.2010.00743 CSTR: 32189.14.SP.J.1077.2010.00743

放电等离子体烧结(SPS)制备多晶La_0.4Pr_0.6B₆块体及其发射性能研究

马汝广¹, 刘丹敏¹, 周身林², 张久兴²

(北京工业大学1. 固体微结构与性能研究所; 2. 材料学院新型功能材料教育部重点实验室, 北京100124)

收稿日期:2009-11-16 修回日期:2010-01-26 出版日期:2010-07-20 网络出版日期:2010-06-10
基金资助:
教育部创新工程重大项目培育基金(705004)

Fabrication and Emission Property of Polycrystalline La_0.4Pr_0.6B₆ Bulk Prepared by Spark Plasma Sintering

MA Ru-Guang¹, LIU Dan-Min¹, ZHOU Shen-Lin², ZHANG Jiu-Xing²

(1. Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124, China; 2. The Key Laboratory of Advanced Functional Materials, Ministry of Education, Beijing University of Technology, Beijing 100124, China)

Received:2009-11-16 Revised:2010-01-26 Published:2010-07-20 Online:2010-06-10

摘要/Abstract

摘要：

采用氢直流电弧法制备了LaH₂和PrH₂粉末, 然后利用放电等离子体烧结(SPS)技术制备了多晶的La_0.4Pr_0.6B₆致密块体. 系统分析了烧结温度对样品微观结构及性能的影响, 研究结果表明: 烧结温度高于1350℃时可形成La_0.4Pr_0.6B₆纯相, 且样品致密度随着烧结温度的升高而增加. 所制备材料的密度、维氏硬度和抗弯强度的最大值分别达到4.82g/cm³、19.14GPa和225.13MPa; 测试了40MPa、1400℃烧结样品的热电子发射性能, 当阴极温度为1873K时最大发射电流密度为30.65A/cm²; 利用Richardson直线法求出了所测试样品绝对零度时的逸出功f₀为2.165eV, 并计算出了样品在不同加热温度时的有效逸出功f_eff, 其平均值为2.84eV.

关键词: 放电等离子体烧结(SPS), 多晶La_0.4Pr_0.6B₆, 热发射性能, 有效逸出功

Abstract:

The LaH₂ and PrH₂ nanopowders were prepared by hydrogen arc plasma method, and then dense single-phase polycrystalline La_0.4Pr_0.6B₆ bulks were reactively fabricated starting from mixture of synthesized LaH₂, PrH₂ nanopowders and boron powders by spark plasma sintering (SPS). The influence of SPS sintering temperature on the microstructure and properties was investigated. Thermionic emission measurement of the sample sintered at 1400℃ and 40MPa was performed. It is shown that the pure phase La_0.4Pr_0.6B₆ bulk can be easily fabricated by SPS when the sintering temperature is higher than 1350℃ and the density of the material increases with increasing temperature. The largest values of densities, Vickers hardness and bend strengths reach 4.82g/cm³, 19.14GPa and 225.13MPa, respectively. The largest emission current density of the cathode heated at 1873K is 30.65A/cm2. The work function at absolute zero is calculated to be 2.165eV by Richardson line method, and then the average value of effective work functions of the cathode at different temperatures are calculated to be 2.84eV.

Key words: spark plasma sintering (SPS), polycrystalline La_0.4Pr_0.6B₆, thermionic emission property, effective work function

中图分类号:

TB34

马汝广, 刘丹敏, 周身林, 张久兴. 放电等离子体烧结(SPS)制备多晶La_0.4Pr_0.6B₆块体及其发射性能研究[J]. 无机材料学报, 2010, 25(7): 743-747.

MA Ru-Guang, LIU Dan-Min, ZHOU Shen-Lin, ZHANG Jiu-Xing. Fabrication and Emission Property of Polycrystalline La_0.4Pr_0.6B₆ Bulk Prepared by Spark Plasma Sintering[J]. Journal of Inorganic Materials, 2010, 25(7): 743-747.

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放电等离子体烧结(SPS)制备多晶La_0.4Pr_0.6B₆块体及其发射性能研究

Fabrication and Emission Property of Polycrystalline La_0.4Pr_0.6B₆ Bulk Prepared by Spark Plasma Sintering

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