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
收稿日期: 2009-11-16
修回日期: 2010-01-26
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 La0.4Pr0.6B6 Bulk Prepared by Spark Plasma Sintering
Received date: 2009-11-16
Revised date: 2010-01-26
Online published: 2010-06-10
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La0.4Pr0.6B6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La0.4Pr0.6B6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feff, 其平均值为2.84eV.
关键词： 放电等离子体烧结(SPS); 多晶La0.4Pr0.6B6; 热发射性能; 有效逸出功
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La0.4Pr0.6B6块体及其发射性能研究[J]. 无机材料学报, 2010 , 25(7) : 743 -747 . DOI: 10.3724/SP.J.1077.2010.00743
The LaH2 and PrH2 nanopowders were prepared by hydrogen arc plasma method, and then dense single-phase polycrystalline La0.4Pr0.6B6 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 La0.4Pr0.6B6 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.
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