粉末粒度对SPS固相烧结La0.6Eu0.4B6阴极材料的影响

采用高能球磨法制备出La0 6Eu0.4B6纳米粉体,将球磨后的纳米粉进行放电等离子(SPS)烧结,制备出了高致密的La0.6Eu0.4B6多晶块体材料.系统研究了烧结温度、烧结压力对样品致密度和力学性能的影响.结果表明,该方法与传统热压烧结方法相比有效降低了烧结温度,制备出的样品密度、维氏硬度和抗弯强度分别达到4.71 g/cm3、23.37 GPa和295.14MPa,这些值均高于传统热压烧结方法.热电子发射结果表明,当阴极温度为1873 K时,最大发射电流密度为33.74 A/cm2.实验过程中还发现,在相同烧结工艺下,球磨纳米粉与粗粉相比,维氏硬度、抗弯强度和热电子发射电流密度分别提高了28％、58％和32％.因此,在固相烧结过程中,粉末粒度的减小,更有助于烧结性能的提高.

Effect of Particle Size on the Solid-Phase Sintered Polycrystalline La0.6Eu0.4B6 Cathode Prepared by Spark Plasma Sintering

The La0.6Eu0.4B6 nanopowders were prepared by high-energy ball milling, and then the ball-milled nanopowder were used to prepare the high-density La0.6Eu0.4B6 polycrystalline bulks by spark plasma sintering (SPS). The influence of sintering temperature and pressure on the sample density and mechanical properties were investigated. The results show that this method reduces the sintering temperature more effectively than the conventional hot-pressing method. The sample density, Vickers hardness and flexural strength are 4.71 g/cm3, 23.37 GPa, and 295.14 MPa, respectively, which ??are also higher than those of conventional hot-pressing methods. The thermionic emission results show that when the cathode temperature is 1873 K, the maximum emission current density of La0.6Eu0.4B6 is 33.74 A/cm2. Under the same sintering condition, the Vickers hardness, flexural strength and thermionic emission current density of ball-milled nanopowder are increased by 28%, 58% and 32% compared with coarse-powder-sintered sample. These results indicate that refining the powder grain size to nano level is beneficial for reducing the sintering temperature and promoting the thermionic emission and mechanical properties.