放电等离子固相烧结制备高密度LaB_6阴极性能

采用放电等离子烧结(SPS)技术,以碳化硼还原法制备的LaB6粉末为原料,制备了高致密LaB6多晶块体阴极,并系统研究了烧结温度、压力对LaB6烧结样品的物相、结构和性能的影响。确定了SPS烧结LaB6的最佳工艺为:压力50MPa,烧结温度1650℃,保温时间10min。实验结果表明:与其它LaB6多晶制备方法相比,SPS制备得到的LaB6烧结块体的力学及发射性能均有大幅提高,样品相对密度达到96.2%,维氏硬度达到1720kg/mm2,抗弯强度达到203.2MPa。样品在1520℃温度下发射电流密度达到17.41A/cm2,功函数为2.40eV。SPS制备法显著降低了LaB的烧结温度,缩短了烧结时间。

Properties of high density LaB_6 cathode prepared by spark plasma solid phase sintering

High density LaB_6 polycrystalline bulks were fabricated by spark plasma sintering(SPS) LaB_6 powders prepared by boron carbide reduction method. The effects of sintering temperature and pressure on the phase formation, microstructure and properties of the sintered LaB_6 bulks were studied systematically. The optimal technological parameters are sintering temperature of 1 650 ℃, sintering pressure of 50 Mpa and holding time of 10 mins. It is shown that, the mechanical and emissive properties of the sintered LaB_6 bulks are much better than that prepared by other methods. The relative density of the LaB_6 sintered by SPS is up to 96.2%, and its vickers hardness reaches 1 720 kg/mm~2. The highest bend strength is 203.2 Mpa. The electron emitting density of the polycrystalline LaB_6 sintered by SPS is 17.41 A/cm~2 at 1 520 ℃, and the work function is 2.40 eV. SPS method obviously decreases the sintering temperature of LaB_6 and shortens the sintering time.