(北京工业大学 新型功能材料教育部重点实验室,北京 100022)
摘 要: 研究了碳化温度、 碳化时间、 碳化时苯的压强对Mo-La2O3阴极碳化度大小和碳化层组织的影响。结果表明:在1723K, 苯的压强为1.5×10-2Pa, 碳化6min后Mo-La2O3阴极碳化度达到19.7%,碳化层为疏松多孔的Mo2C组织, 有利于阴极热电子发射。 应用扫描电镜(SEM)、 X射线衍射仪(XRD)等手段对Mo-La2O3阴极碳化层的显微组织和微观结构、 物相等进行了观察与分析。 并从热力学与动力学两方面对Mo-La2O3阴极碳化机理进行了探讨。
关键字: Mo-La2O3阴极; 碳化度; 组织; 热电子发射; 碳化机理
Mo-La2O3 cathode
(The key Laboratory of Advanced Functional Materials, Ministry of Education, Beijing Polytechnic University,Beijing 100022, China)
Abstract:The carbonizing process of Mo-La2O3 cathode are investigated and the microstructures and phases of it’s carbonized layers are studied by TEM and XRD. The carbonizing temperature, carbonizing time and the pressure of benzene (C6H6) are the decisive factors. In the adequate benzene vapor (1.5×10-2Pa), Mo-La2O3 cathodes carbonized at 1723K and for 6min can obtain maximum carbonized ratio and coarse Mo2C particles carbonized layers, which is beneficial to the migration of activated rareearth element to the surface of the cathode during the operating. The carbonization mechanism of Mo-La2O3 cathode is also discussed.
Key words: Mo-La2O3 cathode; carbonized ratio; microstructure; thermionic electron emission; carbonization mechanism