难熔金属阴极及涂层研究进展

On the Research Advancement of Refractory Metal Cathodes and Coatings

介绍了稀土钼金属陶瓷阴极、钪钨基扩散阴极及化学气相沉积法制备钨涂层。为了满足大功率磁控管的发展要求,研究了新型稀土钼金属陶瓷阴极。经过高温激活处理后,材料的最大次级发射系数达5.24,实用管型测试结果表明,稀土钼金属陶瓷阴极的性能优于钡钨阴极,显示了良好的应用前景。亚微米结构的钪钨基扩散阴极具有优异的热发射性能,850℃下阴极的发射电流密度可达42A/cm2,激活后Ba,Sc,O等元素形成的活性多层,均匀覆盖在阴极表面,促进了阴极的发射。采用热壁开管气流CVD法,以WF6和H2为反应源气体,可以方便地制备成难熔金属钨沉积层。所获得钨沉积层具有高纯度(>99%)和高致密度(>19g/cm3)。

RE2O3-Mo cermet cathode, Scandia doped tungsten matrix dispenser cathode and tungsten coating prepared by chemical vapor deposition have been introduced in this paper. In order to meet the requirement for the high power magnetron, a novel RE2O3-Mo cermet cathode has been invented. The maximum secondary emission yield could reach 5.24 after the cathode being activated. The practical magnetron measurement results indicated that the magnetron equipped with RE2O3-Mo cathode exhibited better performance than that equipped with Ba-W cathode, indicating a high application possibility in the future. The Scandia doped tungsten matrix dispenser cathode exhibited excellent emission property, i.e., the emission current density could get to 42 A/cm2 at the temperature of 850 ℃. A layer composed of active substance of Ba, Sc, and O covers on the cathode surface after activation, leading to this high emission property. High quality tungsten layers could be obtained by hot wall CVD via the H2 reduction of WF6. The obtained tungsten layer has high purity （〉 99 %）and high density（〉 19 g/cm3）.