放电等离子体烧结复合稀土钼阴极的次级发射性能及组织的研究

Secondary Emission Property and Microstructure Analysis on Molybdenum Cathode Doped with Rare Earth Oxides Made by Spark Plasma Sintering

研究了放电等离子体烧结(SPS)复合稀土氧化物的钼阴极材料的二次电子发射系数、致密化、组织、结构,对发射后的材料表面进行了微观组织观察,并与常规烧结(CIP-S)方法进行了比较。在低于常规烧结温度180℃～280℃,保温3min得到的复合稀土氧化物的钼阴极材料的晶粒明显细化,相对密度达95.6%～98.8%,因在激活发射过程中能快速在阴极表面形成高比例的稀土氧化物膜,使二次电子发射系数高于CIP-S烧结材料。但SPS烧结温度高于1600℃,晶粒将急剧长大,二次发射系数也显著下降。

The secondary emission coefficients, densities, microstructures for molybdenum cathodes have been determined. The cathodes doped with higher content of rare earth oxides were produced by SPS. The results were compared with one made by general sinter technique. It is shown that the molybdenum crystals doped with higher content of rare earth oxides are finer, and the secondary emission coefficients are higher than that of CIP-S, and their relative densities are 95.6% similar to 98.8%. Moreover, the temperature of SPS with a holding time of 3 minute is lower 180degreesC to 280degreesC than that of CIP-S. The reason is because that the film with a higher content of rare earth oxides is formed fast in activation and emitting. However, when the temperature is higher than 1600degreesC, the grain size of the cathode increases quickly with decrease of the secondary emission coefficients of the cathode.