Ag400直接替代PdO应用于高真空多层绝热储罐中的研究

Novel Composite Getter Material of Ag400 for High Vacuum Multilayer Insulation Tank

高真空多层绝热因其超好的绝热性能而广泛的应用于低温储罐,但其夹层真空度会随着材料的放气而逐渐降低,放气的主要成分是氢气。为此,对比研究了新型廉价吸氢剂银分子筛(Ag400)和常规高价吸氢剂氧化钯(PdO)的吸氢特性。分别测定了PdO和Ag400的吸附等温线,根据BDDT理论,均为第一类吸附等温线,属于化学吸附,并用Langmuir等温式进行了分析,PdO的吸附系数为8.11,饱和吸附量为228.53 ml/g;Ag400的吸附系数为8.28,饱和吸附量为29.45 ml/g。Ag400的饱和吸附量,平均最大吸附速率和实验周期内平均吸附速率分别是PdO的13.01%,40.89%和15.92%。综合考虑吸附量和吸附速率,认为Ag400进行PdO的直接替代时,质量比例应不低于10∶1。本文可以为工程设计人员应用新型吸氢剂Ag400提供理论依据。

A novel composite getter material,silver-exchanged molecular sieve Ag400,was developed to replace thecostly PdO widely used in high vacuum multilayer insulation tank. The H2-sorption properties of Ag400 and PdO were theoretically analyzed in BDDT theory and experimentally investigated. The measured hydrogen adsorption isotherms of Ag400 and Pa O best resembled Type-I isotherm. As chemisorption,the H2-sorption isotherms in the temperature range of interest were analyzed with Langmuir isotherm equation. The calculated results show that Ag400 outperforms PdO in many ways. For example,the adsorption coefficient andsaturated adsorption of Ag400 were 8. 28 and 29. 45 ml/g,whereas those of PdO were 8. 11 and 29. 45 ml/g,respectively. The saturated adsorption,average maximum adsorption rate and mean measured adsorption rates of Ag400 were found to account for13. 01%,40. 89% and 15. 92% of those of PdO,respectively. We suggest that the substitute ratio should be higher than 10∶ 1（10. 0 g Ag400 for 1. 0 g PdO）.