Magnesium vapor nucleation in phase transitions and condensation under vacuum conditions  

真空条件下镁蒸气相变形核及冷凝(英文)

作　　者：杨成博[1,2,3] 田阳[1,2,3] 曲涛[1,2,3] 杨斌[1,2,3] 徐宝强[1,2,3] 戴永年[1,2,3] 

机构地区：[1]昆明理工大学真空冶金国家工程实验室,昆明650093 [2]云南省有色金属真空冶金重点实验室,昆明650093 [3]云南省复杂有色金属资源清洁利用国家重点实验室(培育基地),昆明650093

出　　处：《Transactions of Nonferrous Metals Society of China》2014年第2期561-569,共9页中国有色金属学报（英文版）

基　　金：Project(51304095)supported by the National Natural Science Foundation of China;Project(S2013FZ029)supported by Science and Technology Planning Project of Yunnan Province

摘　　要：Recent findings related to coagulable magnesium vapor nucleation and growth in vacuum were assessed critically, with emphasis on understanding these processes at a fundamental molecular level. The effects of magnesium vapor pressure, condensation temperature, and condensation zone temperature gradient on magnesium vapor nucleation in phase transitions and condensation from atomic collision and coacervation with collision under vacuum conditions were discussed. Magnesium powder and magnesium lump condensates were produced under different conditions and characterized by scanning electron microscopy （SEM） and energy-dispersive X-ray spectroscopy （EDS）. The right condensation zone temperature approach to the liquid transition primarily improved the magnesium vapor concentration rate. The gas-solid phase transition was primarily inhibited by setting a small condenser temperature gradient. Under the right condensation temperature and temperature gradients, increasing magnesium vapor partial pressure improved crystallization and reduced the oxidation rate.描述真空条件下可凝镁蒸气的形核与长大,并从分子水平的研究原理解释这些过程。在平均真空度为40Pa条件下,分析系统压力、冷凝区温度及温度梯度对镁蒸气冷凝的影响。采用自主设计的多级冷凝设备,通过真空蒸发冷凝制备块状镁和镁粉。利用扫描电镜(SEM)与能谱(EDS)进行分析。结果表明:在真空条件下,适宜的气-液转变温度是提高蒸气冷凝富集率的关键所在;而较小的温度梯度则是抑制蒸气发生气-固转变的主要途径;在特定的冷凝温度及温度梯度下,蒸气分压及浓度的提高可以明显改善镁的结晶形貌,降低氧化率。

关 键 词：magnesium vapor VACUUM phase transition CONDENSATION NUCLEATION 

分 类 号：TF822[冶金工程—有色金属冶金]