(1. 福州大学 材料科学与工程学院，福州 350118； 2. 福州大学 机械工程及自动化学院，福州 350118； 3. 福建工程学院 材料科学与工程学院，福州 350118)
摘 要: 应用纳米扫描俄歇系统、分子动力学模拟和聚合实验，研究A356铝屑表面氧化膜的结构及含碱金属氟化物的熔剂润湿和溶解该氧化膜的行为，并探讨铝屑在熔剂中的聚合机理。结果表明：等摩尔NaCl-KCl熔剂及添加NaF或Na3AlF6后都可以与Al2O3润湿，而添加AlF3的熔剂与Al2O3不润湿。添加氟化物的等摩尔NaCl-KCl熔剂可以溶解氧化膜，并使铝屑聚合为铝球，其中NaF和Na3AlF6对促进聚合的效果最显著，而AlF3效果较差。聚合机理分析表明，熔融熔剂中的自由F-是铝屑聚合的前提条件，熔剂与Al2O3良好的润湿性可以提高氧化膜的溶解程度。氧化膜溶解后被其包裹的铝液滴可以自发地聚合成大的铝球，熔剂与铝液的不润湿性有利于铝液滴的聚合，但加入Na3AlF6后会比较显著提高熔剂黏度，阻碍细小铝球的聚合。
关键字: 铝屑；聚合行为；分子动力学模拟；碱金属氟化物；润湿性
（1. School of Materials Science and Engineering, Fuzhou University, Fuzhou 350118, China; 2. School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou 350118, China; 3. School of Materials Science and Engineering, Fujian University of Technology, Fuzhou 350118, China）
Abstract:Nano scanning auger system, molecular dynamics simulations and coalescence experiments were employed to study the oxide film structure of A356 alloy chips and the behaviors of salt fluxes containing alkali fluorides wetting and melting oxide films. Moreover, the coalescence mechanism was discussed. The results show that equimolar NaCl-KCl with addition of NaF or Na3AlF6 wetted well with Al2O3 inclusions but addition of AlF3. Eequimolar NaCl-KCl containing alkali fluorides can melt oxide film and promote the coalescence of wrapped aluminum droplets in molten fluxes. The effects of NaF and Na3AlF6 on coalescence are more significant than that of AlF3. The coalescence mechanism analysis results show that free F- ions are the premise for chips coalescence and the wetting between fluxes and Al2O3 inclusions improve the coalescence degree. Aluminum droplets can coalesce spontaneously in molten fluxes and the non-wetting between fluxes and aluminum liquid is benefit for the coalescence, but the improvement of fluxes viscosity by Na3AlF6 will resist the coalescence of small aluminum droplets.
Key words: aluminum chip; coalescence behavior; molecular dynamics simulation; alkali fluoride; wetting
