【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。更多还原

【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 Na Cl-KCl with addition of Na F or Na₃AlF₆ wetted well with Al₂O₃ inclusions but addition of AlF₃. Eequimolar Na Cl-KCl containing alkali fluorides can melt oxide film and promote the coalescence of wrapped aluminum droplets in molten fluxes. The effects of Na F and Na₃AlF₆ on coalescence are more significant than that of Al F₃. 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.更多还原