(1. 福州大學(xué) 材料科學(xué)與工程學(xué)院，福州 350118； 2. 福州大學(xué) 機(jī)械工程及自動(dòng)化學(xué)院，福州 350118； 3. 福建工程學(xué)院 材料科學(xué)與工程學(xué)院，福州 350118)
摘 要: 應(yīng)用納米掃描俄歇系統(tǒng)、分子動(dòng)力學(xué)模擬和聚合實(shí)驗(yàn)，研究A356鋁屑表面氧化膜的結(jié)構(gòu)及含堿金屬氟化物的熔劑潤(rùn)濕和溶解該氧化膜的行為，并探討鋁屑在熔劑中的聚合機(jī)理。結(jié)果表明：等摩爾NaCl-KCl熔劑及添加NaF或Na3AlF6后都可以與Al2O3潤(rùn)濕，而添加AlF3的熔劑與Al2O3不潤(rùn)濕。添加氟化物的等摩爾NaCl-KCl熔劑可以溶解氧化膜，并使鋁屑聚合為鋁球，其中NaF和Na3AlF6對(duì)促進(jìn)聚合的效果最顯著，而AlF3效果較差。聚合機(jī)理分析表明，熔融熔劑中的自由F-是鋁屑聚合的前提條件，熔劑與Al2O3良好的潤(rùn)濕性可以提高氧化膜的溶解程度。氧化膜溶解后被其包裹的鋁液滴可以自發(fā)地聚合成大的鋁球，熔劑與鋁液的不潤(rùn)濕性有利于鋁液滴的聚合，但加入Na3AlF6后會(huì)比較顯著提高熔劑黏度，阻礙細(xì)小鋁球的聚合。
關(guān)鍵字: 鋁屑；聚合行為；分子動(dòng)力學(xué)模擬；堿金屬氟化物；潤(rùn)濕性
（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
