含金属氟化物的熔剂与铝液的反应热力学分析

发布时间：2018-05-26 22:25

本文选题：熔剂 + 金属氟化物　；参考：《特种铸造及有色合金》2017年11期

【摘要】：通过热力学分析与试验研究了含金属氟化物的熔剂与A356铝合金中主要元素的反应,以及对铝合金组织与成分,熔剂组成相的影响,采用SEM、EDS和XRD进行组织和成分分析。结果表明,金属氯化物与A356主要元素的置换反应平衡常数大多低于氟化物,表明熔剂中的氯化物具有更好的化学稳定性。含NaF、SrF_2、BaF_2的熔剂中,氟化物较易与A356合金中的Al或Mg反应,在铝熔体中生成游离态Na、Sr、Ba原子,对共晶Si相有显著变质作用。含Na3AlF6的熔剂也会与铝液反应生成少量Na原子,对共晶Si相有一定的变质作用。含AlF_3、MgF_2和CaF_2的熔剂对A356铝合金组织没有明显影响。含NaF和BaF_2的熔剂可分别生成新的KMgF_3和BaFCl相,其他氟化物对熔剂成分没有明显影响。MgF_2、CaF_2、SrF_2和BaF_2由于熔点和密度高,容易在A356铝合金中残留。
[Abstract]:The reaction of fluxes containing metal fluoride with the main elements in A356 aluminum alloy was studied by thermodynamics analysis and experiments. The microstructure and composition of A356 aluminum alloy were analyzed by means of SEM-EDS and XRD. The results show that the equilibrium constants of the replacement reaction between metal chloride and A356 main elements are mostly lower than those of fluoride, which indicates that the chloride in the flux has better chemical stability. In the fluxes containing NaFNSrF2BaF2, fluoride reacts more easily with Al or mg in A356 alloy, and forms free NaOS-Sr-Ba atoms in aluminum melts, which have obvious metamorphism to eutectic Si phase. The flux containing Na3AlF6 also reacts with molten aluminum to form a small amount of Na atoms, which has a certain metamorphism on eutectic Si phase. The fluxes containing Alf _ 3, MgF _ 2 and CaF_2 have no obvious effect on the microstructure of A356 aluminum alloy. New KMgF_3 and BaFCl phases can be formed in fluxes containing NaF and BaF_2, respectively. The other fluorides have no obvious effect on the composition of the fluxes. MgF2Caf2SrF2 and BaF_2 are easy to remain in A356 aluminum alloy due to their high melting point and density.
【作者单位】：福州大学材料科学与工程学院;福建工程学院材料科学与工程学院;福州大学机械工程及自动化学院;
【基金】：国家科技部国际合作项目(2015DFA71350) 福建省科技计划重点项目(2012H0006)
【分类号】：TG146.21

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