PDF《熔盐电解法制备铝锂中间合金》

第18 卷第

8 期 中国有色金属学报

2008 年8月Vol.

18 No.8 The Chinese Journal of Nonferrous Metals Aug..

2008 文章编号:1004-0609(2008)08-1555-05 熔盐电解法制备铝锂中间合金 李继东,张明杰,张廷安,李丹,张卓(东北大学 材料与冶金学院,沈阳 110004) 摘要:研究在LiCl-LiF-Li2CO3纯锂盐体系中下沉式铝液阴极槽结构电解生成铝锂中间合金的工艺过程,尤其是 以Li2CO3为原料代替LiCl的电解过程.采用熔盐电解监控仪测量电解过程中的反电动势、槽电压、电流等工艺参 数及电解波形图,通过电位控制法调节Li2CO3的加料周期,同时根据得到的合金产品中的锂含量探讨影响电流效 率的因素.结果表明,反电动势随电流密度增加而增大,加入 2%的Li2CO3可使反电动势降低 0.5 V;

通过控制电 位法测得加料周期为

15 min;

在680 ℃、电流密度为 0.62 A/cm2 的条件下持续电解

3 h,最终制得了锂含量高达 7.93%的铝锂合金,电流效率可达 74.1%. 关键词:铝锂合金;

熔盐电解;

反电动势;

电流效率 中图分类号:TF 827.2 文献标识码:A Preparation of Al-Li master alloys by molten salt electrolysis LI Ji-dong, ZHANG Ming-jie, ZHANG Ting-an, LI Dan, ZHANG Zhuo (School of Materials and Metallurgy, Northeastern University, Shenyang 110004, China) Abstract: Al-Li master alloys were prepared using sinking-mode aluminum liquid as cathode and a mixture of LiCl-LiF-Li2CO3 as molten salt electrolyte in a laboratory cell. The electrolysis process with Li2CO3 as raw material instead of LiCl was studied in detail. The technological parameters such as back electromotive force, cell voltage, current and electrolysis waveform were measured by testing device of molten salt electrolysis. The period of Li2CO3 feeding was adjusted by the method of electric potential control. At the same time, the factor that affects current efficiency was discussed according to the lithium content of alloys obtained. The results indicate that back electromotive force increases with increasing current density and decreases by 0.5 V after adding 2% Li2CO3, the feeding period is

15 min measured by the method of electric potential control. Finally, the Al-Li alloy with the lithium content of 7.93%(mass fraction) can be obtained by electrolyzing for

3 h at the current density of 0.62 A/cm2 and at

680 ℃, and the current efficiency can reach 74.1%. Key words: Al-Li alloy;

molten salt electrolysis;

back electromotive force;

current density 锂是自然界中最轻的金属元素,密度仅为 0.534 g/cm3 ,向纯铝中掺入 1%(质量分数)的锂可使合金密 度降低 3%,弹性模量增加约 6%,用其代替常规的铝 合金,可使构件质量减轻 10%~15%,刚度提高 15%~20%[1?3] .因此,铝锂合金作为一种低密度、高 弹性模量、高强度和高比刚度的理想结构材料而广泛 应用于航空航天及国防太空等领域[4?5] . 目前, 生产铝锂合金的方法多为对掺法,即向纯铝 中加入金属锂熔炼,配制铸成一定浓度的铝锂合金. 熔盐电解法是以铝液作阴极,电解生成的金属锂在阴 极中析出并扩散在铝液中,一步直接合金化.与对掺 法生产铝锂合金相比,熔盐电解法具有浓度均匀、锂 的烧损率小、生产连续且易控制和低成本等优点,因 而引起了人们的广泛研究[6?11] .同时电解一步合金化 基金项目:国家自然科学基金重点资助项目(50574024) 收稿日期:2007-11-30;

修订日期:2008-04-15 通讯作者:李继东,博士研究生;