Research for the development of high specific strength Al-Li alloy by using new electrolysis method

铝锂合金是铝合金中最轻、强度最高的一种，是一种很有前途的新材料。然而，由于金属锂的化学活性很高，其密度仅为铝的1/5，因此铝锂合金的制备比较困难。这种方法，即熔盐电解，被认为是生产铝锂合金的极好方法，如下：1.不使用危险的金属锂。采用电解法将锂加入到铝液中，使锂含量从零提高到所需浓度。2.由于熔盐起到助熔剂的作用，并保护合金不受空气的影响，因此可以获得清洁的合金。3.可以降低生产铝的成本。由于碳酸锂较便宜且不吸湿，因此通过使用碳酸锂作为锂源来大量制备Li合金。阴极反应锂沉积的电流效率优异，至少高于90%。有害杂质如钾、钠含量很低，约为10 ppm，与纯铝基本相同。阳极反应的结果表明：氯化物熔体作电解液时，有氯气析出;在氯化物熔体中加入碳酸锂，阳极电位急剧下降。电压几乎达到1.3V。不产生氯气，废气由大量二氧化碳和少量一氧化碳组成。这一结果为碳酸锂生产铝锂合金提供了方便。

Al-Li alloy is a promising new material because it is lightest and strongest in all the aluminum alloy. However it is difficult to produce Al-Li alloy because metallic lithium is very active chemically and its density is only 1/5 of that of aluminum. This method, molten salt electrolysis, is considered to be excellent for producing Al-Li alloy as follows ;1.Dangerous metallic lithium is not used. Lithium content increases from zero to desired concentration by putting lithium into molten aluminum by using the electrolysis.2.Clean alloy is obtained because the molten salt acts as the flux and protects the alloy from air.3.It is possible to cut the cost of producing Al-Li alloy largely by using lithium carbonate as the source of lithium because lithium carbonate is less expensive and is not hygroscopic.Following results were obtained on the cathodic rection. The current efficiency of lithium deposition is excellent, at least higher than 90%. Content of farmful impurities, for example, potassium or sodium is very low level, about 10ppm which is almost same to that in pure aluminum. The Al-Li obtained was very clean and showed almost no deffects as cast.The results obtained on anodic reactions are follows ; Chlorine gas is evolved when chloride melt is used as the electrolyte. By adding lithium carbonate into chloride melt, anodic potential decreases drastically. It reaches almost 1.3V.No chlorine gas is evolved and the exhaust consists of large amount of carbon dioxide and small amount of carbon monoxide. This results are convenient for producing Al-Li alloy by using lithium carbonate.