一种新的利用落管实验分析微重力效应方法的探讨

通过对金属液滴在落管中下落过程中热量散失及重力水平的计算,讨论了落管在微重力材料研究上的局限性.为了克服落管材料凝固实验中微重力效应和过冷效应难以区分的问题,选取熔点低、发射率低以及比热较高的Al,Cu合金体系以尽量消除熔滴下落过程中的温度差别,采用硅油快淬的凝固方式对比研究了熔滴在落管中下落前后的微观组织.结果表明,这种实验方式可有效突出微重力效应对合金凝固过程的影响,一定程度上拓展了落管在材料研究上的范围.

A New Way to Explore Microgravity Effect by Drop Tube Experiment

Based on calculating the thermal history and the gravity level of some metallic droplets during their dropping in drop tube under different conditions,the limitation of drop tube investigation on rnicrogravity was analyzed and discussed.In order to solve the problem that the effects of microgravity and undercooling were usually coupled and difficult to distinguish,some liquid metals with low melt points,low radiant emissivities and relative high specific heats,such as Al and Cu alloys,were quenched into silieone oil before and after falling.The difference of microstructures between the both conditions was analyzed both theoretically and experimentally.The results showed that this way could make the temperature difference of droplets before and after falling to be neglected, and thus the microgravity effects on alloy solidification would be much more conspicuously identified. Therefore,the extent of material investigations by drop tubes was expanded.