Experimental investigation of the influence of reactive atmospheres on the surface tension of metallic melts with oscillating single droplets

金属熔体的表面张力是一种热物理性质，在大量涉及金属熔体的过程中，它是选择工艺参数所必需的，它受合金成分和熔体温度的影响。即使是ppm范围内的合金元素也会对表面张力产生相当大的影响。这也适用于可能的污染物，其影响在很大程度上是未知的，但也适用于反应气体气氛的污染。在这个项目中，金属熔体的表面张力将通过在可变的惰性和反应气体气氛中自由落体、振荡的金属液滴的实验来研究。将使用高温单液滴发生器，允许从相同的金属熔体中产生数千个振荡的单液滴。在一次实验中，通过改变熔体温度和气体气氛，可以测定这些液滴的表面张力。为此，需要识别低液滴速度的液滴形成模式，以保持液滴振荡和液滴流动之间的低相互作用。这种相互作用是通过流体流动模拟来研究的，以确定有效性极限和补偿策略。测定表面张力的目标系统包括铁污染的铝合金、铜污染的钢和高熵合金。

The surface tension of metallic melts is a thermophysical property which is essential for the choice of process parameters in a large number of processes involving metallic melts.It is influenced by the composition of the alloy and the melt temperature. Even alloying elements in the ppm range can have a considerable influence on the surface tension. This also applies to possible contaminations, whose influence is largely unknown, but also to contamination by reactive gas atmospheres.In this project, the surface tension of metallic melts is to be investigated by experiments on free-falling, oscillating metal droplets in variable inert and reactive gas atmospheres. A high temperature single droplet generator will be used, which allows the generation of many thousands of oscillating single droplets from the identical metal melt. The surface tension of these droplets can be determined while varying the melt temperature and gas atmosphere within one experiment. For this purpose, drop formation modes with low droplet velocity need to be identified in order to keep the interaction between droplet oscillation and droplet flow low. Such interactions are investigated by means of a fluid flow simulation to determine validity limits and compensation strategies. Target systems for the determination of the surface tension include aluminium alloys with iron contamination, steels with copper contamination and high-entropy alloys.