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，在许多涉及金属熔体的工艺中，它对工艺参数的选择至关重要，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，但也适用于污染的反应性气体气氛。在这个项目中，金属熔体的表面张力是通过实验的自由落体，振荡的金属液滴在可变的惰性和反应性气体气氛。将使用高温单液滴发生器，其允许从相同的金属熔体产生数千个振荡的单液滴。 这些液滴的表面张力可以在一个实验中改变熔体温度和气体气氛的同时确定。为此，需要识别具有低液滴速度的液滴形成模式，以保持液滴振荡和液滴流之间的相互作用低。通过流体流动模拟来研究这种相互作用，以确定有效性限制和补偿策略。用于测定表面张力的目标系统包括含铁污染的铝合金、含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.