Using X-ray tomoscopy to explore the dynamics of foaming metal
Using X-ray tomoscopy to explore the dynamics of foaming metal
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DOI：
10.1038/s41467-019-11521-1
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发表时间：
2019-08-21
影响因子：
16.6
通讯作者：
Banhart, John
中科院分区：
文献类型：
--
作者：
Garcia-Moreno, Francisco;Kamm, Paul Hans;Banhart, John
由于研究高温和不透明体系的困难，液态金属在不断演变的泡沫金属中的复杂流动仍然知之甚少。我们应用X射线断层扫描--连续获取断层(3D)图像--来阐明液态泡沫铝中的关键动态现象，如成核和生长、气泡重排、液体回缩、合并和薄膜破裂。每一种现象都发生在一个典型的时间尺度上，我们通过在长达一分钟的时间内每秒获得208张完整的断层图像来进行覆盖。另一种数据处理算法提供1毫秒尺度的信息。在这里，我们表明，气泡合并不仅是由重力诱导的排水引起的，如失重条件下的实验所表明的那样，也是由泡沫生长引起的应力引起的，也是由发泡剂引起的局部压力峰值引起的。此外，还量化了泡沫膨胀的细节以及破裂前的级联和膜变薄等现象。这些发现使我们能够提出一种方法，以获得气泡更小、尺寸更均匀的泡沫。
The complex flow of liquid metal in evolving metallic foams is still poorly understood due to difficulties in studying hot and opaque systems. We apply X-ray tomoscopy -the continuous acquisition of tomographic (3D) images- to clarify key dynamic phenomena in liquid aluminium foam such as nucleation and growth, bubble rearrangements, liquid retraction, coalescence and the rupture of films. Each phenomenon takes place on a typical timescale which we cover by obtaining 208 full tomograms per second over a period of up to one minute. An additional data processing algorithm provides information on the 1 ms scale. Here we show that bubble coalescence is not only caused by gravity-induced drainage, as experiments under weightlessness show, and by stresses caused by foam growth, but also by local pressure peaks caused by the blowing agent. Moreover, details of foam expansion and phenomena such as rupture cascades and film thinning before rupture are quantified. These findings allow us to propose a way to obtain foams with smaller and more equally sized bubbles.