Images of from a high-speed camera reveal a microbead formation process during the vapor explosion of liquid metal dropping into a pool of water.
The explosive reaction of a liquid metal dropping into water has been captured with high-speed cameras by researchers from King Abdullah University of Science and Technology (KAUST), Saudi Arabia. The images reveal how the explosive formation of water vapor around the liquid metal influences the shape of the metal as it hardens . For certain metals, perfectly-shaped microbeads are created during the powerful reaction with water.
Immersion of hot liquids in other liquids is not uncommon, even outside of the laboratory. An example is hot lava from a volcanic eruption encountering water reservoirs or flowing into the sea. This interaction can lead to dramatic reactions when vapor layer forms around the liquid metal. The vapor layer can become unstable and quickly expands into hot clouds of water and ash, noted Siggi Thoroddsen from the KAUST High-Speed Fluids Imaging Laboratory, who also led the research team.
“This happened when the Icelandic volcano Eyjafjallajökull erupted in 2010 and grounded airplanes all over Europe," he said.
The researchers studied related reactions in the lab using a metal alloy known as Field’s metal, which melts at low temperatures of around 60 degrees Celsius. With experiments conducted at 550 degrees Celsius metal temperature, the transfer of energy between the metal and the water is very violent. KAUST Ph.D. student Nadia Kouraytem wore a full protective facial mask and a fire-resistant lab coat during these experiments. High-speed cameras captured the explosive process at speeds of up to 50,000 frames per second.
The images obtained were dramatic and showed an explosive reaction that tore the metal apart. In the case of Field’s metal, small spherical microbeads formed during the process.
During the reaction, the metal transitioned through several stages with increasing ferocity. While initially only a small part of the metal interacted with the water, over a longer period increasingly more of the metal was exposed and took part in the reaction until the disintegration of the liquid metal into small beads.
The unusual microbead formation occurs due to the low melting temperature. Metals with a higher melting temperature (such as tin) solidify faster because their higher solidification temperature is reached more quickly upon cooling so that there is less time for the material to disintegrate. An example is the porous structures seen in solidified lava from volcanic eruptions.
In the case of Field’s metal, the beads are highly uniform, and it will be interesting to study their creation processes further, noted Thoroddsen.
“In future experiments, we want to better control the original drop, change its size and impact velocity. This should further probe the instabilities of the vapor layer that forms around the metal,” he said.
 Kouraytem, N., Li, E. Q. & Thoroddsen, S.T. Formation of microbeads during vapor explosions of Field’s metal in water. Physical Review E 93, 063108 (2016).
Michelle D'Antoni | Research SEA
For graphite pellets, just add elbow grease
23.03.2018 | Rice University
23.03.2018 | Fraunhofer-Institut für Produktionstechnik und Automatisierung IPA
Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.
The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...
An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.
The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...
In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.
Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.
They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...
23.03.2018 | Event News
19.03.2018 | Event News
16.03.2018 | Event News
23.03.2018 | Materials Sciences
23.03.2018 | Agricultural and Forestry Science
23.03.2018 | Physics and Astronomy