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Electromagnetic Levitator headed to ISS for future materials research

By

March 7, 2014

Example of levitating and heating coil assemblies (Image: ESA)

Example of levitating and heating coil assemblies (Image: ESA)

Image Gallery (8 images)

Astronauts, get your welding goggles on – the space station is going into the foundry business. The International Space Station (ISS) is set to do a spot of industrial research this June, when ESA’s Materials Science Laboratory-Electromagnetic Levitator (MSL-EML) heads for the station aboard Europe's’ Automated Transfer Vehicle 5 (ATV-5) Georges Lemaître unmanned space freighter as part of a program to study the casting of alloys in a weightless environment.

Most metals are crystalline and their properties depend on this microstructure, which develops as they cool. An everyday version of this is tempering, where a steel knife blade is heated to red hot and then plunged into cold water. The sudden cooling alters the crystalline microstructure of the steel, making it hard and able to hold a sharp edge.

The example is a simple one, but the process is actually extremely complex. It’s even more so when molten metal is cooled inside a casting. The temperature and density differences, convection forces as the cooling molten metal rises and falls in the mold, and any number of other factors are among the many reasons why casting metals, especially exotic alloys, is often as much art as science.

Rendering of the Materials Science Laboratory  (Image: ESA)

Microgravity is one way of reducing this complexity, so scientists are better able to understand it. In the absence of gravity, there aren't any convection forces, so metal castings have an even temperature. Furthermore, in a gravity-free environment metal samples can be suspended in a magnetic field and heated using conduction coils. This means there are no complicating factors, such as the molten sample sticking to a crucible wall or being contaminated by it.

By means of microgravity, scientists hope to gain a better understanding of an alloy’s surface tension, viscosity, melting range, fraction solid, specific heat, heat of fusion, mass density, and thermal expansion among other things. This would be of tremendous importance for everything from casting turbine blades to developing lighter weight alloys.

The problem is, there isn't a lot of of microgravity on Earth and most of that involves falling. You can get 20 seconds in an airplane during a parabolic trajectory and six minutes in a sounding rocket, but neither of those are very practical for carrying out metallurgical research. To get serious, you need a space station. And on the ISS, there’s all the microgravity you want.

Working on the Materials Science Laboratory (Image: ESA)

Weighing about 360 kg (795 lb), the MSL-EML was built by Airbus Defence and Space in collaboration with ESA and the DLR Space Administration. It consists of an automated chamber that keeps samples in a vacuum or a controlled gas mixture. In addition to electromagnetic levitation and induction heating coils, there is a digital video observation camera, a high-speed data camera capable of capturing up to 30,000 images per second, and a pyrometer.

When activated, the MSL-EML automatically feeds one of 18 spherical samples, 5 to 8 mm in diameter, consisting of various aluminum, copper, and nickel alloys into the process chamber using a rotating magazine. The machine uses electromagnetic fields to levitate samples in a the container, keeping them out of contact with the walls or any other materials. Then the inductive heating pushes the sample temperatures up to 2,000⁰ C (3,600 ⁰ F), reducing them to a liquid state.

In such a controlled environment, scientists will be able to dial-in various factors and study how such samples change as they cool and solidify. There’s no need for crucibles, which could contaminate the samples, and the samples aren't under the influence of gravity, which would deform the developing crystals or set up convection currents, resulting in uneven cooling. Meanwhile, the sensors record every detail of the process.

The Columbus station module (Image: ESA)

According to ESA, the microgravity containerless system produces a purer sample with fewer variables to take account of. The findings from the MSL-ELM can be compared to computer models and findings from experiments conducted on similar samples on Earth on parabolic flights.

The EML will travel to the space station this June aboard the Georges Lemaître, along with the first batch of samples for experimentation. It will be installed in the MSL, which sits in the European Drawer Rack in the Columbus Laboratory, and it will be controlled from the ground at the German Aerospace Centre’s User Control Centre (MUSC) in Cologne. After each batch of experiments, some samples will return to Earth for further analysis.

ESA says the information generated by the MSL-ELM may one day be used to scale up manufacturing processes that can produce the same properties on Earth on an industrial scale.

Source: ESA

About the Author
David Szondy David Szondy is a freelance writer based in Monroe, Washington. An award-winning playwright, he has contributed to Charged and iQ magazine and is the author of the website Tales of Future Past.   All articles by David Szondy
9 Comments

Very cool, tho speaking of space stations. I wonder why they always end up smelling really funky after a while. But when you see pics from inside of the station its really full of stuff. Its design to be nice and clean, but after a few years they just fill it upp with crap like any teenagers room. NASA could go to the moon but teaching astronauts and cosmonauts to clean they cant. hehe...(And Russians are responsible for there cosmonauts mess.)

Toffe Kaal
8th March, 2014 @ 01:51 am PST

This should be interesting. I've worked with this stuff for years. Only problem will probably be gas bubbles that stay trapped in the molten metal because of the microgravity instead of floating to the top and escaping. The molten metal should continually flow internally until it solidifies. Depending on the alloy, surrounding gases, and cooling rates the resulting micro-structures should be interesting. Throw in a feeder with some hollow wire filled with alloy and perhaps some continuous casting might be done. Maybe some slow motion centrifugal casting.

Bob
9th March, 2014 @ 02:24 pm PDT

this is almost without doubt the first true 'field experiment' for the future of casting plastics resins and molten metals into solid piece objects in outer space.

the asteroid mining fanboys are going to slobber all over this. the results of this experiment will invariably be interpreted as being very 'positive' for asteroid mining as it is more than likely that microgravity will at least result in a few novel process attributes ( namely uniform colling) the result in materials with a few desireable properties.

of course, they will ignore that you are melting metal inside of a space station. what could possibly go wrong if you did this 10,000 times with industrial quantities of metal. nothing i'm sure.

that said----------i do believe that if these techniques can be perfected for automation by machine/manned drone in microgravity in a vaccum external to the iss--- enclosure.

that eventually they will perfect a method of MELTING and repurposing abandoned sattelites.

that in itself could be pretty surprisingsly useful.

envistat has a net 18,000 pounds of weight, much of it repurposeable solar panels.

the rest could be melted and reused for something if the right techniques are used.

considering it costs almost 10,000 dollars a pound to get payload into space. if even 10,000 pounds of envistat can be smelted and repurposed. then you have 100,000,000 dollars gain. and that's just envistat!.

zevulon
9th March, 2014 @ 04:52 pm PDT

Correction!

Quenching hot metal doesn't CHANGE the micro structure, it 'freezes' it in its present state.

Nik
10th March, 2014 @ 02:34 am PDT

cant they use the Nil G already in ISS for tests??

Stephen N Russell
10th March, 2014 @ 04:55 pm PDT

Bob IRC if the experiment is done in a vacuum any gas bubbles should be drawn out of the metal when the metal is in a liquid state.

JoejustJoe
11th March, 2014 @ 12:50 am PDT

Joe, I doubt that the process will be done under a vacuum since it would take a very long time to cool. Most likely an argon or other inert gas will be used. Due to gas solubility in the alloy not all gas will escape and some gases could actually be used to control the micro-structure. While the ability to not use a crucible will allow some interesting experiments, some type of mold or continuous casting will be needed to make the process useful.

Bob
11th March, 2014 @ 07:07 am PDT

While I commend the effort I can't help but be a little jaded. Does anyone even remember G. Harry Stine and his book "The Third Industrial Revolution"?

Published in 1975 it gave a quite detailed description of exactly this process and the implications. It only took 39 years to actually do the research in space.

Russell Poley
12th March, 2014 @ 08:29 am PDT

@ zevulon

What can go wrong in any foundry? Is it worse to die in space?

Slowburn
12th March, 2014 @ 08:20 pm PDT
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