Subscribe free to our newsletters via your
. 24/7 Space News .




TECH SPACE
Researchers predict material with record-setting melting point
by Staff Writers
Providence RI (SPX) Jul 29, 2015


Compounds made from hafnium and carbon have some of the highest known melting points. Using computer simulations, Brown University engineers predict that a material made with hafnium, nitrogen, and carbon will have a higher melting point than any known material. Image courtesy van de Walle lab / Brown University. For a larger version of this image please go here.

Using powerful computer simulations, researchers from Brown University have identified a material with a higher melting point than any known substance.

The computations, described in the journal Physical Review B (Rapid Communications), showed that a material made with just the right amounts of hafnium, nitrogen, and carbon would have a melting point of more than 4,400 kelvins (7,460 degrees Fahrenheit). That's about two-thirds the temperature at the surface of the sun, and 200 kelvins higher than the highest melting point ever recorded experimentally.

The experimental record-holder is a substance made from the elements hafnium, tantalum, and carbon (Hf-Ta-C). But these new calculations suggest that an optimal composition of hafnium, nitrogen, and carbon - HfN0.38C0.51 - is a promising candidate to set a new mark. The next step, which the researchers are undertaking now, is to synthesize material and corroborate the findings in the lab.

"The advantage of starting with the computational approach is we can try lots of different combinations very cheaply and find ones that might be worth experimenting with in the lab," said Axel van de Walle, associate professor of engineering and co-author of the study with postdoctoral researcher Qijun Hong. "Otherwise we'd just be shooting in the dark. Now we know we have something that's worth a try."

The researchers used a computational technique that infers melting points by simulating physical processes at the atomic level, following the law of quantum mechanics. The technique looks at the dynamics of melting as they occur at the nanoscale, in blocks of 100 or so atoms. The technique is more efficient than traditional methods, but still computationally demanding due to the large number of potential compounds to test. The work was done using the National Science Foundation's XSEDE computer network and Brown's "Oscar" high-performance computer cluster.

Van de Walle and Hong started by analyzing the Hf-Ta-C material for which the melting point had already been experimentally determined. The simulation was able to elucidate some of the factors that contribute to the material's remarkable heat tolerance.

The work showed that Hf-Ta-C combined a high heat of fusion (the energy released or absorbed when it transitions from solid to liquid) with a small difference between the entropies (disorder) of the solid and liquid phases. "What makes something melt is the entropy gained in the process of phase transformation," van de Walle explained. "So if the entropy of the solid is already very high, that tends to stabilize the solid and increase the melting point."

The researchers then used those findings to look for compounds that might maximize those properties. They found that a compound with hafnium, nitrogen, and carbon would have a similarly high heat of fusion but a smaller difference between the entropies of the solid and the liquid. When they calculated the melting point using their computational approach, it came out 200 kelvins higher than the experimental record.

Van de Walle and Hong are now collaborating with Alexandra Navrotsky's lab at the University of California-Davis to synthesize the compound and perform the melting point experiments. Navrotksy's lab is equipped for such high-temperature experiments.

The work could ultimately point toward new high-performance materials for a variety of uses, from plating for gas turbines to heat shields on high-speed aircraft. But whether the HfN0.38C0.51 compound itself will be a useful material isn't clear, van de Walle says.

"Melting point isn't the only property that's important [in material applications]," he said. "You would need to consider things like mechanical properties and oxidation resistance and all sorts of other properties. So taking those things into account you may want to mix other things with this that might lower the melting point. But since you're already starting so high, you have more leeway to adjust other properties. So I think this gives people an idea of what can be done."

The work also demonstrates the power of this relatively new computational technique, van de Walle says. In recent years, interest in using computation to explore the material properties of a large number of candidate compounds has increased, but much of that work has focused on properties that are far easier to compute than the melting point.

"Melting point is a really difficult prediction problem compared to what has been done before," van de Walle said. "For the modeling community, I think that's what is special about this."


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only


.


Related Links
Brown University
Space Technology News - Applications and Research






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle








TECH SPACE
Cages offer new direction in sustainable catalyst design
Madison WI (SPX) Jul 28, 2015
University of Wisconsin-Madison engineers have developed a new approach to structuring the catalysts used in essential reactions in the chemical and energy fields. The advance offers a pathway for industries to wean themselves off of platinum, one of the scarcest metals in the earth's crust. In an effort to reduce the catalysis world's dependence on this highly reactive and versatile - but ... read more


TECH SPACE
NASA Could Return Humans to the Moon by 2021

Smithsonian embraces crowdfunding to preserve lunar spacesuit

NASA Sets Sights on Robot-Built Moon Colony

Technique may reveal the age of moon rocks during spaceflight

TECH SPACE
NASA Mars Orbiter Preparing for Mars Lander's 2016 Arrival

New Website Gathering Public Input on NASA Mars Images

Antarctic Offers Insights Into Life on Mars

Earth and Mars Could Share A Life History

TECH SPACE
Japanese firm to mature whisky in space

Start-ups in spotlight at new Hong Kong tech meet

Third spaceflight for astronaut Paolo Nespoli

Solar weather reports key to safe space travel

TECH SPACE
Chinese earth station is for exclusively scientific and civilian purposes

Cooperation in satellite technology put Belgium, China to forefront

China set to bolster space, polar security

China's super "eye" to speed up space rendezvous

TECH SPACE
Space Kombucha in the search for life and its origin

Political Tensions Have No Impact on Space Cooperation- Roscosmos

RED epic dragon camera captures riveting images on space station

Launch, docking returns ISS crew to full strength

TECH SPACE
Payload fit-check for next Ariane 5 mission

SMC goes "2-for-2" on weather delayed launch

China tests new carrier rocket

Arianespace inaugurates new fueling facility for Soyuz upper stage

TECH SPACE
Microlensing used to find distant Uranus-sized planet

NASA's Spitzer Confirms Closest Rocky Exoplanet

Finding Another Earth

Kepler Mission Discovers Bigger, Older Cousin to Earth

TECH SPACE
Cages offer new direction in sustainable catalyst design

Controlling phase changes in solids

Researchers predict material with record-setting melting point

World's most powerful laser fired in Japan




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.