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




TECH SPACE
How to make ceramics that bend without breaking
by David Chandler for MIT News
Cambridge MA (SPX) Oct 01, 2013


When subjected to a load, the molecular structure of the ceramic material studied by the MIT-Singapore team deforms rather than cracking. When heated, it then returns to its original shape. Though they have the same chemical composition, the two molecular configurations correspond to different natural minerals, called austenite and martensite. Graphic: Lai et al.

Ceramics are not known for their flexibility: they tend to crack under stress. But researchers from MIT and Singapore have just found a way around that problem -- for very tiny objects, at least.

The team has developed a way of making minuscule ceramic objects that are not only flexible, but also have a "memory" for shape: When bent and then heated, they return to their original shapes. The surprising discovery is reported this week in the journal Science, in a paper by MIT graduate student Alan Lai, professor Christopher Schuh, and two collaborators in Singapore.

Shape-memory materials, which can bend and then snap back to their original configurations in response to a temperature change, have been known since the 1950s, explains Schuh, the Danae and Vasilis Salapatas Professor of Metallurgy and head of MIT's Department of Materials Science and Engineering. "It's been known in metals, and some polymers," he says, "but not in ceramics."

In principle, the molecular structure of ceramics should make shape memory possible, he says -- but the materials' brittleness and propensity for cracking has been a hurdle. "The concept has been there, but it's never been realized," Schuh says. "That's why we were so excited."

The key to shape-memory ceramics, it turns out, was thinking small.

The team accomplished this in two key ways. First, they created tiny ceramic objects, invisible to the naked eye: "When you make things small, they are more resistant to cracking," Schuh says. Then, the researchers concentrated on making the individual crystal grains span the entire small-scale structure, removing the crystal-grain boundaries where cracks are most likely to occur.

Those tactics resulted in tiny samples of ceramic material -- samples with deformability equivalent to about 7 percent of their size. "Most things can only deform about 1 percent," Lai says, adding that normal ceramics can't even bend that much without cracking.

"Usually if you bend a ceramic by 1 percent, it will shatter," Schuh says. But these tiny filaments, with a diameter of just 1 micrometer -- one millionth of a meter -- can be bent by 7 to 8 percent repeatedly without any cracking, he says.

While a micrometer is pretty tiny by most standards, it's actually not so small in the world of nanotechnology. "It's large compared to a lot of what nanotech people work on," Lai says. As such, these materials could be important tools for those developing micro- and nanodevices, such as for biomedical applications. For example, shape-memory ceramics could be used as microactuators to trigger actions within such devices -- such as the release of drugs from tiny implants.

Compared to the materials currently used in microactuators, Schuh says, the strength of the ceramic would allow it to exert a stronger push in a microdevice. "Microactuation is something we think this might be very good for," he says, because the ceramic material has "the ability to push things with a lot of force -- the highest on record" for its size.

The ceramics used in this research were made of zirconia, but the same techniques should apply to other ceramic materials. Zirconia is "one of the most well-studied ceramics," Lai says, and is already widely used in engineering. It is also used in fuel cells, considered a promising means of providing power for cars, homes and even for the electric grid. While there would be no need for elasticity in such applications, the material's flexibility could make it more resistant to damage.

The material combines some of the best attributes of metals and ceramics, the researchers say: Metals have lower strength but are very deformable, while ceramics have much greater strength, but almost no ductility -- the ability to bend or stretch without breaking. The newly developed ceramics, Schuh says, have "ceramiclike strength, but metallike ductility."

In addition to Schuh and Lai, the work was carried out by Zehui Du and Chee Lip Gan of Nanyang Technological University in Singapore.

.


Related Links
Massachusetts Institute of Technology
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
New sensor could prolong the lifespan of high-temperature engines
Cambridge, UK (SPX) Sep 24, 2013
A temperature sensor developed by researchers at the University of Cambridge could improve the efficiency, control and safety of high-temperature engines. The sensor minimises drift -degradation of the sensor which results in faulty temperature readings and reduces the longevity of engine components. The new sensor, or thermocouple, has been shown to reduce drift by 80 per cent at temperat ... read more


TECH SPACE
China unveils its first and unnamed moon rover

Mission to moon will boost research and awareness

Mighty Eagle Improves Autonomous Landing Software With Successful Flight

Watch Out for the Harvest Moon

TECH SPACE
NASA Mars mission escapes government shutdown, will launch

European rover meant for Mars to undergo earthly desert test

First ARCA flight in the ExoMars Program completed successfully

A Seasonal Ozone Layer Over The Martian South Pole

TECH SPACE
Non-Orbiting Space Junk

Paper written as science hoax published by 157 science journals

Tokyo gadget show offers glimpse of tomorrow

Astronauts Practice Launching in NASA's New Orion Spacecraft

TECH SPACE
Onward and upward as China marks 10 years of manned spaceflight

Chinese VP stresses peaceful use of space

China's space station to open for foreign peers

Last Days for Tiangong

TECH SPACE
Aerojet Rocketdyne Thrusters Help Cygnus Spacecraft Berth at the International Space Station

First CASIS Funded Payloads Berthed to the ISS

Unmanned cargo ship docks with orbiting Space Station

New space crew joins ISS on Olympic torch mission

TECH SPACE
Milky Way-mapping Gaia receives its sunshield

Arianespace's next Ariane 5 mission will serve two key customers: SES and HISPASAT

After Successful Spacecraft Docking, US Orbits Five Satellites

US private spacecraft company SpaceX launches upgraded Falcon rocket

TECH SPACE
Kepler Finds First Signs of Other Earths

Nearby binary star system gets officially confirmed third member

Astronomers create first cloud map of distant planet

How Engineers Revamped Spitzer to Probe Exoplanets

TECH SPACE
Lockheed Martin and Concord Blue to Deploy Advanced Gasification Technology Globally

Lockheed Martin Powers on First GOES-R Weather Satellite

How to make ceramics that bend without breaking

AREVA awarded funding for innovative manufacturing technology




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal 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