Mines researchers discover method to develop tough ceramics

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Mines researchers discover method to develop tough ceramics

GOLDEN, Colo., Feb. 6, 2008 – Colorado School of Mines researchers recently discovered a unique material behavior that could lead to the development of tougher ceramic composites.

According to Mines professor Ivar Reimanis, director of the Colorado Center for Advanced Ceramics, the finding is important because ceramics – hard, corrosion resistant materials that can withstand high temperatures – are inherently brittle. A tougher ceramic could be used in automobile and jet engine components, electronic processing applications, wear-resistant parts such as tools and dies, ceramic armor, and biomedical applications among other uses. 

The key ingredient in the ceramic is a lithium aluminum silicate called beta-eucryptite, a strange material that has a negative coefficient of thermal expansion. Mines researchers believe a high compressive stress, such as that experienced under an indenter (a device used to measure hardness), stimulates a phase transformation to a denser ceramic phase. The reverse phase transformation in the presence of a crack would effectively shut the crack before it could propagate through the composite. Such a process is well-established for another ceramic, zirconia, but has never been realized for other ceramics.

The discovery was made upon indenting beta-eucryptite. When the indenter is removed, a reverse transformation leads to a ‘popcorn’ like effect where particles ranging from submicron to 50 microns are ejected violently from the material – to the unaided eye it appears the ceramic is smoking. There is no known report of this phenomenon in any other material. 

To better understand the phenomenon, Mines researchers are working with collaborators at the National Institute for Standards and Technology in Gaithersburg, Oak Ridge National Laboratory and Los Alamos National Laboratory. The work is funded by the National Science Foundation and the Department of Energy, Office of Basic Energy Sciences.

Founded in 1874, Colorado School of Mines was established to serve the needs of the local mining industry. Today, the School has an international reputation for excellence in both engineering education and the applied sciences with special expertise in the development and stewardship of the Earth's resources. For more information about Colorado School of Mines, visit www.mines.edu.

Karen Gilbert, Public Relations Specialist
303-273-3541 / Karen.Gilbert@is.mines.edu

Marsha Williams, Director of Integrated Marketing Communications
303-273-3326 / marswill@mines.edu

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