07/21/2011.
Flash Sintering
This recently discovered phenomenon is a significant advance in the general area of field-assisted-sintering. As shown in the figure on the right, when yttria-doped zirconia is sintered at a constant heating rate (10degreesC per minute) the application of a dc electric field enhances the sintering process. But remarkably, when the field is increased above a threshold value, in this instance 60V-per-cm, sintering occurs nearly instantaneously. The process occurs in many oxide ceramics, and can lead to a nanometer grain size
ceramics.
Flash sintering raises fundamentally new questions about how electric fields can produce diffusion avalanches. There is considerable industrial interest in it as well.
The work is being carried out by John Francis, a Ph.D. student, and Marco Cologan, a Research Associate. The first publication on this topic appeared in the Journal of the American Ceramic Society in
November, 2010
DOI: 10.1111/j.1551-2916.2010.04089.x
Cologna, Rashkova and Raj, Flash Sinteringof Nanograin Zirconia in <5s at 850oC).
This program is wholly funded by the Basic Energy Sciences Division of the Department of Energy.
National Hypersonics Science Center (NHSC)
This Center, supported by AFOSR and NASA, is focussed on Materials and Structures. It is led by David Marshall at the Teledyne Company, in Thousand Oaks, CA, and includes UC-Santa Barbara, UC-Berkeley, Missouri S&T, Miami University, University of Texas at Arilington, University of Virginia and the University of Colorado. In Boulder we are developing the underlying science for processing and creating new materials that can protect SiC based structures at 1500degreesC and above. These materials are based upon polymer-derived-ceramics (Si-C-N-O) and hafnium. In early results this combination of chemistries produces oxidation protection up to 1600degreesC.
At this time the project in its second year.