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We are planning to held follwoing seminar.
please register your schedule.
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| Venue |
AIST Chubu center, Building A 3F conference Room ‚P |
| Date |
May 26th (Thu) AM11:00-12:00 |
| Title |
Application of Master Sintering Curve Theory To Control
The Processing, Microstructure, and Electrical Properties of ZnO Varistors |
| Speaker |
K.G. Ewsuk
Sandia National Laboratories, Ceramic Processing and Inorganic Materials
Department |
| Outline |
The electrical properties of a sintered ZnO varistor are determined by
its sintered microstructure, which, in turn, is determined by the time-temperature
sintering process. To produce a varistor with the desired electrical performance,
the sintering process must be carefully controlled to produce the required
density and grain size microstructure. Sintering theory and the master
sintering curve (MSC) have been used to provide insight into developing
a more robust and more reproducible sintering process to fabricate controlled
microstructure and property varistors. Constant heating rate dilatometric
sintering shrinkage experiments were used to characterize the sintering
behavior of a dry pressed ZnO mixed-oxide varistor body, and to determine
the activation energy for densification. From these data, a master sintering
curve was constructed and used to systematically design different time-temperature
sintering profiles to produce controlled density ZnO varistors. The objective
was to use the MSC to systematically produce sintered varistors having
the same density and microstructure. Quantitative image analysis was used
to characterize sintered microstructure as a function of the time-temperature
sintering conditions, and to verify the link between sintered density and
microstructure. To assess the electrical properties as a function of processing
and microstructure, the change in current was characterized as a function
of the applied electric field. The results of electrical testing proved
that, regardless of the time-temperature profile used, varistors sintered
to the same density have the same microstructure and the same regulating
voltage. The results demonstrate how MSC theory can be applied to design
a reproducible process to fabricate controlled density, microstructure,
and property varistors.
Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lookheed
Martin company, for the United States Department of Energy's National Nuclear
Security Administration under contract DE-AC04-94AL85000.
Co-author: M.W. Reiterer1, C.B. DiAntonio2, Ian Nettleship3, and Tiandan
Chen3,
1 Sandia National Laboratories, Ceramic Processing and Inorganic Materials
Department, 1815, Albuquerque, NM
2 Sandia National Laboratories, Ceramic and Glass Department, 14154, Albuquerque,
NM
3 University of Pittsburgh, Department of Materials Science and Engineering,
Pittsburgh, PA |
| Inquiry |
Koji Watari, Dr. Eng.
Advanced Sintering Technology Group
National Institute of Advanced Industrial Science and Technology
Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan
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