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Mechanical Engineering Home > Seminars > Spring 2004 Seminars |
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ME/IE 8773-8774
First Donaldson Lecture On interdisciplinary topics in Chemistry, Chemical Engineering, Materials Science and Mechanical Engineering sponsored by the Donaldson Company Superhard Nanocomposites: by Stan Veprek Superhard and functional, nano-sized and nano-structured materials are receiving increasing attention both in basic research and applications. The present talk will concentrate on the recently developed superhard nanocomposites emphasizing the following points: * A brief overview of possible artifacts that may falsify the measured values of hardness when the indentation load-depth-sensing technique is applied to superhard coatings, particularly at a low applied load of = 30 mN ("nanoindentation"). * Preparation techniques and deposition conditions that are needed for reproducible deposition of stable superhard nanocomposites, in particular the importance of the choice of correct conditions and the avoidance of impurities for achieving reproducibility. * Properties of the coatings: The extraordinary mechanical properties of stable super-hard nanocomposites prepared according to our design principle and their excellent thermal stability can be understood in terms of conventional theory of elasticity and fracture scaled down to a crystallite size of few nanometers. The tensile strength of these materials reaches 10 to 40 GPa, approaching the ideal strength of flow-free strong materials. * Recent development of a large-scale industrial deposition technology and of the superhard nanocomposite coatings nc-(AlTi)N/a-Si3N4 that show superior cutting performance as compared to the state-of-the-art best (AlTi)N coatings. Professor Stan Veprek received a doctorate in
physics from the Charles Univer-sity in Prague, Czech Republic,
and a Ph.D. and a Habilitation in inorganic chemistry from the
University of Zurich, Switzerland, in 1962, 1972 and 1977, respectively.
He held positions at the Physics Institute of the Czech Academy
of Sciences, at the Czech Military Academy (as part of his military
service), at the University of Münster, Germany, and at the
University of Zurich, Switzerland. Since 1989 he has been professor
at the Technical University of Munich, Germany, and Director of
the Institute of Information Recording and since 1995 of the Institute
for Chemistry of Inorganic Materials. Prof. Veprek has been working
on plasma process characterization, plasma chemistry of heterogeneous
systems, plasma induced chemical vapor deposition and chemical
transport, and generally in plasma surface interactions for a
wide range of applications, including controlled nuclear fusion,
semiconductor processing, and restoration and preservation of
archaeological artifacts. For the past several years he has pioneered
approaches for depositing nanocomposite films with extraordinary
properties, in particular the preparation and characterization
of nanocrystalline semiconductors, including quantum confinement
phe-nomena and phonon localization in nanocrystals and large organosilicon
molecules, and of light emitting nanocrystalline silicon. Among
the honors he has received are an Honorary Doctorate from the
Masaryk University in Brno, Czech Republic, and an Honorary Professorship
from the Institute of Chemical Technology, Qingdao, China. He
has been elected to the Board of Governors of the European Academy
of Sciences. He is the co-editor of the journal Plasma Chemistry
and Plasma Processing, and he has published more than 320 scientific
papers. ME 8800 - Nano-Sized and Nano-Structured Inorganic
Solids, March 2-March 4, 2004. |
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