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NANOSTRUCTURED COATINGS Maurice Gell Department of Metallurgy and Materials Engineering University of Connecticut Storrs, CT 06269 Nanostructured materials and coatings offer the potential for significant improvements in engineering properties based on improvements in physical and mechanical properties resulting from reducing microstructural features by factors of 100 to 1000 times compared to current engineering materials. The potential benefits include higher hardness and strength in metals and cermets resulting from reduced grain size and slip distance, respectively. In ceramics, higher hardness and toughness may be accomplished with reduced defect size and enhanced grain boundary stress relaxation, even at ambient temperature. Diffusivity is greatly increased, associated with a larger volume of grain boundaries. Thermal conductivity may be reduced because of enhanced phonon scattering from grain boundaries and other nanoscale features. In engineering materials, there is usually a toughness tradeoff with strength and hardness. The possibility exists that this tradeoff will occur at higher levels for ceramics and cermets. This is believed to be the explanation for improved wear and abrasion resistance of monostructured WC-Co. Fischer has shown that the wear track is much smoother and narrower in
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This note was uploaded on 12/24/2009 for the course AEROSPACE engine taught by Professor Prof during the Spring '09 term at École Normale Supérieure.

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