Objective
Mechanisms of heterogeneous high-temperature reactions in systems with fine (nano-scale) solid reactant dimensions are scantily known. This proposal objective is to achieve an experimental characterization of exothermic heterogeneous reaction mechanisms in multilayered thin films, and of product structure formation, both in thin films and coatings on substrates. Multilayer films provide a way for understanding these processes due to simple geometry, cleanness of layer contacts and superposition of heat effects or x-ray diffraction patterns of numerous layers. Special attention will be paid to self-sustained wave-like reaction propagation, which represents a new class of gasless combustion processes.
Multilayer metal/metal and metal/nonmetal films (Ti/Al, Ni/Al, Ti/Ni, Ta/C, Nb/C, Cu/Al, Nb/Si, Ta/Si, Fe/Si, Co/Si, Fe/Al, Co/Ti) with individual layer thickness from 1 to 100 nm, and layer number up to several thousands, will be produced by plasma-assisted sputtering and vacuum deposition. The production efficiency was verified by previous experiments with the systems: Ti/Al, Nb/Al, Ta/Al, and Cu/Al.
Several experimental methods will be used for in situ study of reaction and structure formation processes in thin films alone and/or on substrates: micro-calorimetry, optical (IR) study of combustion wave behaviour, time-resolve x-ray diffraction using synchrotron radiation, real-time TEM observations of the reaction. A set of analytical techniques will be used in order to test electrical, magnetic, mechanical properties, atomic structure of films before and after reaction. Different experimental and analytical methods available in the different teams will give complementary results, which will provide a comprehensive picture of the process mechanisms. It is expected that composition and structure will be determined before, during and after reaction. Heat evolution laws and kinetic parameters (apparent activation energy, diffusivities), data about dynamics of structure transformations will be obtained. New effects of "epitaxial gasless combustion" will find adequate explanation. Based on these data, a new macrokinetic model of heterogeneous reactions in nanotextured systems, with features of structure formation, will be developed. The expected results will be useful for innovating activities aimed at creating new thin film and coating classes with nanoscaled textures. Methods for multilayered film production with composition and structure gradients (functionally graded films) will be also developed. Oxidation, corrosion and wear resistance of the films (coatings) will be tested. Most of research and test works will be carried out in parallel, during the period of 36 month. Identical samples will be distributed among all teams, and all participants will receive the results by e-mail. Three meetings are planned, one for each year, for coordinating, discussing results and plans. Additionally, work in Novosibirsk for experiments using synchrotron is planned.
Topic(s)
Call for proposal
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F54506 Vandoeuvre les Nancy cedex
France