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A micromechanistic model of the combustion synthesis process: Influence of intrinsic kinetics

Published online by Cambridge University Press:  31 January 2011

Cheng He
Affiliation:
Institute for Aerospace Research, National Research Council Canada, Ottawa, Ontario K1A 0R6, Canada
Chantal Blanchetiere
Affiliation:
Institute for National Measurement Standards, National Research Council Canada, Ottawa, Ontario K1A 0R6, Canada
Gregory C. Stangle
Affiliation:
School of Ceramic Engineering and Sciences, New York State College of Ceramics at Alfred University, Alfred, New York 14802
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Abstract

A micromechanistic model of the combustion synthesis of NbC has been developed by combining the results of an experimental study of the intrinsic, pore-level kinetic mechanism [C. He. and G. C. Stangle, J. Mater. Res. 10, 2829–2841 (1995)] and a theoretical model developed previously [Y. Zhang and G. C. Stangle, J. Mater. Res. 9, 2592–2604 (1994); 9, 2605–2619 (1994)], in order to account for the various physical and chemical processes that take place during the combustion synthesis process. Results of the present investigation are interpreted from both a macroscopic and a microscopic point of view. Moreover, the relationship between the microscopic processes and macroscopic features of the combustion synthesis process is discussed. The results show that the formation of a combustion wave in the Nb-C system corresponded to establishment of a proper balance between the rates of enthalpy redistribution within the sample. Furthermore, the pore size had a significant influence on the combustion synthesis process: smaller pores gave rise to a higher area of contact between the reactants, which in turn gave rise to a higher rate of enthalpy increase due to the enhanced rate of product formation. The influence of the pore size distribution on the process is also discussed.

Type
Articles
Copyright
Copyright © Materials Research Society 1998

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References

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