Surface and layer-by-layer modes of niobium combustion in nitrogen gas: Experiment and theory

Infiltration-mediated combustion of porous Nb samples in nitrogen gas under pressures of 0.12–10 MPa was investigated by thermocouple method. Measuring the velocities of front propagation over the sample surface and along the sample axis, it turned out possible to determine the combustion front conc...

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Bibliographic Details
Published in:International journal of self-propagating high-temperature synthesis 2009-09, Vol.18 (3), p.145-150
Main Authors: Linde, A. V., Marin-Ayral, R. -M., Grachev, V. V.
Format: Article
Language:English
Subjects:
Chemistry and Materials Science
Materials Science
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Summary:Infiltration-mediated combustion of porous Nb samples in nitrogen gas under pressures of 0.12–10 MPa was investigated by thermocouple method. Measuring the velocities of front propagation over the sample surface and along the sample axis, it turned out possible to determine the combustion front concavity inside of a sample body. Combustion with a concave front was found to occur within the pressure range 0.12–1.0 MPa while that with a planar front, in the range 1–10 MPa. Elucidated was the effect of sample melting on the phase/chemical composition of combustion products. Derived was an analytical expression for parameter SL defining a limit for deviation from the mode of planar frontal combustion: the criterion SL > 1 defines the domain of combustion with a concave front while SL < 1, the domain of planar-front combustion. Theoretical predictions were found to reasonably agree with experiment.
ISSN:1061-3862
1934-788X
DOI:10.3103/S1061386209030029