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Effect of Product Conductivity on Field‐Activated Combustion Synthesis
Author(s) -
Feng Aigou,
Munir Zuhair A.
Publication year - 1997
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1997.tb02968.x
Subject(s) - combustion , field (mathematics) , niobium , continuous wave , electric field , materials science , self propagating high temperature synthesis , mode (computer interface) , conductivity , product (mathematics) , electrical resistivity and conductivity , condensed matter physics , chemical physics , chemistry , physics , optics , metallurgy , geometry , mathematics , laser , quantum mechanics , computer science , pure mathematics , operating system
Experimental and modeling results on the field‐activated combustion synthesis (FACS) of Nb 5 Si 3 are reported. In the absence of an electric field and without reactant preheating, Nb 5 Si 3 cannot be prepared by self‐propagating high‐temperature synthesis (SHS). Under the influence of a field a self‐sustaining combustion wave is established whose rate of propagation decreases with traveled distance. For relatively low field values, the wave propagation mode changes from a continuous (smooth) to a spin mode. The product of synthesis depends on the mode of propagation. Synthesis during continuous wave propagation results in the formation of Nb 5 Si 3 , primarily in the α‐modification. In contrast, when the wave propagates in a spin mode, the product is NbSi 2 with unreacted niobium. The present observations demonstrate a case where the field effect is not localized, as was the case in previous studies. The difference in behavior is attributed to differences in the electrical conductivities of the product phases.