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Nonisothermal Microwave Processing of Reaction‐Bonded Silicon Nitride
Author(s) -
Thomas Jeffrey J.,
Christensen Renee. J.,
Johnson D. Lynn,
Jennings Hamlin M.
Publication year - 1993
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.1151-2916.1993.tb03773.x
Subject(s) - silicon nitride , materials science , silicon , nitriding , porosity , nitride , microwave , porous silicon , composite material , chemical engineering , layer (electronics) , metallurgy , physics , quantum mechanics , engineering
The size and density of reaction‐bonded silicon nitride (RBSN) specimens are limited by the reduction in pore size and pore volume associated with the nitridation reaction. In particular, under conventional heating, pores at the surface of dense compacts close before the center has reacted fully. Microwave heating offers a unique advantage over conventional heating for the processing of RBSN. A temperature gradient can be maintained within the compact, which causes the reaction to occur preferentially in the interior. This increases the amount of silicon converted to Si 3 N 4 because the center of compacts with a high green density finishes reacting before the porosity near the surface closes. This study follows the reaction process and shows that partially nitrided silicon compacts have composition gradients in the radial direction. Microwave processing also facilitates control of the reaction rate.