Premium
Silicon Nitride Joining
Author(s) -
MECARTNEY M. L.,
SINCLAIR R.,
LOEHMAN R. E.
Publication year - 1985
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.1151-2916.1985.tb15811.x
Subject(s) - silicon nitride , ceramic , materials science , nitride , gibbs free energy , transmission electron microscopy , phase (matter) , oxide , silicon , hot pressing , silicate , diffraction , mineralogy , analytical chemistry (journal) , chemical engineering , crystallography , composite material , metallurgy , chemistry , thermodynamics , nanotechnology , layer (electronics) , optics , physics , organic chemistry , chromatography , engineering
Hot‐pressed Si 3 N 4 was joined using an Mgo‐A1 2 O 3 ‐SiO 2 glass composition chosen to approximate the oxide portion of the grain‐boundary phase in the ceramic. After it has been heated at 1550° to 1650°, the interface of the joined ceramic is an interlocking mixture of Si 2 N 2 O, β‐Si 3 N 4 , and a residual oxy‐nitride glass. The kinetics of reactions between Si 3 N 4 and the molten joining composition were studied by X‐ray diffraction analysis of the phases present in Si 3 N4 powder‐glass mixtures quenched after varied heat treatments. Analytical transmission electron microscopy of the composition and micro‐structure of the reaction zone in joined specimens, together with the X‐ray diffraction results, suggests that the driving force for joining is the lowering of the Si 3 N 4 interfacial energy when it is wet by the molten silicate, augmented by the negative Gibbs energy for the reaction SiO 2 ( l ) + Si 3 N 4 = 2Si 2 N 2 O.