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Sintering Silicon Nitride Ceramics in Air
Author(s) -
Plucknett Kevin P.,
Lin HuaTay
Publication year - 2005
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.1551-2916.2005.00631.x
Subject(s) - sintering , materials science , silicon nitride , ceramic , microstructure , nitride , grain boundary , silicon , crystallization , phase (matter) , metallurgy , volume fraction , grain size , mineralogy , composite material , chemical engineering , chemistry , layer (electronics) , organic chemistry , engineering
Silicon nitride (Si 3 N 4 ) ceramics, prepared with Y 2 O 3 and Al 2 O 3 sintering additives, have been densified in air at temperatures of up to 1750°C using a conventional MoSi 2 element furnace. At the highest sintering temperatures, densities in excess of 98% of theoretical have been achieved for materials prepared with a combined sintering addition of 12 wt% Y 2 O 3 and 3 wt% Al 2 O 3 . Densification is accompanied by a small weight gain (typically <1–2 wt%), because of limited passive oxidation of the sample. Complete α‐ to β‐Si 3 N 4 transformation can be achieved at temperatures above 1650°C, although a low volume fraction of Si 2 N 2 O is also observed to form below 1750°C. Partial crystallization of the residual grain‐boundary glassy phase was also apparent, with β‐Y 2 Si 2 O 7 being noted in the majority of samples. The microstructures of the sintered materials exhibited typical β‐Si 3 N 4 elongated grain morphologies, indicating potential for low‐cost processing of in situ toughened Si 3 N 4 ‐based ceramics.