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Microstructural Changes in Liquid‐Phase‐Sintered Silicon Carbide during Creep in an Oxidizing Environment
Author(s) -
Schneider Judy,
Biswas Koushik,
Rixecker Georg,
Aldinger Fritz
Publication year - 2003
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.1151-2916.2003.tb03328.x
Subject(s) - materials science , creep , sintering , oxidizing agent , silicon carbide , phase (matter) , grain boundary , ceramic , carbide , oxide , composite material , metallurgy , microstructure , chemistry , organic chemistry
The knowledge of the microstructural evolution during exposure to high temperatures is important to understanding the mechanisms responsible for the creep resistance of silicon carbide (SiC) ceramics. This includes not only the phase transformation of the SiC grains, but also the phase transformations of the oxynitride grain‐boundary phases. For this study, a series of SiC specimens were prepared with varying molar ratios of AlN‐Y 2 O 3 additives. Increased creep resistance was observed in specimens with an additive system containing a 2:3 molar ratio or 60 mol% Y 2 O 3 . A continuous oxide layer of Y 2 Si 2 O 7 formed at the surface during elevated temperature testing in air. No blistering or cracking was observed in this oxide coating. Further increase of the creep resistance was achieved by a post‐sintering nitrogen anneal.