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Effect of Oxidation on Mechanical Properties of Fibrous Monolith Si 3 N 4 /BN at Elevated Temperatures in Air
Author(s) -
Koh YoungHag,
Kim HaeWon,
Kim HyounEe,
Halloran John W.
Publication year - 2002
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.1151-2916.2002.tb00597.x
Subject(s) - monolith , materials science , flexural strength , silicate glass , vaporization , phase (matter) , chemical engineering , composite material , chemistry , catalysis , biochemistry , organic chemistry , engineering
The oxidation behavior and its effect on the mechanical properties of fibrous monolith Si 3 N 4 /BN after exposure to air at temperatures ranging from 1000° to 1400°C for up to 20 h were investigated. After exposure at 1000°C, only the BN cell boundary was oxidized, forming a B 2 O 3 liquid phase. With increasing exposure temperature, the Si 3 N 4 cells began to oxidize, forming crystalline Y 2 Si 2 O 7 , SiO 2 , and silicate glass. However, in this case, a weight loss was observed due to extensive vaporization of the B 2 O 3 liquid. After exposure at 1400°C, large Y 2 Si 2 O 7 crystals with a glassy phase formed near the BN cell boundaries. The oxidation behavior significantly affected the mechanical properties of the fibrous monolith. The flexural strength and work‐of‐fracture decreased with increasing exposure temperature, while the noncatastrophic failure was maintained.