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Thermal Stability of Polycarbosilane‐Derived Silicon Carbide Fibers under Reduced Pressures
Author(s) -
Shimoo Toshio,
Takeuchi Hiroshi,
Okamura Kiyohito
Publication year - 2001
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.1151-2916.2001.tb00699.x
Subject(s) - materials science , silicon carbide , composite material , ultimate tensile strength , fiber , thermal stability , thermal decomposition , crystallite , silicon , metallurgy , chemical engineering , chemistry , organic chemistry , engineering
Three types of polycarbosilane‐derived SiC fibers—Nicalon, Hi‐Nicalon, and Hi‐Nicalon S—were exposed at temperatures of 1573–1773 K under a reduced pressure of 1.3 Pa. The thermal stability of the fibers was investigated through examinations of the gas evolution, grain growth, specific resistivity, fiber morphology, and tensile strength. The thermal decomposition of the silicon oxycarbide phase began at 1523 K; then, active oxidation of the β‐SiC crystallites occurred at >1673 K. The active oxidation caused serious damage to the fiber structure, which resulted in significant degradation of the fiber strength. Hi‐Nicalon had a tensile strength of ∼0.5 GPa after exposure at 1773 K, although Nicalon and Hi‐Nicalon S fibers completely lost their strength, even after exposure at 1673 K. Hi‐Nicalon fiber had relatively good thermal stability under reduced pressure.