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Thermodynamic Approach to the Oxidation of Hi‐Nicalon Fiber
Author(s) -
Vahlas Constantin,
Laanani Fadela,
Monthioux Marc
Publication year - 1999
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.1151-2916.1999.tb02112.x
Subject(s) - fiber , oxygen , interphase , diffusion , gibbs free energy , materials science , partial pressure , silicon , chemical engineering , composite material , thermodynamics , chemistry , organic chemistry , metallurgy , physics , biology , engineering , genetics
A thermodynamic investigation of the oxidation of Hi‐Nicalon fiber in air has been performed, based on the minimization of the Gibbs energy of the silicon‐carbon‐oxygen chemical system. The results illustrate the expected stable phases, as a function of temperature and the molar ratio of air over the fiber, which permits simulation of the diffusion‐controlled radial oxidation of the fiber. In agreement with literature information, the model has shown that (i) during oxidation, the external portion of the fiber is transformed to silica while the core remains unaffected, (ii) in certain conditions, a free carbon interphase is produced between the external portion and the core of the fiber, and (iii) low oxygen partial pressure may lead to consumption of the fiber, which illustrates an active oxidation.