Numéro
J. Phys. IV France
Volume 03, Numéro C7, Novembre 1993
The 3rd European Conference on Advanced Materials and Processes
Troisiéme Conférence Européenne sur les Matériaux et les Procédés Avancés
Page(s) C7-1895 - C7-1903
DOI http://dx.doi.org/10.1051/jp4:19937303
The 3rd European Conference on Advanced Materials and Processes
Troisiéme Conférence Européenne sur les Matériaux et les Procédés Avancés

J. Phys. IV France 03 (1993) C7-1895-C7-1903

DOI: 10.1051/jp4:19937303

Carbon-carbon composites : oxidation behavior and coatings protection

M.P. BACOS

Office National d'Etudes et de Recherches Aérospatiales, Direction des Matériaux, BP. 72, 92322 Châtillon cedex, France


Abstract
Based on their good mechanical performances, potential uses of structural carbon materials have been identified in high temperature applications. Many applications require extended periods ranging from a few hours (at high temperature) to a few thousands of hours (at low temperature) in oxidizing environments where unprotected carbon-carbon composites deteriorate rapidly. Therefore numerous investigations have been conducted in an attempt to protect carbon-carbon composites against oxidation. The main protection mechanism relies on the use of a barrier against oxygen diffusion. The problem, when applying this concept, is the thermal mismatch between coating and carbon substrate which results in cracking of the coatings. Thereby, oxygen diffuses through the cracks, causes oxidation of the underlying carbon which leads to the spallation of the coatings. Therefore other approaches have been developed including : (1) intermediate layers, (2) inhibited matrices and (3) fiber protections. The purpose of this work is to examine the oxidation of carbon-carbon composites and to evaluate the inherent limitations of the various current coatings. Recently due to these limitations, composite coatings have been studied. Moreover, a new concept has been developed. It is proposed that the introduction of an inert gas into the boundary layer at the carbon composite surface will provide some protection.



© EDP Sciences 1993