Exploration of Multilayer Concepts for Oxidation Protection of Carbon-Carbon Composites.

摘要

The development of multilayer coating concepts for oxidation protection of carbon-carbon composites is the subject of this work. Property requirements of constituents for candidate systems are presented. In this regard, erosion, carbon and oxygen diffusion, chemical stability, bonding, compliancy and thermal expansion are discussed and the impact they have on coating effectiveness is correlated with experimental coating results. Of particular interest is the ability to manipulate crack origin, propagation direction and stoppage by giving judicious consideration to layer CTE and compliance. This capability increases the opportunity to fabricate multilayer coatings with crack-free oxygen diffusion layers. Chemical vapor deposited SiC on compliant substrates was essentially crack-free and, therefore, provided excellent oxidation protection.