Barrier coated ceramic fiber and coating method

摘要

Oxide-based ceramic fibers are treated in a novel process to create a substantially uniform boron nitride barrier coating at their surface. The process includes the step of heating the fiber, preferably an aluminoborosilicate fiber like NEXTEL, for between about 5-90 minutes in a nitriding atmosphere of ammonia, hydrogen and nitrogen at a temperature of between about 2200 DEG -2600 DEG F. to diffuse boron from the fiber to the surface of the fiber where it reacts to form the boron nitride coating.