Boron nitride paste composition, boron nitride shell coated ceramic structure, and process of manufacturing

摘要

A fully inorganic boron nitride paste, containing 80 to 94% of a boron nitride paint and 6 to 20% of ceramic fibers, is provided to allow the process of manufacturing boron nitride "shell" coatings of 0.0313 to 0.25 inch onto ceramic substrates chosen from a wide range of densities. De-clumping of the ceramic fibers such that fiber lengths are greater than 100 micrometers and clumps are less than 3/32 inch improves boron nitride "shell" layer uniformity. Boron nitride content of greater than 36 wt. % (or about 50 vol. %) in the boron nitride "shell" provides ceramic structures with a matrix of boron nitride that provides long-term nonwetting behavior for molten nonferrous metals.