Abstract: 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 {fraction (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.

Abstract: A ceramic fiber blanket is inserted into a mold, and ceramic fiber slurry, preferably made with refractory ceramic fibers, binders, and water, is deposited on the blanket. Vacuum pressure is created under the blanket to pull the fibers of the slurry toward the fibers of the blanket to entangle them together. The slurry and blanket is then dried to form a rigid yet surface compliant ceramic fiber composite product with superior thermal insulating and acoustic dampening properties.