초록 ▼

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 t

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.

대표청구항 ▼

1. A boron nitride coated ceramic structure comprising a dry coating having a thickness, the coating applied to a ceramic substrate, wherein the coating comprises 36 to 78 weight percent boron nitride powder, ceramic fibers, and an inorganic binder. 2. The structure of claim 1 where the boron nitrid

1. A boron nitride coated ceramic structure comprising a dry coating having a thickness, the coating applied to a ceramic substrate, wherein the coating comprises 36 to 78 weight percent boron nitride powder, ceramic fibers, and an inorganic binder. 2. The structure of claim 1 where the boron nitride coating has a thickness of between 0.0313 and 0.25 inches. 3. The structure of claim 1 further comprising a ceramic pigment in the boron nitride coating. 4. The structure of claim 1 herein the dry ceramic pigment is present from 0.5 to 2.5 wt. %. 5. The structure of claim 1 wherein the said ceramic substrate is selected from the group consisting of: porous ceramics, ceramic fiber materials, near-fully-dense ceramics, and high-porous insulating ceramics. 6. The structure of claim 1 wherein ceramic substrate is an unsintered ceramic. 7. The structure of claim 1 where the non-boron nitride ceramic substrate is a sintered ceramic. 8. The structure of claim 1 wherein said ceramic fibers are selected from the group consisting of: alumina fibers, alumina-silica fibers, and combinations thereof. 9. The structure of claim 1 wherein said ceramic fibers have an average diameter of 2 to 3 micrometers. 10. The structure of claim 9 wherein said ceramic fibers are over 100 micrometers in length with clumps that are less than 3/32 inch in diameter. 11. A boron nitride coated ceramic structure comprising a dry coating having a thickness, the coating applied to a ceramic substrate, wherein the coating comprises: 45 to 70 weight percent of boron nitride; 19 to 48 weight percent of ceramic fibers; and 7 to 12 weight percent of an inorganic binder. 12. The structure of claim 11 wherein said ceramic fibers are selected from the group consisting of: alumina fibers, alumina-silica fibers, and combinations thereof. 13. The structure of claim 11 wherein said ceramic fibers have an average diameter of 2 to 3 micrometers. 14. The structure of claim 13 wherein said ceramic fibers are over 100 micrometers in length with clumps that are less than 3/32 inch in diameter.