Processing silicon nitride by use of boron nitride as a barrier layer
AssigneeGTE Products Corporation
InventorMartin Y. Hsieh
Life of this patent
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Abstract
A process is disclosed for producing a ceramic body coated with boron nitride. A green ceramic body is coated with boron nitride and sintered at a temperature and for a time sufficient for the body to achieve near theoretical density. Ceramic bodies of near theoretical density can be produced without deformation by coating the bodies with boron nitride, assembling the bodies with a supporting ceramic member which is also coated with boron nitride, sintering the assembly at a temperature and for a time for the bodies to achieve near theoretical density without deformation.
Claims8
A process suitable for preventing the deformation of ceramic bodies said process comprising:
- (a) forming a green ceramic body having a portion that during sintering deforms if unsupported,
- (b) forming at least one ceramic member suitable for providing support to said portion,
- (c) coating said body and said member with boron nitride,
- (d) assembling said body and said member whereby said member provides support for said portion and
- (e) sintering the resulting assembly at a temperature for said body to achieve near theoretical density.
An article consisting essentially of body consisting essentially of from about 80% to about 97.5% by weight of silicon nitride and from about 2.5% to about 20% of a sintering aid selected from the group consisting of yttrium oxide, aluminum oxide, magnesium oxide, lanthanum oxide and mixtures thereof and a coating having a thickness of from 0.5 to about 10 mils of boron nitride relatively uniformly distributed over the surface of said body.
A process for producing a ceramic body coated with a boron nitride coating composition comprising coating a green ceramic body with boron nitride and sintering said green ceramic body at a temperature and for a time sufficient for said body to achieve near theoretical density.
Dependencies are inferred from the claim text.