Silicon nitride components with protective coating
AssigneeAlliedSignal Inc.
InventorsChien-Wei Li, Derek Raybould, Milton Ortiz, Thomas Edward Strangman
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Abstract
A turbomachine component includes a silicon nitride substrate and a multi-layer coating bonded to the substrate. The coating includes an interlayer of porous fibrous silicon nitride having a density of between 85-98%. The coating also includes an outer layer formed of an oxide compound, preferably tantalum oxide, that is applied by Electron Beam-Physical Vapor Deposition. The combination of the silicon nitride interlayer and tantalum oxide outer layer serves to protect the substrate from the adverse affects of oxidation, impact by foreign objects and extreme operating temperatures.
Claims22
A method of coating a silicon nitride substrate of a turbomachine component, the method comprising:
- forming a layer of porous beta silicon nitride having whisker fibers extending into the substrate;
- and
- infiltrating an outer surface of the porous beta silicon nitride layer with a precursor solution and heating the precursor solution to densify the porous silicon nitride layer.
A method of coating a component having a silicon nitride substrate, the component designed for operation at a temperature of about 1480C and greater, the method comprising:
- forming a porous beta silicon nitride interlayer on the substrate, the interlayer having whisker fibers adhering to the substrate;
- and
- densifying the beta silicon nitride layer.
A method of applying a multi-layer coating to a silicon nitride material, the method comprising:
- positioning an ingot of tantalum oxide adjacent to the material;
- and
- bombarding the ingot with a high energy electron beam on the ingot, the ingot evaporating at the atomic level and condensing into a layer forming a chemical bond with the silicon nitride material.
A method of coating a silicon nitride substrate, comprising:
- applying a silicon nitride powder slurry onto the silicon nitride substrate;
- sintering the applied slurry to produce a layer of porous beta silicon nitride having whisker fibers extending into the substrate;
- and
- infiltrating the outer surface of the porous beta silicon nitride layer with a pre-ceramic polymer and oxide powder to densify the porous silicon nitride layer.
Dependencies are inferred from the claim text.