Exfoliated boron nitride for interface coating for ceramic matrix composites
A coated fiber structure for use in a ceramic matrix composite comprises a fiber and a fiber coating arrangement applied to and at least partially circumscribing the fiber. The fiber coating arrangement comprises a first boron nitride layer comprising exfoliated hexagonal boron nitride, a silicon carbide layer extending at least partially coaxially with and in direct contact with the first boron nitride layer, and a second boron nitride layer radially opposite the silicon carbide layer, with respect to the first boron nitride layer.
1 . A coated fiber structure for use in a ceramic matrix composite, the coated fiber structure comprising:
a fiber; and
a fiber coating arrangement applied to and at least partially circumscribing the fiber, the fiber coating arrangement comprising:
a first boron nitride layer comprising exfoliated hexagonal boron nitride sheets;
a silicon carbide layer extending at least partially coaxially with and in direct contact with the first boron nitride layer; and
a second boron nitride layer radially opposite the silicon carbide layer, with respect to the first boron nitride layer.
2 . The fiber structure of claim 1 and further comprising: particles within the first boron nitride layer, the particles being formed from at least one of metallics, borides, nitrides, and carbides.
3 . The fiber structure of claim 1 , wherein the first boron nitride layer further comprises at least one of amorphous boron nitride and turbostratic boron nitride.
4 . The fiber structure of claim 1 , wherein the first boron nitride layer extends at least partially coaxially with and in direct contact with the fiber.
5 . The fiber structure of claim 1 , wherein the second boron nitride layer comprises at least one of hexagonal boron nitride, amorphous boron nitride, and turbostratic boron nitride.
6 . The fiber structure of claim 5 and further comprising: particles within the second boron nitride layer, the particles being formed from at least one of metallics, borides, nitrides, and carbides.
7 . The fiber structure of claim 1 and further comprising: a carbon layer extending at least partially coaxially with and in direct contact with the silicon carbide layer.
8 . The fiber structure of claim 1 and further comprising: a silicon-doped boron nitride layer extending at least partially coaxially with and in direct contact with the second boron nitride layer.
9 . A ceramic matrix composite comprising:
a plurality of coated fiber structures of claim 1 ; and
a silicon carbide matrix formed upon the fiber coating arrangement of the plurality of coated fiber structures.
10 . A method of forming a ceramic matrix composite, the method comprising:
applying a mixture of exfoliated hexagonal boron nitride sheets to a plurality of ceramic fibers, the exfoliated hexagonal boron nitride sheets at least partially forming a first boron nitride layer;
depositing a silicon carbide layer on the first boron nitride layer, the silicon carbide layer extending at least partially coaxially with and in direct contact with the first boron nitride layer;
depositing a second boron nitride layer radially opposite the silicon carbide layer with respect to the first boron nitride layer;
wherein the first boron nitride layer, the silicon carbide layer, and the second boron nitride layer form a fiber coating arrangement at least partially circumscribing the plurality of ceramic fibers; and
depositing a silicon carbide matrix on the plurality of ceramic fibers.
11 . The method of claim 10 and further comprising: prior to applying the mixture of exfoliated hexagonal boron nitride, exfoliating stock boron nitride using at least one of a chemical or mechanical exfoliation process.
12 . The method of claim 11 and further comprising: adding a solution of particles to the mixture of exfoliated hexagonal boron nitride, the particles being formed from at least one of metallics, borides, nitrides, and carbides.
13 . The method of claim 10 , wherein the step of applying the mixture of exfoliated hexagonal boron nitride comprises: applying the mixture to individual ones of the plurality of ceramic fibers using at least one of a drop casting, spray coating, dip coating, and vacuum infiltration technique.
14 . The method of claim 13 and further comprising:
weaving the plurality of ceramic fibers into a fabric; and
incorporating the fabric into a fibrous preform.
15 . The method of claim 10 , wherein the step of applying the mixture of exfoliated hexagonal boron nitride comprises: applying the mixture to a preform including the plurality of ceramic fibers using at least one of a drop casting, spray coating, dip coating, and vacuum infiltration technique.
16 . The method of claim 10 and further comprising:
depositing a carbon layer on the silicon carbide layer; and
depositing a silicon-doped boron nitride layer on the second boron nitride layer.
17 . The method of claim 16 , wherein each of the carbon layer and silicon-doped boron nitride layer are deposited using chemical vapor infiltration.
18 . The method of claim 10 , wherein forming the first boron nitride layer further comprises: depositing at least one of hexagonal boron nitride, amorphous boron nitride, and turbostratic boron nitride using chemical vapor infiltration.
19 . The method of claim 10 , wherein the silicon carbide layer is deposited using chemical vapor infiltration.
20 . The method of claim 10 , wherein the matrix is deposited using at least one of chemical vapor infiltration, chemical vapor deposition, slurry infiltration, melt infiltration, and polymer infiltration and pyrolysis.