Method to form aligned interface coating on silicon carbide fibers

1. A fibrous ceramic preform comprising:

a plurality of ceramic fibers;

a first amorphous layer deposited on each of the plurality of ceramic fibers; and

a boron-based interfacial coating layer deposited on the first amorphous layer such that the first amorphous layer of each of the plurality of ceramic fibers is disposed between a respective one of the plurality of ceramic fibers and the respective interfacial coating layer, each of the interfacial coating layers comprising:

an anisotropic region adjacent the first amorphous layer, the anisotropic region comprising hexagonal boron nitride; and

an isotropic region on a side of the anisotropic region opposite the first amorphous layer.

2. The preform of claim 1 and further comprising: a second amorphous layer.

3. The preform of claim 2 , wherein the first amorphous layer is deposited on the plurality of ceramic fibers, the interfacial coating layer is deposited on the first amorphous layer, and the second amorphous layer is deposited on the interfacial coating layer on a side opposite the first amorphous layer.

4. The preform of claim 1 , wherein the plurality of ceramic fibers are formed from silicon carbide.

5. The preform of claim 1 , wherein the first amorphous layer comprises one or a combination of oxygen, carbon, silicon, boron, and nitrogen.

6. The preform of claim 1 , wherein the interfacial coating layer comprises boron nitride, and wherein the anisotropic region of the interfacial coating layer comprises hexagonal boron nitride.

7. The preform of claim 6 , wherein the hexagonal boron nitride is aligned with an axis of the plurality of ceramic fibers.

8. The preform of claim 7 , wherein the axis is a longitudinal axis of the plurality of ceramic fibers.

9. The preform of claim 1 , wherein the interfacial coating layer has a first thickness, and wherein the anisotropic region has a second thickness ranging from 5% to 100% of the first thickness.

10. A ceramic matrix composite comprising:

the preform of claim 1 ; and

a silicon carbide matrix formed upon the preform, wherein the interfacial coating layer is disposed between the ceramic matrix and the plurality of ceramic fibers.

11. The ceramic matrix composite of claim 10 and further comprising: at least one of an environmental barrier coating and a thermal barrier coating.

12. A method of forming a ceramic matrix composite, the method comprising:

forming a fibrous ceramic preform by:

arranging a plurality of ceramic fibers;

depositing a first amorphous layer on each of the plurality of ceramic fibers; and

depositing a boron-based interfacial coating layer on the first amorphous layer such that it is influenced by the first amorphous layer and further such that that the first amorphous layer of each of the plurality of ceramic fibers is disposed between a respective one of the plurality of ceramic fibers and the respective interfacial coating layer, the interfacial coating layer comprising:

an anisotropic region adjacent and promoted by the first amorphous layer, the anisotropic region comprising hexagonal boron nitride; and

an isotropic region on a side of the anisotropic region opposite the first amorphous layer.

13. The method of claim 12 , wherein at least one of the step of depositing the first amorphous layer and depositing the interfacial coating layer comprises chemical vapor infiltration.

14. The method of claim 12 and further comprising: depositing a second amorphous layer.

15. The method of claim 14 , wherein the first amorphous layer is deposited on the plurality of ceramic fibers, the interfacial coating layer is deposited on the first amorphous layer, and the second amorphous layer is deposited on the interfacial coating layer on a side opposite the first amorphous layer.

16. The method of claim 12 and further comprising: densifying the fibrous ceramic preform using chemical vapor depositing to deposit a matrix of silicon carbide.