Ceramic matrix composite articles having different localized properties and methods for forming same
Ceramic matrix composite articles include, for example a first plurality of plies of ceramic fibers in a ceramic matrix defining a first extent, and a local at least one second ply in said ceramic matrix defining a second extent on and/or in said first plurality of plies with the second extent being less than said first extent. The first plurality of plies has a first property, the at least one second ply has at least one second property, and said first property being different from said at least one second property. The different properties may include one or more different mechanical (stress/strain) properties, one or more different thermal conductivity properties, one or more different electrical conductivity properties, one or more different other properties, and combinations thereof.
1. A method for use in forming a ceramic matrix composite article, the method comprising:
laying up a first plurality of plies comprising ceramic fibers in a ceramic matrix, the first plurality of plies defining a first extent; and
laying up at least one second ply defining a second extent on and/or in the layup of the first plurality of plies, the second extent being less than the first extent;
wherein a stack of the first plurality of plies and the at least one second ply within the e second extent defines a localized portion of the ceramic matrix composite article, and a stack of the first plurality of plies within the first extent but not within the second extent defines an exterior portion of the ceramic matrix composite article,
wherein the first plurality of plies comprises a first property, the at least one second ply comprises at least one second property, and the first property is different from the at least one second property such that stresses within the localized portion are lower than stresses within the exterior portion,
wherein the ceramic matrix composite article is a turbine component repair.
2. The method of claim 1 , wherein the at least one second ply comprises ceramic fibers.
3. The method of claim 1 , wherein the laying up the at least one second ply comprises laying up a plurality of second plies, and wherein the plurality of second plies comprises a plurality of second properties different from the first property.
4. The method of claim 1 , wherein the first property comprises a first fiber volume fraction, the at least one second property comprises at least one second fiber volume fraction, and the first fiber volume fraction is different from the at least one second fiber volume fraction.
5. The method of claim 4 , wherein the first fiber volume fraction is about 15 percent to about 30 percent, and the at least one second fiber volume fraction of fiber is about 30 percent to about 40 percent, wherein the first plurality of plies and the second plurality of plies further each have a modulus inversely related to a volume fraction of fiber, and wherein the first plurality of plies comprise a coating having a modulus that is lower than a modulus of the ceramic fibers of a modulus of the ceramic matrix.
6. The method of claim 1 , wherein the first property comprises a first mechanical property, a first thermal property, or a first electrical property; the at least one second property comprises at least one second mechanical property, at least one second thermal property, or at least one second electrical property; and the first mechanical property, the first thermal property, or the first electrical property is different from the at least one second mechanical property, the at least one second thermal property, or the at least one second electrical property.
7. The method of claim 1 , wherein the at least one second ply comprises at least one circular second ply, at least one square second ply, or at least one rectangular second ply.
8. The method of claim 1 , wherein the second extent comprises an aperture, a radius, a bend, or a turn in the ceramic matrix composite article.
9. The method of claim 1 , wherein the laying up the first plurality of plies comprises laying up a first plurality of prepreg plies, and the laying up the at least one second ply comprises laying up at least one second prepreg ply.
10. The method of claim 9 , wherein the first plurality of prepreg plies comprises a first prepreg material, the at least one second prepreg ply comprises a second prepreg material, and the first prepreg material is different from the second prepreg material.
11. The method of claim 1 , wherein the laying up the at least one second ply comprises laying up the at least one second ply between the layup up of the first plurality of plies.
12. The method of claim 1 , wherein the laying up the at least one second ply comprises laying up the at least one second ply on an outer surface of the layup up of the first plurality of plies.
13. The method of claim 1 , wherein the laying up the at least one second ply comprises laying up a plurality of second plies, and wherein the laying up the plurality of second plies comprises interspersing the plurality of second plies in the layup of the first plurality of plies.
14. The method of claim 1 , wherein the first plurality of plies comprises a first plurality of prepreg plies, and the at least one second ply comprises at least one second prepreg ply, and further comprising curing or pyrolyzing the layup of the first plurality of prepreg plies and the at least one second prepreg ply to provide a preform having a porous matrix.
15. The method of claim 14 , further comprising densifying the porous matrix of the preform to form the ceramic matrix composite article.
16. The method of claim 15 , wherein densifying the porous matrix comprises densifying the porous matrix by chemical vapor infiltration, melt infiltration, polymer impregnation and pyrolysis, or any combination that includes one or more of these.
17. The method of claim 15 , further comprising machining at least one aperture into the localized portion of the ceramic matrix composite article, the machined at least one aperture extending through the at least one second ply, the first and second properties are a stress/strain mechanical property, and the stress/strain mechanical property of the second ply surrounding the at least one aperture is greater than the stress/strain mechanical property of the first ply surrounding the at least one aperture.
18. The method of claim 1 , wherein the first extent is a first area and the second extent is a second area.
19. The method of claim 1 , wherein the at least one second ply is situated within one ply from the first plurality of plies such that the at least one second ply and the one ply from the first plurality of plies are situated extending longitudinally in a same plane.
20. A method for use in forming a ceramic matrix composite article, the method comprising:
laying up a first plurality of plies comprising ceramic fibers in a ceramic matrix, the first plurality of plies defining a first extent;
laying up at least one second ply defining a second extent on and/or in the layup of the first plurality of plies, the second extent being less than the first extent, wherein a stack of the first plurality of plies and the at least one second ply within the second extent defines a localized portion of the ceramic matrix composite article, and a stack of the first plurality of plies within the first extent but not within the second extent defines an exterior portion of the ceramic matrix composite article, and
machining at least one aperture into the localized portion of the ceramic matrix composite article,
wherein the first plurality of plies comprises a first property, the at least one second ply comprises at least one second property, and the first property is different from the at least one second property such that stresses within the localized portion are lower than stresses within the exterior portion,
wherein the machined at least one aperture extends through the at least one second ply, the first and second properties are a stress/strain mechanical property, and the stress/strain mechanical property of the second ply surrounding the at least one aperture is greater than the stress/strain mechanical property of the first ply surrounding the at least one aperture.