Ceramic matrix composites having monomodal pore size distribution and low fiber volume fraction

Patent metadata

Field	Value
Publication number	US-2017275210-A1
Application number	US-201615078124-A
Country	US
Kind code	A1
Filing date	Mar 23, 2016
Priority date	Mar 23, 2016
Publication date	Sep 28, 2017
Grant date	—

Abstract

Ceramic matrix composite articles include, for example, a plurality of unidirectional arrays of fiber tows in a matrix having a monomodal pore size distribution, and a fiber volume fraction between about 15 percent and about 35 percent. The articles may be formed by, for example, providing a shaped preform comprising a prepreg tape layup of unidirectional arrays of fiber tows, a matrix precursor, and a pore former, curing the shaped preform to pyrolyze the matrix precursor and burnout the pore former so that the shaped preform comprises the unidirectional arrays of fiber tows and a porous matrix having a monomodal pore size distribution, and subjecting the cured shaped preform to chemical vapor infiltration to densify the porous matrix so that the ceramic matrix composite article has a fiber volume fraction between about 15 percent and about 35 percent.

First claim

1 . A method for forming a ceramic matrix composite article, the method comprising:
curing a shaped preform comprising a prepreg tape layup of unidirectional arrays of fiber tows, a matrix precursor, and a pore fernier to molyze the matrix precursor and burnout the pore former so that the shaped preform comprises the unidirectional arrays of fiber tows and a porous matrix skeleton having a monomodal pore size distribution, wherein a median of the monomodal pore size distribution of the cured preform is between about 1 micrometers and about 30 micrometers: and subjecting the cured shaped preform to chemical vapor infiltration to densify the porous matrix skeleton so that the ceramic matrix composite article has a fiber volume fraction between about 15 percent and about 35 percent.

2 . (canceled)

3 . The method of claim 1 wherein the porous matrix skeleton comprises a uniform spacial porosity distribution.

4 . The method of claim 1 wherein the porous matrix skeleton comprises a ceramic.

5 . The method of claim 4 wherein the ceramic comprises silicon carbide.

6 . The method of claim 4 wherein the ceramic is derived from the pytolysis of the matrix precursor.

7 . The method of claim 1 wherein the matrix precursor is polycarbosilanes, tetraethyl orthosilicates, polysiloxanes, phenolics, furanic compounds and/or polysilazanes.

8 . The method of claim 1 wherein the subjecting comprises subjecting the cured shaped preform to a gaseous mixture that deposits silicon carbide.

9 . The method of claim 5 wherein the subjecting the cured shaped preform to chemical vapor infiltration comprises subjecting the cured shaped preform to a gaseous mixture that deposits silicon carbide.

10 . The method of claim 1 wherein the ceramic matrix composite article comprises interlaminar tensile, strength of over about 6 ksi.

11 . (canceled)

12 . The method of claim 1 wherein a median of the monomodal pore size distribution of the cured preform is between about 1 micrometers and about 20 micrometers.

13 . The method of claim 1 wherein the chemical vapor infiltration comprises a partial chemical vapor infiltration, and further comprising subjecting the partial chemical vapor infiltration densified ceramic matrix composite article to a melt infiltration,

14 . The method of claim 13 wherein the melt infiltration comprises silicon, a silicon alloy, or oxide.

15 . The method of claim 13 wherein after the ceramic matrix composite article subjected to the melt infiltration it comprises a porosity less than about 5 percent.

16 . The method of claim 1 wherein the chemical vapor infiltration comprises a partial chemical vapor infiltration, and further comprising subjecting the partial chemical vapor infiltration densified ceramic matrix composite article to a slurry casting and a melt infiltration.

17 . The method of claim 16 wherein the slurry casting comprises a slurry comprising silicon carbide, boron carbide, one or more oxides, and/or combinations thereof.

18 . The method of claim 1 wherein the cured shaped preform comprises a volume porosity of about 35 percent to about 65 percent.

19 . The method of claim 1 wherein the ceramic matrix composite article comprises a volume porosity of about 5 percent to about 20 percent.

20 . The method of claim 1 wherein the ceramic matrix composite article comprises at least one first portion having a first fiber volume percentage and at least one second portion having a second fiber volume percentage different from said first fiber volume percentage.

21 . The method of claim 1 wherein the pore former comprises polyethylene, polypropylene, polyamide, nylon, polytetrafluoroethylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, or cellulosic powders.

22 . The method of claim 1 wherein the shaped prepreg further comprises silicon carbide particles, boron carbide particles, oxide particles, and/or combinations thereof.

23 . The method of claim 1 wherein the fiber tows comprise silicon carbide fiber tows.

24 . A method for forming a ceramic matrix composite article, the method comprising:
curing a shaped preform comprising a prepreg tape layup of unidirectional arrays of fiber tows, a matrix precursor for forming a ceramic matrix, and a pore former to pyrolyze the matrix precursor and burnout the pore former so that the shaped preform comprises the unidirectional arrays of fiber tows and a porous ceramic matrix skeleton having a monomodal pore size distribution with a median pore size of between about 1 micrometers and about 30 micrometers; and subjecting the cured shaped preform to a partial chemical vapor infiltration and a melt infiltration, or a partial chemical vapor infiltration, a slurry casting, and a melt infiltration, to densify the porous ceramic matrix skeleton so that the ceramic matrix composite article has a fiber volume fraction between about 15 percent and about 35 percent.

25 .- 34 . (canceled)

35 . The method of claim 1 , wherein each fiber tow comprises about 500 individual fibers.

36 . The method of claim 35 , wherein the fibers have a diameter range of about 5 to 20 micrometers.

37 . The method of claim 1 , wherein the shaped prepreg further comprises particles or whiskers of SiC, B 4 C, SiO 2 , HfC, HtB 2 , ZrC, ZrB 2 , MoSi 2 , Si 3 N 4 , Al 2 O 3 , rare earth silicates, or rare earth silicides.

38 . The method of claim 1 , wherein the shaped prepreg further comprises a carrier comprising water, isopropanol, toluene, or acetone.

39 . The method of claim 9 , wherein the gaseous mixture comprises methyl-trichlorosilane, dimethyl-dichlorosilane, silane±methane, and/or tetracholosilane+methane.

40 . The method of claim 16 , wherein the slurry cast comprises silicon carbide, silicon nitride, molybdenum silicides, boron carbide, HfC, ZrC, HfB2, ZrB2, or rare earth silicates.

41 . The method of claim 40 , wherein the melt infiltration comprises silicon, a silicon alloy, a silicide, an oxide, or a combination thereof.

42 . The method of claim 21 , wherein the pore former comprises particles having a median size in a range of about 1 micrometer to about 30 micrometers.

43 . The method of claim 21 , wherein the pore former comprises particles having a median size in a range of about 1 micrometer to about 20 micrometers.

44 . The method of claim 21 , wherein the pore former comprises particles having a median size in a range of about 3 micrometers to about 10 micrometers.

45 . The method of claim 21 , wherein the pore former comprises particles having a median size in a range of about 3.5 micrometers to about 8 micrometers.

Assignees

• Gen Electric

Inventors

• Corman Gregory Scot
• Weaver Jared Hogg
• Luthra Krishan Lal

Classifications

• C04B35/80

  Fibres, filaments, whiskers, platelets, or the like · CPC title

• F05D2300/6033

  Ceramic matrix composites [CMC] · CPC title

• C04B2235/616

  Liquid infiltration of green bodies or pre-forms · CPC title

• C04B2235/5268

  Orientation of the fibers · CPC title

• F01D9/02

  Nozzles; Nozzle boxes; Stator blades; Guide conduits {, e.g. individual nozzles (nozzle boxes F01D9/047)} · CPC title