Claims
- 1. A process for making a fiber reinforced composite structure comprising:
- (a) tape casting a monolayer tape comprising substantially continuous fibers, a polymeric binder, and solid particles of a high temperature metal or intermetallic matrix material selected from the group consisting of titanium alloys, titanium aluminides, nickel aluminides and molybdenum disilicide;
- (b) stacking a plurality of tapes cast in step (a) to form an unconsolidated multilayer composite stack;
- (c) removing said polymeric binder from said unconsolidated stack by heating said stack at an elevated temperature in a vacuum; and
- (d) pressing said unconsolidated stack at an elevated temperature, thereby to form a consolidated, fiber reinforced composite structure.
- 2. The process of claim 1 wherein said binder is selected from the group consisting of polycarbonates, polystyrenes, polyisobutylenes, acrylics and mixtures and copolymers thereof.
- 3. The process of claim 2 wherein said binder is polyisobutylene.
- 4. The process of claim 1 wherein said fibers comprise a ceramic selected from the group consisting of silicon carbide, carbon, silicon nitride, aluminum oxide, mullite and combinations thereof.
- 5. The process of claim 1 wherein said matrix material is a titanium aluminide or a high temperature titanium alloy.
- 6. The process of claim 5 wherein said titanium aluminide or titanium alloy comprises particles having a top size greater than about 50 microns.
- 7. The process of claim 1 wherein said tape casting process further comprises forming a slurry containing an organic solvent comprising an aliphatic or aromatic hydrocarbon together with said binder and said particles.
- 8. The process of claim 7 wherein said organic solvent is toluene.
- 9. The process of claim 1 wherein step (a) includes controlling thickness of said tape by means of a doctor blade.
- 10. The process of claim 1 wherein step (a) comprises:
- (i) coating a substrate covering a generally cylindrical body with a polymeric binder dissolved in an organic solvent and drying to remove said organic solvent;
- (ii) winding a substantially continuous ceramic fiber in a helical pattern onto said coated substrate to form wound fiber and coating said wound fiber with a polymeric binder dissolved in an organic solvent and drying to remove said organic solvent;
- (iii) removing said substrate and said ceramic fiber from said cylindrical body;
- (iv) tape casting a slurry comprising a polymeric binder, an organic solvent and solid particles of titanium alloy or titanium aluminide matrix material onto said ceramic fiber and drying to remove said organic solvent, thereby to form an unconsolidated, ceramic fiber reinforced sheet on said substrate;
- (v) controlling said unconsolidated reinforced sheet to a predetermined thickness by means of a doctor blade spaced from said substrate and having an edge portion extending generally parallel thereto; and
- (vi) separating said unconsolidated reinforced sheet from said substrate.
- 11. The process of claim 1 wherein step (a) comprises:
- (i) coating an elongated substrate with a polymeric binder dissolved in an organic solvent and drying to remove said organic solvent;
- (ii) placing a plurality of substantially continuous ceramic fibers adjacent said coated substrate;
- (iii) tape casting a slurry comprising a polymeric binder, an organic solvent and solid particles of titanium alloy or titanium aluminide matrix material onto said ceramic fiber and said substrate and drying to remove said organic solvent, thereby to form an unconsolidated, organic binder, solid particulate and substantially continuous ceramic fiber sheet on said substrate;
- (iv) controlling said unconsolidated reinforced sheet to a predetermined thickness by means of a doctor blade spaced from said substrate and having an edge portion extending generally parallel thereto; and
- (v) separating said unconsolidated reinforced sheet from said substrate.
- 12. The process of claim 1 wherein step (b) comprises stacking a plurality of sheets made by step (a) to form an unconsolidated multilayer stack and then pressing said unconsolidated multilayer stack to increase its strength and stability.
- 13. The process of claim 1 wherein step (c) comprises:
- (i) encapsulating said unconsolidated stack in a tool comprising a steel bottom pan and a steel top part spaced upwardly of said bottom part and having lesser thickness than said bottom part;
- (ii) compressing said tool so that said top pan plastically deforms around said stack; and
- (iii) heating said stack in a vacuum while purging with a noble gas at an elevated temperature greater than about 600.degree. C., thereby to pyrolyze and remove said polymeric binder.
- 14. The process of claim 1 wherein step (d) comprises hot isostatic pressing said unconsolidated stack, thereby to form a consolidated, fiber reinforced structure.
- 15. The process of claim 1 wherein step (d) comprises hot pressing said unconsolidated stack, thereby to form a consolidated, fiber reinforced structure.
- 16. The process of claim 1 wherein step (d) comprises vacuum hot pressing said unconsolidated stack, thereby to form a consolidated, fiber reinforced structure.
- 17. The process of claim 13 wherein said noble gas comprises argon.
- 18. The processs of claim 13 wherein said noble gas comprises helium.
- 19. A process for making a composite structure comprising a titanium aluminide matrix reinforced with silicon carbide fibers comprising:
- (a) tape casting a tape comprising solid titanium aluminide particles, substantially continuous silicon carbide fibers, and a polymeric binder selected from the group consisting of polycarbonates, polystyrenes, polyisobutylenes, acrylics and mixtures and copolymers thereof, said fibers comprising about 25-45 vol. % of the tape,
- (b) stacking a plurality of tapes cast by the process of step (a) to form an unconsolidated composite stack,
- (c) heating said stack at an elevated temperature in a vacuum, thereby to remove said polymeric binder from said stack, and
- (d) pressing said stack at an elevated temperature, thereby to form a composite structure comprising a titanium aluminide matrix reinforced with silicon carbide fibers.
- 20. The process of claim 19 wherein said binder is polyisobutylene.
PENDING RELATED APPLICATION
This application is a continuation-in-part of copending Edd U.S. Ser. No. 899,696 filed Jun. 16, 1992 and entitled "Rotating Ring Structure for Gas Turbine Engines and Method for its Production."
ORIGIN OF THE INVENTION
The invention described herein was made in the performance of a subcontract with the United States Government and may be manufactured and used for governmental purposes without the payment of any royalties therefor.
US Referenced Citations (8)
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
899696 |
Jun 1992 |
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