Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1998-12-15
2001-08-28
Mayes, Curtis (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S212000, C156S305000
Reexamination Certificate
active
06280550
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the fabrication of composite articles, and, more particularly, to the fabrication of such articles using a fibrous ceramic reinforcing material that is infiltrated with a ceramic matrix material.
In an aircraft gas turbine (jet) engine, air is drawn into the front of the engine, compressed by a shaft-mounted compressor, and mixed with fuel. The mixture is combusted, and the resulting hot exhaust gases are passed through a turbine mounted on the same shaft. The flow of gas turns the turbine, which turns the shaft and provides power to the compressor. The hot exhaust gases flow from the back of the engine, driving it and the aircraft forwardly.
The hotter the exhaust gases, the more efficient is the operation of the jet engine. There is thus an incentive to raise the exhaust gas temperature. However, the maximum temperature of the exhaust gases is normally limited by the materials used to fabricate the turbine vanes and turbine blades of the turbine. In current engines, the turbine vanes and blades are made of nickel-based superalloys and can operate at temperatures of up to 1900-2100° F.
Many approaches have been used to increase the operating temperature limit of the turbine blades and vanes. The compositions and processing of the materials themselves have been improved. Physical cooling techniques are used. In one widely used approach, internal cooling channels are provided within the components, and cool air is forced through the channels during engine operation.
In another approach, ceramic or ceramic composite materials have been used to fabricate some of the hot section components. Most ceramics have very limited fracture toughness, and therefore ceramic composite materials have been considered for such structures. A ceramic composite material of current interest is silicon carbide fibers embedded in a silicon carbide matrix. In one approach, articles are fabricated by collating silicon carbide fibers on a tool, rigidizing the silicon carbide fibers to form a coated preform, and then producing a silicon carbide matrix in the coated preform by chemical vapor deposition (i.e., chemical vapor infiltration) or melt infiltration.
While operable for the fabrication of many articles, the present inventors have recognized that the current manufacturing process has shortcomings when used in the fabrication of other articles. For example, if the article is quite thick, the production of the matrix is slow or may not be possible. Some hollow articles and articles containing cooling channels, such as turbine blades or vanes, cannot be readily prepared by the conventional procedure.
There is a need for an improved approach to the fabrication of composite articles to allow greater flexibility in the preparation of complex and thick sections. The present invention fulfills this need, and further provides related advantages.
SUMMARY OF THE INVENTION
The present invention provides a method for the fabrication of composite articles, and articles prepared by the method. This approach allows the fabrication of significantly thicker articles than possible with conventional procedures. Articles with corners that require doublers at the interior side of the comer may be prepared. Hollow articles with multiple internal cooling passages and externally connecting orifices may be fabricated more easily than with the conventional approach. The finished articles are sound and of high quality throughout.
In accordance with the invention, a method for fabricating a composite article comprises the steps of preparing a porous first region piece comprising a first reinforcement material having no matrix, and thereafter rigidizing the first reinforcement material to form a porous first coated preform. The method further includes applying at least one second-region layer of a second reinforcement material having no matrix in contact with at least a portion of the first coated preform, and thereafter rigidizing the second reinforcement material, to form a second coated preform. A second-region matrix material is deposited into at least some of the porosity of the second coated preform. The reinforcement material is preferably silicon carbide fiber, and the matrix material preferably comprises silicon carbide, either polycrystalline silicon carbide, or a mixture of polycrystalline silicon carbide and silicon.
The present approach may be used to fabricate solid (i.e., not hollow) articles or hollow articles such as turbine components with internal cooling passages and externally connecting cooling orifices. In one embodiment of this approach, the first coated preform is hollow, defining one internal passage, and/or the second-region layer of the second reinforcement material may contact some, but not all, of the outer periphery of the first coated preform. In another embodiment, to make a hollow article with an internal rib defining a second large internal passage, a third coated preform is made and assembled with the first coated preform. Both the first and third coated preforms are overlaid with the second reinforcement material, and the matrix material is infiltrated to form the shell of the hollow article. With the prior approach, it is quite difficult to fabricate an article having an internal rib.
Optionally, a first-region matrix material may be deposited into at least some of the porosity of the first coated preform after the step of rigidizing the first reinforcement material and before the step of applying at least one second-region layer. This allows a progressive infiltration of the matrix material, or the use of a different matrix material. The thickness of some articles made by the prior approach is limited by the ability to infiltrate the matrix material into the porosity of the fibrous coated preform, and the present approach overcomes that limitation so that thicker articles may be made than heretofore possible.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The scope of the invention is not, however, limited to this preferred embodiment.
REFERENCES:
patent: 4396663 (1983-08-01), Mitchell et al.
patent: 4722762 (1988-02-01), Luhleich et al.
patent: 4741873 (1988-05-01), Fisher et al.
patent: 4762269 (1988-08-01), Gyarmarti et al.
patent: 4921554 (1990-05-01), Bates et al.
patent: 5015540 (1991-05-01), Borom et al.
patent: 5067999 (1991-11-01), Streckert et al.
patent: 5080851 (1992-01-01), Flonc et al.
patent: 5112545 (1992-05-01), Spain et al.
patent: 5196120 (1993-03-01), White
patent: 5296311 (1994-03-01), McMurtry et al.
patent: 5330854 (1994-07-01), Singh et al.
patent: 5336350 (1994-08-01), Singh
patent: 5350545 (1994-09-01), Streckert et al.
patent: 5436042 (1995-07-01), Lau et al.
patent: 5474635 (1995-12-01), Jacob et al.
patent: 5480603 (1996-01-01), Lopez et al.
patent: 5866060 (1999-02-01), Buckley
patent: 5893955 (1999-04-01), Rousseau et al.
patent: 5922628 (1999-07-01), Barton et al.
patent: 5942064 (1999-08-01), Krenkel et al.
patent: 5980669 (1999-11-01), Maumus et al.
patent: 6030575 (2000-02-01), Barron et al.
patent: 6106650 (2000-08-01), Cheshire
Fabrication of Ceramic-Ceramic Composites by Chemical Vapor Deposition by DP Stinton, WJ Lackey, RJ Lauf, and TM Besmann, Oak Ridge Natl Laboratory pp. 668-676.
Onderko Kenneth P.
Steibel James D.
General Electric Company
Hess Andrew C.
Mayes Curtis
Narciso David L.
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