Metal fusion bonding – Process – Repairing – restoring – or renewing product for reuse
Reexamination Certificate
1999-05-28
2001-09-04
Dunn, Tom (Department: 1725)
Metal fusion bonding
Process
Repairing, restoring, or renewing product for reuse
C029S889100, C164S092100
Reexamination Certificate
active
06283356
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to repair of a recess in an article surface. More particularly, it relates to repair of a recess generated during operation of a power generating apparatus, for example a gas turbine engine.
During the operation of such power generating apparatus as a gas turbine engine, components in the gas stream, particularly in the hot operating portions, are subjected to strenuous operating conditions. Such conditions include a combination of oxidation and corrosion materials and gasses, erosive airborne particles, and mechanical actions resulting from rotation of the engine. As a result, it has been observed that one or more recesses are produced in a surface of components. Recesses, as used herein, include cracks, crevices, surface erosion, dents, indentations, separations, holes in or through the substrate, etc., commonly observed by those working in the repair of gas turbine engine components.
Current methods to repair recesses include application of repair material over the recess to fill and repair the recess. For example, material missing from a recess has been provided by applying and heating weld wire, metal powder mixed with a binder, and metal tapes and shims. Metal powders used for such a purpose include metal alloys and mixtures of metal or alloy powders, some of which are described in such U.S. Patents as U.S. Pat. No. 3,700,427—Hoppin et al. (patented Oct. 24, 1972); U.S. Pat. No. 3,759,692—Zelahy (patented Sep. 18, 1973); U.S. Pat. No. 4,004,047—Grisik (patented Jan. 18, 1977); U.S. Pat. No. 4,830,934—Ferrigno et al. (patented May 16, 1989); and U.S. Pat. No. 5,071,054—Dzugan et al. (patented Dec. 10, 1991).
The success of a repair using such materials has depended on the degree to which the repair material fills the recess. Forms of powder slurries with binders currently in use have been observed to separate and result in voids in a final structure. Inadequate filling can result in a porous article portion of reduced mechanical properties and integrity.
BRIEF SUMMARY OF THE INVENTION
The present invention, in one form, provides a method for repairing a recess in an article surface, including providing first and second metallic powders with different melting temperatures, the second having a melting temperature lower than the first. The first powder is disposed in the recess substantially to fill the recess. The second powder is disposed over the first powder in an amount that at least will fill the recess up to the article surface after melting and flowing of the second powder into the recess. The powders then are heated to a treatment temperature at least at the melting temperature of the second powder and less than the melting temperature of the first powder for a time sufficient to melt the second powder, to flow the melted second powder about the first powder, and to bond the second powder to a surface of the recess. Then the material in the recess is cooled to provide a repair material in the recess.
REFERENCES:
patent: 4004047 (1977-01-01), Grisik
patent: 4381944 (1983-05-01), Smith, Jr. et al.
patent: 4493451 (1985-01-01), Clark et al.
patent: 4830934 (1989-05-01), Ferrigno et al.
patent: 5040718 (1991-08-01), Lee et al.
patent: 5071054 (1991-12-01), Dzugan et al.
patent: 5156321 (1992-10-01), Liburdi et al.
patent: 5240491 (1993-08-01), Budinger et al.
patent: 5458461 (1995-10-01), Lee et al.
patent: 5549767 (1996-08-01), Pietruska et al.
patent: 5735448 (1998-04-01), Draghi et al.
patent: 5806751 (1998-09-01), Schaefer et al.
Dunn Tom
General Electric Company
Gressel Gerry S.
Hess Andrew C.
Kerns Kevin P.
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