Patent Application
20160129533
The subject matter disclosed herein relates to braze tapes and methods and, more specifically, to hybrid braze tapes and methods combining braze tapes with polytetrafluoroethylene (“PTFE”) tapes.
A wide variety of industry components may undergo a braze operation to add new material, modify existing material, modify the shape of a component, join multiple components together, or otherwise alter the original component. The braze operation may general comprise heating a braze alloy composition above its melting temperature (i.e., above its liquidus temperature) while disposed on a base substrate (i.e., the original component) and subsequently cool the materials to join the braze alloy and the base substrate together.
Various turbine components may, for example, undergo one or more braze cycles during original manufacture or modification pre or post utilization in a turbine. Some particular turbine components may also possess very high strength, toughness and/or other physical properties to facilitate sustained operation. Turbine components such as buckets (blades), nozzles (vanes), and other hot gas path components and combustions components of industrial and aircraft gas turbine engines may be formed of nickel, cobalt or iron-base superalloys with suitable mechanical and environmental properties.
In even some instances, because the efficiency of a turbomachine can be at least partially dependent on its operating temperatures, there may be a demand for components such as turbine buckets and nozzles to be capable of withstanding increasingly higher temperatures. Likewise, components in the fuel systems may require increasingly intricate designs to facilitate the mixing of air and/or fuel.
Components, including turbine components, that have undergone a braze cycle may thereby be reshaped, joined or otherwise modified into a suitable configuration. Braze tapes may be one option of delivering the braze alloy composition to the component. However, braze tapes may be relatively brittle and not be susceptible to working in tight gaps.
Accordingly, alternative hybrid braze tapes and methods would be welcome in the art.
In one embodiment, a hybrid braze tape is disclosed. The hybrid braze tape includes a braze tape layer comprising a braze alloy composition and a binder, and, a polytetrafluoroethylene (“PTFE”) tape layer disposed adjacent a surface of the braze tape layer.
In another embodiment, a hybrid braze tape method is disclosed. The hybrid braze tape method includes providing a base component comprising a surface and disposing a hybrid braze tape on the surface of the base component. The hybrid braze tape includes a braze tape layer comprising a braze alloy composition and a binder, and, a polytetrafluoroethylene (“PTFE”) tape layer disposed adjacent a surface of the braze tape layer. The hybrid braze tape method further includes applying heat to burn away the PTFE tape layer and to melt the braze tape layer so that it at least partially bonds with the base component.
These and additional features provided by the embodiments discussed herein will be more fully understood in view of the following detailed description, in conjunction with the drawings.
The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the inventions defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:
One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
Referring now to
The braze tape layer 20 of the hybrid braze tape 10 generally comprises a braze alloy composition and a binder. The braze alloy composition may comprise any braze material or combinations of braze materials that combine to have a melting temperature such that a sufficient application of heat can melt the braze alloy composition so that it at least partially bonds with the adjacent component. In some embodiments, the melting temperature of the braze alloy composition may be sufficiently high enough such that any suitable heat application during the brazing process can also fully burn away the PTFE tape layer 30.
In some embodiments, the braze alloy composition may comprise one or more nickel-, cobalt-, or iron-based alloys. For example, the braze alloy composition may be the same or similar to the compositions of commercially available Amdry B-93 braze material, Amdry 788 braze material, or Amdry 805 braze material respectively. In some embodiments, the braze alloy composition may comprise about 70.9 percent nickel, about 19 percent chromium and about 10.1 percent silicon such as in commercially available BNi-5 braze tape. In some particular embodiments, the braze alloy composition and the component may comprise the same material (i.e., they share the same material composition).
The binder of the braze tape layer 20 can comprise any suitable binder commercially available for application in braze tapes. For example, in some embodiments, the binder may comprise fibrillated PTFE. In some embodiments, the binder may comprise any other suitable binder to keep the braze alloy composition together in tape form and potentially provide some flexibility.
The polytetrafluoroethylene (“PTFE”) tape layer 30 of the hybrid braze tape 10 generally comprises any polytetrafluoroethylene tape such as those used for pipe fitting applications. For example, in some embodiments, the PTFE tape layer 30 may comprise what is sometimes commercially referred to as Teflon tape or plumber's tape.
The PTFE tape layer 30 can help provide flexibility to the hybrid braze tape 10 by helping to hold the braze tape layer 20 together while the overall hybrid braze tape 10 is manipulated (such as when it is applied one or more components—e.g., wrapped around a threaded pipe). Moreover, as the PTFE tape layer 30 burns away in subsequent brazing processes, the fluorine released therefrom can even help facilitate the cleaning of the surface of the component such as by helping to remove contaminants.
Referring now to
With reference to
However, in some embodiments, the hybrid braze tape 10 may comprise one or more additional braze tape layers 21 and or one or more additional PTFE tape layers 31 (with or without additional adhesive material 40 disposed there between). For example, as illustrated in
Depending on the application of the hybrid braze tape (e.g., gap size, shape, etc.), one or more dimensions may be controlled. For example, in some embodiments, the braze tape layer 20 and the PTFE tape layer 30 of the hybrid braze tape 10 may comprise for a total thickness of greater than or equal to about 0.003 inches. Conversely, in some embodiments, the braze tape layer 20 and the PTFE tape layer 30 of the hybrid braze tape 10 may comprise for a total thickness of less than or equal to about 0.08 inches.
In even some embodiments, one either the braze tape layer 20 or the PTFE tape layer 30 may be oversized with respect to the other to ensure sufficient coverage as desired. For example, in some embodiments, the surface area of the PTFE tape layer 30 may be greater than the surface area of the braze tape layer 20 to ensure all of the braze tape layer 20 can be supported by the PTFE tape layer 30. Conversely, in some embodiments, the surface area of the braze tape layer 20 may be greater than the surface area of the PTFE tape layer 30 when relatively less PTFE material is required to provide sufficient flexibility for the braze tape layer 20.
Referring now additionally to
The hybrid braze tape method 100 first comprises providing a base component 50 in step 110. The base component 50 can comprise any metal or alloy substrate suitable for a braze application. For example, the present disclosure is generally applicable to any metal or alloy component that may be brazed, particularly those components that operate within environments characterized by relatively high stresses and/or temperatures. Notable examples of such components include turbine components such as turbine buckets (blades), nozzles (vanes), shrouds, and other hot gas path and combustion components of a turbine, such as an industrial gas or steam turbine or an aircraft gas turbine engine.
For example, in some embodiments, the base component 50 may comprise a stainless steel such as 304 stainless steel. In some embodiments, the base component 50 may comprise nickel-, cobalt-, or iron-based superalloys. For example, the base component may comprise nickel-based superalloys such as Rene N4, Rene N5, Rene 108, GTD-111®, GTD-222®, GTD-444®, IN-738 and MarM 247 or cobalt-based superalloys such as FSX-414. The base component 50 may be formed as an equiaxed, directionally solidified (DS), or single crystal (SX) casting to withstand relatively higher temperatures and stresses such as may be present within a gas or steam turbine.
In some embodiments, the base component 50 may comprise a tube, such as a tube which is to be joined via braze to a plate (as exemplarily illustrated in
Still referring additionally to
Moreover, it should be appreciated that the base component 50 may undergo any suitable preparation prior to the deposition of the hybrid braze tape 10. For example, the base component 50 may be grinded, blasted, cleaned, treated or otherwise modified prior to the placement of the hybrid braze tape 10. Moreover, the hybrid braze tape 10 may be disposed in any orientation relative the base component 50 suitable for the particular application. For example, either the braze tape layer 20 of the PTFE tape layer 30 may be the layer disposed directly onto the surface of the base component 50. Furthermore, in some embodiments, multiple pieces of hybrid braze tape 10 may be utilized at one or more different locations relative the base component 50.
In some embodiments, the hybrid braze tape 10 may be used to braze two pieces of material together (such as a pipe to a plate as illustrated in
For example, in embodiments where the base component 50 comprises a pipe, the additional component 55 can comprise a plate such as illustrated in
Still referring additionally to
The temperature, heat source(s), iterations, ramp rate, hold time, cycle and any other relevant parameters of heat application can be adjusted so as to at least partially melt the hybrid braze tape 10. For example, in some embodiments, heat may be applied within a non-oxidizing atmosphere (e.g., vacuum or inert gas). In some embodiments, heat may be applied within a range of about 2050° F. to about 2336° F. (about 1120° C. to about 1280° C.), depending on composition, for a period of about 10 minutes to about 60 minutes.
As illustrated in
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
