COMPONENTS TECHNICAL FIELD

[0001] The present disclosure relates generally to the field of materials technology, and particularly to, methods for structural repair of industrial machine components, e.g., nickel base components of a gas turbine engine, with a bilayer or dual braze repair/build up layer.

BACKGROUND

[0002] In a turbomachine, such as a gas turbine engine, air is pressurized in a compressor section then mixed with fuel and burned in a combustion section to generate hot combustion gases. The hot combustion gases are expanded within a turbine section of the engine where energy is extracted to provide output power used to produce electricity. The hot combustion gases travel through a series of stages when passing through the turbine section. A stage may include a row of stationary airfoils, i.e., vanes, followed by a row of rotating airfoils, i.e., blades, where the blades extract energy from the hot combustion gases for providing output power. Since the components within the combustion and turbine section are directly exposed to the hot combustion gases, these components may become eroded, damaged and in need of repair.

SUMMARY

[0003] In one embodiment, a bilayer braze material is provided. The bilayer braze material includes a first layer comprised of mostly a braze metal powder and a second layer comprised of mostly a base metal powder. The bilayer braze material is constructed such that brazing of the bilayer braze material causes the braze metal of the first layer to melt and infiltrate the base metal powder of the second layer to diffuse the bilayer braze material to a damaged industrial machine component.

[0004] In another exemplary embodiment, a method for braze repairing one or more components of an industrial machine, e.g., a turbomachine engine is provided. The method includes the step of placing or applying a bilayer braze material onto an eroded/damaged component, and heating the bilayer braze material to a braze temperature to cause braze metals in an upper layer of the bilayer braze material to melt and infiltrate the base metal powders in a lower layer of the bilayer braze material, resulting in a buildup layer diffusing with the component and comprising similar compositions and properties to the component.

[0005] In a further exemplary embodiment, a second method for braze repairing one or more components is provided. The method includes the step of placing or applying a braze material onto an eroded/damaged component, the braze material having a first and second portion, wherein the first portion comprises mostly of braze metal powder and the second portion comprises mostly of base metal powder, the base metal being a base metal of the component or similar in composition and property to the component base metal. The method further includes the step of orienting the braze material such that the portion comprising the base metal is proximate to a surface of the component and disposed between the component and the portion comprising the braze metal powder. The method also includes the step of brazing the braze material at a braze temperature and melting the braze metal such that the braze metal infiltrates the base metal powder and diffuses the braze material to the base metal powder and component.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Fig. 1 illustrates a schematic illustration of an eroded/damaged industrial machine component prior to braze repair;

[0007] Fig. 2 illustrates a schematic illustration of a bilayer braze material placed onto a surface of the component of Fig. 1, and in accordance with the disclosure provided herein;

[0008] Fig. 3 illustrates schematic illustration of the bilayer braze material of Fig. 2 after undergoing a braze operation, and in accordance with the disclosure provided herein; and

[0009] Fig. 4 illustrates a block diagram of a braze repair method for a component, and in accordance with the disclosure provided herein.

DETAILED DESCRIPTION

[0010] Referring now to the drawings wherein the showings are for purposes of illustrating embodiments of the subject matter herein only and not for limiting the same, Fig. 7 is a schematic illustration of an eroded/damaged industrial machine component, e.g., a turbomachine engine blade, vane, etc.

[0011] It should be appreciated that rotating industrial machine components, e.g., nickel base turbine blades, are not structurally repaired due to the difficulties in repairing the damaged component with materials similar in composition and properties to the component's base materials. These difficulties arise due to the a presence of non-metallic elements, e.g., boron, silicon and phosphorus, in many of the prior art braze materials, which reduces the fatigue life of the component.

[0012] The inventor, familiar with the above difficulties, has developed a novel method of repair in which application of the in accordance with the present disclosure results in a layer of repair material(s) being similar to the base metal, i.e., the component base metal, in composition and properties.

[0013] With reference now to Fig. 2, a schematic illustration of a braze material 200 placed onto a surface 12 of the component 10 is shown. In one exemplary embodiment, the braze material 200 may be a single layered powder braze material comprised of at least two portions. A first portion may include mostly a braze metal powder material, and a second powdered portion different from the first portion, which may include mostly a base metal powder, e.g., the component's 10 base metal. In this embodiment, and during the brazing operation carried out at, e.g., a braze temperature, the single layered braze material 200 should be oriented, i.e., positioned such that the portion of the material comprising mostly of the base metals is nearest to the surface 12 and disposed between the component 10 and the portion of the braze material 200 comprising mostly the braze metals. This positioning of the single layered braze material 200 during the brazing operation may be consistently held in the above orientation throughout the brazing operation such that a directional brazing of the single layered braze material 200 directionally melts the braze metal causing it to infiltrate the base metal portion of the single layered braze material 200 and diffusing the braze material 200 to the component 10. [0014] Additionally or alternatively, the braze material 200 may be double layered braze material or a bilayer braze material, e.g., a single material arrangement comprised of at least two distinct layers. The bilayer brazed material 200 may include a first powdered layer 210 selectively disposed or otherwise positioned/arranged onto a second powdered layer 220, which is selectively disposed or otherwise arranged onto the surface 12. The first layer 210, e.g., the upper layer 210 (Fig. 2), may include mostly a braze metal powder, comprising or consisting essentially of a Ni-Cr-Ti, Ni- Cr-Ti-Zr or Ni-Ti-Zr. It should be appreciated that because the braze is non-boron and non-silicon, e.g., made of all metallic elements, the buildup region (layer) may include the same or similar properties of the base metal, i.e., the component 10.

[0015] The second layer 220, e.g., the lower layer 220 (Fig. 2) may be disposed between the first layer 210 and the surface 12 of the component 10 and may include mostly a base metal powder. As used herein, base metal may be the same or similar to the base metal forming the component being repaired, i.e., it may be the component base metal in a particle or powdered form. For example, in an embodiment where the component 10 may be comprised of the superalloy CM 247, the base metal powder may include mostly CM 247 particles in the powder.

[0016] Additionally or alternatively, the braze material 200 may include a binder (not shown) mixed therewith. The binder may be mixed in one or more of the braze metal 210 or base metal 220 powders in equal or varying proportions. For example, in an exemplary embodiment, the braze material 200 may be include up to 10% of the binder material. Each layer may include different percentages of the binder material mixed therewith, or each layer may be made up of 10% binder material. [0017] It should be appreciated that the binder may not be present in any additional base metal powder used for filing cracks in the substrate, as binders may restrict the base metal powder from filling of any cracks. The binders may be organic, acrylic or alginate base. It should be further appreciated that other binders known in the art and capable of being mixed with any of the powdered layers and applied at room temperature may be used.

[0018] With continued reference to the figures, and now to Figs. 3 and 4, a method 1000 for braze repairing a component, e.g., a gas turbine engine eroded nickel based component, with a braze material 200 in accordance with the present disclosure is provided.

[0019] After removal of a damaged component 10 from, e.g., the turbomachine engine, the method 1000 may begin with steps for preparing the component 10 for braze repair, e.g., by mechanically or chemically removing any coatings, e.g., metallic and/or ceramic coatings, from the component 10 (1010).

[0020] In this exemplary step, and because many turbomachine engine components typically have one or more coatings protecting the component and/or underlying substrate during operation, removal of those coatings may be required for repairing the damaged component. Examples of types of mechanical removal processes may include removal via grit blasting, sanding, and/or shot peening. Chemical removal processes may include, e.g., removal via chemical stripping and/or etching.

[0021] After removal of any coatings, the preparing step may further include a cleaning process, e.g., via a fluoride ion cleaning (FIC) or similar process, to remove, e.g., any oxides from cracks in the component 10. It should be appreciated that in the presence of tight cracks, e.g., extremely tight cracks, a carbide burr tool or Dremel® cutting wheel may be used for opening the tight cracks prior to undergoing the cleaning process.

[0022] Upon completion of the cleaning process, or alternatively, if no cleaning was required, the method 1000 may include the step of selectively apply ing/arranging or placing a braze material 200 onto a surface 12 of the component 10 (1020). The braze material 200 may be, e.g., a braze material with two or more portions, a double layered braze material, or a bilayer braze material. In this step, where the braze material 200 is a double layered material 200 (Fig. 2), the double layered braze material 200 may include a first powdered layer 210 comprised mostly of braze metal and a second powdered layer 220 comprised mostly of a base metal, e.g., the component base metal. The second layer including mostly the base metal powder 220 may be selectively deposited, placed, or otherwise arranged on the surface 12 of component 10, followed by the first layer including mostly the braze metal powder 210. This arrangement is shown in Fig. 2, e.g., where the base metal powder 220 is disposed between the braze metal powder 210 and the underlying substrate (component 10).

[0023] It should be appreciated that in embodiments where the damaged component 10 includes one or more large cracks, e.g., larger than 40 micron, e.g., 50 microns, the crack(s) may be filled with an additional base metal powder 220 prior to applying embodiments of the braze material 200. [0024] Additionally or alternatively, in an embodiment where the braze material is a bilayer material, i.e., a single braze material constructed of two distinct layers, the bilayer material 200 may be selectively arranged such that the layer 220 including mostly the base metal powder is the layer nearest to the surface 12 and disposed between the component and the layer 210 including mostly the braze material. In this embodiment, each layer (e.g., 210 and 220) may be contained in a tube-like housing or cover (not shown) comprised of similar materials to one or more of the layers of the bilayer material. For example, the cover may be comprised of materials similar to the base metal or the braze metal. Additionally or alternatively, the cover may be comprised of both the base metal and braze metal materials, and aligned to cover both layers such that the base metal portion of the covers mostly the base metal powder layer and the braze metal portion covers mostly the braze metal powder layer. It should be appreciated that in embodiments where the braze material comprises the cover, because the cover includes the base metal powder therein, if one or more cracks are present, additional base metal powder 210 may be deposited within the crack(s) to arranging embodiment of the braze material onto the surface 12.

[0025] Additionally or alternatively, in yet a further embodiment where the braze material 200 is a single layer braze material 200 with at least two portions, the step of applying the single layer braze material 200 may include positioning or orienting the single layer braze material 200 such that a portion of the single layer braze material including mostly the base metal powder, i.e., the base metal portion, is the portion adjacent the surface 12, and disposed between the surface 12 and a portion of the single layer braze material including mostly a braze metal powder, i.e., the braze metal portion. [0026] With continue reference to the figures, once the braze material 200 has been placed onto the surface 12 of the component 10, the method 1000 includes the step of brazing repairing the component 10 at a braze temperature (1030). The brazing operation may be by any known means for brazing, e.g., vacuum furnace brazing, brazing under partial pressure, endothermic furnace brazing or torch brazing.

[0027] In this step 1030, the brazing operation is carried out by melting the braze material 200 such that the braze metal, e.g., in the layer comprising mostly the braze metal powder 210 or in the braze metal portion, melts and infiltrates the layer 220 or portion including mostly the base metal powder, and diffuses to the component 10. The melting results in an infiltrated base metal layer 300 (Fig. 3) which may include be the same or similar in composition and properties to the substrate or component 10 being repaired.

[0028] It should be appreciated, in an embodiment where a single layer braze material 200 is provided, it may be necessary to continuously maintain the orientation of the single layer braze material during brazing so that the base metal portion remains the portion between the component 10 and the braze metal portion to allow for the melted braze metal to, e.g., infiltrate downwards or towards the surface 12 and into the base metal portion. After braze repair, the component 10 may be allowed to cool, e.g., to room temperature. The component may be cooled naturally, i.e., without assistance from any cooling system or other device, or cooling of the component may be via a cooling system (not shown) or by any means known in the art for cooling components. [0029] With continue reference to the figures, and after the brazing operation, the method 1000 may further include the step of removing any excess or undesired materials remaining on the component 10 from the braze repair operation. Removal of these materials may be by, e.g., machining, or any other mechanical materials removal process known in the art for removing excess materials. Additionally or alternatively, the method 1000 may further include the step of testing the repaired component 10, e.g., via non-destructive testing or any other testing means known in the art to determine whether the integrity of the component 10 has been compromised during brazing and prior to returning the component 10 to operation. The testing may be carried out during the cooling of the component 10 or at any time prior to returning the component 10 to operation. Additionally or alternatively, and prior to returning the repaired component 10 to operation, the method 1000 may further include applying one or more coatings to the component 10. The coatings may be applied via known means in the art for applying coatings to the component 10, e.g., via spraying, vapor deposition etc.

[0030] While specific embodiments have been described in detail, those with ordinary skill in the art will appreciate that various modifications and alternative to those details could be developed in light of the overall teachings of the disclosure. For example, elements described in association with different embodiments may be combined. Accordingly, the particular arrangements disclosed are meant to be illustrative only and should not be construed as limiting the scope of the claims or disclosure, which are to be given the full breadth of the appended claims, and any and all equivalents thereof. It should be noted that the term "comprising" does not exclude other elements or steps and the use of articles "a" or "an" does not exclude a plurality.