Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D9/00—Stators
  • F01D9/02—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles
  • F01D9/04—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles forming ring or sector
  • F01D9/041—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles forming ring or sector using blades
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
  • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
  • C23C4/06—Metallic material
  • C23C4/073—Metallic material containing MCrAl or MCrAlY alloys, where M is nickel, cobalt or iron, with or without non-metal elements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
  • F01D5/12—Blades
  • F01D5/28—Selecting particular materials; Particular measures relating thereto; Measures against erosion or corrosion
  • F01D5/288—Protective coatings for blades
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
  • F05C2201/00—Metals
  • F05C2201/04—Heavy metals
  • F05C2201/0433—Iron group; Ferrous alloys, e.g. steel
  • F05C2201/0463—Cobalt
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
  • F05C2201/00—Metals
  • F05C2201/04—Heavy metals
  • F05C2201/0433—Iron group; Ferrous alloys, e.g. steel
  • F05C2201/0466—Nickel
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/10—Metals, alloys or intermetallic compounds
  • F05D2300/12—Light metals
  • F05D2300/121—Aluminium
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/10—Metals, alloys or intermetallic compounds
  • F05D2300/13—Refractory metals, i.e. Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W
  • F05D2300/132—Chromium
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/10—Metals, alloys or intermetallic compounds
  • F05D2300/15—Rare earth metals, i.e. Sc, Y, lanthanides

Definitions

• the present invention relates to an airfoil with a MCrAlY coating and preferably an Aluminide coating, an airfoil ar- rangement for a gas turbine and to a method for manufacturing an airfoil for a gas turbine.
• stator vanes and the rotor blades in a gas turbine are exposed to the high temperature of the working fluid passing the vanes and the blades. Due to the high temperature a sig ⁇ nificant oxidation of the base alloy can occur at the leading edge of an airfoil of the stator vane or, the rotor blade. Furthermore, oxidation at the inner platform of the inner shroud and/or outer shroud of the stator vane or the rotor blade can also occur. Such degradation is currently the life limiting mechanism on this component.
• the subject may be solved by an airfoil for a gas turbine, an airfoil arrangement and by a method for manufacturing an air ⁇ foil for a gas turbine.
• an air ⁇ foil such as a stator vane or a rotor blade, for a gas tur- bine.
• the airfoil comprises a coated surface section (e.g. a coated "patch") which is coated with a MCrAlY coating and which represents at least a part of the total surface of the airfoil.
• a method for manufacturing an airfoil arrangement for a gas turbine comprises an airfoil.
• the airfoil is coated with a coated surface section comprising a MCrAlY coating, wherein the surface section represents at least a part of the total surface of the airfoil.
• the airfoil arrangement may describe a rotor blade arrange- ment or a stator vane arrangement.
• the airfoil as described above is e.g. a vane, wherein the stator vane arrangement is fixed to a casing of the gas turbine .
• a rotor blade arrangement is fixed to a rotary shaft of the gas turbine and rotates with respect to the stator vane de ⁇ vice.
• the airfoil of a rotor blade arrangement is a blade which is driven by the working fluid of the gas turbine.
• the airfoil comprises a leading edge and a trailing edge. At the leading edge, the airfoil has a maximum curvature, for example.
• the fluid which flows against the airfoil contacts firstly the leading edge and the fluid is divided into a first part which flows along a suction side of the airfoil and in a second part which flows along a pressure side of the airfoil.
• the suction side is generally associated with higher velocity and thus lower static pressure.
• the pressure side has a comparatively higher static pressure than the suction side.
• the trailing edge defines the edge of the airfoil where the fluid flowing along the suction surface and the fluid flowing along the pressure surface is again merged to one flow stream.
• the airfoil arrangement may comprise one airfoil or a plural- ity of further airfoils which are spaced apart from each other along a circumferential direction with respect to a ro ⁇ tary axis of the gas turbine.
• the airfoil arrangement further comprises an inner shroud and an outer shroud.
• the airfoil is arranged between the inner shroud and the outer shroud.
• the leading edge and the trailing edge extend between the inner shroud and the outer shroud.
• the inner shroud is located closer to the rotary axis of the gas turbine than the outer shroud.
• the inner shroud comprises a first inner platform and the outer shroud comprises a sec ⁇ ond inner platform, wherein respective inner surfaces of the first and second inner platforms face the inner volume of the gas turbine through which inner volume the hot working gas streams.
• the respective inner surfaces of the first and second inner platforms are gas-washed by the hot working gas of the gas turbine.
• the hot working gas contacts first of all the leading edge section of the airfoil before flowing along the suction side and the pressure side to the trailing edge section. For this reason, the leading edge section is more affected by the working fluid than the trailing edge section.
• the airfoil and specifically a section around the leading edge comprise a coated surface section which is coated with a MCrAlY coating in order to reduce the oxidation in this most critical section of the airfoil, namely the leading edge sec ⁇ tion .
• the coated surface section may be defined as the section of the airfoil which has a predefined width in the direction from the leading edge to the trailing edge along the suction side and/or the pressure side of the airfoil.
• the width may be of (approximately) 5% to 100%, preferably (approximately) 5% to (approximately) 25% of a total width (100%) of a line between the leading edge to the trailing edge along the suction side and/or the pressure side.
• the air- foil comprises a cross-section, which is located within a cross-sectional plane.
• the width of the coated surface sec ⁇ tion may be defined by the width measured along a line con ⁇ necting running within the cross-sectional plane along the suction or pressure side of the airfoil and connecting the leading edge and the trailing edge.
• the complete surface of the airfoil may be covered by the coated surface section and hence may be coated with MCrAlY.
• the MCrAlY composition comprises indicated by the "M” in par ⁇ ticular Nickel (Ni) , Cobalt (Co) or a mixture of both.
• the MCrAlY coating may be coated onto the coated surface section by application methods such as electro-plating, thermal spray techniques or Electron Beam Vapour Deposition (EPPVD) .
• EPPVD Electron Beam Vapour Deposition
• the thickness of the MCrAlY coating may be between (ap- proximately) 0,025 mm to (approximately) 0,3 mm, in particu ⁇ lar between (approximately) 0,05 mm to (approximately) 0,25 mm.
• the coated surface section is spaced from the inner shroud and/or the outer shroud with a first distance.
• the first distance, at either extremity of the coated patch may be between (approximately) 2.5% and (ap- proximately) 45%, in particular between (approximately) 5% and (approximately) 25% of a total length (100%) of the air ⁇ foil between the inner shroud and the outer shroud.
• a coating thinning out section may be still located between the coated surface section and the inner shroud or the outer shroud. In the thinning out section the thickness of the coating is con ⁇ stantly reduced along a run to the inner or outer shroud un ⁇ til no coating is left at the inner or outer shroud.
• the airfoil further com- prises a further coated surface section (e.g. a further coated "patch") which e.g. surrounds, overlaps or covers the coated surface section.
• the further coated surface section comprises an aluminide anti-corrosive and oxidative coating, such as a pack cementation or Vapour Phase Aluminide (VPA) coating but is not limited to these processes.
• a smooth transition may be formed in order to not affect the flow of the working fluid along the airfoil.
• a so-called MCrAlY patch may have feathered edges and thus allows some overspray beyond the edges of the coated surface section.
• the aluminide coating on the further coated section covers at least partially or fully the MCrAlY anti-oxidative coating of the coated surface section, e.g. additionally the MCrAlY coated surface section may be over-aluminised by using e.g. a VPA coating .
• the (e.g. com- plete) airfoil and in an exemplary embodiment also the inner surface of the inner platform of the inner shroud and the in ⁇ ner surface of the inner platform of the outer shroud may be coated by using an aluminide coating. Additionally there may be an internal coating of the aerofoil to provide oxidation and corrosion protection.
• the above described exemplary embodiment im ⁇ proves the design life of the airfoil arrangement by provid ⁇ ing a MCrAlY coating at the coated surface section and addi ⁇ tionally by providing a further coated surface section, such as the above described aluminide coating to form e.g. alumin ⁇ ium oxide scales onto the airfoil.
• the addi ⁇ tional aluminium from the MCrAlY coating enables a stable aluminium scale to increase oxidation and corrosion life.
• the airfoil may be exposed to a heat treatment, so that a diffusion be ⁇ tween the coated layers in particular of aluminium occurs. Additional, a final ageing heat treatment may be applied for the component substrate material.
• Fig. 1 shows schematically an airfoil arrangement accord ⁇ ing to an exemplary embodiment of the present invention
• Fig. 2 shows a cross-section of an airfoil according to an exemplary embodiment of the present invention
• Fig. 3 shows a perspective view of an airfoil arrangement according to an exemplary embodiment of the present invention .
• FIG. 1 shows an airfoil arrangement 100, in particular a sta- tor vane arrangement, for a gas turbine.
• the airfoil arrange ⁇ ment 100 comprises an airfoil 101 (e.g. a vane) with a lead ⁇ ing edge 102 and a trailing edge 103.
• the leading edge 102 is covered by a coated surface section 104 (also called patch) which comprises a MCrAlY coating.
• the airfoil 101 is arranged between an inner shroud 110 and an outer shroud 120.
• the leading edge 102 and the trailing edge 103 extend between the inner shroud 110 and the outer shroud 120.
• Fig. 1 further shows a flow direction F of a working fluid of the gas turbine.
• the working fluid flows against the leading edge 102.
• the working fluid streams along the surfaces of the airfoil 101, i.e. the pressure side 202 and the suction side 201 (see Fig. 2), and leave the airfoil 101 at the trailing edge 103.
• the coated surface section 104 is shown which comprises a MCrAlY coating.
• the coated surface section 104 comprises a width xl, wherein the width xl may be defined by a distance between the leading edge 102 and the trailing edge 103.
• the coated surface section 104 may be spaced apart from the respective inner shroud 110 or the outer shroud 120. Between the coated surface section 104 and the respective inner shroud 110 or the outer shroud 120 a transition section may be formed.
• the coated surface section 104 is spaced from the inner shroud 110 and/or the outer shroud 120 with a distance x2.
• the distance x2 is measured e.g. by a length along a normal of a plane in which the inner surface 302 (see Fig. 3) of the inner shroud 110 or the inner surface of the outer shroud 120 is located.
• the distance x2 to the inner shroud 110 may be the same or different than the distance x2 to the outer shroud 120.
• the coated surface section 104 may be surrounded by a further coated surface section 105 which comprises for example a MCrAlY coating or a VPA coating.
• the further coated surface section 105 is an anti-oxidative and anti- corrosive coating.
• the coating of the further coated surface section 105 may have a different thickness than the thickness of the MCrAlY coating of the coated surface section 104.
• guiding rails located at the inner shroud 110 and/or at the outer shroud 120.
• the guiding rails are needed for a fixation of the airfoil arrangement 100 to a respective housing of the turbine or for guiding cooling fluid.
• At se- lective sections of the inner shroud 110 and the outer shroud 120 further surface sections 106, 106', 106''may be coated for example with a anti-oxidation coating, such as a VPA coating .
• Fig. 2 shows a sketch II-II which is indicated in Fig. 1.
• the sketch II-II shows a cross-section of the airfoil 101 within a cross-sectional plane.
• the airfoil 101 comprises the leading edge 102 on which the working fluid impinges.
• the flow direction of the working fluid is indicated by the arrow F.
• the trailing edge 103 is shown. From the leading edge 102, a part of the working fluid flows along a suction side (surface) 201 and another part flows along a pressure side (surface) 202 to the trailing edge 103.
• the width xl of the coated surface section 104 is shown.
• the width xl is defined by a width starting from the leading edge 102 and running from the leading edge 102 along the suction side 201 and/or the pressure side 202 within the cross-sectional plane until the coated surface section 104 ends.
• the further coated surface section 105 which may be an anti- oxidation and/or anti-corrosion coating, covers the airfoil 101.
• Fig. 3 shows an exemplary embodiment of an airfoil arrange ⁇ ment 100 which comprises the airfoil 101 and further airfoils 301, 301', 301".
• the airfoils 101, 301, 301', 301" are ar ⁇ ranged between the inner shroud 110 and the outer shroud 120. Furthermore, in Fig. 3 an inner surface 302 of the inner shroud 110 is shown. The inner surface 302 of the inner shroud faces the inner volume of the gas turbine through which the hot working fluid flows. Hence, the inner surface 302 is washed by the hot working fluid. Specifically, the inner surface 302 of the inner shroud 110 and/or the inner surface of the outer shrouds 120 may be coated with an anti-oxidative coating in order to reduce oxi ⁇ dation . Seal slots, such as scallop seal slots, and machined surfaces of the airfoil arrangement 100 may be kept free from any coating in order to maintain the original dimensions.
• the airfoil is coated with a MCrAlY coating which represents at least a part of the total surface of the airfoil 101 and particularly the MCrAlY coating may be limited to a leading edge section of the airfoil.
• the MCrAlY coating may be applied to a pressure and a suction side of the airfoil.
• the MCrAlY coating may not extend over the full airfoil height. In respect of the height of the airfoil, the MCrAlY coating may be limited to a middle section of the airfoil.
• the MCrAlY coating may be limited to a straight section of the leading edge of the airfoil.
• the MCrAlY coating may be applied as an additional patch on top of a previously applied further coating. Or the MCrAlY coating may be applied as an additional patch underneath of a later applied further coat ing .

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Turbine Rotor Nozzle Sealing (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=48045481

Family Applications (1)

Country Status (2)

Citations (2)

• 2012
  • 2012-05-09 EP EP12167244.8A patent/EP2662530A1/de not_active Withdrawn
• 2013
  • 2013-03-26 WO PCT/EP2013/056346 patent/WO2013167313A1/en active Application Filing

Patent Citations (2)

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