Classifications

• • 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
  • C23C4/18—After-treatment
• • 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
  • F01D5/286—Particular treatment of blades, e.g. to increase durability or resistance against corrosion or erosion
• • 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
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2230/00—Manufacture
  • F05D2230/90—Coating; Surface treatment
• • 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
  • F05D2300/60—Properties or characteristics given to material by treatment or manufacturing
  • F05D2300/611—Coating

Definitions

• the invention relates to a turbine blade according to the preamble of claim 1.
• MCrAlY protective layers are generally applied by plasma spraying.
• the alloy solidifies in two phases. This results in an unfavorable basis for the formation of A ⁇ O ⁇ cover layers on the surface.
• the formation of a homogeneous oxide layer is hindered on the surface of the two-phase alloy.
• the oxide cover layers that form tend to spall (flake).
• this two-phase alloy can be converted into a single-phase one by means of a remelting process using laser beams.
• the disadvantages of this method are, on the one hand, the small spatial expansion of the laser beam (at the power densities of 10 5 - 106 w / cm 2 required here) of ⁇ 10 ⁇ 2 cm 2 , and on the other hand the low penetration depth of the Laser radiation in the material.
• the spatially limited energy input leads to strong thermal tensions, which is noticeable through the formation of cracks, both in the longitudinal and in the transverse direction. Cracking reduces the spallation resistance of the oxide layers and thus the corrosion resistance.
• Another consequence of the small beam diameter is the formation of beads on the surface and phase deposits and recrystallizations in the surface layer caused by scanning with the laser beam.
• the relatively long irradiation time of a few milliseconds, for melting through a few 10 ⁇ m layer thickness, leads to a change in the original stoichiometry in the layer, i. H. to reduce the proportion of light elements (Al, Y) which are swept to the surface by convection and are thus absent from the process of renewing the oxide cover layer.
• the object of the invention is to provide a turbine blade in which the cover layer does not tend to spallation.
• the invention is explained in more detail below on the basis of an exemplary embodiment with the aid of the figure.
• the figure shows a schematic section through a conventional two-phase MCrAlY turbine blade guard layer before (a) and after the remelting process (b).
• a further advantage of the turbine blade protection layer is that the manufacturing-related micro-roughness of the surface is eliminated by the process of surface treatment and thus the heat exchange between the gas and the surface is reduced and thus higher gas inlet temperatures are possible. Higher gas inlet temperatures lead to an increase in efficiency.
• a uniform spallation-resistant oxide cover layer most effectively prevents the penetration of oxygen and slows down the depletion of the protective layer of Al by the formation of a new oxide cover layer.
• a pulsed electron beam with a large beam cross section is used to produce the corrosion protection layers.
• the beam cross section should be between 25 and 100 cm 2 .
• Cross sections between 50 and 100 cm 2 are optimal.
• the advantages of the pulsed electron beam are the large beam diameter and the large penetration depth of the electrons into the material, which can be easily controlled via the energy of the electrons.
• the depth of the melted layer is set via the energy, the pulse duration and the power density of the electron beam.
• the decisive factor for the absence of stress cracks perpendicular to the surface and the conversion of the two-phase alloy into the single-phase amorphous to nanocrystalline structure is the cooling rate in the process of self-quenching.
• the cooling rates during self-quenching can be influenced by the electron energy (this sets the melting depth), the power density and the pulse duration. Increasing the penetration depth of the electrons (melting depth) and reducing the power density lead to lower cooling rates.
• Electron energy 50 - 150 keV power density: 5-10 5 - 3 « 10 6 W / cm 2 pulse duration: 10 - 60 ⁇ sec
• the stabilizing effect of the alloyed elements is only required in the layer near the surface that is strongly exposed to corrosion, so that according to claim 3 it is proposed to apply the additional elements superficially by means of a coating (eg PVD) and to incorporate them via the remelting process has the economic advantage that a substantial part of the quantity of the, usually very expensive, elements to be processed could be saved.
• a coating eg PVD

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Physics & Mathematics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Turbine Rotor Nozzle Sealing (AREA)
• Other Surface Treatments For Metallic Materials (AREA)
• Coating By Spraying Or Casting (AREA)
• Physical Vapour Deposition (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 1996
  • 1996-03-13 DE DE19609690A patent/DE19609690C2/de not_active Expired - Fee Related
• 1997
  • 1997-02-12 AT AT97904418T patent/ATE218670T1/de not_active IP Right Cessation
  • 1997-02-12 DE DE59707422T patent/DE59707422D1/de not_active Expired - Lifetime
  • 1997-02-12 EP EP97904418A patent/EP0886721B1/fr not_active Expired - Lifetime
  • 1997-02-12 WO PCT/EP1997/000630 patent/WO1997034076A1/fr not_active Ceased
  • 1997-02-12 JP JP53222097A patent/JP3320739B2/ja not_active Expired - Fee Related

Non-Patent Citations (1)

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