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
  • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
  • C23C28/04—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material
  • C23C28/042—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material including a refractory ceramic layer, e.g. refractory metal oxides, ZrO2, rare earth oxides
• • 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
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/20—Oxide or non-oxide ceramics
  • F05D2300/21—Oxide ceramics

Definitions

• the present invention relates to a ceramic coating for a component which is exposed to high temperatures, in particular ceramic coatings for a turbine blade.
• Ceramic coatings for turbine blades are, for example, from DE 198 01 424 known.
• the ceramic coatings described in this application relate to compositions consisting essentially of barium zirconate and / or lanthanum zirconate and / or strontium zirconate.
• coatings for turbine blades consist of zirconia or by the addition of yttria partially stabilized zirconia.
• a disadvantage of yttria-stabilized zirconia ceramics is that when used as a coating for turbine blades operated under heavy oil conditions, they may be subject to degradation phenomena.
• the object of the present invention is to provide a ceramic coating for components of the type mentioned, which have good thermal insulation properties at the same time high stability even in aggressive environments.
• the object is achieved according to the invention by a ceramic coating which contains one or more compounds selected from Al 2 TiO 5 , alkaline earth silicates, magnesium titanates, ZrV 2 O 7 and Mg 3 (VO 4 ) 2 .
• the invention is based on the finding that the conventionally used for turbine blades Ceramic coatings based on yttrium-stabilized zirconia are decomposed by the attack of sodium, potassium, vanadium or magnesium. These elements occur primarily in the operation of a gas turbine under heavy oil conditions or in contact with low-purity synthesis gases.
• the contact of the yttria-stabilized zirconia with the above-mentioned elements in detail leads to a destabilization of the yttria, whereby the destruction of the ceramic is caused.
• the ceramic coatings according to the invention can generally be used for components which are exposed to high temperatures.
• a possible method for producing such a coating is that a coating of the type according to the invention is applied to a substrate which predetermines the basic shape of the component.
• the coating can be effected by physical vapor deposition, which is also referred to as PVD (physical vapor deposition), in particular also by physical electron beam vapor deposition (EB-PVD method, electron beam physical vapor deposition).
• PVD physical vapor deposition
• EB-PVD method electron beam physical vapor deposition
• the coating can also be applied by plasma spraying, in particular by atmospheric plasma spraying.
• the coating according to the invention contains at least 90 wt.%, In particular at least 95 wt.%, Particularly preferably greater than 99 wt.% Of Al 2 TiO 5 , alkaline earth silicates, magnesium titanates, ZrV 2 O 7 and Mg 3 (VO 4 ) 2 .
• This is particularly advantageous because ceramics of these compounds already without further additives have good thermal insulation properties and high resistance to aggressive environments.
• the coating according to the invention consists exclusively of the abovementioned compounds, in particular of a single one of the abovementioned compounds.
• the presence of small amounts of impurities in particular in the order of less than 1 wt.%, In particular less than 0.1 wt.% Possible.
• the alkaline earth silicates are selected from steatite, cordierite, barium silicate and calcium silicate. It is also preferable that the magnesium titanates are selected from MgTiO 3 and Mg 2 TiO 4 . This is particularly advantageous because coatings of ceramic materials of this type have a particularly high resistance to attack by sodium, potassium, vanadium or magnesium.
• the coating according to the invention has no addition of stabilizers. This is particularly advantageous since the coatings according to the invention can thus be applied as a single-phase system. Possible errors in the weighing of stabilizing additives can be ruled out from the outset. The possibility to dispense with the addition of stabilizers is due to the high resistance of the coatings according to the invention even in aggressive environments.
• the coatings according to the invention are largely free of yttrium oxide.
• the coatings according to the invention do not contain yttrium oxide. This is special advantageous, since this stabilizer commonly used in coating ceramics for turbine blades is responsible for the destruction of the ceramic materials under the aggressive conditions described above.
• the coatings according to the invention do not require the addition of yttrium or yttrium oxide.
• the coating has a thickness of 200 to 1000 .mu.m, in particular from 200 to 500 .mu.m.
• Coatings, which are applied with these thicknesses to the components to be coated have the particular advantage that even with coatings of this thickness sufficient thermal insulation of the underlying material is ensured at the same time good stability against aggressive environments.
• Another object of the present invention relates to a layer system which contains at least one coating of the type according to the invention.
• a particularly preferred layer system is formed by applying a coating according to the invention to a layer of partially stabilized zirconium oxide already present on the component. If appropriate, further layers, in particular adhesion promoter layers, may be introduced between the layer of partially stabilized zirconium oxide and the component surface.
• a multilayer coating system of this type is particularly advantageous since possible differences in the coefficients of thermal expansion of the coatings of the invention and the base material can be compensated by the intermediate layer of partially stabilized zirconium oxide, whereby the thermal stability of the coating can be increased. Turbines coated with the layer systems according to the invention can therefore be operated at higher temperatures. This is special This is relevant because the operating efficiency of turbines increases with their operating temperature.
• Another object of the present invention is the use of a coating according to the invention or a layer system which contains a coating according to the invention, as a thermal barrier coating for a component which is exposed to high temperatures.
• a coating according to the invention or a layer system which contains a coating according to the invention as a thermal barrier coating for a component which is exposed to high temperatures.
• the coatings and layer systems according to the invention have good heat-insulating properties combined with high resistance even in aggressive environments. These properties are particularly advantageous when using such a coating or such a layer system as a coating for a turbine blade, in particular a turbine blade for a steam turbine.
• Another object of the present invention is a turbine blade having a coating according to the invention or a layer system of the type mentioned above. This is particularly advantageous, since turbine blades with such ceramic coatings, especially when used in a steam turbine, have a very high temperature resistance and are operated under severe oil conditions or under contact with low-purity synthesis gases due to the good stability of the coating or the layer systems against aggressive environments at high temperatures can.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Inorganic Chemistry (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)

Priority Applications (4)

Applications Claiming Priority (1)

Publications (1)

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Citations (6)

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• 2008
  • 2008-02-04 EP EP08002050A patent/EP2085498A1/fr not_active Withdrawn
  • 2008-12-04 US US12/865,910 patent/US8592044B2/en not_active Expired - Fee Related
  • 2008-12-04 EP EP08872105A patent/EP2238278B1/fr not_active Not-in-force
  • 2008-12-04 WO PCT/EP2008/066809 patent/WO2009097931A1/fr active Application Filing

Patent Citations (6)

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