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
  • C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
• • 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
• • 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
  • C23C4/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
• • 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
  • F01D5/284—Selection of ceramic materials
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
  • F02C7/00—Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants
  • F02C7/24—Heat or noise insulation
• • 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

Definitions

• the invention relates to a product with a base body consisting of a superalloy and a layer system thereon for protecting the base body against an aggressive hot gas, the layer system having a ceramic thermal insulation layer with an outer surface which can be exposed to the gas.
• the invention relates in particular to such a certificate, which is designed as a component for one
• Gas turbine in particular as a rotor blade, guide vane or heat shield, generally as a component which is exposed to a hot flue gas during its regular operation, which can be both oxidative and corrosive.
• a product as described at the outset is apparent from US Pat. No. 4,321,310, US Pat. No. 4,321,311, US Pat. No. 4,055,705 and US Pat. No. 5,262,245.
• the products described in these patents can be viewed as alternative configurations of a basic form of a corresponding product.
• the product has a base made of a superalloy and an outer surface which is formed by a ceramic thermal barrier coating. Most are presented between the ceramic thermal barrier coating and the base body Embodiments a metallic adhesive layer.
• This adhesive layer can have a composition of the MCrAlY type, ie a composition in the manner of an alloy which has iron, cobalt and / or nickel as the basis (for which the "M” stands) and chromium, aluminum and yttrium or as further essential constituents has an element equivalent to yttrium, such as scandium or a rare earth element.
• the MCrAlY composition is well known in the art; it is also generally known that this composition can be further developed by adding further elements. As such further elements, silicon, hafnium, tantalum, titanium, platinum and rhenium are representative of many.
• Known alternative compositions for the adhesive layer are intermetallic compounds made of nickel and aluminum or platinum and aluminum.
• WO 89/07159 AI, EP 0 486 489 B1 and EP 0 412 397 AI each show a layer system for protecting a base body made of a superalloy against an aggressive hot gas, which layer system is primarily metallic and one Contains a layer of an alloy of the type MCrAlY. Particularly favorable compositions for alloys of the MCrAlY type are also described, which are characterized by an additional rhenium content.
• the Swiss patent specification CH 660 200 A5 describes a method for applying a high-temperature corrosion protection layer to a component consisting of a superalloy or a high-melting metal in the base body.
• the component is a turbine blade, the high-temperature corrosion protection layer consisting of a metallic alloy, in particular an iron-cobalt or nickel-based alloy.
• a coherent intermediate layer serving as a diffusion barrier for the elements forming protective oxide is placed on the metallic base body, in particular made of a nickel-based superalloy applied from a platinum metal or rhenium.
• the actual metallic high-temperature corrosion protection layer is applied to this intermediate layer.
• the intermediate layer has a thickness between 5 ⁇ m and 100 ⁇ m.
• the growth rate of the oxide layer between a metallic adhesive layer and a ceramic thermal barrier layer represents a factor determining the service life, an alloy with a low oxidation rate is preferred for the adhesive layer. As already mentioned, this results in the preference of the corresponding alloys containing rhenium.
• the ceramic thermal barrier coating is also the subject of further development with regard to its chemical composition and the structure and type of its connection to the adhesive layer. At present, thermal insulation is mainly used layer of a zirconium oxide partially or completely stabilized with yttrium oxide.
• Such a thermal barrier coating is produced by atmospheric plasma spraying, in which the relevant properties of the thermal barrier coating are adjusted by setting a defined porosity and a layer-like to micro-segmented structure, and by predominantly mechanical interlocking on a correspondingly porous adhesive layer.
• a thermal barrier coating is produced by a vapor deposition process, in which the thermal barrier coating has an elongation-tolerant columnar crystalline structure and a mainly chemical bond to the correspondingly smooth adhesive layer to be provided. The chemical bonding of the thermal insulation layer to the adhesive layer takes place via a thin oxide layer formed between these layers. This is, if appropriate by means of appropriately formed intermediate connections, firmly connected both to the thermal insulation layer and to the adhesive layer.
• a layer system usually fails because, in addition to the oxidation of the adhesive layer, there are also thermal-mechanical alternating stresses, which can cause cracks to spread in the thermal insulation layer. In the case of a sprayed thermal insulation layer, this ultimately leads to flaking above the boundary between the ceramic and the metal, in the case of a thermal insulation layer separated from the vapor phase to flaking in the oxide layer formed between the actual thermal insulation layer and the adhesive layer. Following the flaking off of the thermal barrier coating, there is an increase in temperature on the surface of the adhesive layer, which in turn leads to rapid oxidation and the resulting rapid degradation of the adhesive layer.
• the invention is based on the object of specifying a product of the type specified in the introduction, in which the use of an advantage which can result from the use of rhenium takes place in an alternative manner.
• a product is provided with a base body consisting of a superalloy and a layer system thereon for protecting the base body against an aggressive hot gas, the layer system having a ceramic thermal insulation layer with an outer surface which can be exposed to the gas, and wherein the thermal barrier coating rests on an intermediate layer which rests on the base body and has the following composition of chemical elements by mass fraction: rhenium 35% to 60%, aluminum 10% to 20
• a special intermediate layer which contains at least a substantial proportion of the rhenium content desired in the layer system.
• the rhenium can be applied precisely where it is of particular interest because of its function as a means of reducing oxidation, namely at a boundary between the ceramic thermal barrier coating and the base body or on lying metallic adhesive layer. Since the intermediate layer can be applied thinly, its mechanical properties, in particular the question of whether it is more ductile or brittle, only play a marginal role.
• the intermediate layer is also comparatively rich in aluminum, optionally also gallium and / or silicon, and thus provides starting elements for forming an oxidic layer between the metallic part of the layer system and the ceramic thermal insulation layer.
• the material of the adhesive layer is preferably supplemented by an active element such as hafnium, yttrium or an element equivalent thereto such as scandium or the rare earth elements, since these elements make a desirable contribution to anchoring the oxidic layer mentioned to the intermediate layer.
• an active element such as hafnium, yttrium or an element equivalent thereto such as scandium or the rare earth elements, since these elements make a desirable contribution to anchoring the oxidic layer mentioned to the intermediate layer.
• a preferred composition for the intermediate layer has the following composition in mass proportions: rhenium 47%; Aluminum 15%;
• the intermediate layer of the product preferably lies on a metallic adhesive layer which consists of an alloy of the MCrAlY type, where M stands for at least one metal from the group comprising iron, cobalt and nickel as the basis of the alloy.
• This alloy also preferably contains additional rhenium, preferably with a mass fraction between 1% and 15%.
• the intermediate layer preferably has a thickness of less than 10 ⁇ m, in particular a thickness of approximately 5 ⁇ m. This ensures that the mechanical properties of the intermediate layer, in particular any brittleness, cannot adversely affect the entire layer system.
• the superalloy forming the base body is furthermore preferably a nickel-based or cobalt-based superalloy, examples of which are the generally known nickel-based superalloy IN738LC and the cobalt-based superalloy MAR-M-509 .
• the intermediate layer of the product is preferably a dispersion of a phase consisting essentially of an intermetallic compound of rhenium and chromium in a metallic matrix.
• the intermetallic compound has in particular the approximate composition Cr 3 Re, for which in particular chromium and rhenium with approximately equal proportions by weight must be present.
• the major part of the aluminum and any other elements which may be present is mainly present in the metallic matrix and is available from this matrix to form the oxide layer between the intermediate layer and the thermal insulation layer.
• the heat insulation layer of the product preferably consists essentially of an at least partially stabilized zirconium oxide, which is stabilized in particular by the addition of yttrium oxide.
• Zirconium oxide is characterized in that its relevant mechanical properties are relatively similar to the corresponding properties of the metals and alloys used.
• the stabilization of the zirconium oxide serves to prevent or at least slow down a phase transition in the structure of the zirconium oxide, which could occur in pure zirconium oxide under appropriate thermal stress.
• the product is preferably designed as a component for a gas turbine, in particular as a rotor blade, guide blade or heat shield. In this context, the product is suitable for use in a gas turbine. This is particularly so because it can withstand a temperature of up to 1000 ° C. and beyond when exposed to an oxidizing and corrosive flue gas, as is usually formed in a stationary gas turbine.
• a method for producing a product with a base body consisting of a superalloy and a layer system thereon for protecting the base body against an aggressive hot gas is provided, an intermediate layer being used to form the layer system is applied to the base body and a ceramic thermal insulation layer is applied to the intermediate layer, the intermediate layer having the following composition of chemical elements according to mass proportions: rhenium 35% to 60%, aluminum 10% to 20%, gallium 0% to 10%, silicon 0% to 2 hafnium 0% to 2%, an active element from the group containing yttrium, scandium and the rare earth elements:
• the intermediate layer is applied by plasma spraying, in particular vacuum plasma spraying or vapor deposition.
• a metallic adhesive layer is preferably first applied to the base body and then the intermediate layer is formed on the adhesive layer.
• a gas turbine component in particular a rotor blade, a guide blade or a heat shield element, with a base body consisting of the super alloy IN738LC is provided with a metallic adhesive layer which has a composition as described in the article cited by N. Czech, F. Schmitz and W. Stamm can be seen and which in particular requires a mass fraction of rhenium in an alloy based on nickel.
• This adhesive layer is applied by means of vacuum plasma spraying and compacted by blasting with glass beads or the like. There is no further surface treatment, especially smoothing.
• the intermediate layer is also applied by vacuum plasma spraying, to a thickness of approximately 5 ⁇ m.
• a ceramic thermal barrier coating made from partially stabilized zirconium oxide is then applied to the intermediate layer, by atmospheric plasma spraying.
• the ceramic thermal barrier coating is anchored to the intermediate layer and the adhesive layer partly by chemical bonding as already described, partly by mechanical bonding to the surface structures of the intermediate layer which remain due to the production.
• An adhesive layer corresponding to the adhesive layer from the present example is applied to a gas turbine component with a base body consisting of the cobalt-based superalloy MAR-M-509 and polished after the application and blasting.
• the intermediate layer is applied to the adhesive layer prepared in this way as described in the previous example, and a ceramic thermal insulation layer made of partially stabilized zirconium oxide is applied to the intermediate layer by physical vapor deposition with electron beam evaporation (EB-PVD).
• EB-PVD electron beam evaporation
• This heat-insulating layer has a columnar crystalline structure and is accordingly very tolerant of thermal expansion, since the columnar-shaped crystallites of the heat-insulating layer can move relatively freely against one another when the metallic structure expands from the base body and the metallic part of the layer system lying thereon. In terms of function, such a layer system is quite preferred over the layer system of the first example; it is due to its elaborate
• the intermediate layer is constructed in two phases; it is in the form of a dispersion of a phase consisting essentially of an intermetallic compound of rhenium and chromium in a metallic matrix.
• the intermetallic compound has the approximate composition Cr 3 Re, and the metallic matrix contains the other chemical besides rhenium and chromium Elements of the composition.
• the intermediate layer does not significantly impair the properties of the entire layer system, since it is very thin and, due to its high rhenium content, does not allow elements to diffuse to a significant extent. Accordingly, it fits easily between the metallic adhesive layer and the ceramic thermal barrier layer. It offers all essential properties in connection with oxidation and corrosion, which the chemical element rhenium can contribute, without further rhenium having to be added to the adhesive layer and possibly impairing its properties.
• the invention thus offers a powerful layer system for protecting a base body, in particular a base body of a gas turbine component, against an aggressive hot gas, at a temperature of 1000 ° C. or more.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Combustion & Propulsion (AREA)
• General Engineering & Computer Science (AREA)
• Metallurgy (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Chemistry (AREA)
• Plasma & Fusion (AREA)
• Physics & Mathematics (AREA)
• Ceramic Engineering (AREA)
• Coating By Spraying Or Casting (AREA)
• Other Surface Treatments For Metallic Materials (AREA)

Applications Claiming Priority (3)

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• 1996
  • 1996-05-30 DE DE19621763A patent/DE19621763A1/de not_active Ceased
• 1997
  • 1997-05-16 JP JP10500074A patent/JP2000511236A/ja active Pending
  • 1997-05-16 EP EP97924892A patent/EP0907765A1/de not_active Ceased
  • 1997-05-16 KR KR1019980709780A patent/KR20000016211A/ko not_active Application Discontinuation
  • 1997-05-16 WO PCT/DE1997/000997 patent/WO1997046734A1/de not_active Application Discontinuation

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