Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/03—Alloys based on nickel or cobalt based on nickel
  • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
  • C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
  • C22C19/055—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 20% but less than 30%
• • 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
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12861—Group VIII or IB metal-base component
  • Y10T428/12937—Co- or Ni-base component next to Fe-base component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12861—Group VIII or IB metal-base component
  • Y10T428/12944—Ni-base component

Definitions

• the invention relates to a high-temperature protective layer according to the preamble of claim 1.
• Such high-temperature protective layers are used above all where the base material of components made of heat-resistant steels and / or alloys that are used at temperatures above 600 ° C is to be protected.
• high-temperature protective layers are to slow down or completely prevent the action of high-temperature corrosion, especially of sulfur, oil ash, oxygen, alkaline earths and vanadium.
• Such high-temperature protective layers are designed so that they can be applied directly to the base material of the component to be protected.
• High-temperature protective layers are of particular importance for components of gas turbines. They are mainly applied to rotor blades and guide vanes as well as to heat accumulation segments in gas turbines.
• An austenitic material based on nickel, cobalt or iron is preferably used to manufacture these components.
• nickel superalloys in particular are used as the base material.
• Such high-temperature protective layers have a matrix in which an aluminum-containing phase is embedded. If a component that is provided with such a high-temperature protective layer is treated at an operating temperature of more than 950 ° C., the aluminum contained in the phase begins to diffuse to the surface, where an aluminum oxide cover layer is formed.
• This cover layer does not have particularly good adhesion, and is therefore worn away over time by the action of corrosion, so that the protection for the high-temperature protective layer that is automatically created as a result is lost.
• the invention is therefore based on the object of providing a high-temperature protective layer which adheres firmly itself and also has a firmly adhering and durable top layer.
• the protective layer according to the invention is an oxide dispersion hardened alloy. It shows a significant improvement in oxide resistance compared to the already known high-temperature protective layers.
• the high-temperature protective layer according to the invention it should be noted that it also has aluminum-containing phases which enable the formation of an aluminum oxide-containing cover layer. If zirconium and silicon are added to the base material that forms the high-temperature protective layer, an additional aluminum-nickel-chromium-oxide layer is formed on the aluminum oxide-containing cover layer, which significantly increases the protection of the high-temperature protective layer and the component underneath. With the addition of silicon and tantalum, the formation of an aluminum oxide cover layer can also be achieved.
• the high-temperature protective layer according to the invention produced with one or the other additive experiences a considerably better adhesive strength on the components than known layers of this type. This also applies to its cover layers.
• the firm and permanent adhesion of the protective layer and its cover layer is achieved by the percentage of yttrium specified for the alloy.
• the addition of yttrium and hafnium has been found to achieve particularly good adhesion of the layers. It has also been shown that good adhesion can also be achieved by hafnium alone when exposed to certain pollutants.
• yttrium in quantities of 0.2 to 2 % By weight, the rate of oxidation on the surface of the high-temperature protection layer is reduced to an unprecedented degree. This effect is even somewhat enhanced by the addition of hafnium.
• the high-temperature protective layer according to the invention is formed by an alloy which contains chromium, aluminum, nickel, yttrium, silicon and zirconium.
• ytrium yttrium and hafnium or hafnium alone can also be used.
• a preferred composition of this alloy has 25 to 27% by weight of chromium, 4 to 7% by weight of aluminum, 0.2 to 2% by weight of yttrium, 1 to 3% by weight of silicon, and 1 to 2% by weight of zirconium, the remaining part of the alloy being formed by nickel.
• the 0.2 to 2% by weight of ytrrium can also be replaced by 0.2 to 2% by weight of yttrium and hafnium or by 0.2 to 2% by weight of hafnium.
• a high temperature protective layer with the same properties is achieved by using an alloy containing chromium, aluminum, yttrium, nickel, silicon and tantalum.
• the yttrium content can be replaced by yttrium and hafnium or hafnium alone.
• An alloy is preferably used which contains 23 to 27 wt.% Chromium, 3 to 5 wt.% Aluminum, 0.2 to 2 wt.% Yttrium, 1 to 2.5 wt.% Silicon, 1 to 3 wt.% Tantalum contains, the remaining part of the alloy consists of nickel.
• the 0.2 to 2% by weight of yttrium can also be replaced by 0.2 to 2% by weight of yttrium and hafnium or by 0.2 to 2% by weight of hafnium. All weights refer to the total weight of the respective alloy.
• All the alloys described here are used in the same way for the formation of a high temperature Suitable protective layer. Regardless of which of the alloys described above, they are formed in any case under operating conditions on these protective layers of aluminum oxide cover layers, which form equally quickly and equally with each of the alloy compositions according to the invention, and which also at temperatures greater than 950 ° C are not removed.
• the invention is explained in more detail using an exemplary embodiment which describes the production of a coated gas turbine component.
• the gas turbine component to be coated is made of an austenitic material, in particular a nickel superalloy. Before coating, the component is first chemically cleaned and then roughened with a sandblast. The component is coated under vacuum using plasma spraying. An alloy is used for the coating, the 25 to 27 wt.% Chromium, 4 to 7 wt.% Aluminum, 0.2 to 2 wt.% Yttrium, 1 to 3 wt.% Silicon, 1 to 2 wt.% Zirconium having. The rest of the alloy consists of nickel.
• the 0.2 to 2% by weight of yttrium can also be replaced by 0.2 to 2% by weight of yttrium and hafnium or by 0.2 to 2% by weight of hafnium.
• an alloy can also be used which contains 23 to 27% by weight of chromium, 3 to 5% by weight of aluminum, 0.2 to 2% by weight of yttrium, 1 to 2.5% by weight of silicon, 0.1 up to 3% by weight of tantalum, the remainder of the alloy being nickel.
• the 0.2 to 2% by weight of yttrium can also be replaced by 0.2 to 2% by weight of yttrium and hafnium or by the same amount of hafnium alone. All weight figures refer to the total weight of the alloy used.
• the material forming the alloy is in powder form and preferably has a grain size of 45 ⁇ m.
• the component is heated to 800 ° C. using the plasma.
• the alloy is applied directly to the base material of the component.
• Argon and hydrogen are used as the plasma gas.
• the component is subjected to a heat treatment. This takes place in a high vacuum annealing furnace. A pressure of less than 5x10 ⁇ 3 Torr is maintained in it. After reaching the vacuum, the furnace is heated to a temperature of 1100 ° C. The above temperature is held for about 1 hour with a tolerance of about +/- 4 ° C. The heating of the furnace is then switched off.
• the coated and heat-treated component is slowly cooled in the oven. Its production is finished after cooling. All alloy variants are applied in the same way.

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

Applications Claiming Priority (2)

Publications (2)

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Citations (8)

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• 1987
  • 1987-11-28 DE DE3740478A patent/DE3740478C1/de not_active Expired
• 1988
  • 1988-11-22 DE DE8888119394T patent/DE3882024D1/de not_active Expired - Lifetime
  • 1988-11-22 EP EP88119394A patent/EP0318803B1/fr not_active Expired - Lifetime
  • 1988-11-28 US US07/276,881 patent/US4973445A/en not_active Expired - Lifetime

Patent Citations (8)

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