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EP-4735657-A1 - ANTI-HOT-CORROSION COATINGS FOR TURBINE DISCS

EP4735657A1EP 4735657 A1EP4735657 A1EP 4735657A1EP-4735657-A1

Abstract

The present invention relates to the general field of protection against hot corrosion of nickel-based alloys, in particular in the aeronautical sector, in particular for turbine discs. More particularly, it relates to nickel alloy parts, in particular gamma/gamma prime (γ/γ') nickel alloy parts, coated with a nickel-based alloy anti-hot-corrosion coating composition, and to the use thereof in the aeronautical sector, in particular for turbine discs.

Inventors

  • DESGRANGES, Clara
  • KNITTEL, Stéphane
  • MALACARNE, Romain
  • MATHIEU, Stéphane
  • VILASI, Michel
  • SANVIEMVONGSAK, Tom

Assignees

  • Safran
  • Université de Lorraine
  • Centre National de la Recherche Scientifique

Dates

Publication Date
20260506
Application Date
20240619

Claims (11)

  1. 1. Part made of nickel alloy, in particular of gamma/gamma prime (y/f) nickel alloy, coated with a hot anti-corrosion coating composition of nickel-based alloy, characterized in that said composition comprises: - 16 to 18.5% by mass of chromium, - 12 to 25% by mass of iron, - 1 to 5% by mass of titanium, - 1.5 to 5% by mass of aluminum, - 0 to 5% by mass of tungsten, - 0 to 5% by mass of tantalum, - 0 to 1% by mass of niobium, - 0 to 5.5% by mass of molybdenum, relative to the total mass of the composition, and in that the total quantity of tungsten, tantalum and/or niobium, when present in the composition, remains less than 5% by mass, relative to the total mass of the composition, the remainder being constituted by nickel and unavoidable impurities whose total content in the composition is at most 0.5% by mass, relative to the total mass of the composition.
  2. 2. Part according to claim 1, characterized in that the composition comprises 16.8 to 18% by mass of chromium, relative to the total mass of the composition.
  3. 3. Part according to one of claims 1 or 2, characterized in that the composition comprises 18 to 25% by mass of iron, relative to the total mass of the composition.
  4. 4. Part according to any one of claims 1 to 3, characterized in that the composition comprises 1 to 3.5% by mass of titanium, relative to the total mass of the composition.
  5. 5. Part according to any one of claims 1 to 4, characterized in that the composition comprises 2 to 4% by mass of aluminum, relative to the total mass of the composition.
  6. 6. Hot anti-corrosion coating composition of nickel-based alloy, characterized in that it comprises: - 16.8% by mass of chromium, - 18% iron by mass, - 3.5% by mass of titanium, - 2.1% by mass of aluminum, - 5% by mass of molybdenum, relative to the total mass of the composition, the remainder being constituted by nickel and unavoidable impurities whose total content in the composition is at most 0.5% by mass, relative to the total mass of the composition.
  7. 7. Hot-dip anti-corrosion coating composition of nickel-based alloy, characterized in that it comprises: - 18% by mass of chromium, - 25% iron by mass, - 3.5% by mass of titanium, - 2% by mass of aluminum, - 5% by mass of molybdenum, relative to the total mass of the composition, the remainder being constituted by nickel and unavoidable impurities whose total content in the composition is at most 0.5% by mass, relative to the total mass of the composition.
  8. 8. Hot-dip anti-corrosion coating composition of nickel-based alloy, characterized in that it comprises: - 18% by mass of chromium, - 25% iron by mass, - 1% by mass of titanium, - 4% by mass of aluminum, - 5% by mass of molybdenum, relative to the total mass of the composition, the remainder being constituted by nickel and unavoidable impurities whose total content in the composition is at most 0.5% by mass, relative to the total mass of the composition.
  9. 9. Use of a nickel-based alloy coated with a hot anti-corrosion coating composition of nickel-based alloy according to any one of claims 6 to 8, for the manufacture of a part for aeronautical turbines, gas turbines, land and marine turbines.
  10. 10. Part made of nickel alloy, in particular of gamma/gamma prime (y/f) nickel alloy, coated with a hot anti-corrosion coating composition of nickel-based alloy according to any one of claims 6 to 8.
  11. 11. Part according to any one of claims 1 to 5 and 10, characterized in that it is a part of a turbojet, in particular a disk of aeronautical turbines, gas turbines, land and marine turbines.

Description

DESCRIPTION TITLE: HOT ANTI-CORROSION COATINGS FOR TURBINE DISCS Field of invention The present invention relates to the general field of protection against hot corrosion of nickel-based alloys, in particular in the field of aeronautics, in particular for turbine disks. It more particularly targets nickel alloy parts, in particular gamma/gamma prime (y/f) nickel alloy, coated with a hot anti-corrosion coating composition, in particular type II, typically between 600°C and 850°C, of nickel-based alloy, and their application in the field of aeronautics, in particular for turbine disks. Technical background In high and low pressure turbines, forged nickel-based alloys are used for the manufacture of discs. These materials are also used for aeronautical turbine, gas turbine, land and marine turbine applications. For this application, the Inconel 718 alloy (according to AFNOR standard: NC19FeNb) serves as the reference material in terms of mechanical strength and resistance to the operating environment for temperatures up to 650°C. However, improving the performance of the turbine parts requires an increase in temperatures at the combustion chamber outlet and therefore an increase in the temperatures experienced by the turbines, and more particularly by the disks. The mechanical stresses (creep, fatigue, etc.) experienced by the parts in service are also increased. Thus, due to the microstructural instability of Inconel 718 (evolution of the hardening phases y” 5) above 650°C, forged nickel-based alloys with a y/f structure such as TAD730 are used, and preferred for the hottest disk stages. The AD730 alloy developed by Aubert & Duval appears to be a candidate for these hot turbine disk applications. This alloy, however, remains in the same range as others grades of y/f alloys already used for this type of application due to its proximity to their composition and microstructure. These materials operate in hot environments with maximum temperatures ranging from 650 to 750°C, reaching peaks of 800°C over short periods, particularly between 700 and 750°C, and more particularly between 700 and 710°C. They are also exposed to atmospheres containing gaseous sulfur derivatives (SO2(g)/SO3(g)) from the combustion of kerosene and reactions with pollutants ingested by the engine during operation. In addition, it is possible to see the accumulation of pollutant deposits (mainly sand) in the retention areas of the discs. Thus, the combined effect of temperature, atmosphere and pollutant deposits can lead to the initiation of hot corrosion phenomena. Wrought nickel-based alloy materials intended for use such as turbine disks contain chromium in order to harden the y matrix of the material so as to improve the mechanical characteristics but also to allow the development of a protective layer of chromia (C^Os) when exposed to heat. Although relatively loaded with chromium, nickel-based alloys of structure y/y 1 for disks have a lower resistance in comparison with the Inconel 718 alloy despite relatively close chromium contents. The other alloying elements constituting the material therefore have an indirect role on the propensity of the substrate to develop a protective oxide layer via the establishment of an external oxide layer effective against type II hot corrosion. Depending on the operating conditions (temperature, duration of exposure, presence of pollutants), it may however be necessary to coat the turbine discs with nickel-based alloy of structure y/y 1 or y/y” in order to provide them with a protective barrier against the environment. These coatings have the major disadvantage of including chromates in their compositions, which are a species impacted by REACH regulations; The work carried out by Safran aimed at studying the hot behavior of nickel-based alloys with y/y 1 structure for new generation discs such as AD730, has shown that these alloys appear more sensitive to phenomena oxidation and corrosion than Inconel 718 as shown, respectively, in figures [Fig.1] and [Fig.2], New architectures that will incorporate these forged nickel-based alloys of type y/f could be limited by the susceptibility of these alloys to the operating environment in which they will have to endure: - increased mechanical stresses and, consequently, the acceptable threshold for indicating corrosion will have to be reassessed; - higher temperatures, leading to increased kinetics of chemical phenomena. There is therefore a need for new corrosion protection coatings, adapted to future developments in turbines and which are compatible with the REACH regulation with regard to substances derived from hexavalent chromium (Cr vl ). It is therefore necessary to have coatings that limit the appearance of hot corrosion in areas likely to see this phenomenon appear and which would increase the service life of parts in critical areas likely to see corrosion appear. Summary of the invention Nickel alloy part, in particular gamma/gamma prime (y/f) nickel