EP0318724B1 - Verfahren zum chemischen Ablösen einer hochchromhaltigen Oberflächenschutzschicht vom Grundkörper eines aus einer Nickel- oder Kobaltbasis-Superlegierung bestehenden Bauteils - Google Patents

Verfahren zum chemischen Ablösen einer hochchromhaltigen Oberflächenschutzschicht vom Grundkörper eines aus einer Nickel- oder Kobaltbasis-Superlegierung bestehenden Bauteils Download PDF

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Publication number
EP0318724B1
EP0318724B1 EP88118502A EP88118502A EP0318724B1 EP 0318724 B1 EP0318724 B1 EP 0318724B1 EP 88118502 A EP88118502 A EP 88118502A EP 88118502 A EP88118502 A EP 88118502A EP 0318724 B1 EP0318724 B1 EP 0318724B1
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EP
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Prior art keywords
solution
fecl3
cucl2
following composition
nickel
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EP88118502A
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German (de)
English (en)
French (fr)
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EP0318724A1 (de
Inventor
Vladimir Sova
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BBC Brown Boveri AG Switzerland
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BBC Brown Boveri AG Switzerland
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    • 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
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F1/00—Etching metallic material by chemical means
    • C23F1/44—Compositions for etching metallic material from a metallic material substrate of different composition

Definitions

  • the blade is a critical component, with protective layers against erosion, wear, corrosion and oxidation gaining in importance at high temperatures.
  • the protective layer usually has a shorter lifespan than the core material of the blade, which is why the renewability of the former is becoming increasingly important.
  • the invention relates to the further development of methods for repairing, repairing and renewing components of thermal machines which have been rendered unusable by erosion, wear, corrosion, oxidation or mechanical damage and are provided with protective layers.
  • the old existing protective layer must first be removed, which can basically be done mechanically or chemically.
  • the chemical method generally occupies a leading position in the field of surface change by erosion.
  • it relates to a method for chemically detaching a high-chromium surface protection layer from the base body of a component consisting of a nickel or cobalt-based superalloy.
  • a method of the type mentioned in the preamble of claim 1 is known from FR-A-2 349 663.
  • a coating containing aluminum, chromium and cobalt is removed from a substrate based on a nickel-based alloy by immersion in a solution kept at a temperature between 15 and 75 ° C.
  • This solution contains ferric sulfate and hydrochloric acid.
  • the proportion of iron (III) sulfate should preferably be 8 to 10 percent by weight and the proportion of hydrochloric acid should preferably be 7 to 9 percent by weight. With such high hydrochloric acid concentrations, the risk of the substrate being adversely affected, in particular due to corrosion pitting, cannot be ruled out with certainty.
  • US Pat. No. 4,339,282 describes a process for detaching nickel aluminide coatings from a substrate based on a nickel-based superalloy, in which an aqueous, predominantly nitric acid and to a lesser extent hydrochloric acid, and smaller proportions of iron III Solution containing chloride and copper (II) sulfate is used to remove the coating.
  • this solution does not attack the substrate, which also contains chromium, among other things, it is, however, not suitable for dissolving a surface layer containing high chromium.
  • Such a protective layer has a positive potential in relation to the substrate in a strongly oxidizing solution caused by the nitric acid can then not be removed by chemical or electrolytic means without significantly affecting the substrate.
  • solutions which contain nitrobenzenesulfonic acid and Na compounds for the chemical leaching of so-called "aluminum diffusion layers" on blade materials (cf. EP-A-0 161 387).
  • solutions containing iron sulfate and hydrochloric acid are recommended for removing chromium and aluminum-containing protective coatings based on cobalt, the iron sulfate having an oxidizing effect directly or via hydrolysis as sulfuric acid (cf. DE-B-27 17 435).
  • solutions with HNO3 and HF have been used to remove chromium- and aluminum-containing or aluminum-containing protective layers of nickel or cobalt-based alloys with a chromium content of more than 18% (cf. US-A-3 458 353).
  • the known processes using oxidizing solutions are based on the fact that they only weakly attack the core material of the base body, in the present case a nickel or cobalt-based superalloy, if it contains at least 7% by weight Cr.
  • the transition to ever higher Cr contents of the protective layers reverses the ratio of the electrochemical potentials of the core material to that of the protective layer: the protective layer becomes positive with respect to the base body in oxidizing solution.
  • the protective layer cannot be removed electrolytically or electrolessly.
  • the base body is always attacked preferentially, while the protective layer to be removed withstands longer. Therefore, the known methods mentioned above are not applicable to the modern material combinations of high-chromium protective layer / moderately chromium-containing superalloy.
  • the invention is based on the object of specifying a method for detaching a surface protection layer based on a Ni or Co alloy with a high Cr content from the base body of a component which consists of a chromium-containing Ni and / or Co-based alloy.
  • the surface layer should be completely removed without the material of the base body being attacked, removed or damaged or its chemical-physical properties and its behavior with regard to compatibility being impaired or changed, particularly when a surface protective layer is subsequently reapplied (renewed).
  • 1 shows a schematic cross section through the active part of the contents of a vessel for carrying out the method.
  • 1 is the chloride solution for chemical attack
  • 2 the base body (substrate) made of a nickel or cobalt-based superalloy (core material).
  • 3 represents the high-chromium surface protection layer. It can in principle be constructed on a nickel or cobalt basis.
  • 4 are pores in the surface protective layer 3, which have been formed by the chemical attack of the chloride solution 1.
  • 5 is an intermediate diffusion layer between the base body 2 and the surface protective layer 3, which is formed by a heat treatment during manufacture or in operation.
  • the surface protective layer 3 When immersed in the solution 1, the surface protective layer 3 shows a negative potential (indicated by the sign - and +) compared to the base body 2, which is the basis for the currentless selective removal of the former.
  • the mainly present ions H tripod; Fe3+; Cu2+; Cl ⁇
  • the mechanism of the resolution is shown schematically by symbols and arrows.
  • the less noble chrome is preferred in solution (Cr3+), while part of the iron and copper sink to the bottom as sludge (Fe o ; Cr o ), the rest remains in solution in the form of low valences (Fe2+; Cu+).
  • FIG. 2 shows a schematic metallographic section through the grain structure of the surface protection layer.
  • 6 are grains of the high-chromium surface protection layer 3 based on nickel or cobalt, which generally contain Al and Si in addition to Cr. At least part of the surface of the grains 6 is coated with a Cr2O3 cover layer, which has a passivating effect.
  • the mainly effective reaction mechanisms are indicated by arrows and symbols.
  • the invention is based on the selective dissolution of metals, characterized by different electrochemical potentials, which are immersed in an aggressive chemical solution. As a rule, the less noble elemental metal displaces the more noble from the solution and thereby goes into solution itself.
  • the general reaction scheme is as follows: Me + Fe3+ ⁇ Me+ + Fe2+ Me+ + Fe3+ ⁇ Me2+ + Fe2+ Me + Cu2+ ⁇ Me+ + Cu+ Me+ + Cu2+ ⁇ Me2+ + Cu+
  • the used scoop was cleaned by first immersing it in a 20% solution of NaOH at 100 ° C. for 24 h. The paddle was then removed from the solution, rinsed and immersed in concentrated HCl at 40 ° C for 24 hours. Finally, the shovel was rinsed and brushed with a steel brush.
  • the shovel was left in this bath for 15 hours, then removed, rinsed and brushed. No damage to the core material due to chemical attack was found.
  • a gas turbine blade provided with a surface protection layer and irregularly worn along the entire length of the airfoil was treated according to the currentless method according to Example 1.
  • the airfoil had the same dimensions and the core material (MA 6000) the same composition as in Example 1.
  • the surface layer of 120 ⁇ m thick had been applied to the core material by plasma spraying and had the same composition as in Example 1.
  • the used blade was cleaned according to Example 1 by immersion in NaOH and HCl solution and treatment with a steel brush.
  • the bath had a temperature of 50 ° C. After a reaction time of 14 hours, the scoop was removed from the bath, rinsed, brushed and dried. The surface layer had been completely dissolved without attacking the substrate.
  • the partially corroded blade was cleaned according to Example 1 and then placed in a solution of the following composition: 200 g / l FeCl3 ⁇ 6H2O 1 g / l CuCl2 ⁇ 2H2O 10 ml / l glycerin 30 ml / l concentrated HCl rest H2O
  • the bath had a temperature of 70 ° C.
  • the treated gas turbine blade was removed from the bath after a reaction time of 144 hours, rinsed, brushed and dried. After the surface protective layer had completely dissolved, no attack on the core material could be determined.
  • a gas turbine blade provided with a surface protection layer and irregularly corroded along the entire length of the airfoil was treated in a manner similar to Example 1 using the currentless method.
  • the airfoil had the same dimensions and the core material (IN 738) the same composition as in Example 3.
  • the surface protective layer was on average 150 ⁇ m thick and was previously applied to the core material by plasma spraying. It had the same composition as that of Example 3.
  • the used scoop was cleaned according to Example 1 and then immersed in a solution of the following composition: 300 g / l FeCl3 ⁇ 6H2O 2 g / l CuCl2 ⁇ 2H2O 20 ml / l concentrated HCl rest H2O
  • the bath had a temperature of 60 ° C. After a reaction time of 120 hours, the blade was removed from the solution, rinsed, brushed and dried. When the surface protective layer was completely dissolved, no attack on the core material could be determined.
  • the bath temperature was 60 ° C, the total reaction time 1 h.
  • the core material remained unaffected after the treatment.
  • a corroded gas turbine blade provided with a surface protection view and irregular over the entire length of the airfoil was treated in the same way as in Example 1 by the currentless method.
  • the airfoil had the same dimensions and the core material (IN 738) the same composition as in Example 3.
  • the surface protection view was on average 120 ⁇ m thick and was previously applied to the core material by plasma spraying. It had the same composition as that of Example 3.
  • the used scoop was cleaned according to example 1 and then immersed in a solution of the following composition: 250 g / l FeCl3 ⁇ 6H2O 1 g / l CuCl2 ⁇ 2H2O 100 g / l NaCl 200 g / l citric acid rest H2O
  • the bath had a temperature of 65 ° C. After a reaction time of 100 h, the scoop was removed from the solution, rinsed, brushed and dried. When the surface protection view was completely dissolved, no attack on the core material could be determined.
  • the bath temperature was 60 ° C, the total reaction time 1 h.
  • the core material remained unaffected after the treatment.
  • the invention is not limited to the exemplary embodiments.
  • the electroless chemical detachment of a high-chromium surface protection view from a nickel or cobalt-based superalloy is achieved by immersing the component in question in an aqueous chloride solution containing non-oxygen, containing iron III and copper II, which also contains other additives however no constituents forming chromium oxide contains, valued for a period of 1 h to 150 h at a temperature of 50 to 70 ° C.
  • the chloride solution advantageously has the composition: 200 - 400 g / l FeCl3 ⁇ 6H2O 0.5 - 5 g / l CuCl2 ⁇ 2H2O 10 - 20 ml / l glycerin 120-200 ml / l concentrated HCl rest H2O

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • ing And Chemical Polishing (AREA)
  • Chemically Coating (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
EP88118502A 1987-12-01 1988-11-07 Verfahren zum chemischen Ablösen einer hochchromhaltigen Oberflächenschutzschicht vom Grundkörper eines aus einer Nickel- oder Kobaltbasis-Superlegierung bestehenden Bauteils Expired - Lifetime EP0318724B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH4675/87 1987-12-01
CH4675/87A CH674851A5 (enrdf_load_stackoverflow) 1987-12-01 1987-12-01

Publications (2)

Publication Number Publication Date
EP0318724A1 EP0318724A1 (de) 1989-06-07
EP0318724B1 true EP0318724B1 (de) 1993-03-24

Family

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Application Number Title Priority Date Filing Date
EP88118502A Expired - Lifetime EP0318724B1 (de) 1987-12-01 1988-11-07 Verfahren zum chemischen Ablösen einer hochchromhaltigen Oberflächenschutzschicht vom Grundkörper eines aus einer Nickel- oder Kobaltbasis-Superlegierung bestehenden Bauteils

Country Status (5)

Country Link
US (1) US4944807A (enrdf_load_stackoverflow)
EP (1) EP0318724B1 (enrdf_load_stackoverflow)
JP (1) JPH01195290A (enrdf_load_stackoverflow)
CH (1) CH674851A5 (enrdf_load_stackoverflow)
DE (1) DE3879634D1 (enrdf_load_stackoverflow)

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07122152B2 (ja) * 1990-06-19 1995-12-25 日本パーカライジング株式会社 アルミニウム用酸性洗浄液
US5034093A (en) * 1990-09-25 1991-07-23 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Metal etching composition
DE4120305C1 (enrdf_load_stackoverflow) * 1991-06-20 1992-08-27 Mtu Muenchen Gmbh
FR2695142B1 (fr) * 1992-08-27 1994-11-04 Europ Gas Turbines Sa Revêtement anti-usure au cobalt d'une pièce en alliage de nickel.
US6454870B1 (en) 2001-11-26 2002-09-24 General Electric Co. Chemical removal of a chromium oxide coating from an article
US6699101B2 (en) * 2001-11-29 2004-03-02 General Electric Company Method for removing a damaged substrate region beneath a coating
ITPD20040106A1 (it) * 2004-04-27 2004-07-27 Birame Boye Demetallizzazione ecocompatibile di oggetti plastici cromati ed estensione a substrati metallici passivabili
US6878215B1 (en) 2004-05-27 2005-04-12 General Electric Company Chemical removal of a metal oxide coating from a superalloy article
EP2166125A1 (en) 2008-09-19 2010-03-24 ALSTOM Technology Ltd Method for the restoration of a metallic coating
US8859479B2 (en) * 2011-08-26 2014-10-14 United Technologies Corporation Chemical stripping composition and method
JP6508823B2 (ja) * 2015-05-08 2019-05-08 三菱重工航空エンジン株式会社 酸化膜除去方法
CN107099799A (zh) * 2017-03-31 2017-08-29 李世华 一种氯化铜蚀刻液及其制备方法
CN111188042A (zh) * 2020-01-14 2020-05-22 东莞市美贝仕铜材处理剂开发有限公司 一种铜材抛光预处理液、其制备方法及使用方法
CN111139487A (zh) * 2020-01-14 2020-05-12 东莞市美贝仕铜材处理剂开发有限公司 一种铜材抛光预处理液、其制备方法及使用方法
CN112881139B (zh) * 2021-01-25 2022-08-23 河北工业大学 一种因瓦合金腐蚀液及其应用

Family Cites Families (13)

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Publication number Priority date Publication date Assignee Title
US3458353A (en) * 1966-11-16 1969-07-29 Alloy Surfaces Co Inc Process of removing coatings from nickel and cobalt base refractory alloys
US3562040A (en) * 1967-05-03 1971-02-09 Itt Method of uniformally and rapidly etching nichrome
US3622391A (en) * 1969-04-04 1971-11-23 Alloy Surfaces Co Inc Process of stripping aluminide coating from cobalt and nickel base alloys
US3607398A (en) * 1969-06-18 1971-09-21 Avco Corp Chemical stripping process
US3833414A (en) * 1972-09-05 1974-09-03 Gen Electric Aluminide coating removal method
ES427394A1 (es) * 1973-06-18 1977-02-01 Oxy Metal Industries Corp Mejoras introducidas en un metodo de decapado de depositos de niquel acumulados en los dispositivos de metalizado y si-milares.
GB1521783A (en) * 1976-04-27 1978-08-16 Rolls Royce Method of and mixture for alloy coating removal
US4244833A (en) * 1979-11-15 1981-01-13 Oxy Metal Industries Corporation Composition and process for chemically stripping metallic deposits
US4339282A (en) * 1981-06-03 1982-07-13 United Technologies Corporation Method and composition for removing aluminide coatings from nickel superalloys
SE8206447L (sv) * 1981-11-24 1983-05-25 Occidental Chem Co Avmetalliseringskomposition och -forfarande
US4425185A (en) * 1982-03-18 1984-01-10 United Technologies Corporation Method and composition for removing nickel aluminide coatings from nickel superalloys
US4554049A (en) * 1984-06-07 1985-11-19 Enthone, Incorporated Selective nickel stripping compositions and method of stripping
DE3567626D1 (en) * 1984-10-26 1989-02-23 Umwelt & Hygienetechnik Solution process and solvent for hardly soluble carbonates

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Publication number Publication date
US4944807A (en) 1990-07-31
JPH01195290A (ja) 1989-08-07
DE3879634D1 (de) 1993-04-29
EP0318724A1 (de) 1989-06-07
CH674851A5 (enrdf_load_stackoverflow) 1990-07-31

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