EP0161387A2 - Process for chemically stripping diffused aluminium coatings, and its use - Google Patents

Process for chemically stripping diffused aluminium coatings, and its use Download PDF

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Publication number
EP0161387A2
EP0161387A2 EP85100926A EP85100926A EP0161387A2 EP 0161387 A2 EP0161387 A2 EP 0161387A2 EP 85100926 A EP85100926 A EP 85100926A EP 85100926 A EP85100926 A EP 85100926A EP 0161387 A2 EP0161387 A2 EP 0161387A2
Authority
EP
European Patent Office
Prior art keywords
diffusion layers
aluminum diffusion
chemical removal
sodium
aqueous solution
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP85100926A
Other languages
German (de)
French (fr)
Other versions
EP0161387A3 (en
Inventor
Manfred Hirschmeier
Josef Kreitl
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
MTU Aero Engines GmbH
Original Assignee
MTU Motoren und Turbinen Union Muenchen GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by MTU Motoren und Turbinen Union Muenchen GmbH filed Critical MTU Motoren und Turbinen Union Muenchen GmbH
Publication of EP0161387A2 publication Critical patent/EP0161387A2/en
Publication of EP0161387A3 publication Critical patent/EP0161387A3/en
Withdrawn legal-status Critical Current

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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
    • 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 invention relates to a method for the ' chemical removal of aluminum diffusion layers on workpieces, in particular those which have already been shaped, such as blades of turbomachines.
  • the agents used for the treatment consist of nitric acid 370-470 g / 1 and phosphoric acid 620-720 g / l.
  • the object of the invention is to provide a method for removing aluminum diffusion layers which is simple and economical to use and in which the risk that the base material is attacked or damaged is eliminated or substantially reduced.
  • the main advantage of the invention can be seen in the fact that after a single treatment, a conventional aluminum diffusion layer could be completely removed from a workpiece. The time was just under an hour and the process could be carried out at 45 ° C.
  • a bath is made up of about 50 kg of nitrobenzenesulfonic acid, about between 100 and 150 kg of sodium cyanide and only about 1/10 of this amount of sodium hydroxide, the rest of water per 1000 liters. or kg.
  • the shaped workpieces here blades of compressors or turbines of a gas turbine aircraft engine, with base material made of superalloy, steel alloy, nickel-iron alloy, titanium and other alloys are coated with an aluminum diffusion layer in a thickness from the micrometer to the mm range.
  • the layer was completely removed. If a cover is required at all, covering the blade root with wax is sufficient or rubber mask which is easy to remove after the melting process.

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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)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

Verfahren zum chemischen Abtragen von Aluminiumdiffusionsschichten auf Werkstücken unter Verwendung einer Nitrobenzolsulfonsäure in wäßriger Lösung, bevorzugt zusammen mit anderen, an sich bekannten Bestandteilen wie Natriumverbindungen. Anwendung insbesondere bei der Herstellung von Schaufeln für Verdichter und Turbinen.Process for the chemical removal of aluminum diffusion layers on workpieces using a nitrobenzenesulfonic acid in aqueous solution, preferably together with other components known per se, such as sodium compounds. Application particularly in the manufacture of blades for compressors and turbines.

Description

Die Erfindung betrifft ein Verfahren zum 'chemischen Abtragen von Aluminiumdiffusionsschichten auf Werkstücken insbesondere solchen die ihre Formgebung bereits hinter sich haben, wie z.B. Schaufeln von Strömungsmaschinen.The invention relates to a method for the ' chemical removal of aluminum diffusion layers on workpieces, in particular those which have already been shaped, such as blades of turbomachines.

Bekannte Verfahren zum chemischen Abtragen von Aluminiumdiffusionsschichten sind häufig recht aufwendig erfordern eine hohe Temperatur des Bades (z.B. 750C und mehr) und eine lange Behandlungsdauer in mehreren Stufen zwischen denen auch Zwischenarbeitsgänge wie Abstrahlen (nass) erforderlich sind. Zum Schluß muß noch ein Abdecklack entfernt werden. In der Regel bestehen die für die Behandlung verwendeten Mittel aus Salpetersäure 370-470 g/1 und Phosphorsäure 620-720 g/l.Known processes for the chemical removal of aluminum diffusion layers are often quite complex and require a high bath temperature (for example 75 ° C. and more) and a long treatment time in several stages between which intermediate steps such as blasting (wet) are also required. Finally, a covering varnish has to be removed. As a rule, the agents used for the treatment consist of nitric acid 370-470 g / 1 and phosphoric acid 620-720 g / l.

Durch das mehrmalige Behandeln ist die Gefahr nicht auszuschließen, daß der Grundwerkstoff eines geformten Werkstücks angegriffen und beschädigt wird. Außerdem ist das genannte Verfahren wegen des erheblichen Arbeits-und Materialaufwands relativ unwirtschaftlich.Repeated treatment means that there is a risk that the base material of a shaped workpiece will be attacked and damaged. In addition, the method mentioned is relatively uneconomical because of the considerable labor and material involved.

Aufgabe der Erfindung ist es ein Verfahren zum Abtragen von Aluminiumdiffusionsschichten anzugeben, das einfach und wirtschaftlich anzuwenden ist und bei dem die Gefahr daß der Grundwerkstoff angegriffen oder beschädigt wird beseitigt bzw. wesentlich verringert wird.The object of the invention is to provide a method for removing aluminum diffusion layers which is simple and economical to use and in which the risk that the base material is attacked or damaged is eliminated or substantially reduced.

Gelöst wird diese Aufgabe durch das im Hauptanspruch angegebene Verfahren. Weitere Merkmale er Erfindung sind in den Unteransprüchen, in der Verwendung von Nitrobenzolsulfonsäure und in der Anwendung des Verfahrens zu sehen.This problem is solved by the method specified in the main claim. Further features of the invention can be seen in the subclaims, in the use of nitrobenzenesulfonic acid and in the application of the method.

Der wesentliche Vorteil der Erfindung ist darin zu sehen, daß bereits nach einmaliger Behandlung eine übliche Aluminiumdiffusionsschicht von einem Werkstück vollständig entfernt werden konnte. Die Zeitdauer betrug etwas- unter einer Stunde und das Verfahren konnte bei 45°C durchgeführt werden.The main advantage of the invention can be seen in the fact that after a single treatment, a conventional aluminum diffusion layer could be completely removed from a workpiece. The time was just under an hour and the process could be carried out at 45 ° C.

Für das chemische Abtragen wird ein Bad angesetzt aus etwa 50 kg Nitrobenzolsulfonsäure, etwa zwischen 100 und 150 kg Natriumcyanid und nur etwa 1/10 dieser Menge an Natriumhydroxid, Rest Wasser auf 1000 ltr. bzw. kg.For the chemical removal, a bath is made up of about 50 kg of nitrobenzenesulfonic acid, about between 100 and 150 kg of sodium cyanide and only about 1/10 of this amount of sodium hydroxide, the rest of water per 1000 liters. or kg.

Die geformten Werkstücke, hier Laufschaufeln von Verdichtern oder Turbinen-eines Gasturbinenflugtriebwerks, mit Grundwerkstoff aus Superlegierung, Stahllegierung, Nickel-Eisen-Legierung, Titan- u.a. Legierungen sind mit einer Aluminiumdiffusionsschicht in einer Stärke vom Mikrometerbereich bis mm-Bereich überzogen. Nach Eintauchen in das angesetzte Bad, mit obigen Bestandteilen, bei einer Temperatur geringer als 50°C und einer Zeitdauer von je nach Schichtdicke etwa einer Stunde, war die Schicht vollständig entfernt. Wenn überhaupt eine Abdeckung erforderlich ist genügt eine Abdeckung des Schaufelfußes mit Wachs oder Gummimaske was leicht nach dem Ausschmelzverfahren zu entfernen ist.The shaped workpieces, here blades of compressors or turbines of a gas turbine aircraft engine, with base material made of superalloy, steel alloy, nickel-iron alloy, titanium and other alloys are coated with an aluminum diffusion layer in a thickness from the micrometer to the mm range. After immersion in the prepared bath, with the above components, at a temperature lower than 50 ° C. and for a period of time of about one hour depending on the layer thickness, the layer was completely removed. If a cover is required at all, covering the blade root with wax is sufficient or rubber mask which is easy to remove after the melting process.

Abwandlungen der Erfindungen können im Rahmen der Ansprüche durchgeführt werden ohne hierdurch die Erfindung zu verlassen. Zur Erfindung gehören ausdrücklich alle Kombinationen und Unterkombinationen der beanspruchten und beschriebenen Merkmale sowohl untereinander als auch mit an sich bekannten Merkmalen. Die Erfindung ist nicht auf die beschriebene Anwendung beschränkt. Das Verfahren ist auch zum Entfernen anderer aluminiumhaltiger Spritzschichten geeignet.Modifications of the inventions can be carried out within the scope of the claims without thereby leaving the invention. The invention expressly includes all combinations and subcombinations of the claimed and described features both with one another and with features known per se. The invention is not restricted to the application described. The process is also suitable for the removal of other aluminum-containing spray layers.

Claims (6)

1. Verfahren zum chemischen Abtragen von Aluminiumdiffusionsschichten auf Werkstücken durch Behandeln derselben mittels nitrobenzolsulfonsäure-, natriumcyanid-und natriumhydroxidhaltiger wässriger Lösung.1. Process for the chemical removal of aluminum diffusion layers on workpieces by treating them with an aqueous solution containing nitrobenzenesulfonic acid, sodium cyanide and sodium hydroxide. 2. Verfahren zum chemischen Abtragen von Aluminiumdiffusionsschichten nach Anspruch 1, dadurch gekennzeichnet, daß die Behandlung etwa 30 bis 90 Minuten bei einer Temperatur von etwa 500 oder darunter erfolgt2. A method for the chemical removal of aluminum diffusion layers according to claim 1, characterized in that the treatment is carried out for about 30 to 90 minutes at a temperature of about 50 0 or below 3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das Natriumcyanid den Hauptbestandteil der Lösung ausmacht, das Natriumhydroxid etwa 1/10 des ersteren und die Säure weniger als die Hälfte des ersteren.3. The method according to claim 1, characterized in that the sodium cyanide is the main component of the solution, the sodium hydroxide about 1/10 of the former and the acid less than half of the former. 4. Verwendung von Nitrobenzolsulfonsäure zusammen mit an sich bekannten Natriumverbindungen in wässriger Lösung zum chemischen Abtragen von Aluminiumdiffusionsschichten auf Formkörpern.4. Use of nitrobenzenesulfonic acid together with sodium compounds known per se in aqueous solution for the chemical removal of aluminum diffusion layers on moldings. 5. Verwendung des Verfahrens nach einem der Ansprüche 1 bis 3 bei der Herstellung von Verdichter- oder Turbinenschaufeln in Gasturbinenanlagen bzw. -triebwerken.5. Use of the method according to one of claims 1 to 3 in the manufacture of compressor or turbine blades in gas turbine systems or engines. 6. Abdecken der Schaufelfüße mit Wachs oder Gummimaske bei einem Verfahren nach Anspruch 5.6. Covering the blade feet with wax or rubber mask in a method according to claim 5.
EP85100926A 1984-04-16 1985-01-30 Process for chemically stripping diffused aluminium coatings, and its use Withdrawn EP0161387A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3414383 1984-04-16
DE3414383A DE3414383C2 (en) 1984-04-16 1984-04-16 Process for the chemical removal of aluminum diffusion layers

Publications (2)

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EP0161387A2 true EP0161387A2 (en) 1985-11-21
EP0161387A3 EP0161387A3 (en) 1987-05-27

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EP85100926A Withdrawn EP0161387A3 (en) 1984-04-16 1985-01-30 Process for chemically stripping diffused aluminium coatings, and its use

Country Status (4)

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US (1) US4619707A (en)
EP (1) EP0161387A3 (en)
JP (1) JPS60224792A (en)
DE (1) DE3414383C2 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992019792A1 (en) * 1991-04-24 1992-11-12 Kernforschungszentrum Karlsruhe Gmbh Etching solution
EP1050604A1 (en) * 1999-05-03 2000-11-08 General Electric Company Method for removing an aluminide coating from a substrate

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01184282A (en) * 1988-01-14 1989-07-21 Nishiyama Stainless Chem Kk Masking agent
US5232619A (en) * 1990-10-19 1993-08-03 Praxair S.T. Technology, Inc. Stripping solution for stripping compounds of titanium from base metals
US6042879A (en) * 1997-07-02 2000-03-28 United Technologies Corporation Method for preparing an apertured article to be recoated
US6305077B1 (en) * 1999-11-18 2001-10-23 General Electric Company Repair of coated turbine components
US10125425B2 (en) 2013-07-01 2018-11-13 General Electric Company Method for smut removal during stripping of coating
KR101539010B1 (en) * 2013-12-27 2015-07-24 한국원자력연구원 Method for etching of super alloy and the super alloy thereby

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2649361A (en) * 1949-05-13 1953-08-18 Enthone Method of dissolving metals and compostion therefor
US3095380A (en) * 1958-07-14 1963-06-25 Purex Corp Ltd Composition for removal of heat scale and carbon deposits
FR2198004A1 (en) * 1972-09-05 1974-03-29 Gen Electric
US4282041A (en) * 1978-12-05 1981-08-04 Rolls-Royce Limited Method for removing aluminide coatings from nickel or cobalt base alloys

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3356550A (en) * 1964-03-16 1967-12-05 Boeing Co Chemical milling of aluminum alloys
US3300349A (en) * 1964-04-15 1967-01-24 Boeing Co Chemical milling process and related solutions for aluminum

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2649361A (en) * 1949-05-13 1953-08-18 Enthone Method of dissolving metals and compostion therefor
US3095380A (en) * 1958-07-14 1963-06-25 Purex Corp Ltd Composition for removal of heat scale and carbon deposits
FR2198004A1 (en) * 1972-09-05 1974-03-29 Gen Electric
US4282041A (en) * 1978-12-05 1981-08-04 Rolls-Royce Limited Method for removing aluminide coatings from nickel or cobalt base alloys

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992019792A1 (en) * 1991-04-24 1992-11-12 Kernforschungszentrum Karlsruhe Gmbh Etching solution
US5462640A (en) * 1991-04-24 1995-10-31 Kernforschungszentrum Karlsruhe Gmbh Etching solution
US6494960B1 (en) 1998-04-27 2002-12-17 General Electric Company Method for removing an aluminide coating from a substrate
EP1050604A1 (en) * 1999-05-03 2000-11-08 General Electric Company Method for removing an aluminide coating from a substrate
SG91274A1 (en) * 1999-05-03 2002-09-17 Gen Electric Method for removing an aluminide coating from a substrate

Also Published As

Publication number Publication date
JPS60224792A (en) 1985-11-09
EP0161387A3 (en) 1987-05-27
US4619707A (en) 1986-10-28
DE3414383A1 (en) 1985-10-17
JPS6345462B2 (en) 1988-09-09
DE3414383C2 (en) 1986-09-04

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