EP2679705A1 - Elektrolytisches Ablösen - Google Patents

Elektrolytisches Ablösen Download PDF

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Publication number
EP2679705A1
EP2679705A1 EP12174048.4A EP12174048A EP2679705A1 EP 2679705 A1 EP2679705 A1 EP 2679705A1 EP 12174048 A EP12174048 A EP 12174048A EP 2679705 A1 EP2679705 A1 EP 2679705A1
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EP
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Prior art keywords
test sample
stripping
polarisation
corrosion
oxidation resistant
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.)
Granted
Application number
EP12174048.4A
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English (en)
French (fr)
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EP2679705B1 (de
Inventor
Billy Power
Fernando Pedraza Diaz
Baptiste Bouchaud
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.)
La Rochelle Universite
SR Technics Airfoil Services Ltd
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La Rochelle Universite
SR Technics Airfoil Services Ltd
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Publication date
Application filed by La Rochelle Universite, SR Technics Airfoil Services Ltd filed Critical La Rochelle Universite
Priority to EP20120174048 priority Critical patent/EP2679705B1/de
Priority to PCT/EP2013/063743 priority patent/WO2014001555A1/en
Publication of EP2679705A1 publication Critical patent/EP2679705A1/de
Application granted granted Critical
Publication of EP2679705B1 publication Critical patent/EP2679705B1/de
Not-in-force legal-status Critical Current
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling
    • C25F1/02—Pickling; Descaling
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F5/00—Electrolytic stripping of metallic layers or coatings

Definitions

  • the present invention is directed to an improved electrolytic stripping method.
  • turbine components operate at high pressure and temperature in an extreme corrosive environment and are thus subjected to both high thermal and mechanical stresses.
  • turbine components have to be made from specifically-designed materials such as superalloys.
  • these turbine components must also be coated, hence increasing their lifetime in service by forming a protective oxide scale on the surface.
  • the coatings are generally based on diffusion coatings (mostly aluminium diffusion coatings, including pure and modified aluminides) or overlays coatings (MCrAlY) as oxidation resistant coatings or as bondcoat layers for full Thermal Barrier Coatings (TBC) systems.
  • diffusion coatings mostly aluminium diffusion coatings, including pure and modified aluminides
  • MrAlY overlays coatings
  • TBC Thermal Barrier Coatings
  • the repair process involves various steps, including stripping of the old coating and deposition of a new one in the affected area.
  • stripping of old coatings from these components prior to the subsequent repair step is generally carried out using chemical baths to remove (a) the corrosion products, usually an oxide scale, and (b) the damaged coating layers.
  • the components are immersed in baths, containing mineral acid solutions comprising Hydrochloric Acid (HCl), Nitric Acid (HNO 3 ), Sulphamic Acid (H 3 NSO 3 ), Phosphoric Acid (H 3 PO 4 ) and alkaline solutions mainly based on Sodium Hydroxide (NaOH).
  • stripping solutions are toxic and harmful and waste from these processes must be properly treated and/or disposed of. Additionally, many of the solutions require high temperatures to operate, thus, entailing evaporation issues and requiring additional exhausting systems and safety as well as handling precautions while also raising energy costs.
  • electrochemical approaches may also be adopted.
  • US 2,840,521 (1958 ) is directed to the use of electrolytic stripping by applying current density (i.e. galvanostatic mode) to remove metal coatings from aluminium immersed in diluted sulphuric acid H 2 SO 4 .
  • Current density i.e. galvanostatic mode
  • Water mixtures of fluoroboric acid (HBF 4 ) and phosphoric acid (H 3 PO 4 ) also allowed to remove as-plated metal coatings from substrates of the group of titanium and of tungsten ( US 3,793,172 (1972 )).
  • HPF 4 fluoroboric acid
  • H 3 PO 4 phosphoric acid
  • the majority of these electrochemical stripping approaches only remove the coatings (aluminide and MCrAlY) on the base metal or superalloy and do not address the removal of the corrosion or oxidation products grown from such coatings in the same electrolyte (bath).
  • the present invention is directed to an improved process for treating turbine components for use in the engine maintenance and repair industry.
  • the present invention is directed towards an electrochemical process for stripping corrosion and oxide products and oxidation resistant metallic coatings from a superalloy test sample comprising connecting the test sample to a lead of a power supply; submerging a portion of the test sample into a bath of electrolytic stripping solution with a pH less than 1, wherein the stripping solution comprises nitric acid (HNO 3 ) at a concentration from 2% to 20% by weight; hydrochloric acid (HCl) at a concentration from 1% to 10% by weight; and ammonium molybdate salt at a concentration from 0.2% to 3% by weight; and, water up to 100% by weight; subjecting the test sample to combined cycles of anodic and cathodic polarisation steps for a period of time effective to strip the corrosion and the oxide products and oxidation resistant metallic coatings from the test sample, wherein anodic polarisation involves making the test sample the anode at a potential lower than +2 volts for 1 min to 2 hours and cathodic polarisation involves making the test
  • the test sample is close to that of the original superalloy test sample or the current value is getting closer to the passivation current value of the base material; subjecting the test sample to a final cleaning and final rinsing step wherein the final cleaning step comprises i) placing the test sample in a chemical etching solution comprising a mixture from 40/60 to 60/40 in volume ratio of Hydrochloric acid (HCl) and Isopropyl Alcohol (C 3 H 8 O) with Copper Chloride salt (CuCl 2 ) at a concentration from 2 g/l to 20 g/l, for 1 to 60 min; and the final rinsing step comprises ii) rinsing the test sample in water at room temperature for at least 1 min.
  • HCl Hydrochloric acid
  • C 3 H 8 O Isopropyl Alcohol
  • CuCl 2 Copper Chloride salt
  • test sample is a gas turbine hot section part made of Fe-, Ni-, Co- or Ti-based alloys.
  • test sample is coated either with an aluminide or a modified aluminide coating.
  • the base material is a gas turbine hot section part, having a distinct electrochemically composition feature from the coating, including any component made of Fe-, Ni-, Co- or Ti-based alloys.
  • cathodic polarisation is carried out at potentials ranging from -0.8 V/o.c.p. to -0.4 V/o.c.p. for steps between 2 to 10 minutes each and anodic polarisation is carried out at potentials ranging from +0.4 V/SCE to +0.75 V/SCE for steps between 5 to 10 minutes each.
  • the final cleaning step takes place for 5 to 15 minutes at a temperature below 75°C.
  • the final rinsing step additionally uses ultrasonic waves.
  • the process of the invention can be carried out for localized coating removal, for example, the tip area of the turbine blade. Alternatively, it can also be used to remove the complete coating by immersing the entire airfoil/turbine part in the stripping solution.
  • the present invention is directed to an improved electrochemical process which strips corrosion and oxides products and aluminide coatings from a test sample in the electrolytic stripping solution in an alternate manner by switching the polarity of the test sample.
  • the process of the present invention is highly selective and maintains the integrity of the base metal. This method preserves the desired structural and dimensional integrity of the underlying base metal, thus, reducing scrap parts and reducing reworking operations.
  • the strong oxidizing substances in the bath allow the base material to develop a passive film.
  • the process of the invention minimizes or completely eliminates the need for masking. Only those parts which need to be stripped are allowed in contact with a bath where the afore-mentioned process is carried out. This greatly speeds up the process as no masking is required on critical parts of the test sample unless it is a requirement of process specifications.
  • the method of present invention is more environmentally friendly than conventional processes and produces less hazardous effluents and does not result in the formation of excessive hazardous fumes.
  • the method of the present invention operates at lower acid concentrations, lower temperatures than conventional techniques and under normal atmospheric conditions, without any special requirements of heating and stirring. Processing times are shorter than conventional techniques. Thus, the method of the present invention is simpler and more cost effective than conventional techniques.
  • the method of the present invention is based on a three-electrode cell, whose a schematic diagram of the set-up is shown in Fig. 1 , whereby:
  • test sample (or at least a portion of test sample) is immersed in contact with the highly conductive and acidic oxidizing electrolytic stripping solution up to the desired section of the blade and connected to a power supply.
  • the test sample is polarized in such a manner that the test sample is alternatively the cathode and the anode. Therefore, the process allows to both dissolve the coating layers (stripping) as well as to remove the corrosion and oxide products through in situ gas bubbling that makes them brittle enough to detach from the surface.
  • the computerised system allows an in situ full feedback control of the electrical potential with respect to the reference electrode or of the electrical current at the surface of the part to be stripped.
  • the electrolytic stripping solution is a water-based stripping solution comprises a strong oxidizing inorganic acid in the form of nitric acid (HNO 3 ); a reducing and pitting inorganic acid in the form of hydrochloric acid (HCl); and a composition comprising both a corrosion inhibitor and an oxidizing agent in the form of an ammonium molybdate salt.
  • the chemical composition of the water-based electrolytic solution includes
  • Such a chemical composition ensures high electrical conductivity of the electrolyte and makes the pH to be lower than 1 over the entire stripping cycle and does not degrade the conventional waxes employed to protect the internal cooling holes and the roots of some of the components.
  • the exact chemistry of the bath must be adjusted depending upon the exact coating and base metal combination.
  • a potential is preferably imposed to the part to remove all the coating from the localized region after an efficient period of time.
  • the process parameters are related to coating thickness and composition as well as to the oxide scale features (cracking, composition, thickness) and part electro-active area and must be adjusted accordingly for each configuration.
  • the base material Due to the high electrochemical selectivity and to the fully in situ monitored process, the base material is not affected as it passivates itself when it comes in contact with the electrolyte, thus preserving its structural and dimensional integrity and extending part life, while dissolution reactions still occurs on partially removed portions of the coating to complete the removal process.
  • Completion of the stripping process is achieved once the preset value of the current or of the potential is reached. This value is predetermined either by an extrapolation of the current/voltage polarisation curve, by a ratio of the initial potential or current, by intercalated open circuit potential measurements.
  • the method of the invention involves the following general steps:
  • This steps involves fixing the test sample to the insulated fixture that ensures the electrical contact to the test sample, putting in contact the desired portion of the test sample with the electrolyte (e.g. by immersion in a bath) operating at ambient temperature under soft magnetic stirring and connection of the fixture to one channel of the power source at least.
  • the electrolyte e.g. by immersion in a bath
  • This step involves measuring the electrochemical activity of the test sample to be stripped (open circuit potential - o.c.p.) for 1 to 10 min.
  • test sample is alternatively made the cathode (connected to the negative lead of the power source) at a potential higher than -1.5 volts for 1 min to 20 min and the anode (connected to the positive lead of the power source) at a potential lower than +2 volts for 1 min to 2 hours.
  • Agitation of the solution is provided by any convenient means such as mechanical or magnetic stirring, air or ultrasonic agitation, or by constant circulation of the solution using a pump system, which can further allow the filtration of the electrolyte.
  • the required efficient stripping time to strip the test sample is subject to many parameters such as the applied voltage or current density, the concentration of the electrolyte, the coating thickness and/or composition and/or microstructure, the basis material and the distance between the electrodes. Nevertheless, if portions of the test sample are removed more quickly than others, overrun will not lead to undesirable effects on structural and critical dimensions integrity of the part, owing to the above-mentioned selectivity of the process/solution and spontaneous passivation of the exposed base material.
  • Erosive rinsing of the test sample after complete stripping procedure and the removal from the electrolyte to tear off smut and/or sludge as well as coating porous layers, if any, using preferably deionised water at room temperature coupled to light erosive/abrasive particles/powder, e.g. pumice, grit particles or any other similar flaky particles/powder, for at least 1 min under ultrasonic agitation.
  • this can be achieved through any known agitation way in order to maintain a turbulent flow and a homogeneous suspension of particles/powder.
  • any other erosive, abrasive means may be employed, e.g. scrubbing with a stiff brush or gentle grit blasting.
  • HCl Hydrochloric acid
  • C 3 H 8 O Isopropyl Alcohol
  • CuCl 2 Copper Chloride salt
  • This step ensures even and smooth surfaces are obtained ready for subsequent repair steps without damaging the base material and avoiding grit blasting.
  • test samples used in the following examples were derived from scrap metal parts from the airline industry, either complete scrap metal parts such as engine/turbine blade parts or gas turbine hot section parts or similar scrap metal samples cut into pieces to produce testing samples, or pieces made from a nickel-based superalloy, whose chemical composition is given in the table below: Substrate Ni Al Cr Co Mo W Ta Ti C B Zr other wt. % RENETM 125 59 4.8 8.5 10 2 8 3.4 2.5 0.11 0.015 0.05 1.4Hf DS 200 59.6 5 9 10 12.5 2 0.15 0.015 0.05 1.8Hf INCONEL 100 60 5.5 10 15 3 4.7 0.18 0.014 0.06 1.0 V
  • test samples were extensively stripped, grit blasted and cleaned/degreased
  • the stripping process consisted of a) aqueous cleaning, b) wet abrasive blasting, c) immersion in a stripping bath consisting of a mixture of nitric acid (HNO 3 ) and sulfamic acid (H 3 NSO 3 ), d) aqueous rinsing, e) scrubbing and f) final coarse grit blasting] for each test sample.
  • test samples were then aluminised using a conventional vapour phase process (the SVPA method (SNECMA vapour phase aluminising) is a commonly used and well-known aluminising treatment in the aircraft coatings technology) in which the aluminium-containing vapour species are generated from reaction between a donor (Cr-Al nuggets) and an activator (ammonium fluoride) at 1150°C/3 h for INCO-100 and RENE125 and at 1100°C/5h for DS200 material.
  • the resulting thickness of coatings is of about 60 microns on average.
  • test samples were cyclically oxidised for cycles of 24h at 1100°C to promote interdiffusion with the substrate's elements and deplete the aluminium reservoir of the coating.
  • This type of procedure also aimed at inducing cracking of the oxide scale to provide further easy penetration of the stripping solution to ensure that the following examples were performed on components as close as possible to real components after exposure to engine conditions (service).
  • the aluminised and oxidised test samples were then subjected to the following stripping methods.
  • test samples were firstly degreased, grit blasted and then immersed in a stripping bath consisting in a mixture of nitric acid at a concentration of approximately 14%wt and sulfamic acid at a concentration of approximately 5%wt. Water up to 100%wt is added to the mixture. After approximately 5 hours, samples were removed from the bath, rinsed with water and gently grit blasted.
  • Fig. 3 is a cross-section of an airfoil portion of a turbine blade made of a superalloy.
  • the dotted circles surround the degradation (i.e. general corrosion, pitting and/or intergranular attack) that can occur to the turbine blade using the chemical stripping method of this comparative example.
  • These comparative methods reduce the wall section and induce crack formation, hence decreasing the mechanical properties for which the blade was designed for.
  • the throat dimension between adjacent blades in an engine is defined by the distance between the trailing edge (TE) of one blade and the convex surface of the adjacent blade.
  • the trailing edge (TE) of an airfoil is a very thin and critical section that must not be altered.
  • Fig. 4 shows the difficulties experienced using the stripping method of the comparative example.
  • the airfoil convex side (CV) mostly suffers from pitting and IGA due to the higher removal rate of the coating compared to the concave side (CC), which is less exposed to the solution, if not suspended or hung in the bath, due to the geometry and the difficulty to agitate and/or create a turbulent flow to regenerate the stripping solution close to this part. In this particular case, it will give rise to remnant portions of coatings on the CC most of the times.
  • test sample was gently blasted with #220 mesh sieved alumina particles, immersed in the electrolyte operating at ambient temperature under soft magnetic stirring and connected to the power source.
  • the o.c.p. (open circuit potential) value of the test sample was measured according for 1 to 10 min.
  • Step 3 Electrolytic stripping.
  • test sample is alternatively made the cathode (connected to the negative lead of the power source) at a potential of -0.8V/o.c.p. for 5 min and the anode (connected to the positive lead of the power source) at a potential of + 0.5V/SCE for 6 min.
  • the counter-electrode is connected to the other lead of the power source accordingly and the potential between the reference electrode and the working electrode is live monitored through the full computerised system connected to the three-electrode cell or by mean of any voltmeter/ammeter.
  • Agitation of the solution is provided by any convenient means such as mechanical or magnetic stirring, air or ultrasonic agitation, or by constant circulation of the solution using a pump system, which can further allow the filtration of the electrolyte.
  • the stripping solution is magnetically agitated softly.
  • test sample was removed from the bath, ultrasonically rinsed according to the following step 4.
  • Step 4 Erosive ultrasonic rinsing
  • test strip is removed from the electrolyte.
  • Smut and/or sludge as well as coating porous layers are removed using preferably deionised water at room temperature coupled to light erosive/abrasive particles/powder, e.g. pumice, grit particles or any other similar flaky particles/powder, for at least 1 min under ultrasonic agitation.
  • light erosive/abrasive particles/powder e.g. pumice, grit particles or any other similar flaky particles/powder, for at least 1 min under ultrasonic agitation.
  • the rinsing has been carried out in water under ultrasonic agitation and then scrubbing the samples with a stiff brush before being cleaned (step 5).
  • Final cleaning takes place using a chemical etching solution at ambient temperature, in a solution composed of a 50/50 (by volume) mixture of hydrochloric acid and isopropyl alcohol plus 1 wt. % of copper chloride CuCl 2 with ultrasonic waves before rinsing in water and drying with dry/hot air (step 6).
  • Fig. 5 shows the evolution of the E o.c.p. (E corr ) and of the current density with the number of stripping steps.
  • the typical overall trends of E o.c.p. and of current density evolution during the stripping process are given in Fig. 5 (a) and (b) respectively.
  • the o.c.p. value stabilises at a value, which is close to the originally coated substrate.
  • cathodic bubbling/anodic dissolution steps bring about an increase of the o.c.p. value close to that of the raw substrate as a result of the effective removal of the coating layers.
  • the complete removal of the aluminide coating is strongly indicated by a slowdown of the dissolution kinetics associated with the passivation of the underlying substrate.
  • the following Examples relate to investigations of the cross-sections of the coating/base material systems using either optical or electron microscopy after different stages of processing according to the method of Example 1.
  • Step 3 procedure was repeated 5 times in a row.
  • Check-ups of the E o.c.p. (E corr ) are monitored after each anodic polarisation.
  • the sample was ultrasonically rinsed in deionised water for 2 min then scrubbed with a stiff brush before being ultrasonically cleaned for 5 min and dried with air (Steps 4 to 6).
  • Fig. 6 shows cross-sections of the coating before and after stripping.
  • test sample was clamped by the root to a polymer fixture ensuring the electrical contact through inert platinum wires.
  • the test sample was immersed tip downwards in the solution until the platform level so that the electrolyte was in contact with the areas requiring a coating removal but not the root section.
  • the electrolytic stripping procedure was repeated several times until an o.c.p. value or a current density close to the one of the raw substrate was reached.
  • the sample was ultrasonically rinsed in deionised water for 2 min then scrubbed with a stiff brush before being ultrasonically cleaned for 10 min, and dried with air (steps 4 to 6).
  • Fig. 7 shows cross-sections of the coating after stripping.
  • Step 3 procedure repeated 5 times in a row.
  • Check-ups of the E o.c.p. (E corr ) are monitored after each anodic polarisation.
  • the sample was ultrasonically rinsed in deionised water for 2 min then scrubbed with a stiff brush before being ultrasonically cleaned for 5 min and dried with air.
  • Fig. 8 shows cross-sections of the aluminide coating before and after stripping.
  • test sample was clamped by the root to a polymer fixture ensuring the electrical contact through inert platinum wires.
  • the test sample was immersed tip downwards in the solution until the platform level so that the acid solution contacted the areas requiring a coating removal (only the tip of the airfoil) but not the entire part of the airfoil or the root.
  • Step 3 procedure repeated 8 times in a row.
  • Check-ups of the E o.c.p. (E corr ) are monitored after each anodic polarisation.
  • the electrolytic stripping procedure was repeated several times until an o.c.p. value or a current density close to the one of the raw substrate was reached.
  • the sample was ultrasonically rinsed in deionised water for 4 min then scrubbed with a stiff brush before being ultrasonically cleaned for 10 min and dried with air (steps 4 to 6)
  • Fig. 9 shows cross-sections of the Pt/Al coating before and after stripping.
  • the sample was ultrasonically rinsed in deionised water for 4 min then scrubbed with a stiff brush before being ultrasonically cleaned for 10 min and dried with air.
  • Fig. 10 shows cross-sections of the aluminide coating before and after stripping using the present invention.
  • the method of the invention using this improved electrolyte solution enables a highly selective coating removal while ensuring in every instance the structural and dimensional integrity of the base material/test sample is maintains.
  • Another advantage of this method is that the base material/test sample passivates itself when becoming in contact with the stripping solution.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)
  • ing And Chemical Polishing (AREA)
EP20120174048 2012-06-28 2012-06-28 Elektrolytisches Ablösen Not-in-force EP2679705B1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP20120174048 EP2679705B1 (de) 2012-06-28 2012-06-28 Elektrolytisches Ablösen
PCT/EP2013/063743 WO2014001555A1 (en) 2012-06-28 2013-06-28 Electrolytic stripping

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP20120174048 EP2679705B1 (de) 2012-06-28 2012-06-28 Elektrolytisches Ablösen

Publications (2)

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EP2679705A1 true EP2679705A1 (de) 2014-01-01
EP2679705B1 EP2679705B1 (de) 2015-05-06

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WO (1) WO2014001555A1 (de)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111487267B (zh) * 2020-04-09 2023-04-14 哈尔滨工业大学 一种剥离铝青铜合金中双层氧化膜缺陷的方法
CN114075690B (zh) * 2020-08-14 2022-11-22 中国科学院金属研究所 一种电化学退除MCrAlY涂层的方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2840521A (en) 1956-09-21 1958-06-24 Tiarco Corp Electrolytic stripping
US3409487A (en) * 1964-11-09 1968-11-05 Union Carbide Corp Use of a phenolic resin and ethylene oxide polymer as an etching resist
US3793172A (en) 1972-09-01 1974-02-19 Western Electric Co Processes and baths for electro-stripping plated metal deposits from articles
US5202002A (en) * 1991-05-14 1993-04-13 Nippon Steel Corporation Process for pickling steel-based metallic materials at a high speed
US6176999B1 (en) * 1998-12-18 2001-01-23 United Technologies Corporation Feedback controlled stripping of airfoils

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2840521A (en) 1956-09-21 1958-06-24 Tiarco Corp Electrolytic stripping
US3409487A (en) * 1964-11-09 1968-11-05 Union Carbide Corp Use of a phenolic resin and ethylene oxide polymer as an etching resist
US3793172A (en) 1972-09-01 1974-02-19 Western Electric Co Processes and baths for electro-stripping plated metal deposits from articles
US5202002A (en) * 1991-05-14 1993-04-13 Nippon Steel Corporation Process for pickling steel-based metallic materials at a high speed
US6176999B1 (en) * 1998-12-18 2001-01-23 United Technologies Corporation Feedback controlled stripping of airfoils

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"Controlled stripping of aluminide coatings on nickel superalloys through electrolytic techniques", J APPL ELECTROCHEM, vol. 38, 2008, pages 817 - 825

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EP2679705B1 (de) 2015-05-06
WO2014001555A1 (en) 2014-01-03

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