EP1472388B1 - Method for pickling martensitic or ferritic high-grade steel - Google Patents

Method for pickling martensitic or ferritic high-grade steel Download PDF

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Publication number
EP1472388B1
EP1472388B1 EP02785414A EP02785414A EP1472388B1 EP 1472388 B1 EP1472388 B1 EP 1472388B1 EP 02785414 A EP02785414 A EP 02785414A EP 02785414 A EP02785414 A EP 02785414A EP 1472388 B1 EP1472388 B1 EP 1472388B1
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Prior art keywords
pickling
ions
pickling solution
solution
iii
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EP02785414A
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German (de)
French (fr)
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EP1472388A2 (en
Inventor
Paolo Giordani
Dario Negri
Mauro Rigamonti
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Henkel AG and Co KGaA
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Henkel AG and Co KGaA
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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
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
    • C23G1/08—Iron or steel
    • C23G1/086—Iron or steel solutions containing HF
    • 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
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
    • C23G1/08—Iron or steel
    • 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
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • 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
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
    • C23C22/08—Orthophosphates
    • C23C22/10—Orthophosphates containing oxidants
    • 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
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts

Definitions

  • the invention relates to a method for pickling martensitic or ferritic stainless steel (also referred to as "stainless steel”), in particular in the form of wire, tubes or rods.
  • stainless or stainless steels are generally used in the language where under normal environmental conditions such. B. the presence of atmospheric oxygen and moisture and in aqueous solutions, the rust formation is prevented. Harsher corrosion conditions such as acids and salt solutions resist the usually higher alloyed so-called corrosion-resistant or acid-resistant steels. In summary, these steels are referred to as stainless steels. In Ullmanns Encyklopadie der ischen Chemie, 4th Edition, Volume 22, pp.
  • Stainless steels are iron-based alloys that contain at least 10% chromium. The formation of chromium oxide on the material surface gives the stainless steels their corrosion-resistant character.
  • Stainless steels can be divided into families: austenitic steels, ferritic steels, martensitic steels, precipitation hardened steels and duplex steels. These groups differ in their physical and mechanical properties as well as in their corrosion resistance, which are caused by the different alloying constituents.
  • the surface layer During annealing or hot rolling etc. of stainless steel, a layer of scale is formed on the surface, which takes the desired shiny metallic appearance of the steel surface. After this production step, this surface layer must therefore be removed. This can be done by the pickling process according to the invention.
  • the oxide-containing surface layer to be removed is fundamentally different from the oxide layer on low-alloy steels or on carbon steels.
  • the surface layer contains oxides of the alloying elements such as chromium, nickel, aluminum, titanium or niobium. On heating, the surface layer accumulates on chromium oxide, since chromium is thermodynamically less noble than iron. This enriches chromium for iron in the oxide layer.
  • the surface After pickling, the surface is chemically activated so that it recovers in the air with an optically disturbing surface layer. This can be prevented by passivating the freshly pickled surfaces after or during pickling. This can be done in treatment solutions similar to the Beiziösungen, but one sets for the passivation, a higher redox potential than for the pickling.
  • the targeted passivation step forms an optically invisible passivation layer on the metal surface. As a result, the steel surface preserves its shiny metallic appearance. Whether or not a treatment solution has a protective effect on stainless steel or passivating depends mainly on the set redox potential.
  • Acid solutions with pH values below about 2.5 are effective if they have a redox potential over a silver / silver chloride electrode in the range of about 100 to about 350 mV due to the presence of oxidizing agents. Increasing the redox potential to values above about 350 mV, the treatment solution acts passivating, depending on the type of stainless steel different minimum values for the potential must be set.
  • Stainless steel pickling processes are well known in the art. Older processes use pickling baths containing nitric acid. These often also contain hydrofluoric acid, which promotes the pickling process due to its complexing effect on iron ions. Although such pickling baths are economically efficient and technically satisfactory, they have the great ecological disadvantage that they emit considerable amounts of nitrogen oxides and that high nitrate concentrations enter the wastewater. The required suction devices make the process more expensive and the quantities of nitrogen oxide finally released into the atmosphere have a considerable potential for damaging the environment.
  • oxidizing agents such as hydrogen peroxide or other oxidizing agents such as perborates
  • peracids or organic peroxides is oxidized divalent iron ions back to the trivalent stage. This preserves the redox potential required for the pickling or passivation effect.
  • EP-B-505606 a nitric acid-free process for pickling and passivating stainless steel, in which the material to be treated is contacted with a bath having a temperature between 30 and 70 ° C and at least at the beginning of the pickling at least 150 g / l sulfuric acid containing at least 15 g / l of Fe (III) ions and at least 40 g / l of HF. Furthermore, this bath contains up to about 1 g / l of additives such as nonionic surfactants and pickling inhibitors. The bath is added continuously or discontinuously to such amounts of hydrogen peroxide that the redox potential is maintained in the desired range.
  • the other bath components are replenished in such a way that their concentration remains in the optimal working range.
  • the pickling bath By blowing in air, the pickling bath is kept in motion. A movement of the pickling bath is required to achieve a uniform Beizgebnis.
  • a similar process, which differs essentially only by the set redox potential, is in the EP-A-582 121 described.
  • document EP0769575 discloses a method for martensitic steel pickling with a pickling solution comprising H2S04, Fe3 + and HF, the pickling solution having a temperature in the range of 30 to 70 ° C.
  • document ep1050605 discloses a method for pickling stainless steel with a pickling solution, wherein the proportion of free HF is from 5 to 40 g / l, and the temperature of the pickling solution in the range of 20 to 70 ° C.
  • the above-mentioned pickling processes are technically satisfactory and have the ecological advantage of not emitting nitrogen oxides into the environment. They are especially optimized for pickling austinitic stainless steels, which account for about 65 to 85% of the stainless steel market.
  • these pickling solutions are found to be too aggressive. They attack the base alloy of these types of steel too much, so that the risk of fürbeizens exists.
  • the pickling process continues at places already stained and destroys the surface. Excessive staining produces more divalent iron ions than necessary to maintain the redox potential at the trivalent stage must be oxidized. This increases the consumption of oxidizing agent and thus makes the pickling process more expensive.
  • This object is achieved by a method for pickling martensitic or ferritic stainless steel, wherein the stainless steel is contacted with a pickling solution containing Fe (III) ions, sulfuric acid and HF, characterized in that the pickling solution has a temperature in the range of 15 to 29 ° C and 50 to 120 g / l of free sulfuric acid, 5 to 40 g / l free HF and 5 to 40 g / l of Fe (III) ions.
  • the concentrations of the individual components of this pickling bath are each in a range which is known per se in the prior art. However, the concentrations are coordinated so that no over-pickling of the martensitic or ferritic substrates occurs.
  • An essential parameter for avoiding over-pickling is the temperature, which according to the invention is set in the range between 15 and 29 ° C. Preferably, it is between 20 and 29 ° C and especially between 23 and 28.5 ° C. If the temperature exceeds 30 ° C, there is an increasing risk of over-pickling.
  • the duration of the pickling process depends on the selected temperature, the adjusted free acid concentrations and the pretreatment of the articles prior to the actual pickling process.
  • the pickling time is in the range of about 5 minutes for blasted substrates, 10 to 15 minutes for molten salt-treated substrates and 10 to 25 minutes in a pretreatment with a strongly alkaline solution of potassium permanganate. In this case, it may be necessary to repeat the steps pretreatment and pickling for a complete digestion. The mentioned pickling times then apply to the respective individual steps.
  • concentrations of free sulfuric acid and free HF are the concentrations of each free acid.
  • acid anions which are present in salt form, are not included.
  • the minimum concentration of free hydrofluoric acid depends on which pickling time is considered acceptable.
  • the concentration of free HF is at least 10 g / l in order to achieve the aforementioned pickling times.
  • the maximum concentration in practice may range between about 25 and about 30 g / L. If particularly short pickling times are desired, the maximum concentration can be set to about 35 g / l. Even with an upper limit of 40 g / l free HF, the pickling process is still manageable. At higher concentrations, however, the risk of over-pickling increases.
  • the minimum concentration of free sulfuric acid is preferably set between 55 and 60 g / l, the upper limit between 70 and 100 g / l.
  • the pickling solution may contain 55 to 75 g / l of free sulfuric acid.
  • oxidizing agent such as hydrogen peroxide or with a hydrogen peroxide-releasing substance
  • a strong oxidizing agent such as hydrogen peroxide or with a hydrogen peroxide-releasing substance
  • Such substances are, for example, inorganic or organic peracids or peroxo acids.
  • peroxo-sulfuric acid or peroxodisulfuric acid is suitable.
  • oxidizing halogen acids such as chloric acid or perchloric acid are possible, but less preferred for practical reasons.
  • the divalent iron can be oxidized to the trivalent state by catalytic oxidation with an oxygen-containing gas, preferably air, using a homogeneous or heterogeneous oxidation catalyst.
  • a homogeneous oxidation catalyst for example, copper ions can be used, as in the German patent application DE-A-197 55 350 described.
  • the bivalent iron can be catalytically oxidized to trivalent with oxygen or air in an external fixed bed reactor. Such a method is from the EP-A-795,628 known.
  • the divalent iron can be oxidized directly or indirectly by electrochemical oxidation to the trivalent level. Such a method is for example in the WO 00/15880 and described in the literature cited therein.
  • the concentration of Fe (II) ions in the pickling solution depends on the operating state of the pickling solution. For a fresh pickling solution, this concentration can be 0. It increases during the pickling process, with the increase being controlled by the oxidation of Fe (II) to Fe (III).
  • the concentration of Fe (II) may increase up to 70 to 80 g / l. In practical experiments with the pickling method according to the invention, Fe (II) concentrations in the range between 40 and 60 g / l were observed after one week of operation.
  • the concentration of divalent and trivalent iron ions exceeds a limit value which may for example be in the range from 90 to 110 g / l, it is advisable to drain a part, for example 2/3, of the pickling solution and add fresh pickling solution which does not contain Fe ( II) -lone replaces. It is sufficient to post-dose only the acids, as usually sufficient amounts of Fe (III) ions remain in the solution. If necessary, some of the remaining Fe (II) ions can also be oxidized to Fe (III). As a result, the concentration of Fe (II) ions decreases again, for example to a value in the range of 20 g / l.
  • the pickling solution may be moved relative to the substrate surface, preferably by pumping, stirring or blowing air. This is particularly the case when the articles to be sharped are bundled or rolled up into bundles.
  • a movement of the pickling solution facilitates the replacement of the pickling solution in bottlenecks between the surfaces to be pickled and thus leads to a uniform pickling result. This is especially the case when the martensitic or ferritic stainless steel is in the form of wire, tubes or rods.
  • the inventive method is particularly suitable.
  • the pickling solution may contain other auxiliaries or additives.
  • it is customary, in the case of oxidation with hydrogen peroxide, to add this in the form of a stabilized aqueous solution.
  • stabilizer for H 2 O 2 enters the pickling bath.
  • This is for example from the cited EP-A-582 121 known where as stabilizers 8-hydroxyquinoline, sodium stannate, phosphoric acid, salicylic acid, pyridinecarboxylic acid and in particular phenacetin may be mentioned.
  • a particularly preferred stabilizer for H 2 O 2 is a mixture of phosphoric acid and glycol ether, as used, for example, in US Pat WO 01/49899 is described.
  • the pickling solution contains surface-active substances, in particular those of the nonionic type.
  • these are fatty alcohol ethoxylates or fatty alcohol ethoxylates / propoxylates.
  • the C chain length of the fatty alcohols is preferably in the range between 8 and 22, in particular between 12 and 18.
  • further treatment stages may be provided, for example between steps a) and b) a pre-pickling with a solution containing one or more acids (HCl, H 2 SO 4 , HF).
  • a solution containing one or more acids HCl, H 2 SO 4 , HF
  • rinsing and / or neutralization steps are preferably provided between the individual treatment steps, which however can also be dispensed with immediately after radiation.
  • a treatment a which breaks up oxidic deposits, is common in the prior art before a pickling treatment.
  • Said permanganate / alkali hydroxide solution is preferably a solution containing 5 to 20% by weight of NaOH and 5 to 20% by weight of potassium permanganate. Preferably, this solution has a temperature in the range of 95 to 100 ° C.
  • a neutralization is preferably provided before step b), for example by treating the substrate with dilute sulfuric acid. Even after radiation, this can be useful.
  • the passivation solution for sub-step c) must have a redox potential which is (under the same measuring conditions) above the potential set in step b), for example in the range from about 600 to about 800 mV.
  • a nitric acid-containing solution is suitable, but less preferred for reasons of environmental protection.
  • a passivating solution containing sulfuric acid and hydrogen peroxide may be used.
  • the passivation solution preferably additionally contains a stabilizer for H 2 O 2 , for example according to WO 01/49899 a mixture of phosphoric acid and glycol ether.
  • the passivation solutions may additionally have low levels of HF, for example in the range of 5 g / l.
  • dark deposits on the substrate surface are removed at the same time, which can form in the pickling step b).
  • suitable substrates may first be blasted in step a): then in step b) the pickling treatment is carried out at 28 ° C for a period of time in the range of 5 to 10 minutes, followed by a water rinse and the passivation step c) as in 9 above.

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Abstract

A process for pickling martensitic or ferritic stainless steel, preferably in the form of wires, tubes or rods, wherein the stainless steel is placed in contact with a pickling solution which has a temperature in the range 15 to 29° C. and contains 50 to 120 g/l of free sulfuric acid, 5 to 40 g/l of free HF and 5 to 40 g/l of Fe(III) ions. Such pickling may be incorporated into a sequential process, wherein the stainless steel is a) subjected to a treatment during which the oxidic coating is applied, preferably sand-blasting or metal-blasting, treatment with a molten salt or treatment with an aqueous permanganate/alkali metal hydroxide solution, b) pickled in accordance with the aforedescribed process, and c) post-treated with a passivating solution.

Description

Die Erfindung betrifft ein Verfahren zum Beizen von martensitischem oder ferritischem Edelstahl (auch als "rostfreier Stahl" bezeichnet), insbesondere in Form von Draht, Röhren oder Stäben. Als nichtrostend bzw. rostfrei werden im allgemeinen Sprachgebrauch Stähle bezeichnet, bei denen unter üblichen Umweltbedingungen wie z. B. der Anwesenheit von Luftsauerstoff und Feuchtigkeit und in wäßrigen Lösungen die Rostbildung verhindert wird. Härteren Korrosionsbedingungen wie beispielsweise Säuren und Salzlösungen widerstehen die meist höherlegierten sogenannten korrosionsbeständigen oder säurebeständigen Stähle. Zusammenfassend werden diese Stähle als Edelstähle bezeichnet. In Ullmanns Encyklopädie der technischen Chemie, 4. Auflage, Band 22, SS. 106-112 und in der Deutschen Industrienorm DIN 17440, Juli 1985, ist eine Auflistung der technisch wichtigsten Edelstähle mit ihren Werkstoffnummern, Bezeichnungen und Legierungskomponenten sowie mechanischen und chemischen Eigenschaften enthalten. Edelstähle sind eisenbasierte Legierungen, die mindestens 10 % Chrom enthalten. Die Bildung von Chromoxid auf der Materialoberfläche verleiht den Edelstählen ihren korrosionsresistenten Charakter.The invention relates to a method for pickling martensitic or ferritic stainless steel (also referred to as "stainless steel"), in particular in the form of wire, tubes or rods. As stainless or stainless steels are generally used in the language where under normal environmental conditions such. B. the presence of atmospheric oxygen and moisture and in aqueous solutions, the rust formation is prevented. Harsher corrosion conditions such as acids and salt solutions resist the usually higher alloyed so-called corrosion-resistant or acid-resistant steels. In summary, these steels are referred to as stainless steels. In Ullmanns Encyklopadie der technischen Chemie, 4th Edition, Volume 22, pp. 106-112 and in the German industrial standard DIN 17440, July 1985, a listing of the most technically important stainless steels with their material numbers, names and alloying components as well as mechanical and chemical properties is included. Stainless steels are iron-based alloys that contain at least 10% chromium. The formation of chromium oxide on the material surface gives the stainless steels their corrosion-resistant character.

Edelstähle lassen sich einteilen in die Familien: austenitische Stähle, ferritische Stähle, martensitische Stähle, ausscheidungsgehärtete Stähle und Duplexstähle. Diese Gruppen unterscheiden sich in ihren physikalischen und mechanischen Eigenschaften sowie in ihrer Korrosionsresistenz, die durch die verschiedenen Legierungsbestandteile hervorgerufen werden.Stainless steels can be divided into families: austenitic steels, ferritic steels, martensitic steels, precipitation hardened steels and duplex steels. These groups differ in their physical and mechanical properties as well as in their corrosion resistance, which are caused by the different alloying constituents.

Beim Glühen bzw. Warmwalzen etc. von Edelstahl bildet sich an der Oberfläche eine Schicht von Zunder aus, die der Stahloberfläche das erwünschte metallisch-glänzende Aussehen nimmt. Nach diesem Produktionsschritt muß diese Oberflächenschicht daher entfernt werden. Dies kann durch das erfindungsgemäße Beizverfahren erfolgen. Die zu entfernende oxidhaltige Oberflächenschicht unterscheidet sich grundlegend von der Oxidschicht auf niedriglegierten Stählen oder auf Kohlenstoffstählen. Außer Eisenoxiden enthält die Oberflächenschicht Oxide der Legierungselemente wie beispielsweise Chrom, Nickel, Aluminium, Titan oder Niob. Beim Erhitzen reichert sich die Oberflächenschicht an Chromoxid an, da Chrom thermodynamisch unedler ist als Eisen. Hierdurch wird Chrom gegenüber Eisen in der Oxidschicht angereichert. Umgekehrt führt dies dazu, daß die Stahlschicht unmittelbar unter der Oxidschicht an Chrom verarmt ist. Ein Beizprozeß mit geeigneten sauren Beizlösungen löst bevorzugt diese chromverarmte Schicht unterhalb der Oxidschicht auf, so daß die Oxidschicht abgesprengt wird.During annealing or hot rolling etc. of stainless steel, a layer of scale is formed on the surface, which takes the desired shiny metallic appearance of the steel surface. After this production step, this surface layer must therefore be removed. This can be done by the pickling process according to the invention. The oxide-containing surface layer to be removed is fundamentally different from the oxide layer on low-alloy steels or on carbon steels. In addition to iron oxides, the surface layer contains oxides of the alloying elements such as chromium, nickel, aluminum, titanium or niobium. On heating, the surface layer accumulates on chromium oxide, since chromium is thermodynamically less noble than iron. This enriches chromium for iron in the oxide layer. Conversely, this leads to the Steel layer immediately below the oxide layer is depleted of chromium. A pickling process with suitable acid pickling solutions preferably dissolves this chromium-depleted layer below the oxide layer, so that the oxide layer is blasted off.

Nach dem Beizen ist die Oberfläche chemisch aktiviert, so daß sie sich an der Luft wieder mit einer optisch störenden Oberflächenschicht überzieht. Dies kann dadurch verhindert werden, daß man die frisch gebeizten Oberflächen nach oder während dem Beizen passiviert. Dies kann in Behandlungslösungen ähnlich den Beiziösungen erfolgen, wobei man für die Passivierung jedoch ein höheres Redoxpotential einstellt als für den Beizvorgang. Durch den gezielten Passivierungsschritt bildet sich an der Metalloberfläche eine optisch nicht sichtbare Passivierungsschicht aus. Hierdurch bewahrt die Stahloberfläche ihr metallisch-glänzendes Aussehen. Ob eine Behandlungslösung gegenüber Edelstahl beizend oder passivierend wirkt, hängt hauptsächlich vom eingestellten Redoxpotential ab. Saure Lösungen mit pH-Werten unterhalb von etwa 2,5 wirken beizend, wenn sie aufgrund der Anwesenheit von Oxidationsmitteln ein Redoxpotential gegenüber einer Silber/Silberchloridelektrode im Bereich von etwa 100 bis etwa 350 mV aufweisen. Erhöht man das Redoxpotential auf Werte oberhalb etwa 350 mV, wirkt die Behandlungslösung passivierend, wobei je nach Edelstahlsorte unterschiedliche Mindestwerte für das Potential eingestellt werden müssen.After pickling, the surface is chemically activated so that it recovers in the air with an optically disturbing surface layer. This can be prevented by passivating the freshly pickled surfaces after or during pickling. This can be done in treatment solutions similar to the Beiziösungen, but one sets for the passivation, a higher redox potential than for the pickling. The targeted passivation step forms an optically invisible passivation layer on the metal surface. As a result, the steel surface preserves its shiny metallic appearance. Whether or not a treatment solution has a protective effect on stainless steel or passivating depends mainly on the set redox potential. Acid solutions with pH values below about 2.5 are effective if they have a redox potential over a silver / silver chloride electrode in the range of about 100 to about 350 mV due to the presence of oxidizing agents. Increasing the redox potential to values above about 350 mV, the treatment solution acts passivating, depending on the type of stainless steel different minimum values for the potential must be set.

Beizverfahren für Edelstahl sind in der Technik gut bekannt. Ältere Verfahren verwenden Salpetersäure-haltige Beizbäder. Diese enthalten häufig zusätzlich Flußsäure, die durch ihre komplexierende Wirkung gegenüber Eisenionen den Beizvorgang fördert. Derartige Beizbäder sind zwar ökonomisch effizient und technisch zufriedenstellend, weisen jedoch den großen ökologischen Nachteil auf, daß sie beträchtliche Mengen Stickoxide emittieren und daß hohe Nitratkonzentrationen ins Abwasser gelangen. Die erforderlichen Absaugvorrichtungen verteuern den Prozeß und die letztlich in die Atmosphäre gelangenden Stickoxidmengen haben ein beträchtliches umweltschädigendes Potential.Stainless steel pickling processes are well known in the art. Older processes use pickling baths containing nitric acid. These often also contain hydrofluoric acid, which promotes the pickling process due to its complexing effect on iron ions. Although such pickling baths are economically efficient and technically satisfactory, they have the great ecological disadvantage that they emit considerable amounts of nitrogen oxides and that high nitrate concentrations enter the wastewater. The required suction devices make the process more expensive and the quantities of nitrogen oxide finally released into the atmosphere have a considerable potential for damaging the environment.

Daher wurde in der Technik intensiv nach alternativen Beiz- und Passivierverfahren gesucht, die ohne Verwendung von Salpetersäure auskommen. Ein möglicher Ersatz für die Oxidationswirkung der Salpetersäure sind Fe(III)-lonen. Ihre Konzentration kann beispielsweise durch Wasserstoffperoxid, das den Behandlungsbädern kontinuierlich oder diskontinuierlich zugesetzt wird, aufrecht erhalten werden. Derartige Beiz- oder Passivierungsbäder enthalten etwa 15 bis etwa 65 g/l dreiwertige Eisenionen. Während des Beizvorgangs werden dreiwertige Eisenionen zur zweiwertigen Stufe reduziert. Gleichzeitig werden aus der gebeizten Oberfläche weitere zweiwertige Eisenionen herausgelöst. Das Beizbad verarmt daher während des Betriebs an dreiwertigen Eisenionen, während sich zweiwertige Eisenionen anreichern. Hierdurch verschiebt sich das Redoxpotential der Behandlungslösung, so daß diese schließlich ihre Beizwirkung verliert.For this reason, the art has been intensively searching for alternative pickling and passivation processes which do not require the use of nitric acid. A possible replacement for the oxidation effect of nitric acid are Fe (III) ions. Their concentration can be maintained, for example, by hydrogen peroxide, which is added to the treatment baths continuously or discontinuously. Such pickling or passivating baths contain from about 15 to about 65 g / l of trivalent iron ions. During the pickling process trivalent iron ions are reduced to the bivalent level. At the same time further bivalent iron ions are dissolved out of the pickled surface. The pickling bath therefore depletes of trivalent iron ions during operation, while divalent iron ions accumulate. This shifts the redox potential of the treatment solution so that it eventually loses its pickling effect.

Durch kontinuierliche oder diskontinuierliche Zugabe von Oxidationsmitteln wie beispielsweise Wasserstoffperoxid oder andere Oxidationsmittel wie Perborate, Persäuren oder auch organische Peroxide oxidiert man zweiwertige Eisenionen zurück zur dreiwertigen Stufe. Hierdurch bleibt das für die Beiz- bzw. Passivierwirkung erforderliche Redoxpotential erhalten.By continuous or discontinuous addition of oxidizing agents such as hydrogen peroxide or other oxidizing agents such as perborates, peracids or organic peroxides is oxidized divalent iron ions back to the trivalent stage. This preserves the redox potential required for the pickling or passivation effect.

Beispielsweise beschreibt die EP-B-505 606 ein Salpetersäure-freies Verfahren zum Beizen und Passivieren von rostfreiem Stahl, bei dem man das zu behandelnde Material mit einem Bad in Berührung bringt, das eine Temperatur zwischen 30 und 70 °C aufweist und das zumindest zu Beginn des Beizvorgangs mindestens 150 g/l Schwefelsäure, mindestens 15 g/l Fe(III)-lonen und zumindest 40 g/l HF enthält. Weiterhin enthält dieses Bad bis zu etwa 1 g/l Additive wie nichtionische Tenside und Beizinhibitoren. Dem Bad gibt man kontinuierlich oder diskontinuierlich solche Mengen Wasserstoffperoxid zu, daß das Redoxpotential im erwünschten Bereich gehalten wird. Auch die anderen Badbestandteile werden derart nachdosiert, daß deren Konzentration im optimalen Arbeitsbereich bleibt. Durch Einblasen von Luft wird das Beizbad in Bewegung gehalten. Eine Bewegung des Beizbades ist erforderlich, um ein gleichmäßiges Beizergebnis zu erzielen. Ein ähnliches Verfahren, das sich hiervon im wesentlichen nur durch das eingestellte Redoxpotential unterscheidet, ist in der EP-A-582 121 beschrieben.For example, this describes EP-B-505606 a nitric acid-free process for pickling and passivating stainless steel, in which the material to be treated is contacted with a bath having a temperature between 30 and 70 ° C and at least at the beginning of the pickling at least 150 g / l sulfuric acid containing at least 15 g / l of Fe (III) ions and at least 40 g / l of HF. Furthermore, this bath contains up to about 1 g / l of additives such as nonionic surfactants and pickling inhibitors. The bath is added continuously or discontinuously to such amounts of hydrogen peroxide that the redox potential is maintained in the desired range. The other bath components are replenished in such a way that their concentration remains in the optimal working range. By blowing in air, the pickling bath is kept in motion. A movement of the pickling bath is required to achieve a uniform Beizgebnis. A similar process, which differs essentially only by the set redox potential, is in the EP-A-582 121 described.

Dokument EP0769575 offenbart ein Verfahren zum Beizen martensitischen Stahl mit einer Beizlösung umfassend H2S04, Fe3+ und HF, wobei die Beizlösung eine Temperature im Bereich von 30 bis 70 °C aufweist. Dokument ep1050605 offenbart ein Verfahren zum Beizen Edelstahl mit einer Beizlösung, wobei der Anteil an freies HF von 5 bis 40g/l liegt, und die Temperatur der Beizlösung im bereich von 20 bis 70°C.document EP0769575 discloses a method for martensitic steel pickling with a pickling solution comprising H2S04, Fe3 + and HF, the pickling solution having a temperature in the range of 30 to 70 ° C. document ep1050605 discloses a method for pickling stainless steel with a pickling solution, wherein the proportion of free HF is from 5 to 40 g / l, and the temperature of the pickling solution in the range of 20 to 70 ° C.

Die vorstehend genannten Beizverfahren arbeiten technisch zufriedenstellend und haben den ökologischen Vorteil, keine Stickoxide in die Umwelt zu emittieren. Sie sind besonders auf das Beizen von austinitischen Edelstählen optimiert, die etwa 65 bis 85 % des Edelstahlmarktes ausmachen. Für Gegenstände aus martensitischem oder ferritischem Edelstahl, besonders wenn diese in Form von Draht, Röhren oder Stäben vorliegen, erweisen sich diese Beizlösungen jedoch als zu aggressiv. Sie greifen die Basislegierung dieser Stahltypen zu stark an, so daß das Risiko des Überbeizens besteht. Der Beizvorgang setzt sich an bereits gebeizten Stellen in die Tiefe fort und zerstört die Oberfläche. Durch das Überbeizen entstehen mehr zweiwertige Eisenionen als erforderlich, die zur Aufrechterhaltung des Redox-Potentials zur dreiwertigen Stufe oxidiert werden müssen. Dies erhöht den Verbrauch an Oxidationsmittel und verteuert somit den Beizvorgang. Weiterhin erhöht sich die Menge der letztlich zu entsorgenden Eisensalze. Daher besteht ein Bedarf nach einem weniger aggressiven Beizverfahren, mit dem sich Gegenstände aus martensitischem oder ferritischem Edelstahl zuverlässig beizen lassen, so daß Oberflächenbeläge gleichmäßig entfernt werden, jedoch kein Überbeizen eintritt.The above-mentioned pickling processes are technically satisfactory and have the ecological advantage of not emitting nitrogen oxides into the environment. They are especially optimized for pickling austinitic stainless steels, which account for about 65 to 85% of the stainless steel market. However, for martensitic or ferritic stainless steel items, especially those in the form of wire, tubes, or rods, these pickling solutions are found to be too aggressive. They attack the base alloy of these types of steel too much, so that the risk of Überbeizens exists. The pickling process continues at places already stained and destroys the surface. Excessive staining produces more divalent iron ions than necessary to maintain the redox potential at the trivalent stage must be oxidized. This increases the consumption of oxidizing agent and thus makes the pickling process more expensive. Furthermore, the amount of iron salts ultimately to be disposed of increases. Therefore, there is a need for a less aggressive pickling process that can reliably pickle martensitic or ferritic stainless steel articles so that surface coverings are evenly removed, but no over-pickling occurs.

Diese Aufgabe wird gelöst durch ein Verfahren zum Beizen von martensitischem oder ferritischem Edelstahl, wobei man den Edelstahl mit einer Beizlösung in Kontakt bringt, die Fe(III)-lonen, Schwefelsäure und HF enthält, dadurch gekennzeichnet, daß die Beizlösung
eine Temperatur im Bereich von 15 bis 29 °C aufweist und
50 bis 120 g/l freie Schwefelsäure,
5 bis 40 g/l freies HF und
5 bis 40 g/l Fe(III)-lonen enthält.This object is achieved by a method for pickling martensitic or ferritic stainless steel, wherein the stainless steel is contacted with a pickling solution containing Fe (III) ions, sulfuric acid and HF, characterized in that the pickling solution
has a temperature in the range of 15 to 29 ° C and
50 to 120 g / l of free sulfuric acid,
5 to 40 g / l free HF and
5 to 40 g / l of Fe (III) ions.

Die Konzentrationen der einzelnen Komponenten dieses Beizbads liegen jeweils in einem Bereich, der an sich im Stand der Technik bekannt ist. Die Konzentrationen sind jedoch so aufeinander abgestimmt, daß kein Überbeizen der martensitischen oder ferritischen Substrate eintritt. Ein wesentlicher Parameter zum Vermeiden eines Überbeizens ist die Temperatur, die erfindungsgemäß im Bereich zwischen 15 und 29 °C eingestellt wird. Vorzugsweise liegt sie zwischen 20 und 29 °C und insbesondere zwischen 23 und 28,5 °C. Überschreitet die Temperatur 30 °C, besteht zunehmend die Gefahr eines Überbeizens.The concentrations of the individual components of this pickling bath are each in a range which is known per se in the prior art. However, the concentrations are coordinated so that no over-pickling of the martensitic or ferritic substrates occurs. An essential parameter for avoiding over-pickling is the temperature, which according to the invention is set in the range between 15 and 29 ° C. Preferably, it is between 20 and 29 ° C and especially between 23 and 28.5 ° C. If the temperature exceeds 30 ° C, there is an increasing risk of over-pickling.

Die Zeitdauer für den Beizprozeß hängt von der gewählten Temperatur, den eingestellten Konzentrationen an freier Säure und der Vorbehandlung der Gegenstände vor dem eigentlichen Beizprozeß ab. Die Beizdauer liegt im Bereich von etwa 5 Minuten für gestrahlte Substrate, 10 bis 15 Minuten für in einer Salzschmelze behandelte Substrate und 10 bis 25 Minuten bei einer Vorbehandlung mit einer stark alkalischen Lösung von Kaliumpermanganat. Dabei kann es für einen vollständigen Beizerfolg erforderlich sein, die Schritte Vorbehandlung und Beizen zu wiederholen. Die genannten Beizzeiten gelten dann für die jeweiligen Einzelschritte.The duration of the pickling process depends on the selected temperature, the adjusted free acid concentrations and the pretreatment of the articles prior to the actual pickling process. The pickling time is in the range of about 5 minutes for blasted substrates, 10 to 15 minutes for molten salt-treated substrates and 10 to 25 minutes in a pretreatment with a strongly alkaline solution of potassium permanganate. In this case, it may be necessary to repeat the steps pretreatment and pickling for a complete digestion. The mentioned pickling times then apply to the respective individual steps.

Bei den vorstehend genannten Konzentrationen an freier Schwefelsäure und freiem HF ist zu beachten, daß es sich hierbei um die Konzentrationen an jeweils freier Säure handelt. Hierbei werden Säureanionen, die in Salzform vorliegen, nicht mit gerechnet. Die Mindestkonzentration an freier Flußsäure hängt davon ab, welche Beizdauer man als akzeptabel betrachtet. Vorzugsweise beträgt die Konzentration an freiem HF mindestens 10 g/l, um die vorstehend genannten Beizzeiten zu erreichen. Die Maximalkonzentration kann in der Praxis im Bereich zwischen etwa 25 und etwa 30 g/l liegen. Werden besonders kurze Beizzeiten angestrebt, kann die Maximalkonzentration auf etwa 35 g/l eingestellt werden. Auch bei einer Obergrenze von 40 g/l freies HF ist der Beizvorgang noch beherrschbar. Bei höheren Konzentrationen erhöht sich jedoch die Gefahr des Überbeizens. Die Minimalkonzentration an freier Schwefelsäure stellt man vorzugsweise zwischen 55 und 60 g/l, die Obergrenze zwischen 70 und 100 g/l ein. Beispielsweise kann die Beizlösung 55 bis 75 g/l freie Schwefelsäure enthalten.At the above-mentioned concentrations of free sulfuric acid and free HF, it should be noted that these are the concentrations of each free acid. In this case, acid anions, which are present in salt form, are not included. The minimum concentration of free hydrofluoric acid depends on which pickling time is considered acceptable. Preferably, the concentration of free HF is at least 10 g / l in order to achieve the aforementioned pickling times. The maximum concentration in practice may range between about 25 and about 30 g / L. If particularly short pickling times are desired, the maximum concentration can be set to about 35 g / l. Even with an upper limit of 40 g / l free HF, the pickling process is still manageable. At higher concentrations, however, the risk of over-pickling increases. The minimum concentration of free sulfuric acid is preferably set between 55 and 60 g / l, the upper limit between 70 and 100 g / l. For example, the pickling solution may contain 55 to 75 g / l of free sulfuric acid.

Die Konzentration an Fe(III)-lonen nimmt im Verlauf des Beizprozesses ab, da diese durch die Redox-Reaktion mit dem elementaren Eisen der Stahloberfläche zur zweiwertigen Stufe reduziert werden. Vorzugsweise regelt man die Konzentration an Fe(III)-lonen so ein, daß die Beizlösung in eingearbeitetem Zustand zwischen etwa 10 und etwa 25 g/l dieser lonen enthält. Dies geschieht vorzugsweise dadurch, daß man die entstehenden Fe(II)-lonen im entsprechenden Ausmaß zur dreiwertigen Stufe oxidiert. Je nach Mengenverhältnis zwischen zweiwertigen und dreiwertigen Eisenionen in der Beizlösung weist diese ein bestimmtes Redox-Potential auf. Daher ist die Beizlösung auch über das gemessene Redox-Potential steuerbar. Für das erfindungsgemäße Verfahren weist die Beizlösung in eingearbeitetem Zustand vorzugsweise ein Redox-Potential, gemessen bei 25 °C mit einer Platinelektrode relativ zu einer Ag/AgCl-Referenzelektrode, von 100 bis 240 mV, insbesondere von 150 bis 235 mV auf. Durch Verbrauch von dreiwertigen Eisenionen unter Bildung zweiwertiger Eisenionen sinkt das Redox-Potential im Verlauf des Beizprozesses ab. Durch Oxidation zweiwertiger Eisensionen zur dreiwertigen Stufe kann es wieder angehoben werden. Vorzugsweise stellt man im erfindungsgemäßen Verfahren das Redox-Potential dadurch ein, daß man eine oder mehrere der folgenden Aktionen vornimmt:

  1. a) Zugabe eines Reagenzes zu der Beizlösung, das in der Beizlösung Fe(II)-lonen zu Fe(III)-lonen zu oxidieren vermag, vorzugsweise Wasserstoffperoxid oder eine Wasserstoffperoxid abspaltende Substanz,
  2. b) Katalytische Oxidation mit einem stauerstoffhaltigen Gas unter Verwendung eines homogenen oder heterogenen Oxidationskatalysators,
  3. c) Elektrochemische Oxidation.
The concentration of Fe (III) ions decreases in the course of the pickling process, as they are reduced to the bivalent level by the redox reaction with the elemental iron of the steel surface. Preferably, the concentration of Fe (III) ions is adjusted so that the pickling solution in the incorporated state contains between about 10 and about 25 g / l of these ions. This is preferably done by oxidizing the resulting Fe (II) ions to the appropriate extent to the trivalent stage. Depending on the quantitative ratio between divalent and trivalent iron ions in the pickling solution, this has a certain redox potential. Therefore, the pickling solution can also be controlled via the measured redox potential. For the novel process, the pickling solution in the incorporated state preferably has a redox potential, measured at 25 ° C. with a platinum electrode relative to an Ag / AgCl reference electrode, of 100 to 240 mV, in particular 150 to 235 mV. By consumption of trivalent iron ions to form divalent iron ions, the redox potential decreases during the pickling process. By oxidation of divalent iron ions to the trivalent stage, it can be raised again. Preferably, in the process according to the invention, the redox potential is adjusted by carrying out one or more of the following actions:
  1. a) addition of a reagent to the pickling solution which is capable of oxidizing Fe (II) ions to Fe (III) ions in the pickling solution, preferably hydrogen peroxide or a hydrogen peroxide releasing substance,
  2. b) Catalytic oxidation with a gas containing oxygen using a homogeneous or heterogeneous oxidation catalyst,
  3. c) Electrochemical oxidation.

Zur Oxidation von zweiwertigem Eisen und damit zur Regulierung des Redox-Potentials ist also die direkte Oxidation mit einem starken Oxidationsmittel wie Wasserstoffperoxid oder mit einer Wasserstoffperoxid-abspaltenden Substanz möglich. Solche Substanzen sind beispielsweise anorganische oder organische Persäuren oder Peroxo-Säuren. Beispielsweise ist Peroxo-Schwefelsäure oder Peroxo-Dischwefelsäure geeignet. Auch oxidierende Halogensäuren wie beispielsweise Chlorsäure oder Perchlorsäure sind möglich, aus praktischen Gründen jedoch weniger bevorzugt.For the oxidation of divalent iron and thus to regulate the redox potential so the direct oxidation with a strong oxidizing agent such as hydrogen peroxide or with a hydrogen peroxide-releasing substance is possible. Such substances are, for example, inorganic or organic peracids or peroxo acids. For example, peroxo-sulfuric acid or peroxodisulfuric acid is suitable. Also oxidizing halogen acids such as chloric acid or perchloric acid are possible, but less preferred for practical reasons.

Alternativ hierzu kann das zweiwertige Eisen durch katalytische Oxidation mit einem sauerstoffhaltigen Gas, vorzugsweise mit Luft, unter Verwendung eines homogenen oder heterogenen Oxidationskatalysators zur dreiwertigen Stufe oxidiert werden. Als homogener Oxidationskatalysator können beispielsweise Kupferionen eingesetzt werden, wie in der deutschen Patentanmeldung DE-A-197 55 350 beschrieben. Möchte man die Anwesenheit von Kupferionen in der Beizlösung vermeiden, kann das zweiwertige Eisen in einem externen Festbettreaktor mit Sauerstoff oder Luft katalytisch zur dreiwertigen Stufe oxidiert werden. Ein solches Verfahren ist aus der EP-A-795 628 bekannt. Schließlich kann das zweiwertige Eisen direkt oder indirekt durch elektrochemische Oxidation zur dreiwertigen Stufe oxidiert werden. Ein solches Verfahren ist beispielsweise in der WO 00/15880 und in der dort zitierten Literatur beschrieben.Alternatively, the divalent iron can be oxidized to the trivalent state by catalytic oxidation with an oxygen-containing gas, preferably air, using a homogeneous or heterogeneous oxidation catalyst. As a homogeneous oxidation catalyst, for example, copper ions can be used, as in the German patent application DE-A-197 55 350 described. If it is desired to avoid the presence of copper ions in the pickling solution, the bivalent iron can be catalytically oxidized to trivalent with oxygen or air in an external fixed bed reactor. Such a method is from the EP-A-795,628 known. Finally, the divalent iron can be oxidized directly or indirectly by electrochemical oxidation to the trivalent level. Such a method is for example in the WO 00/15880 and described in the literature cited therein.

Aus dem Vorstehenden ergibt sich, daß die Konzentration an Fe(II)-lonen in der Beizlösung vom Betriebszustand der Beizlösung abhängt. Bei einer frisch angesetzten Beizlösung kann diese Konzentration 0 betragen. Sie steigt im Verlauf des Beizprozesses an, wobei der Anstieg durch die Oxidation von Fe(II) zu Fe(III) gesteuert wird. Dabei kann die Konzentration an Fe(II) auf bis zu 70 bis 80 g/l ansteigen. Bei Praxisversuchen mit dem erfindungsgemäßen Beizverfahren wurden nach einer Woche Betriebsdauer Fe(II)-Konzentrationen im Bereich zwischen 40 und 60 g/l beobachtet. Übersteigt die Gesamtkonzentration an zweiwertigen und dreiwertigen Eisenionen einen vorzugebenden Grenzwert, der beispielsweise im Bereich von 90 bis 110 g/l liegen kann, empfiehlt es sich, einen Teil, beispielsweise 2/3, der Beizlösung abzulassen und durch frische Beizlösung, die keine Fe(II)-lonen enthält, zu ersetzen. Dabei genügt es, nur die Säuren nachzudosieren, da in der Regel noch ausreichende Mengen an Fe(III)-lonen in der Lösung verbleiben. Erforderlichenfalls kann auch ein Teil der verbliebenen Fe(II)-lonen zu Fe(III) oxidiert werden. Hierdurch sinkt die Konzentration an Fe(II)-lonen wieder ab, beispielsweise auf einen Wert im Bereich von 20 g/l.From the above, it follows that the concentration of Fe (II) ions in the pickling solution depends on the operating state of the pickling solution. For a fresh pickling solution, this concentration can be 0. It increases during the pickling process, with the increase being controlled by the oxidation of Fe (II) to Fe (III). The concentration of Fe (II) may increase up to 70 to 80 g / l. In practical experiments with the pickling method according to the invention, Fe (II) concentrations in the range between 40 and 60 g / l were observed after one week of operation. If the total concentration of divalent and trivalent iron ions exceeds a limit value which may for example be in the range from 90 to 110 g / l, it is advisable to drain a part, for example 2/3, of the pickling solution and add fresh pickling solution which does not contain Fe ( II) -lone replaces. It is sufficient to post-dose only the acids, as usually sufficient amounts of Fe (III) ions remain in the solution. If necessary, some of the remaining Fe (II) ions can also be oxidized to Fe (III). As a result, the concentration of Fe (II) ions decreases again, for example to a value in the range of 20 g / l.

Im erfindungsgemäßen Verfahren kann es bevorzugt sein, die Beizlösung relativ zur Substratoberfläche zu bewegen, vorzugsweise durch Umpumpen, Rühren oder Einblasen von Luft. Dies ist insbesondere der Fall, wenn die zu beizenden Gegenstände zu Bündeln zusammengefaßt oder zu Bunden aufgerollt sind. Eine Bewegung der Beizlösung erleichtert den Austausch der Beizlösung in Engstellen zwischen den zu beizenden Oberflächen und führt damit zu einem gleichmäßigen Beizergebnis. Dies ist insbesondere dann der Fall, wenn der martensitische oder ferritische Edelstahl in Form von Draht, Röhren oder Stäben vorliegt. Für derartige Substrate ist das erfindungsgemäße Verfahren besonders geeignet.In the process of the invention, it may be preferable to move the pickling solution relative to the substrate surface, preferably by pumping, stirring or blowing air. This is particularly the case when the articles to be sharped are bundled or rolled up into bundles. A movement of the pickling solution facilitates the replacement of the pickling solution in bottlenecks between the surfaces to be pickled and thus leads to a uniform pickling result. This is especially the case when the martensitic or ferritic stainless steel is in the form of wire, tubes or rods. For such substrates, the inventive method is particularly suitable.

Außer den genannten essentiellen Komponenten kann die Beizlösung weitere Hilfsstoffe oder Additive enthalten. Beispielsweise ist es üblich, im Falle der Oxidation mit Wasserstoffperoxid dieses in Form einer stabilisierten wäßrigen Lösung zuzugeben. Auf diese Weise gelangt Stabilisator für H2O2 in das Beizbad. Dies ist beispielsweise aus der zitierten EP-A-582 121 bekannt, wo als Stabilisatoren 8-Hydroxychinolin, Natriumstannat, Phosphorsäure, Salicylsäure, Pyridincarbonsäure und insbesondere Phenacetin genannt werden. Ein besonders bevorzugter Stabilisator für H2O2 ist eine Mischung aus Phosphorsäure und Glykolether, wie sie beispielsweise in WO 01/49899 beschrieben ist. Zum Erzielen einer besonders gleichmäßig gebeizten Oberfläche ist es vorteilhaft, wenn die Beizlösung oberflächenaktive Substanzen, insbesondere solche vom nichtionischen Typ enthält. Beispiele hierfür sind Fettalkoholethoxylate oder Fettalkoholethoxylate/propoxylate. Dabei liegt die C-Kettenlänge der Fettalkohole vorzugsweise im Bereich zwischen 8 und 22, insbesondere zwischen 12 und 18.In addition to the essential components mentioned, the pickling solution may contain other auxiliaries or additives. For example, it is customary, in the case of oxidation with hydrogen peroxide, to add this in the form of a stabilized aqueous solution. In this way stabilizer for H 2 O 2 enters the pickling bath. This is for example from the cited EP-A-582 121 known where as stabilizers 8-hydroxyquinoline, sodium stannate, phosphoric acid, salicylic acid, pyridinecarboxylic acid and in particular phenacetin may be mentioned. A particularly preferred stabilizer for H 2 O 2 is a mixture of phosphoric acid and glycol ether, as used, for example, in US Pat WO 01/49899 is described. To achieve a particularly uniformly stained surface, it is advantageous if the pickling solution contains surface-active substances, in particular those of the nonionic type. Examples of these are fatty alcohol ethoxylates or fatty alcohol ethoxylates / propoxylates. The C chain length of the fatty alcohols is preferably in the range between 8 and 22, in particular between 12 and 18.

Das erfindungsgemäße Beizverfahren stellt üblicherweise einen Teilschritt in der gesamten Oberflächenbehandlungsfolge der genannten Gegenstände dar. Diese Behandlungsfolge umfaßt vor dem Beizen eine Vorbehandlung, die oxidische Beläge aufbricht, und nach dem Beizschritt eine passivierende Nachbehandlung, um die Oberflächen metallisch-blank zu halten. Demgemäß umfaßt die vorliegende Erfindung auch eine Verfahrensabfolge zur Oberflächenbehandlung von martensitischem oder ferritischem Edelstahl, vorzugsweise von Gegenständen in Form von Draht, Röhren oder Stäben, wobei man den Edelstahl mindestens

  • a) einer Behandlung unterzieht, die oxidische Beläge aufbricht, vorzugsweise einer Sand- oder Schrotstrahlung, einer Behandlung mit einer Salzschmelze oder einer Behandlung mit einer wässrigen Permanganat/Alkalihydroxid-Lösung,
  • b) mit dem Verfahren nach einem oder mehreren der Ansprüche 1 bis 6 beizt,
  • c) mit einer Passivierungslösung nachbehandelt.
The pickling process according to the invention usually represents a partial step in the entire surface treatment sequence of said articles. This treatment sequence comprises a pretreatment which breaks up oxidic deposits before pickling and, after the pickling step, a passivating after-treatment in order to keep the surfaces metallically bright. Accordingly, the present invention also includes a process sequence for the surface treatment of martensitic or ferritic stainless steel, preferably articles in the form of wire, tubes or rods, wherein the stainless steel is at least
  • a) subjecting to a treatment which breaks up oxidic deposits, preferably a sand or shot blasting, a treatment with a salt melt or a treatment with an aqueous permanganate / alkali hydroxide solution,
  • b) with the method according to one or more of claims 1 to 6,
  • c) aftertreated with a passivation solution.

Je nach Substrat können weitere Behandlungsstufen vorgesehen werden, beispielsweise zwischen den Schritten a) und b) eine Vorbeize mit einer Lösung, die eine oder mehrere Säuren (HCl, H2SO4, HF) enthält.Depending on the substrate, further treatment stages may be provided, for example between steps a) and b) a pre-pickling with a solution containing one or more acids (HCl, H 2 SO 4 , HF).

Dabei werden vorzugsweise zwischen den einzelnen Behandlungsschritten Spül- und/oder Neutralisationsschritte vorgesehen, die allerdings unmittelbar nach einer Strahlung auch entfallen können. Eine Behandlung a), die oxidische Beläge aufbricht, ist im Stand der Technik vor einer Beizbehandlung üblich. Die genannte Permanganat/Alkalihydroxidlösung ist vorzugsweise eine Lösung, die 5 bis 20 Gew.-% NaOH und 5 bis 20 Gew.-% Kaliumpermanganat enthält. Vorzugsweise hat diese Lösung eine Temperatur im Bereich von 95 bis 100 °C. Setzt man für Schritt a) alkalische Produkte ein, sieht man vor Schritt b) vorzugsweise eine Neutralisation vor, beispielsweise durch Behandeln des Substrats mit verdünnter Schwefelsäure. Auch nach Strahlung kann dies sinnvoll sein.In this case, rinsing and / or neutralization steps are preferably provided between the individual treatment steps, which however can also be dispensed with immediately after radiation. A treatment a), which breaks up oxidic deposits, is common in the prior art before a pickling treatment. Said permanganate / alkali hydroxide solution is preferably a solution containing 5 to 20% by weight of NaOH and 5 to 20% by weight of potassium permanganate. Preferably, this solution has a temperature in the range of 95 to 100 ° C. If alkaline products are used for step a), a neutralization is preferably provided before step b), for example by treating the substrate with dilute sulfuric acid. Even after radiation, this can be useful.

Die Passivierungslösung für den Teilschritt c) muß ein Redox-Potential aufweisen, das (unter gleichen Meßbedingungen) oberhalb dem im Schritt b) eingestellten Potential liegt, beispielsweise im Bereich von etwa 600 bis etwa 800 mV. Hierfür ist beispielsweise eine Salpetersäure-haltige Lösung geeignet, jedoch aus Gründen des Umweltschutzes weniger bevorzugt. Alternativ hierzu kann eine Passivierungslösung verwendet werden, die Schwefelsäure und Wasserstoffperoxid enthält. In diesem Falle enthält die Passivierungslösung vorzugsweise zusätzlich einen Stabilisator für H2O2, beispielsweise gemäß WO 01/49899 eine Mischung von Phosphorsäure und Glykolether. In beiden Fällen können die Passivierungslösungen zusätzlich geringe Gehalte von HF, beispielsweise im Bereich von 5 g/l, aufweisen. Im Passivierungsschritt c) werden gleichzeitig dunkle Beläge auf der Substratoberfläche entfernt, die sich im Beizschritt b) bilden können.The passivation solution for sub-step c) must have a redox potential which is (under the same measuring conditions) above the potential set in step b), for example in the range from about 600 to about 800 mV. For this purpose, for example, a nitric acid-containing solution is suitable, but less preferred for reasons of environmental protection. Alternatively, a passivating solution containing sulfuric acid and hydrogen peroxide may be used. In this case, the passivation solution preferably additionally contains a stabilizer for H 2 O 2 , for example according to WO 01/49899 a mixture of phosphoric acid and glycol ether. In both cases, the passivation solutions may additionally have low levels of HF, for example in the range of 5 g / l. In the passivation step c) dark deposits on the substrate surface are removed at the same time, which can form in the pickling step b).

Dabei kann es für ein gleichmäßiges Beizergebnis vorteilhaft sein, die Schritte a) und b) einmal oder mehrmals zu wiederholen. Beispielsweise kann eine erfindungsgemäße Verfahrensfolge folgendermaßen aussehen:

  1. 1. Vorbehandeln mit einer wäßrigen Lösung, die jeweils 10 Gew.% NaOH und KMnO4 enthält und eine Temperatur von 95 °C aufweist, für eine Behandlungsdauer von 20 Minuten.
  2. 2. Wasserspülung oder vorzugsweise Neutralisationsspülung mit verdünnter Schwefelsäure.
  3. 3. Erfindungsgemäße Beizbehandlung mit einem der beiden Beizbäder gemäß nachstehender Tabelle, Temperatur 28 °C, 10 Minuten.
  4. 4. Wasserspülung, vorzugsweise als Hochdruck-Spritzspülung.
  5. 5. Erneute Vorbehandlung wie unter 1.
  6. 6. Wasserspülung.
  7. 7. Erneute Beizbehandlung wie unter 3.
  8. 8. Wasserspülung wie unter 4.
  9. 9. Passivierungsbehandlung in Salpetersäure oder in einer Passivierungs-/Glänzlösung gemäß WO 01/49899 , die Schwefelsäure, H2O2 und eine Stabilisierungsmischung aus Phosphorsäure und Glykolether (z.B. Ethylenglykol- oder Diethylenglykol-mono-n-butylether) enthält.
  10. 10. Wasserspülung, vorzugsweise als Spritzspülung.
  11. 11. Gegebenenfalls Neutralisationsbehandlung, beispielsweise mit Kalk.
In this case, it may be advantageous for a uniform pickling result to repeat steps a) and b) once or several times. For example, a sequence of the invention may look like this:
  1. 1. pretreatment with an aqueous solution, each containing 10 wt.% NaOH and KMnO 4 and having a temperature of 95 ° C, for a treatment time of 20 minutes.
  2. 2. Water rinse or preferably neutralization rinse with dilute sulfuric acid.
  3. 3. Pickling treatment according to the invention with one of the two pickling baths according to the following table, temperature 28 ° C., 10 minutes.
  4. 4. Water rinse, preferably as a high-pressure spray rinse.
  5. 5. Re-pretreatment as in 1.
  6. 6. Water rinse.
  7. 7. Re-pickling as under 3.
  8. 8. Water rinse as under 4.
  9. 9. passivation treatment in nitric acid or in a passivation / glazing solution according to WO 01/49899 containing sulfuric acid, H 2 O 2 and a stabilizing mixture of phosphoric acid and glycol ether (eg, ethylene glycol or diethylene glycol mono-n-butyl ether).
  10. 10. Water rinse, preferably as a spray rinse.
  11. 11. Optionally neutralization treatment, for example with lime.

Alternativ hierzu können geeignete Substrate zunächst im Teilschritt a) gestrahlt werden: Danach erfolgt im Teilschritt b) die Beizbehandlung bei 28 °C für eine Zeitdauer im Bereich von 5 bis 10 Minuten, gefolgt von einer Wasserspülung und dem Passivierungsschritt c) wie vorstehend unter 9.Alternatively, suitable substrates may first be blasted in step a): then in step b) the pickling treatment is carried out at 28 ° C for a period of time in the range of 5 to 10 minutes, followed by a water rinse and the passivation step c) as in 9 above.

In einem erfolgreichen Praxisversuch wurden 2 Beizlösungen verwendet, die nach einer Betriebsdauer von einer Woche eine Zusammensetzung gemäß nachstehender Tabelle aufwiesen. Dabei wurde das Redox-Potential bzw. die Konzentration an Fe(III) durch Zugabe von H2O2 eingestellt. Bei den Säurekonzentrationen handelt es sich um die freien Säuren. Tabelle: Erfindungsgemäße Beizlösungen (Konzentrationsangaben in g/l) Lösung 1 Lösung 2 H2SO4 60,7 68,5 HF 33,0 33,4 Fe2+ 55,0 44,4 Fe3+ 10,1 13,5 E,mV (Ag/AgCl/Pt; T = 25°C) 199 229 Beiztemperatur 28 °C 28 °C In a successful field trial, 2 pickling solutions were used which had a composition according to the following table after one week of operation. The redox potential or the concentration of Fe (III) was adjusted by adding H 2 O 2 . The acid concentrations are the free acids. Table: Pickling solutions according to the invention (concentration data in g / l) Solution 1 Solution 2 H 2 SO 4 60.7 68.5 HF 33,0 33.4 Fe 2+ 55.0 44.4 Fe 3+ 10.1 13.5 E, mV (Ag / AgCl / Pt; T = 25 ° C) 199 229 pickling temperature 28 ° C 28 ° C

Claims (9)

  1. A method for pickling martensitic or ferritic high-grade steel, the high-grade steel being brought into contact with a pickling solution which contains Fe(III) ions, sulfuric acid and HF, characterized in that the pickling solution has a temperature in the range from 15 to 29°C and contains
    50 to 120 g/l of free sulfuric acid,
    5 to 40 g/l of free HF and
    5 to 40 g/l of Fe(III) ions.
  2. The method according to claim 1, characterized in that the pickling solution contains 55 to 75 g/l of free sulfuric acid.
  3. The method according to one or both of claims 1 and 2, characterized in that the pickling solution contains 10 to 25 g/l of Fe(III) ions in the worked-in state.
  4. The method according to one or more of claims 1 to 3, characterized in that the pickling solution in the worked-in state has a redox potential from 100 to 240 mV, measured at 25°C with a platinum electrode relatively to a Ag/AgCl reference electrode.
  5. The method according to one or more of claims 1 to 4, characterized in that the redox potential is adjusted by proceeding with one or more of the following actions:
    a) addition of a reagent to the pickling solution, which is capable of oxidizing Fe(II) ions into Fe(III) ions in the pickling solution, preferably hydrogen peroxide or a substance splitting off hydrogen peroxide,
    b) catalytic oxidation with an oxygen-containing gas with the use of a homogeneous or heterogeneous oxidation catalyst,
    c) electrochemical oxidation.
  6. The method according to one or more of claims 1 to 5, characterized in that the pickling solution is set into motion, preferably by pumping, stirring or blowing air.
  7. The method according to one or more of claims 1 to 6, characterized in that the martensitic or ferritic high-grade steel is present in the form of wire, tubes or bars.
  8. A procedural sequence for surface treatment of martensitic or ferritic high-grade steel, wherein the high-grade steel
    a) is subject to a treatment which breaks open the oxide coatings,
    b) is etched with the method according to one or more of claims 1 to 6,
    c) is post-treated with a passivation solution.
  9. The procedural sequence according to claim 8, characterized in that the steps a) and b) are repeated once or several times.
EP02785414A 2001-12-07 2002-11-28 Method for pickling martensitic or ferritic high-grade steel Expired - Lifetime EP1472388B1 (en)

Applications Claiming Priority (3)

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DE10160318A DE10160318A1 (en) 2001-12-07 2001-12-07 Process for pickling martensitic or ferritic stainless steel
DE10160318 2001-12-07
PCT/EP2002/013415 WO2003048418A2 (en) 2001-12-07 2002-11-28 Method for pickling martensitic or ferritic high-grade steel

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EP1472388B1 true EP1472388B1 (en) 2011-07-13

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KR (1) KR100926924B1 (en)
AT (1) ATE516386T1 (en)
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ES (1) ES2367424T3 (en)
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102012004907A1 (en) 2012-03-02 2013-09-05 Sms Siemag Ag Pickling standard steels using iron(II)ions containing pickling solution, comprises oxidizing iron(II)ions to iron(III)ions by passing oxygen gas into pickling solution, where passed oxygen is mixed with pickling solution, and is discharged

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4378773B2 (en) * 2005-05-16 2009-12-09 独立行政法人物質・材料研究機構 Stainless steel product manufacturing method and stainless steel product
CA2677753C (en) * 2007-02-12 2016-03-29 Henkel Ag & Co. Kgaa Process for treating metal surfaces
BRPI0921093A2 (en) * 2008-11-14 2015-12-15 Ak Steel Properties Inc ferric pickling of silicon steel.
KR101228730B1 (en) * 2010-12-28 2013-02-01 주식회사 포스코 High Speed Pickling Method for Surface Improvement of High Chromium Ferritic Stainless Cold Steel Strip
KR101289147B1 (en) * 2010-12-28 2013-07-23 주식회사 포스코 Environmental-Friendly and High Speed Pickling Process for Ferritic Stainless Cold Strip with Good Surface Quality
KR101273936B1 (en) * 2011-08-12 2013-06-11 한국과학기술연구원 Ferritic stainless steel with excellent oxidation resistance, manufacturing method thereof and fuel cell interconnector using the same
CN104043651A (en) * 2014-06-20 2014-09-17 甘肃酒钢集团宏兴钢铁股份有限公司 Novel pickling method for ferritic stainless steel black coil and continuous pickling line
JP6008066B2 (en) * 2014-10-08 2016-10-19 新日鐵住金株式会社 Heat-treated steel product having high strength and excellent chemical conversion treatment and method for producing the same
CN114231998A (en) * 2021-12-20 2022-03-25 太原科技大学 Pickling process of ferrite/austenite duplex stainless steel welded pipe

Family Cites Families (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2115005A (en) * 1936-10-15 1938-04-26 Samuel J Blaut Electrochemical treatment of metal
ATE121804T1 (en) * 1985-01-22 1995-05-15 Ugine Sa METHOD FOR ACID PICKLING STEEL, PARTICULARLY STAINLESS STEEL.
IT1245594B (en) 1991-03-29 1994-09-29 Itb Srl PICKLING AND PASSIVATION PROCESS OF STAINLESS STEEL WITHOUT NITRIC ACID
FR2683551B1 (en) * 1991-11-07 1994-09-16 Ugine Sa PROCESS FOR STRIPPING STEEL MATERIALS ON A PROCESSING LINE.
IT1255655B (en) * 1992-08-06 1995-11-09 STAINLESS STEEL PICKLING AND PASSIVATION PROCESS WITHOUT THE USE OF NITRIC ACID
SE504733C2 (en) * 1994-06-17 1997-04-14 Ta Chemistry Ab Pickling procedure
IT1276954B1 (en) * 1995-10-18 1997-11-03 Novamax Itb S R L PICKLING AND PASSIVATION PROCESS OF STAINLESS STEEL WITHOUT THE USE OF NITRIC ACID
DE19543468A1 (en) * 1995-11-22 1997-05-28 Metallgesellschaft Ag Waste water-free special steel pickling process
SE510298C2 (en) * 1995-11-28 1999-05-10 Eka Chemicals Ab Procedure when picking steel
FR2745301B1 (en) * 1996-02-27 1998-04-03 Usinor Sacilor PROCESS FOR STRIPPING A STEEL PART AND PARTICULARLY A STAINLESS STEEL SHEET STRIP
DE69612957T2 (en) 1996-03-14 2001-09-06 Condoroil Impianti S R L Pickling of stainless steel with continuous catalytic oxidation of the pickling solution
IT1282979B1 (en) * 1996-05-09 1998-04-03 Novamax Itb S R L PROCEDURE FOR STEEL PICKLING IN WHICH THE OXIDATION OF THE FERROUS ION IS CARRIED OUT BY ELECTROCHEMISTRY
JPH10324984A (en) * 1997-05-23 1998-12-08 Kurita Water Ind Ltd Acid pickling solution of stainless steel
JP3882866B2 (en) * 1997-12-09 2007-02-21 大同特殊鋼株式会社 Stainless steel descaling method
DE19755350A1 (en) * 1997-12-12 1999-06-17 Henkel Kgaa Process for pickling and passivating stainless steel
JP4045006B2 (en) * 1998-03-16 2008-02-13 株式会社パーカーコーポレーション Stainless steel descaling solution and method of use
GB9807286D0 (en) * 1998-04-06 1998-06-03 Solvay Interox Ltd Pickling process
DE19833990A1 (en) * 1998-07-29 2000-02-10 Metallgesellschaft Ag Mordant for stainless steels
IT1302202B1 (en) * 1998-09-11 2000-07-31 Henkel Kgaa ELECTROLYTIC PICKLING PROCESS WITH SOLUTIONS FREE FROM ACIDONITRICO.
IT1312556B1 (en) * 1999-05-03 2002-04-22 Henkel Kgaa STAINLESS STEEL PICKLING PROCESS IN THE ABSENCE OF ACIDONITRICO AND IN THE PRESENCE OF CHLORIDE IONS
KR100748054B1 (en) 1999-12-30 2007-08-09 헨켈 코만디트게젤샤프트 아우프 악티엔 Brightening/passivating metal surfaces without hazard from emissions of oxides of nitrogen
US6858097B2 (en) * 1999-12-30 2005-02-22 Henkel Kommanditgesellschaft Auf Aktien (Henkel Kgaa) Brightening/passivating metal surfaces without hazard from emissions of oxides of nitrogen
IT1317896B1 (en) * 2000-08-10 2003-07-15 Ct Sviluppo Materiali Spa CONTINUOUS ELECTROLYTIC PICKLING METHOD OF METAL PRODUCTS CONCELLS POWERED BY ALTERNATING CURRENT.
CN1244717C (en) * 2001-04-09 2006-03-08 Ak资产公司 Hydrogen peroxide pickling scheme for stainless steel grades

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102012004907A1 (en) 2012-03-02 2013-09-05 Sms Siemag Ag Pickling standard steels using iron(II)ions containing pickling solution, comprises oxidizing iron(II)ions to iron(III)ions by passing oxygen gas into pickling solution, where passed oxygen is mixed with pickling solution, and is discharged

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ES2367424T3 (en) 2011-11-03
PT1472388E (en) 2011-09-08
WO2003048418A3 (en) 2004-08-26
WO2003048418A2 (en) 2003-06-12
KR20040083468A (en) 2004-10-02
KR100926924B1 (en) 2009-11-17
US7229506B2 (en) 2007-06-12
DE10160318A1 (en) 2003-06-18
ATE516386T1 (en) 2011-07-15
EP1472388A2 (en) 2004-11-03
US20050016634A1 (en) 2005-01-27

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