EP0711849B1 - Process for applying phosphate coatings - Google Patents

Process for applying phosphate coatings Download PDF

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Publication number
EP0711849B1
EP0711849B1 EP95115909A EP95115909A EP0711849B1 EP 0711849 B1 EP0711849 B1 EP 0711849B1 EP 95115909 A EP95115909 A EP 95115909A EP 95115909 A EP95115909 A EP 95115909A EP 0711849 B1 EP0711849 B1 EP 0711849B1
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Prior art keywords
ions
phosphate
workpieces
phosphating
solution
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German (de)
French (fr)
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EP0711849A1 (en
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Klaus-Dieter Nittel
Karl-Heinz Nuss
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Chemetall GmbH
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Metallgesellschaft AG
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    • CCHEMISTRY; METALLURGY
    • C23COATING 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
    • C23CCOATING 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
    • C23C22/00Chemical 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
    • C23C22/05Chemical 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
    • C23C22/06Chemical 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
    • C23C22/34Chemical 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 fluorides or complex fluorides
    • C23C22/36Chemical 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 fluorides or complex fluorides containing also phosphates
    • C23C22/368Chemical 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 fluorides or complex fluorides containing also phosphates containing magnesium cations
    • CCHEMISTRY; METALLURGY
    • C23COATING 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
    • C23CCOATING 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
    • C23C22/00Chemical 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
    • C23C22/05Chemical 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
    • C23C22/06Chemical 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
    • C23C22/07Chemical 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
    • C23C22/08Orthophosphates
    • C23C22/18Orthophosphates containing manganese cations
    • C23C22/188Orthophosphates containing manganese cations containing also magnesium cations

Definitions

  • the invention relates to a method for applying Phosphate coatings on steel workpieces with the help of nickel-free acidic aqueous manganese, phosphate, nitrate and possibly iron (II) ions containing phosphating solutions and the application of Process for the treatment of sliding friction Workpieces.
  • manganese phosphate coatings have become due well proven in their high mechanical resistance. With the manganese phosphate solutions initially used, however, were obtained relatively thick, coarsely crystalline layers, in particular are disadvantageous when fine mechanical parts are treated should. Aiming at thin fine crystalline manganese phosphate coatings generate, numerous proposals have therefore been made. So it is known, for example, by adding condensed Phosphates to obtain a refinement of the phosphate layer.
  • phosphating solutions based on manganese phosphate are used in generally used at high temperatures, so that as a result of high temperatures considerable hydrolysis the effectiveness of condensed phosphates quickly subsides or constantly condensed Phosphate must be added.
  • Nickel as an indispensable part of the phosphating solutions was valid.
  • the advantages of nickel are that the Pickling attack on the base material and therefore in one Improved adhesion of the phosphate layer obtained. Furthermore the content of nickel ions improves the optical appearance of the generated phosphate layer due to a generally desirable Darkening.
  • nickel compounds in the phosphate layers formed in that disadvantages, as nickel and nickel compounds from the perspective of Occupational hygiene and environmental protection can be classified as questionable are.
  • the object of the invention is therefore to provide a method for applying Phosphate coatings on steel workpieces using acidic, aqueous manganese, phosphate, nitrate and possibly iron (II) ions provide phosphating solutions containing the Disadvantages of the known, in particular the aforementioned methods are not has, in particular is nickel-free, but despite being nickel-free Leads phosphate layers, the quality of which is practically those of Phosphating solutions containing nickel ions can be achieved, equals.
  • the above total score is determined by adding 10 ml the phosphating solution after dilution with water to about 50 ml using phenolphthalein as an indicator up to Color change from colorless to red can be titrated. The number of ml 0.1 n sodium hydroxide consumed for this result in the Total points.
  • Other indicators suitable for titration are Thymolphthalein and ortho-cresolphthalein.
  • the electrical Indications with a pH of 8.5 can be used as an end point.
  • the weight ratio Mn: Mg (5 to 50): 1 makes one Maximum layer weight achieved with a minimum of pickling removal.
  • Another advantageous embodiment of the invention provides that Bring workpieces into contact with a phosphating solution that additionally complexing carboxylic acid, such as citric acid or Tartaric acid, in a concentration of 0.1 to 2.0 g / l.
  • a phosphating solution that additionally complexing carboxylic acid, such as citric acid or Tartaric acid, in a concentration of 0.1 to 2.0 g / l.
  • carboxylic acid such as citric acid or Tartaric acid
  • the workpieces come into contact with the phosphating solution preferably at a temperature in the range of 75 to 95 ° C.
  • the workpieces can be made with the phosphating solution in any Be brought into contact, preferred is the immersion treatment.
  • the treatment time is generally 1 to 15 minutes.
  • phosphate coatings with a layer weight of generally 5 to 25 g / m 2 are achieved.
  • the phosphate coatings produced by the invention can in themselves painted in a known manner or provided with plastic coatings will. In conjunction with corrosion protection oils, they are used for Increased rust resistance.
  • the main use case of However, the method according to the invention lies in the treatment of Workpieces that are subject to sliding friction.
  • Gear parts made of steel were first degreased with a strongly alkaline, aqueous cleaner in immersion, then rinsed with water, then rinsed in a slurry of finely divided manganese phosphate and finally phosphated in a phosphating solution at a temperature of 80 ° C. for a period of 10 min in immersion.
  • the phosphating solution contained: 11.8 g / l manganese 0.5 g / l magnesium 0.1 g / l Iron (II) 36 g / l Phosphate (calculated as P 2 O 5 ) 4.6 g / l Nitrate and 0.36 g / l Citrate (calculated as citric acid).
  • the total score of the phosphating solution was 80, the score of free acid 11 points (measured with 60 g concentrate per 1 liter of water). To determine the total number of points, reference is made to the explanations above.
  • 10 ml bath solution after dilution to approx. 50 ml with dist. Titrate water, if necessary with the addition of K 3 (Co (CN) 6 ) or K 4 (Fe (CN) 6 ) to remove interfering metal cations, using dimethyl yellow as an indicator with n / 10 NaOH until it changes from pink to yellow .
  • the ml n / 10 NaOH consumed give the free acid. They are often referred to as the Free Acid Score (FS).
  • FS Free Acid Score

Abstract

A process for applying phosphate coatings to steel workpieces involves contacting the workpieces with a nickel-free soln. contg. 2-20 g/l. Mn ions, 0.2-4 g/l Mg ions, up to 12 g/l Fe(II) ions, 5-50 g/l phosphate ions (calculated as P2O5) and 1-20 g/l nitrate ions, the phosphating soln. having a total points number of 20-150 and a Mn:Mg wt. ratio of 5-50:1.

Description

Die Erfindung betrifft ein Verfahren zum Aufbringen von Phosphatüberzügen auf Werkstücke aus Stahl mit Hilfe von nickelfreien sauren, wäßrigen Mangan-, Phosphat-, Nitrat- und ggf. Eisen(II)-Ionen enthaltenden Phosphatierungslösungen sowie die Anwendung des Verfahrens zur Behandlung von einer gleitenden Reibung ausgesetzten Werkstücken.The invention relates to a method for applying Phosphate coatings on steel workpieces with the help of nickel-free acidic aqueous manganese, phosphate, nitrate and possibly iron (II) ions containing phosphating solutions and the application of Process for the treatment of sliding friction Workpieces.

Für verschiedene Anwendungszwecke, z.B. die Verminderung der Reibung aufeinandergleitender Metallflächen oder die Erleichterung der Kaltumformung von Metallen, haben sich Manganphosphatüberzüge wegen ihrer hohen mechanischen Beständigkeit gut bewährt. Mit den anfänglich gebräuchlichen Manganphosphatlösungen erhielt man jedoch verhältnismäßig dicke, grobkristalline Schichten, die insbesondere dann nachteilig sind, wenn feinmechanische Teile behandelt werden sollen. Mit dem Ziel, dünne feinkristalline Manganphosphatüberzüge zu erzeugen, sind daher zahlreiche Vorschläge unterbreitet worden. So ist es beispielsweise bekannt, durch Zusatz von kondensierten Phosphaten eine Verfeinerung der Phosphatschicht zu erhalten. Phosphatierungslösungen auf Basis Manganphosphat werden jedoch im allgemeinen bei hohen Temperaturen eingesetzt, so daß infolge der bei hohen Temperaturen beträchtlichen Hydrolyse die Wirksamkeit der kondensierten Phosphate schnell nachläßt bzw. ständig kondensiertes Phosphat nachdosiert werden muß. For various purposes, e.g. the reduction in friction superimposed metal surfaces or the relief of Cold forming of metals, manganese phosphate coatings have become due well proven in their high mechanical resistance. With the manganese phosphate solutions initially used, however, were obtained relatively thick, coarsely crystalline layers, in particular are disadvantageous when fine mechanical parts are treated should. Aiming at thin fine crystalline manganese phosphate coatings generate, numerous proposals have therefore been made. So it is known, for example, by adding condensed Phosphates to obtain a refinement of the phosphate layer. However, phosphating solutions based on manganese phosphate are used in generally used at high temperatures, so that as a result of high temperatures considerable hydrolysis the effectiveness of condensed phosphates quickly subsides or constantly condensed Phosphate must be added.

Einen anderen Weg beschreibt die deutsche Auslegeschrift 1 109 484, um zu feinkörnigen Phosphatüberzügen zu gelangen. Danach werden nitrathaltige Phosphatlösungen eingesetzt, bei denen die Nitratmenge die Phosphatmenge übersteigt. Die Lösungen sollen ein Verhältnis von Nitrat zu Phosphat von etwa (1,5 bis 4,5) : 1 aufweisen. Es zeigte sich jedoch, daß in vielen Fällen die beabsichtigte Wirkung nicht erzielt wird.Another way describes the German Auslegeschrift 1 109 484, to get to fine-grained phosphate coatings. After that nitrate-containing phosphate solutions are used, in which the amount of nitrate the amount of phosphate exceeds. The solutions are said to have a ratio of Have nitrate to phosphate of about (1.5 to 4.5): 1. It showed however, that in many cases the intended effect is not is achieved.

Weiterhin ist ein Verfahren bekannt, bei dem gezielt mit einem überhöhten Anteil an freier Säure in der Phosphatierungslösung gearbeitet wird, um besonders dünne Schichten zu erzeugen (DE-C-12 46 356). Diese Schichten sind jedoch wegen ihres niedrigen Flächengewichtes nur für Spezialfälle praktisch anwendbar.Furthermore, a method is known in which a specific excessive amount of free acid in the phosphating solution is worked to produce particularly thin layers (DE-C-12 46 356). However, these layers are because of their low Basis weight practically only applicable for special cases.

Schließlich ist es bekannt, einer Phosphatierungslösung auf Basis Manganphosphat bzw. Mangan-Eisenphosphat, bei der die Konzentrationen hinsichtlich Mangan-, Eisen(II)-, Phosphat- und Nitrat-Ionen innerhalb bestimmter Grenzen liegen, mehr freies P2O5 im Verhältnis zum Gesamt-P2O5 zuzuführen als dem Phosphatierungsgleichgewicht in der arbeitenden Phosphatierungslösung entspricht. Durch die vorgenannte Maßnahme soll als Vorteil erzielt werden, daß eine deutliche Verminderung des bei der Phosphatierung gebildeten Schlammes und eine Herabsetzung der zur Erzeugung einer bestimmten Überzugsmenge erforderlichen Chemikalien erzielt wird (DE-B-22 13 781).Finally, it is known that a phosphating solution based on manganese phosphate or manganese iron phosphate, in which the concentrations with respect to manganese, iron (II), phosphate and nitrate ions are within certain limits, more free P 2 O 5 in relation to Total P 2 O 5 to be supplied as the phosphating equilibrium in the working phosphating solution. The above measure is said to have the advantage that a significant reduction in the sludge formed in the phosphating and a reduction in the chemicals required to produce a certain amount of coating is achieved (DE-B-22 13 781).

In der Praxis war den vorstehend referierten Verfahren gemeinsam, daß Nickel als unverzichtbarer Bestandteil der Phosphatierungslösungen galt. Die Vorteile von Nickel bestehen in einer Vergleichmäßigung des Beizangriffes auf das Grundmaterial und dadurch bedingt in einer Haftungsverbesserung der erhaltenen Phosphatschicht. Außerdem verbessert der Gehalt an Nickel-Ionen das optische Aussehen der erzeugten Phosphatschicht infolge einer im allgemeinen erwünschten Dunkelfärbung.In practice, the methods discussed above had in common that Nickel as an indispensable part of the phosphating solutions was valid. The advantages of nickel are that the Pickling attack on the base material and therefore in one Improved adhesion of the phosphate layer obtained. Furthermore the content of nickel ions improves the optical appearance of the generated phosphate layer due to a generally desirable Darkening.

Der Nickelgehalt in den Phosphatierungslösungen und von Nickel bzw. Nickelverbindungen in den gebildeten Phosphatschichten bringt jedoch insofern Nachteile, als Nickel und Nickelverbindungen aus Sicht der Arbeitsplatzhygiene und des Umweltschutzes als bedenklich einzustufen sind.The nickel content in the phosphating solutions and of nickel or However, nickel compounds in the phosphate layers formed in that disadvantages, as nickel and nickel compounds from the perspective of Occupational hygiene and environmental protection can be classified as questionable are.

Es ist daher in den Dokumenten WO-A-94/14999, WO-A-90/15889 und EP-A-459 541 vorgeschlagen worden, auf einen Nickelzusatz gänzlich zu verzichten oder diesen möglichst niedrig zu halten. Die in den genannten Dokumenten beschriebenen nickelfreien Phosphatierungslösungen, die Zink-, Mangan-, Magnesium-, Phosphat- und Nitrat-Ionen enthalten, und Phosphatierverfahren bezwecken die Erzeugung von Zinkphosphatüberzügen entsprechend der Niedrigzink-Technologie. It is therefore in documents WO-A-94/14999, WO-A-90/15889 and EP-A-459 541 has been proposed to add nickel entirely waive or keep it as low as possible. The in the described nickel-free phosphating solutions described above, which contain zinc, manganese, magnesium, phosphate and nitrate ions, and Phosphating processes are used to produce Zinc phosphate coatings according to the Low zinc technology.

Aufgabe der Erfindung ist es daher, ein Verfahren zum Aufbringen von Phosphatüberzügen auf Werkstücke aus Stahl mit Hilfe von sauren, wäßrigen Mangan-, Phosphat-, Nitrat- und ggf. Eisen(II)-Ionen enthaltenden Phosphatierungslösungen bereitzustellen, das die Nachteile der bekannten, insbesondere vorgenannten Verfahren nicht aufweist, insbesondere nickelfrei ist, jedoch trotz Nickelfreiheit zu Phosphatschichten führt, deren Qualität praktisch denen, die mit Nickel-Ionen enthaltenden Phosphatierungslösungen erzielt werden, gleichkommt.The object of the invention is therefore to provide a method for applying Phosphate coatings on steel workpieces using acidic, aqueous manganese, phosphate, nitrate and possibly iron (II) ions provide phosphating solutions containing the Disadvantages of the known, in particular the aforementioned methods are not has, in particular is nickel-free, but despite being nickel-free Leads phosphate layers, the quality of which is practically those of Phosphating solutions containing nickel ions can be achieved, equals.

Die Aufgabe wird gelöst, indem das Verfahren der eingangs genannten Art entsprechend der Erfindung in der Weise ausgebildet wird, daß man die Werkstücke mit einer Lösung in Kontakt bringt, die, 2 bis 20 g/l Mangan-Ionen 0,2 bis 4 g/l Magnesium-Ionen bis 12 g/l Eisen(II)-Ionen 5 bis 50 g/l Phosphat-Ionen (berechnet als P2O5) und 1 bis 20 g/l Nitrat-Ionen enthält, eine Gesamtpunktezahl von 20 bis 150 aufweist und in der das Gewichtsverhältnis
Mn : Mg = (5 bis 50) : 1 beträgt.
The object is achieved by designing the method of the type mentioned at the outset in accordance with the invention in such a way that the workpieces are brought into contact with a solution which 2 to 20 g / l Manganese ions 0.2 to 4 g / l Magnesium ions up to 12 g / l Iron (II) ions 5 to 50 g / l Phosphate ions (calculated as P 2 O 5 ) and 1 to 20 g / l Nitrate ions contains, has a total score of 20 to 150 and in which the weight ratio
Mn: Mg = (5 to 50): 1.

Die vorstehend genannte Gesamtpunktezahl wird ermittelt, indem 10 ml der Phosphatierungslösung nach Verdünnung mit Wasser auf etwa 50 ml unter Verwendung von Phenolphthalein als Indikator bis zum Farbumschlag von farblos nach rot titriert werden. Die Anzahl der hierfür verbrauchten ml 0,1 n Natronlauge ergeben die Gesamtpunktezahl. Andere für die Titration geeignete Indikatoren sind Thymolphthalein und ortho-Kresolphthalein. Ferner ist die elektrische Indikation mit einem pH-Wert von 8,5 als Endpunkt anwendbar. The above total score is determined by adding 10 ml the phosphating solution after dilution with water to about 50 ml using phenolphthalein as an indicator up to Color change from colorless to red can be titrated. The number of ml 0.1 n sodium hydroxide consumed for this result in the Total points. Other indicators suitable for titration are Thymolphthalein and ortho-cresolphthalein. Furthermore, the electrical Indications with a pH of 8.5 can be used as an end point.

Durch das Gewichtsverhältnis Mn : Mg = (5 bis 50) : 1 wird ein Maximum an Schichtgewicht bei einem Minimum an Beizabtrag erzielt.The weight ratio Mn: Mg = (5 to 50): 1 makes one Maximum layer weight achieved with a minimum of pickling removal.

Eine weitere vorteilhafte Ausgestaltung der Erfindung sieht vor, die Werkstücke mit einer Phosphatierungslösung in Kontakt zu bringen, die zusätzlich komplexierend wirkende Carbonsäure, wie Zitronensäure oder Weinsäure, in einer Konzentration von 0,1 bis 2,0 g/l enthält. Der Komplexbildnerzusatz verhindert insbesondere eine Trübung der Phosphatierungslösung. Der Kontakt der Werkstücke mit der Phosphatierungslösung erfolgt vorzugsweise bei einer Temperatur im Bereich von 75 bis 95°C.Another advantageous embodiment of the invention provides that Bring workpieces into contact with a phosphating solution that additionally complexing carboxylic acid, such as citric acid or Tartaric acid, in a concentration of 0.1 to 2.0 g / l. Of the Complexing agent in particular prevents clouding of the Phosphating solution. The workpieces come into contact with the phosphating solution preferably at a temperature in the range of 75 to 95 ° C.

Die Werkstücke können mit der Phosphatierungslösung in beliebiger Weise in Kontakt gebracht werden, bevorzugt ist die Tauchbehandlung. Als Behandlungsdauer sind im allgemeinen 1 bis 15 min angemessen.The workpieces can be made with the phosphating solution in any Be brought into contact, preferred is the immersion treatment. The treatment time is generally 1 to 15 minutes.

In der Regel ist es erforderlich, die Werkstücke vor der Phosphatierung zu reinigen. Hierzu dienen saure, neutrale oder alkalische Reiniger. Im allgemeinen wird zwischen der Reinigung der Werkstücke und der Phosphatierung gründlich mit Wasser gespült. Insbesondere nach einer Behandlung mit Alkalien und Säuren sollten die Werkstücke in einer wäßrigen Aufschlämmung von feinverteiltem Manganphosphat vorgespült werden, um bei der anschließenden Phosphatierung die Ausbildung besonders gleichmäßiger feinkristalliner Schichten zu fördern. Der Effekt ist bei der Phosphatierung in Phosphatierungslösung, die neben Mangan- auch Eisen(II)-Ionen enthalten, besonders ausgeprägt.As a rule, it is necessary to place the workpieces before the To clean phosphating. Acid, neutral or alkaline cleaner. In general, between cleaning the Workpieces and phosphating thoroughly rinsed with water. Especially after treatment with alkalis and acids the workpieces in an aqueous slurry of finely divided Manganese phosphate can be pre-rinsed at the subsequent Phosphating the training particularly evenly to promote fine crystalline layers. The effect is with the Phosphating in phosphating solution, which in addition to manganese Contain iron (II) ions, particularly pronounced.

Mit Hilfe des erfindungsgemäßen Verfahrens werden Phosphatüberzüge mit einem Schichtgewicht von im allgemeinen 5 bis 25 g/m2 erzielt.With the aid of the method according to the invention, phosphate coatings with a layer weight of generally 5 to 25 g / m 2 are achieved.

Überraschenderweise hat sich gezeigt, daß der Einsatz von Magnesium-Ionen enthaltenden Phosphatierungslösungen entsprechend dem erfindungsgemäßen Verfahren nicht nur zu Phosphatschichten führt, die hinsichtlich ihrer Qualität den mit Nickel-Ionen enthaltenden Phosphatierungslösungen erzielten Phosphatschichten gleichkommen, sondern daß sich der Gehalt an Magnesium-Ionen verbrauchsmindernd hinsichtlich des gesamten Chemikalienverbrauchs auswirkt.Surprisingly, it has been shown that the use of Phosphating solutions containing magnesium ions corresponding to the The inventive method not only leads to phosphate layers that in terms of their quality, those containing nickel ions Phosphating solutions are equivalent to phosphate layers, but that the content of magnesium ions reduces consumption in terms of total chemical consumption.

Die mit der Erfindung erzeugten Phosphatüberzüge können in an sich bekannter Weise lackiert oder mit Kunststoffüberzügen versehen werden. In Verbindung mit Korrosionsschutzölen dienen sie zur Erhöhung der Rostbeständigkeit. Der Hauptanwendungsfall des erfindungsgemäßen Verfahrens liegt jedoch in der Behandlung von Werkstücken, die einer gleitenden Reibung ausgesetzt werden.The phosphate coatings produced by the invention can in themselves painted in a known manner or provided with plastic coatings will. In conjunction with corrosion protection oils, they are used for Increased rust resistance. The main use case of However, the method according to the invention lies in the treatment of Workpieces that are subject to sliding friction.

Die Erfindung wird anhand des folgenden Beispiels näher und beispielsweise erläutert.The invention is illustrated in the following example and for example explained.

Beispielexample

Getriebeteile aus Stahl wurden zunächst mit einem stark alkalischen, wäßrigen Reiniger im Tauchen entfettet, anschließend mit Wasser gespült, danach in einer Aufschlämmung von feinverteiltem Manganphosphat vorgespült und schließlich in einer Phosphatierungslösung einer Temperatur von 80°C für die Dauer von 10 min im Tauchen phosphatiert. Die Phosphatierungslösung enthielt: 11,8 g/l Mangan 0,5 g/l Magnesium 0,1 g/l Eisen (II) 36 g/l Phosphat (berechnet als P2O5) 4,6 g/l Nitrat und 0,36 g/l Citrat (berechnet als Zitronensäure). Gear parts made of steel were first degreased with a strongly alkaline, aqueous cleaner in immersion, then rinsed with water, then rinsed in a slurry of finely divided manganese phosphate and finally phosphated in a phosphating solution at a temperature of 80 ° C. for a period of 10 min in immersion. The phosphating solution contained: 11.8 g / l manganese 0.5 g / l magnesium 0.1 g / l Iron (II) 36 g / l Phosphate (calculated as P 2 O 5 ) 4.6 g / l Nitrate and 0.36 g / l Citrate (calculated as citric acid).

Die Gesamtpunktezahl der Phosphatierungslösung betrug 80, die Punktezahl der Freien Säure 11 Punkte (gemessen mit 60 g Konzentrat pro 1 l Wasser). Zur Bestimmung der Gesamtpunktezahl wird auf die obigen Ausführungen verwiesen. Zur Bestimmung der Freien Säure werden 10 ml Badlösung nach Verdünnung auf ca. 50 ml mit dest. Wasser, ggf. unter Zusatz von K3(Co(CN)6) oder K4(Fe(CN)6) zwecks Beseitigung störender Metallkationen, unter Verwendung von Dimethylgelb als Indikator mit n/10 NaOH bis zum Umschlag von Rosa nach Gelb titriert. Die verbrauchten ml n/10 NaOH ergeben die Freie Säure. Sie werden vielfach auch als Punktezahl der Freien Säure bezeichnet (FS).
   1 ml 0,1 n Natronlauge _ and 7,098 mg freies P2O5.
The total score of the phosphating solution was 80, the score of free acid 11 points (measured with 60 g concentrate per 1 liter of water). To determine the total number of points, reference is made to the explanations above. To determine the free acid, 10 ml bath solution after dilution to approx. 50 ml with dist. Titrate water, if necessary with the addition of K 3 (Co (CN) 6 ) or K 4 (Fe (CN) 6 ) to remove interfering metal cations, using dimethyl yellow as an indicator with n / 10 NaOH until it changes from pink to yellow . The ml n / 10 NaOH consumed give the free acid. They are often referred to as the Free Acid Score (FS).
1 ml 0.1 N sodium hydroxide solution and 7.098 mg free P 2 O 5 .

Zum Ansatz der Phosphatierungslösung diente ein Konzentrat, das 6,39 Gew.-% Mangan, 0,27 Gew.-% Magnesium, 0,05 Gew.-% Eisen(II), 19,8 Gew.-% Phosphat (berechnet als P2O5), 2,52 Gew.-% Nitrat und 0,197 Gew.-% Citrat (berechnet als Zitronensäure) enthielt. Im Anschluß an die Phosphatierbehandlung wurde erneut mit Wasser gespült und abschließend getrocknet. Es wurden feinkörnige, gleichmäßig deckende Phosphatüberzüge hoher Flächendichte von dunkler Farbe erhalten. Sie entsprachen in ihrer Qualität mindestens denen, die mit nickelhaltigen Phosphatierungslösungen erhalten werden. Das Schichtgewicht lag bei 10 g/m2.A concentrate containing 6.39% by weight of manganese, 0.27% by weight of magnesium, 0.05% by weight of iron (II), 19.8% by weight of phosphate (calculated as P 2 O 5 ), 2.52% by weight of nitrate and 0.197% by weight of citrate (calculated as citric acid). Following the phosphating treatment, it was rinsed again with water and finally dried. Fine-grained, uniformly covering phosphate coatings of high surface density and dark color were obtained. Their quality corresponded at least to those obtained with phosphating solutions containing nickel. The layer weight was 10 g / m 2 .

Im Zusammenwirken mit der üblichen Ölbehandlung besaßen die Getriebeteile hervorragende Einlaufeigenschaften.In cooperation with the usual oil treatment they had Gear parts have excellent running-in properties.

Claims (5)

  1. A method for the application of phosphate coatings to steel workpieces with the aid of nickel-free, acidic, aqueous phosphating solutions containing manganese, magnesium, phosphate, nitrate and optionally iron(II) ions, characterised in that the workpieces are brought into contact with a solution which contains 2 to 20 g/l manganese ions 0.2 to 4 g/l magnesium ions up to 12 g/l iron(II) ions 5 to 50 g/l phosphate ions (calculated as P2O5) and 1 to 20 g/l nitrate ions,
    has a total point number of 20 to 150 and in which the weight ratio Mn : Mg = (5 to 50) : 1.
  2. A method according to Claim 1, characterised in that the workpieces are brought into contact with a solution which additionally contains complexing carboxylic acid in a concentration of 0.1 to 2.0 g/l.
  3. A method according to Claim 2, characterised in that the workpieces are brought into contact with a solution which contains citric acid and/or tartaric acid as complexing carboxylic acid.
  4. A method according to one or more of Claims 1 to 3, characterised in that the workpieces are brought into contact with a solution which is at a temperature of 75 to 95°C.
  5. Application of the method according to one or more of Claims 1 to 4 to the treatment of workpieces which are subjected to sliding friction.
EP95115909A 1994-11-11 1995-10-10 Process for applying phosphate coatings Expired - Lifetime EP0711849B1 (en)

Applications Claiming Priority (2)

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DE4440300 1994-11-11
DE4440300A DE4440300A1 (en) 1994-11-11 1994-11-11 Process for applying phosphate coatings

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EP0711849B1 true EP0711849B1 (en) 1998-01-14

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CN102094196A (en) * 2011-03-24 2011-06-15 上海奉贤钢管厂 Process for parkerising internal surface of long thin steel tube with manganese phosphate
WO2018202859A1 (en) 2017-05-05 2018-11-08 Federal-Mogul Nürnberg GmbH Thermal insulation of a steel piston by means of a manganese phosphate layer and a sealing layer on the basis of polysilazane, waterglass or polysiloxane

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Publication number Priority date Publication date Assignee Title
US5728235A (en) * 1996-02-14 1998-03-17 Henkel Corporation Moderate temperature manganese phosphate conversion coating composition and process
US20040221924A1 (en) 1999-09-30 2004-11-11 Klaus-Dieter Nittel Method for applying manganese phosphate layers
DE19947232A1 (en) * 1999-09-30 2001-04-05 Chemetall Gmbh Process for applying manganese phosphate layers
JP3872621B2 (en) * 1999-11-05 2007-01-24 新日本製鐵株式会社 Galvanized steel sheet for automobile bodies
CN109609942B (en) * 2018-12-28 2020-12-04 湖南金化科技集团有限公司 Manganese-magnesium phosphating solution

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DE2213718C3 (en) * 1972-03-21 1975-12-18 8641 Unterrodach Switching device
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EP0675972B1 (en) * 1992-12-22 1999-08-11 Henkel Corporation Substantially nickel-free phosphate conversion coating composition and process

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CN102094196A (en) * 2011-03-24 2011-06-15 上海奉贤钢管厂 Process for parkerising internal surface of long thin steel tube with manganese phosphate
CN102094196B (en) * 2011-03-24 2012-07-04 上海奉贤钢管厂 Process for parkerising internal surface of long thin steel tube with manganese phosphate
WO2018202859A1 (en) 2017-05-05 2018-11-08 Federal-Mogul Nürnberg GmbH Thermal insulation of a steel piston by means of a manganese phosphate layer and a sealing layer on the basis of polysilazane, waterglass or polysiloxane

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ATE162232T1 (en) 1998-01-15
DE59501279D1 (en) 1998-02-19
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ES2112593T3 (en) 1998-04-01
DK0711849T3 (en) 1998-03-16
DE4440300A1 (en) 1996-05-15

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