EP0045110B1 - Method for the production of phosphate coatings on iron and steel surfaces, and its use - Google Patents

Method for the production of phosphate coatings on iron and steel surfaces, and its use Download PDF

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Publication number
EP0045110B1
EP0045110B1 EP81200830A EP81200830A EP0045110B1 EP 0045110 B1 EP0045110 B1 EP 0045110B1 EP 81200830 A EP81200830 A EP 81200830A EP 81200830 A EP81200830 A EP 81200830A EP 0045110 B1 EP0045110 B1 EP 0045110B1
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Prior art keywords
weight
solution
iron
ratio
contact
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EP81200830A
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German (de)
French (fr)
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EP0045110A1 (en
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Kevin Brown
Jon Darby
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Chemetall Ltd
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Metallgesellschaft AG
Continentale Parker Ste
Continentale Parker SA
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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
    • 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
    • C23C22/34—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 fluorides or complex fluorides
    • C23C22/36—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 fluorides or complex fluorides containing also phosphates
    • C23C22/362—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 fluorides or complex fluorides containing also phosphates containing also zinc cations
    • 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
    • C23C22/12—Orthophosphates containing zinc cations
    • C23C22/14—Orthophosphates containing zinc cations containing also chlorate anions
    • 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
    • C23C22/22—Orthophosphates containing alkaline earth metal cations

Definitions

  • the invention relates to a process for the production of phosphate coatings on iron or steel surfaces by immersion or flooding with an aqueous acidic zinc phosphate solution and its application to the preparation of metal surfaces for cold forming.
  • phosphate coatings on metal surfaces in particular from iron and steel, by treatment with a zinc phosphate solution is generally common.
  • one or more oxidizing agents are added to the phosphating solution.
  • phosphating processes uses phosphating solutions which contain oxidizing agents which convert iron (II) to iron (III), so that insoluble iron phosphate is formed. With increasing throughput on the surface, considerable amounts of sludge then arise, which are physically removed. In some processes, however, the physical removal of sludge is difficult or difficult to carry out, so that it is more advantageous to conduct the phosphating process in such a way that practically no or only a little sludge is formed.
  • the phosphating solution is formulated from chemicals that do not convert the iron that is in solution into the trivalent state. This can be achieved, for example, by using nitrate or similarly weak oxidizing agents as accelerators.
  • urea is to be added to the phosphating bath, as a result of which the temperature during the phosphating can be increased without risking significantly increased sludge formation. Accelerated phosphate layer formation is also associated with this.
  • the other disadvantages mentioned above also remain here.
  • heating of the phosphating solution which is not per se energy-wasting, is required.
  • attempts have been made to solve the sludge problem by increasing its solids content and consequently reducing the amount of sludge (GB-PS 1 555 529).
  • the metal surfaces are treated with a solution which contains at least 6 g / 1 Zn, 5 g / IP 2 O 5 , 1 g / l C10 3 and 8 g / l NO 3 .
  • the ratio P 2 O 5 : Zn should be in the range of 1: (0.8--4).
  • the object of the invention is to provide a process for producing phosphate coatings on iron or steel surfaces which does not have the known, in particular the aforementioned disadvantages, and is simple to carry out without additional chemicals and without sacrificing layer quality.
  • the object is achieved by carrying out the method of the type mentioned at the outset in accordance with the invention in such a way that the surfaces are brought into contact with a solution which contains at least 0.3% by weight of Zn and at least 0.3% by weight of PO 4 and contains at least 0.75% by weight of NO 3 or a similarly acting iron (II) non-oxidizing accelerator, in which the weight ratio Zn: P0 4 is greater than 0.8, the ratio of total acid to free acid is at least 5 and in which an iron (II) content of 0.05 to 1% by weight is set by suitable dimensioning of ClO 3 or an accelerator which oxidizes iron (II) to iron (III).
  • a solution which contains at least 0.3% by weight of Zn and at least 0.3% by weight of PO 4 and contains at least 0.75% by weight of NO 3 or a similarly acting iron (II) non-oxidizing accelerator, in which the weight ratio Zn: P0 4 is greater than 0.8, the ratio of total acid to free acid is at least 5 and in which an iron (II
  • An advantageous embodiment of the invention consists in bringing the surface into contact with a solution which contains a maximum of 2.2% by weight of Zn, max. 2.2% by weight PO 4 and max. Contains 5.5% by weight of NO 3 or an accelerator with the same effect, in which the weight ratio Zn: PO 4 is less than 4 and the ratio of total acid to free acid is max. 30.
  • a treatment solution should preferably be used which contains 0.3 to 1% by weight of Zn, 0.3 to 1% by weight of PO 4 and 1 to 3% by weight of NO 3 or an accelerator with the same effect, in which the Weight ratio Zn: P0 4 0.8 to 2, in particular 0.8 to 1.4 and which is a ratio of total acid to free acid of max. 15, in particular 7 to 12, and in which one by suitable dimensioning of chlorate or an equivalent accelerator sets an iron (II) content of 0.08 to 0.5, in particular up to 0.2,% by weight.
  • nitroguanidine is also suitable, for example.
  • the expenditure of chlorate or an iron (II) which has the same effect as iron (III) oxidizing accelerator is such that its concentration in the treatment solution is generally less than 0.1% by weight (calc ClO 3 ). Higher doses cause the iron (II) content to be too low and considerable sludge formation occurs.
  • chlorate content or an equivalent accelerator is set to concentrations below 0.05% by weight, preferably below 0.035% by weight (calculated as CI0 3 ).
  • CI0 3 concentrations below 0.05% by weight
  • Optimal results are obtained at concentrations in the range of 0.001 to 0.035% by weight (calculated as ClO 3 ).
  • the phosphating bath e.g. does not contain any iron (II) ions in the starting phase. It is therefore not necessary to add the iron (II) oxidizing accelerator at this point. It is also not necessary to meter this accelerator continuously. It can also be introduced with the chemicals that are usually added to the bath supplement.
  • a further development of the method provides for the surfaces to be brought into contact with a solution which additionally contains calcium in quantities of 0.01 to 0.88% by weight, preferably 0.15 to 0.5% by weight.
  • the weight ratio Zn: Ca should be 1.5 to 4. Best results are achieved with a ratio of 2.5.
  • the phosphating solution can also contain other additives which are customary for zinc phosphating solutions, such as copper, cobalt, nickel, simple or complex fluoride. When dosing with fluoride, make sure that no calcium fluoride fails. Magnesium can partially or completely replace calcium.
  • urea can be added to the phosphating solution.
  • the surfaces to be brought into contact with the method according to the invention must be free of rust and scale and should therefore first be pickled with mineral acid, such as hydrochloric or sulfuric acid, and then rinsed with water. Depending on the level of contamination, degreasing or other treatment can also be carried out to clean the surfaces, for example with an organic solvent or an alkaline cleaner, followed by a water rinse.
  • mineral acid such as hydrochloric or sulfuric acid
  • the cleaned surfaces can be subjected to an activation treatment, e.g. B. by hot water rinsing or with a titanium orthophosphate dispersion.
  • an activation treatment e.g. B. by hot water rinsing or with a titanium orthophosphate dispersion.
  • the dipping or flooding of the surfaces which, in contrast to spraying, largely avoids sludge formation due to oxidation by atmospheric oxygen, is carried out according to a preferred embodiment of the process according to the invention at a temperature of 35 to 98 ° C., preferably 55 to 85 ° C.
  • the duration of the Contact between the surface and the phosphating solution is preferably in the range from 5 to 15 minutes.
  • the phosphate coating After the phosphate coating has been formed, it can be rinsed with cold water and treated with a passivating rinse solution. There can also be a lubricant coating on the Phosphate layer can be applied.
  • the method according to the invention has proven particularly useful as a preparation for non-cutting cold forming. However, it is also advantageous in the other fields of application of phosphating, e.g. for corrosion protection, to facilitate sliding friction and for electrical insulation.
  • a phosphating solution was prepared from a batch concentrate which contained and had a ratio of total acid to free acid of 7. The dilution was carried out in the ratio of one part of concentrate to 20 parts of water.
  • Wire was immersed in the phosphating bath kept at a temperature of 70 ° C. After a contact time of 10 minutes, the wire was removed, rinsed with water, provided with a lubricant coating and pulled in the usual way.
  • the phosphating bath could be kept practically constant at concentrations of being held.
  • the ratio of total acid to free acid was 8.7.
  • the process could be operated for a long time with only a small amount of sludge.

Abstract

Phosphate coatings are formed on ferrous surfaces by dipping or flooding the surfaces with an acidic zinc phosphate solution containing a high zinc content, nitrate or other oxidising agent incapable of oxidising ferrous to ferric and a low controlled amount of chlorate or other oxidising agent capable of oxidising ferrous to ferric such that the solution contains 0.05 to 1% dissolved iron. This process can be achieved but using novel replenishment and make up solutions. The initial make up solution may be free of chlorate but the replenishment solution will contain a low amount of chlorate or other suitable oxidising agent. The phosphating solution preferably has a zinc/phosphate ratio in the range 0.8-4, a Zn/Ca ratio of 1-4 and a total acid/free acid ratio of 5-9. Use of the solution gives rise to reduced sludge production. The solution may contain conventional additives such as Cu, Co, Ni, fluorides, urea. The surfaces to be treated may first be pickled, degreased then preactivated with either hot water or a titanium ortho- phosphate dispersion.

Description

Die Erfindung betrifft ein Verfahren zur Herstellung von Phosphatüberzügen auf Eisen- oder Stahloberflächen im Tauch- oder Flutverfahren mit einer wäßrigen sauren Zinkphosphatlösung sowie dessen Anwendung auf die Vorbereitung von Metalloberflächen für die Kaltverformung.The invention relates to a process for the production of phosphate coatings on iron or steel surfaces by immersion or flooding with an aqueous acidic zinc phosphate solution and its application to the preparation of metal surfaces for cold forming.

Die Herstellung von Phosphatüberzügen auf Metalloberflächen, insbesondere aus Eisen und Stahl, durch Behandlung mit einer Zinkphosphatlösung ist generell üblich. Zur Beschleunigung der Phosphatschichtausbildung werden dabei der Phosphatierungslösung ein oder mehrere Oxidationsmittel zugesetzt.The production of phosphate coatings on metal surfaces, in particular from iron and steel, by treatment with a zinc phosphate solution is generally common. To accelerate the formation of the phosphate layer, one or more oxidizing agents are added to the phosphating solution.

Ein besonderes Problem, das sich bei der Herstellung von Phosphatüberzügen auf Eisen- und Stahloberflächen stellt, ist die mit der Phosphatierung verbundene Auflösung von Eisen, das in Form von Eisen(II)ionen in Lösung geht.A particular problem that arises in the production of phosphate coatings on iron and steel surfaces is the dissolution of iron associated with phosphating, which dissolves in the form of iron (II) ions.

Bei einer Kategorie von Phosphatierverfahren arbeitet man mit Phosphatierungslösungen, die Eisen(II) in Eisen(III) überführende Oxidationsmittel enthalten, so daß unlösliches Eisenphosphat gebildet wird. Mit zunehmendem Durchsatz an Oberfläche entstehen dann erhebliche Schlammengen, die physikalisch entfernt werden. Bei einigen Verfahren bereitet jedoch die physikalische Schlammentfernung Schwierigkeiten bzw. ist schwer durchführbar, so daß es vorteilhafter ist, das Phosphatierverfahren so zu leiten, daß praktisch kein oder nur wenig Schlamm gebildet wird.One category of phosphating processes uses phosphating solutions which contain oxidizing agents which convert iron (II) to iron (III), so that insoluble iron phosphate is formed. With increasing throughput on the surface, considerable amounts of sludge then arise, which are physically removed. In some processes, however, the physical removal of sludge is difficult or difficult to carry out, so that it is more advantageous to conduct the phosphating process in such a way that practically no or only a little sludge is formed.

Bei dieser Kategorie von Phosphatierverfahren, die »auf der Eisenseite« arbeiten, wird die Phophatierlösung aus Chemikalien formuliert, die das in Lösung gehende Eisen nicht in den dreiwertigen Zustand überführen. Dies gelingt beispielsweise durch Verwendung von Nitrat oder ähnlich schwachen Oxidationsmitteln als Beschleuniger.In this category of phosphating processes that work "on the iron side", the phosphating solution is formulated from chemicals that do not convert the iron that is in solution into the trivalent state. This can be achieved, for example, by using nitrate or similarly weak oxidizing agents as accelerators.

Obgleich bei den »auf der Eisenseite« arbeitenden Phosphatierverfahren die Schlammbildung weitgehend unterdrückt ist, haften ihnen andere Nachteile an. So ist infolge Abwesenheit starker Oxidationsmittel die Phosphatschichtausbildung langsam. Durch die Anreicherung von Eisen(II)phosphat in der Lösung kann zudem der Anteil des Eisenphosphats in der gebildeten Phosphatschicht unerwünscht hoch werden. Auch neigen die gebildeten Phosphatschichten zur Grobkörnigkeit. Es hat nicht an Versuchen gefehlt, die verschiedenartigsten Probleme auszuräumen.Although sludge formation is largely suppressed in the phosphating processes that work on the iron side, they have other disadvantages. Due to the absence of strong oxidizing agents, the formation of the phosphate layer is slow. The enrichment of iron (II) phosphate in the solution can also make the proportion of iron phosphate in the phosphate layer undesirably high. The phosphate layers formed also tend to be coarse. There has been no shortage of attempts to solve a wide variety of problems.

Aus der GB-PS 932 987 ist es bekannt, die Metalloberflächen vor der Phosphatierung durch Inkontaktbringen mit einer Titan enthaltenden Lösung zu aktivieren. Hierdurch wird die Phosphatschichtausbildung zwar beschleunigt, die anderen Nachteile bleiben jedoch bestehen. Insbesondere sind zusätzliche Behandlungsvorrichtungen nötig.From GB-PS 932 987 it is known to activate the metal surfaces prior to phosphating by contacting them with a solution containing titanium. This accelerates the formation of the phosphate layer, but the other disadvantages remain. In particular, additional treatment devices are necessary.

Bei dem Verfahren gemäß GB-PS 996 418 soll Harnstoff dem Phosphatierbad zugesetzt werden, wodurch die Temperatur bei der Phosphatierung erhöht werden kann, ohne eine wesentlich erhöhte Schlammbildung zu riskieren. Auch hiermit ist eine beschleunigte Phosphatschichtausbildung verbunden. Die anderen zuvor genannten Nachteile bleiben jedoch auch hier bestehen. Darüber hinaus entsteht der zusätzliche Nachteil, daß eine an sich nicht erforderliche, energieverschwendende Aufheizung der Phosphatierungslösung erforderlich ist. Bei einem anderen, nicht »auf der Eisenseite« arbeitenden Bad hat man versucht, das Schlammproblem zu lösen, indem desen Feststoffgehalt erhöht und infolgedessen die Schlammenge reduziert wird (GB-PS 1 555 529).In the process according to GB-PS 996 418, urea is to be added to the phosphating bath, as a result of which the temperature during the phosphating can be increased without risking significantly increased sludge formation. Accelerated phosphate layer formation is also associated with this. However, the other disadvantages mentioned above also remain here. In addition, there is the additional disadvantage that heating of the phosphating solution, which is not per se energy-wasting, is required. In another bath which does not work "on the iron side", attempts have been made to solve the sludge problem by increasing its solids content and consequently reducing the amount of sludge (GB-PS 1 555 529).

Hierzu werden die Metalloberflächen mit einer Lösung behandelt, die wenigstens 6 g/1 Zn, 5 g/I P2O5, 1 g/l C103 und 8 g/l NO3 enthalten. Das Verhältnis P2O5 : Zn soll dabei im Bereich von 1:(0,8--4) liegen. Obgleich bei diesem Verfahren ein kompakter Schlamm erhalten wird und demzufolge die Intervalle zwischen der erforderlichen Entschlammung der jeweiligen Behandlungvorrichtung größer sind, hat sich gezeigt, daß es schwieriger sein kann, kompakten Schlamm anstelle von leichtem, voluminösem Schlamm zu entfernen.For this purpose, the metal surfaces are treated with a solution which contains at least 6 g / 1 Zn, 5 g / IP 2 O 5 , 1 g / l C10 3 and 8 g / l NO 3 . The ratio P 2 O 5 : Zn should be in the range of 1: (0.8--4). Although a compact sludge is obtained in this process and consequently the intervals between the required desludging of the respective treatment device are larger, it has been shown that it can be more difficult to remove compact sludge instead of light, voluminous sludge.

Aufgabe der Erfindung ist es, ein Verfahren zur Herstellung von Phosphatüberzügen auf Eisen- oder Stahloberflächen bereitzustellen, das die bekannten, insbesondere vorgenannten Nachteile nicht aufweist und ohne Mehraufwand an Chemikalien und ohne Einbuße in der Schichtqualität einfach in der Durchführung ist.The object of the invention is to provide a process for producing phosphate coatings on iron or steel surfaces which does not have the known, in particular the aforementioned disadvantages, and is simple to carry out without additional chemicals and without sacrificing layer quality.

Die Aufgabe wird gelöst, indem das Verfahren der eingangs genannten Art entsprechend der Erfindung derart durchgeführt wird, daß man die Oberflächen mit einer Lösung in Berührung bringt, die mindestens 0,3 Gew.-% Zn, mindestens 0,3 Gew.-% PO4 und mindestens 0,75 Gew.-% NO3 oder eines gleichwirkenden Eisen(II) nicht oxidierenden Beschleunigers enthält, in der das Gewichtsverhältnis Zn:P04 größer als 0,8 ist, das Verhältnis von Gesamtsäure zu Freier Säure mindestens 5 beträgt und in der man durch geeignete Bemessung von ClO3 oder einem gleichwirkenden Eisen(II) zu Eisen(III) oxidierenden Beschleuniger einen Eisen(II)-Gehalt von 0,05 bis 1 Gew.-% einstellt.The object is achieved by carrying out the method of the type mentioned at the outset in accordance with the invention in such a way that the surfaces are brought into contact with a solution which contains at least 0.3% by weight of Zn and at least 0.3% by weight of PO 4 and contains at least 0.75% by weight of NO 3 or a similarly acting iron (II) non-oxidizing accelerator, in which the weight ratio Zn: P0 4 is greater than 0.8, the ratio of total acid to free acid is at least 5 and in which an iron (II) content of 0.05 to 1% by weight is set by suitable dimensioning of ClO 3 or an accelerator which oxidizes iron (II) to iron (III).

Eine vorteilhafte Ausgestaltung der Erfindung besteht darin, die Oberfläche mit einer Lösung in Berührung zu bringen, die maximal 2,2 Gew.-% Zn, max. 2,2 Gew. % PO4 und max. 5,5 Gew.-% NO3 oder eines gleichwirkenden Beschleunigers enthält, in dor das Gowichtsverhältnis Zn:PO4 kleiner als 4 ist und das Verhältnis von Gesamtsäure zu Freier Säure max- 30 beträgt.An advantageous embodiment of the invention consists in bringing the surface into contact with a solution which contains a maximum of 2.2% by weight of Zn, max. 2.2% by weight PO 4 and max. Contains 5.5% by weight of NO 3 or an accelerator with the same effect, in which the weight ratio Zn: PO 4 is less than 4 and the ratio of total acid to free acid is max. 30.

Vorzugsweise sollte eine Behandlungslösung zum Einsatz kommen, die 0,3 bis 1 Gew.-% Zn, 0,3 bis 1 Gew.-% PO4 und 1 bis 3 Gew.-% NO3 oder eines gleichwirkenden Beschleunigers enthält, in der das Gewichtsverhältnis Zn:P04 0,8 bis 2, insbesondere 0,8 bis 1,4 beträgt und die ein Verhältnis von Gesamtsäure zu Freier Säure von max. 15, insbesondere 7 bis 12, aufweist und in der man durch geeignete Bemessung von Chlorat oder einem gleichwirkenden Beschleuniger einen Eisen(II)-Gehalt von 0,08 bis 0,5, insbesondere bis 0,2, Gew.-% einstellt.A treatment solution should preferably be used which contains 0.3 to 1% by weight of Zn, 0.3 to 1% by weight of PO 4 and 1 to 3% by weight of NO 3 or an accelerator with the same effect, in which the Weight ratio Zn: P0 4 0.8 to 2, in particular 0.8 to 1.4 and which is a ratio of total acid to free acid of max. 15, in particular 7 to 12, and in which one by suitable dimensioning of chlorate or an equivalent accelerator sets an iron (II) content of 0.08 to 0.5, in particular up to 0.2,% by weight.

Außer Nitrat als Eisen(II) nicht oxidierender Beschleuniger ist beispielsweise auch Nitroguanidin geeignet.In addition to nitrate as an iron (II) non-oxidizing accelerator, nitroguanidine is also suitable, for example.

Zur Einstellung des Gehaltes an Eisen(11) ist der Aufwand an Chlorat oder einem gleichwirkenden Eisen(II) zu Eisen(III) oxidierenden Beschleuniger derart, daß dessen Konzentration in der Behandlungslösung im allgemeinen kleiner als 0,1 Gew. % (ber. als ClO3) ist. Höhere Dosierungen bewirken, daß der Eisen(II)-Gehalt zu gering wird und eine erhebliche Schlammbildung auftritt.To adjust the iron (11) content, the expenditure of chlorate or an iron (II) which has the same effect as iron (III) oxidizing accelerator is such that its concentration in the treatment solution is generally less than 0.1% by weight (calc ClO 3 ). Higher doses cause the iron (II) content to be too low and considerable sludge formation occurs.

Die besten Ergebnisse werden erzielt, wenn der Gehalt an Chlorat oder einem gleichwirkenden Beschleuniger auf Konzentrationen unter 0,05 Gew.-%, vorzugsweise unter 0,035 Gew.-% (ber. als CI03) eingestellt wird. Optimale Ergebnisse werden bei Konzentrationen im Bereich von 0,001 bis 0,035 Gew.-% (ber. als ClO3) erhalten.The best results are achieved if the chlorate content or an equivalent accelerator is set to concentrations below 0.05% by weight, preferably below 0.035% by weight (calculated as CI0 3 ). Optimal results are obtained at concentrations in the range of 0.001 to 0.035% by weight (calculated as ClO 3 ).

Bei der Bemessung des das Eisen(II) zu Eisen(III) oxidierenden Beschleunigers ist zu berücksichtigen, daß das Phosphatierbad z.B. in der Startphase noch keine Eisen(II)ionen enthält. Zu diesem Zeitpunkt ist daher eine Zugabe des Eisen(II) oxidierenden Beschleunigers nicht erforderlich. Auch ist es nicht erforderlich, diesen Beschleuniger ständig zu dosieren. Er kann durchaus auch mit den zur Badergänzung üblicherweise zugegebener Chemikalien eingebracht werden.When dimensioning the accelerator oxidizing the iron (II) to iron (III), it must be taken into account that the phosphating bath e.g. does not contain any iron (II) ions in the starting phase. It is therefore not necessary to add the iron (II) oxidizing accelerator at this point. It is also not necessary to meter this accelerator continuously. It can also be introduced with the chemicals that are usually added to the bath supplement.

Eine Weiterbildung des Verfahrens sieht vor, die Oberflächen mit einer Lösung in Berührung zu bringen, die zusätzlich Kalzium in Mengen von 0,01 bis 0,88 Gew.-%, vorzugsweise 0,15 bis 0,5 Gew.-%, enthält.A further development of the method provides for the surfaces to be brought into contact with a solution which additionally contains calcium in quantities of 0.01 to 0.88% by weight, preferably 0.15 to 0.5% by weight.

Dabei sollte das Gewichtsverhältnis Zn:Ca 1,5 bis 4 betragen. Beste Ergebnisse werden mit einem Verhältnis von 2,5 erzielt.The weight ratio Zn: Ca should be 1.5 to 4. Best results are achieved with a ratio of 2.5.

Schließlich kann die Phosphatierlösung noch weitere für Zinkphosphatierlösungen an sich übliche Zusätze, wie Kupfer, Kobalt, Nickel, einfaches oder komplexes Fluorid, enthalten. Bei der Fluoriddosierung ist zu beachten, daß kein Kalziumfluorid ausfällt. Magnesium kann das Kalzium teilweise oder ganz ersetzen. Schließlich kann - wie in der GB-PS 996 418 vorgeschlagen - der Phosphatierlösung Harnstoff zugesetzt werden.Finally, the phosphating solution can also contain other additives which are customary for zinc phosphating solutions, such as copper, cobalt, nickel, simple or complex fluoride. When dosing with fluoride, make sure that no calcium fluoride fails. Magnesium can partially or completely replace calcium. Finally, as suggested in GB-PS 996 418, urea can be added to the phosphating solution.

Die mit dem erfindungsgemäßen Verfahren in Berührung zu bringenden Oberflächen müssen frei von Rost und Zunder sein und sollten daher zunächst mit Mineralsäure, wie Salz- oder Schwefelsäure, gebeizt und anschließend mit Wasser gespült werden. Je nach Verunreinigung kann zur Reinigung der Oberflächen auch eine Entfettung oder andersartige Behandlung vorgenommen werden, beispielsweise mit einem organischen Lösungsmittel oder einem alkalischen Reiniger, gefolgt von einer Wasserspülung.The surfaces to be brought into contact with the method according to the invention must be free of rust and scale and should therefore first be pickled with mineral acid, such as hydrochloric or sulfuric acid, and then rinsed with water. Depending on the level of contamination, degreasing or other treatment can also be carried out to clean the surfaces, for example with an organic solvent or an alkaline cleaner, followed by a water rinse.

Die gereinigten Oberflächen können schließlich einer Aktivierungsbehandlung, z. B. durch Heißwasserspülung oder mit einer Titanorthophosphatdispersion, unterworfen werden.Finally, the cleaned surfaces can be subjected to an activation treatment, e.g. B. by hot water rinsing or with a titanium orthophosphate dispersion.

Das Tauchen oder Fluten der Oberflächen, das im Unterschied zum Spritzen eine Schlammbildung infolge Oxidation durch Luftsauerstoff weitgehend vermeidet, erfolgt gemäß einer bevorzugten Ausgestaltung des erfindungsgemäßen Verfahrens bei einer Temperatur von 35 bis 98°C, vorzugsweise bei 55 bis 85° C. Die Zeitdauer der Berührung zwischen Oberfläche und Phosphatierungslösung liegt vorzugsweise im Bereich von 5 bis 15 Minuten.The dipping or flooding of the surfaces, which, in contrast to spraying, largely avoids sludge formation due to oxidation by atmospheric oxygen, is carried out according to a preferred embodiment of the process according to the invention at a temperature of 35 to 98 ° C., preferably 55 to 85 ° C. The duration of the Contact between the surface and the phosphating solution is preferably in the range from 5 to 15 minutes.

Vorteilhaft ist es, das Phosphatierbad mit einem Konzentrat anzusetzen, das

Figure imgb0001

  • Gewichtsverhältnis von Zn : P04 von 0,8 bis 4, vorzugsweise von 0,8 bis 1,4,
  • ein Gewichtsverhältnis von Zn : Ca von 1 bis 4, vorzugsweise von 2 bis 3,

und ein Verhältnis von Gesamtsäure zu Freier Säure von 5 bis 9, vorzugsweise 6 bis 8, aufweist.It is advantageous to prepare the phosphating bath with a concentrate that
Figure imgb0001
  • Weight ratio of Zn: P0 4 from 0.8 to 4, preferably from 0.8 to 1.4,
  • a weight ratio of Zn: Ca from 1 to 4, preferably from 2 to 3,

and has a total acid to free acid ratio of 5 to 9, preferably 6 to 8.

Eine vorteilhafte Weiterbildung des erfindungsgsmäßen Verfahrens besteht darin, die Oberflächen mit einer Lösung in Berührung zu bringen, die mit einem Konzentrat ergänzt wird, das

Figure imgb0002
entnait, in aem aas

  • Gewichtsverhältnis Zn : P04 0,3 bis 0,6, vorzugsweise 0,3 bis 0,4,
  • das Gewichtsverhältnis Zn : Ca 2 bis 8, vorzugsweise 3 bis 6,

und das Verhältnis Gesamtsäure zu Freier Säure 3 bis 6, vorzugsweise 4 bis 5, beträgt.An advantageous development of the method according to the invention consists in bringing the surfaces into contact with a solution which is supplemented with a concentrate which
Figure imgb0002
 entnait, in aem aas
  • Weight ratio Zn: P0 4 0.3 to 0.6, preferably 0.3 to 0.4,
  • the weight ratio Zn: Ca 2 to 8, preferably 3 to 6,

and the ratio of total acid to free acid is 3 to 6, preferably 4 to 5.

Nach Ausbildung des Phosphatüberzuges kann mit kaltem Wasser gespült und mit einer passivierenden Nachspüllösung nachbehandelt werden. Es kann auch ein Schmiermittelüberzug auf die Phosphatschicht aufgebracht werden.After the phosphate coating has been formed, it can be rinsed with cold water and treated with a passivating rinse solution. There can also be a lubricant coating on the Phosphate layer can be applied.

Das erfindungsgemäße Verfahren hat sich insbesondere als Vorbereitung für die spanlose Kaltumformung bewährt. Es ist jedoch auch mit Vorteil auf den übrigen Anwendungsgebieten der Phosphatierung, z.B. für den Korrosionsschutz, zur Erleichterung der gleitenden Reibung und zur elektrischen Isolation einzusetzen.The method according to the invention has proven particularly useful as a preparation for non-cutting cold forming. However, it is also advantageous in the other fields of application of phosphating, e.g. for corrosion protection, to facilitate sliding friction and for electrical insulation.

Die Erfindung wird anhand des Beispiels beispielsweise und näher erläutert.The invention is explained by way of example and in more detail.

Beispielexample

Es wurde eine Phosphatierungslösung aus einem Ansatzkonzentrat hergestellt, das

Figure imgb0003
enthielt und ein Verhältnis von Gesamtsäure zu Freier Säure von 7 aufwies. Die Verdünnung erfolgte im Verhältnis ein Teil Konzentrat, 20 Teile Wasser.A phosphating solution was prepared from a batch concentrate which
Figure imgb0003
 contained and had a ratio of total acid to free acid of 7. The dilution was carried out in the ratio of one part of concentrate to 20 parts of water.

In dem auf einer Temperatur von 70° C gehaltenen Phosphatierbad wurde Draht im Tauchverfahren behandelt. Nach einer Kontaktzeit von 10 Minuten wurde der Draht entfernt, mit Wasser gespült, mit einem Schmiermittelüberzug versehen und auf übliche Art gezogen.Wire was immersed in the phosphating bath kept at a temperature of 70 ° C. After a contact time of 10 minutes, the wire was removed, rinsed with water, provided with a lubricant coating and pulled in the usual way.

Nach einem bestimmten Durchsatz wurde mit einem Ergänzungskonzentrat, das

Figure imgb0004
enthielt und ein Verhältnis von Gesamtsäure zu Freier Säure von 4,6 aufwies, ergänzt.After a certain throughput was supplemented with a concentrate that
Figure imgb0004
 contained and had a ratio of total acid to free acid of 4.6, supplemented.

Bei geeignetem Zusatz der Ergänzungslösung konnte das Phosphatierbad praktisch konstant bei Konzentrationen von

Figure imgb0005
gehalten werden. Das Verhältnis Gesamtsäure zu Freier Säure lag bei 8,7.With a suitable addition of the supplementary solution, the phosphating bath could be kept practically constant at concentrations of
Figure imgb0005
 being held. The ratio of total acid to free acid was 8.7.

Das Verfahren konnte auf längere Zeit mit nur geringer Schlammbildung betrieben werden.The process could be operated for a long time with only a small amount of sludge.

Wurde hingegen zum Vergleich das Verfahren gemäß Beispiel 5 der GB-PS 1 555 529 betrieben, wurde zwar ebenfalls eine einwandfreie Phosphatschicht erhalten, jedoch war nach längerer Betriebsdauer der Chemikalienverbrauch etwa 40% höher und das Gewicht des zu entfernenden Schlammes etwa 60% größer.On the other hand, if the method according to Example 5 of GB-PS 1 555 529 was operated for comparison, a perfect phosphate layer was also obtained, but after a longer period of operation the chemical consumption was about 40% higher and the weight of the sludge to be removed was about 60% greater.

Claims (9)

1. Process for the production of phosphate coatings on iron and steel surfaces by dipping or flooding in an aqueous acidic zinc phosphate solution, characterized in that the surfaces are brought in contact with a solution, which contains at least 0,3% by weight Zn, at least 0,3% by weight PO4, and at least 0,75% by weight NO3 or of an equivalent accelerator incapable of oxidizing iron (II), in wich the weight ratio of Zn : P04 is greater than 0,8, the ratio of total acid to free acid is at least 5 and in which by an appropriate addition of ClO3 or of an equivalent accelerator capable of oxidizing iron (II) to iron (III) an iron (II)-content of 0,05 to 1% by weight is adjusted.
2. Process according to claim 1, characterized in that the surfaces are brought in contact with a solution, which contains utmost 2,2% by weight Zn, utmost 2,2% by weight PO4 and utmost 5,5% by weight NO3 or of an equivalent accelerator and in which the weight ratio of Zn : PO4 is lower than 4 and the ratio of total acid to free acid is utmost 30.
3. Process according to claim 1 or 2, characterized in that the surfaces are brought in contact with a solution, which contains 0,3 to 1% by weight Zn, 0,3 to 1% by weight PO4 and 1 to 3% by weight NO3 or of an equivalent accelerator, in which the weight ratrio of Zn : PO4 is 0,8 to 2, particularly 0,8 to 1,4, and in which the ratio of total acid to free acid is utmost 15, particularly 7 to 12, and in which by an appropriate addition of chlorate or of an equivalent accelerator an iron (II)-content of 0,08 to 0,5, particularly up to 0,2% by weight, is adjusted.
4. Process according to claim 1, 2 or 3, characterized in that the surfaces are brought in contact with a solution, which contains in addition calcium in an amount of 0,1 to 0,88% by weight, preferably of 0,15 to 0,5% by weight.
5. Process according to claim 1, 2, 3 or 4, characterized in that the surfaces are brought in contact with a solution, which contains in addition copper, cobalt, nickel, simple or complex fluorid.
6. Process according to any of the claims 1 to 5, characterized in that the surfaces are brought in contact with the solution at a temperature of 35 to 98° C, preferably of 55 to 85° C.
7. Process according to any of the claims 1 to 6, characterized in that the surfaces are brought in contact with the solution with a contact time of 5 to 15 minutes.
8. Process according to any the claims 1 to 7, characterized in that the surfaces are brought in contact with a solution, which is replenished with a concentrate containing
Figure imgb0007
and in which the weight ratio of Zn : P04 is 0,3 to 0,6 preferably 0,3 to 0,4
the weight ratio of Zn : Ca is
2 to 8, preferably 3 to 6,
and the ratio of total acid to free acid is 3 to 6, preferably 4 to 5.
9. Use of the process according to any of the claims 1 to 8 for preparing metal surfaces for cold forming.
EP81200830A 1980-07-25 1981-07-21 Method for the production of phosphate coatings on iron and steel surfaces, and its use Expired EP0045110B1 (en)

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AT81200830T ATE9823T1 (en) 1980-07-25 1981-07-21 PROCESS FOR THE PRODUCTION OF PHOSPHATE COATINGS ON IRON AND STEEL SURFACES AND THEIR APPLICATION.

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GB8024465 1980-07-25
GB8024465 1980-07-25

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EP0045110B1 true EP0045110B1 (en) 1984-10-10

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GB (1) GB2080835B (en)
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DE3244715A1 (en) * 1982-12-03 1984-06-07 Gerhard Collardin GmbH, 5000 Köln METHOD FOR PHOSPHATING METAL SURFACES, AND BATH SOLUTIONS SUITABLE FOR THIS
JPS6081850A (en) * 1983-10-11 1985-05-09 Nec Kansai Ltd Manufacture of semiconductor device
DE3407513A1 (en) * 1984-03-01 1985-09-05 Gerhard Collardin GmbH, 5000 Köln METHOD FOR ZINC-CALCIUM PHOSPHATION OF METAL SURFACES AT LOW TREATMENT TEMPERATURE
DE3636390A1 (en) * 1986-10-25 1988-04-28 Metallgesellschaft Ag METHOD FOR PRODUCING PHOSPHATE COATINGS ON METALS
JPS63270478A (en) * 1986-12-09 1988-11-08 Nippon Denso Co Ltd Phosphating method
US5236565A (en) * 1987-04-11 1993-08-17 Metallgesellschaft Aktiengesellschaft Process of phosphating before electroimmersion painting
DE3712339A1 (en) * 1987-04-11 1988-10-20 Metallgesellschaft Ag METHOD FOR PHOSPHATIZING BEFORE ELECTROPLATING
JPH01108754A (en) * 1987-10-21 1989-04-26 Toshiba Corp Lead frame for semiconductor device
DE3742634A1 (en) * 1987-12-16 1989-06-29 Collardin Gmbh Gerhard METHOD FOR THE COLLIGHTING OF PHOSPHATING BAEDERS AND DEVICE FOR THIS METHOD
DE3800835A1 (en) * 1988-01-14 1989-07-27 Henkel Kgaa METHOD FOR PHOSPHATING METAL SURFACES
EP0327153B1 (en) * 1988-02-03 1993-08-04 Metallgesellschaft Ag Process for applying phosphate coatings to metals
JPH02101174A (en) * 1988-10-06 1990-04-12 Nippon Paint Co Ltd Treatment with zinc phosphate for cold working
DE3840668A1 (en) * 1988-12-02 1990-06-07 Metallgesellschaft Ag METHOD FOR PHOSPHATING METAL SURFACES
JPH0375379A (en) * 1989-05-15 1991-03-29 Nippon Paint Co Ltd Coated product, production thereof, concentrated phosphating agent and concentrated treating agent for replenishment
DE4306446A1 (en) * 1993-03-02 1994-09-08 Metallgesellschaft Ag Procedures to facilitate cold forming
DE19634685A1 (en) * 1996-08-28 1998-03-05 Metallgesellschaft Ag Aqueous solution and process for phosphating metallic surfaces
US5954892A (en) * 1998-03-02 1999-09-21 Bulk Chemicals, Inc. Method and composition for producing zinc phosphate coatings on metal surfaces
WO2004007799A2 (en) 2002-07-10 2004-01-22 Chemetall Gmbh Method for coating metallic surfaces
DE10320313B4 (en) * 2003-05-06 2005-08-11 Chemetall Gmbh A method of coating metallic bodies with a phosphating solution, phosphating solution and the use of the coated article
CN101665936B (en) * 2009-09-27 2012-11-28 大连三达奥克化学股份有限公司 Normal-temperature phosphating agent for pre-processing before spray-coating of steel plate workpiece and preparation method thereof

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DE2540685C2 (en) * 1975-09-12 1985-06-27 Metallgesellschaft Ag, 6000 Frankfurt Process for the production of phosphate coatings

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ES504609A0 (en) 1982-11-16
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GB2080835A (en) 1982-02-10
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IT8123121A0 (en) 1981-07-24
IT1167480B (en) 1987-05-13

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