EP0171043B1 - Passivating process for lead and lead-containing surfaces - Google Patents
Passivating process for lead and lead-containing surfaces Download PDFInfo
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- EP0171043B1 EP0171043B1 EP85109735A EP85109735A EP0171043B1 EP 0171043 B1 EP0171043 B1 EP 0171043B1 EP 85109735 A EP85109735 A EP 85109735A EP 85109735 A EP85109735 A EP 85109735A EP 0171043 B1 EP0171043 B1 EP 0171043B1
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- Prior art keywords
- lead
- chromium
- iii
- ions
- solutions
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Classifications
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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
- C23C22/48—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 not containing phosphates, hexavalent chromium compounds, fluorides or complex fluorides, molybdates, tungstates, vanadates or oxalates
- C23C22/58—Treatment of other metallic material
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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
- C23C22/07—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
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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
- C23C2222/00—Aspects relating to chemical surface treatment of metallic material by reaction of the surface with a reactive medium
- C23C2222/10—Use of solutions containing trivalent chromium but free of hexavalent chromium
Definitions
- the invention relates to a method for the passivation of lead and lead-containing surfaces.
- lead and lead-containing alloys Numerous valuable specific properties, such as high corrosion resistance, good workability, resistance to thermal cycling, good insulation properties against noise and high resistance to chemicals, have led to a wide range of applications for lead and lead-containing alloys.
- lead-containing materials are being used to an increasing extent in construction, chemical apparatus engineering, radiation protection, automotive engineering and other areas.
- US-A-3 592 747 relates to a method for producing decorative, corrosion and abrasion-resistant protective layers on surfaces, in particular metal surfaces.
- a loosely adhering, porous film is first formed on the surface to be treated.
- An aqueous silicate solution is subsequently applied to this film, dried and made insoluble by subsequent heating.
- An example of this patent describes the chemical conversion of a lead surface.
- the cleaned lead surface is treated for a period of one minute at 38 ° C. with an aqueous solution which has the following composition: 100 g of chromic acid, 60 ml of 90% formic acid and 1000 ml of water.
- the resulting loose-adhering, porous film is deep yellow. It is then treated further with an aqueous sodium silicate solution.
- the present invention was based on the object of providing a method which leads to a passivation of surfaces of lead or of lead-based alloys, the passivation produced ensuring a high level of protection against corrosion and the surfaces thus treated for the subsequent application of paints and other coating agents is optimally prepared.
- lead surfaces are understood to mean surfaces of workpieces which consist 100% of lead or can also consist of another metal which is coated with an electrolytically or otherwise produced surface of metallic lead.
- lead-containing surfaces are understood to mean surfaces of workpieces which consist 100% of a binary or also higher alloy of the metal lead or of another metal which is coated with a more or less thin surface of a binary or also higher lead-containing mixture is.
- aqueous solutions which contain chromium (III) ions in an amount of 0.01 to 10 g. 1 ⁇ 1, preferably in an amount of 0.02 to 5 g. 1 ⁇ 1 application solution included.
- solutions have proven particularly useful whose chromium (III) ion content is in the range from 0.4 to 3 g. 1 ⁇ 1 application solution.
- This salt is readily soluble in water in the temperature range of the process.
- the chromium (III) ethanate is also advantageous in the sense of the invention because the anion acts as a buffer in the application solutions and also forms a complex with the chromium (III) cation which has sufficient stability to avoid environmental damage to the passivation solution having.
- Such solutions can be obtained by dissolving chromium (III) ions in suitable amounts containing solid or liquid concentrates in water in a manner known per se.
- Chromium (III) ethanate of analytical quality can be used to prepare the treatment solutions according to the invention, but this is not to be regarded as advantageous because of the high costs.
- Industrial chromium (III) ethanate is used in industrial applications, the aqueous solution of which generally has a pH in the range from 3 to 5.
- the aqueous application solutions containing chromium (III) ions preferably have a pH in the range from 2 to 6, in particular in the range from 3.2 to 4.2. This pH value can be established immediately by dissolving the technical chromium (III) ethanate in water. If, after dissolving the chromium (III) ethanate used in water, the pH is outside the pH range from 2 to 6, it is adjusted to the desired value by adding phosphoric acid.
- phosphate is added to the solutions for the passivation of lead and lead-containing surfaces. This is done in such a way that phosphoric acid is added to the solutions in an amount such that the phosphate content of the application solutions is in the range from 0.001 to 10 g. 1 ⁇ 1, preferably in the range of 0.01 to 5 g. 1 ⁇ 1 phosphate ions in the application solution.
- the process according to the invention for the passivation of lead and lead-containing surfaces by means of acidic, aqueous solutions works in the temperature range from 20 to 50 ° C., preferably in the range from 25 to 40 ° C. Treatment times of approximately 1 minute are sufficient to achieve an excellent passivation of the lead and lead-containing surfaces even at these temperatures.
- the process according to the invention is carried out in such a way that, with an alkaline aqueous solution at 55 to 65 ° C. for 60 to 180 seconds, sprayed lead-cleaned or lead-containing surfaces according to the present process with an acidic, aqueous solution in the temperature range from 20 to 40 ° C to be treated.
- spray processes, immersion processes or other methods of application known to the person skilled in the art such as e.g. Spray dipping or flooding, suitable for passivation.
- the treatment time is usually 1 minute.
- the passivated lead or lead-containing surfaces are rinsed with deionized water and then dried with compressed air. Then it is found that a visible, uniform passivation layer has formed on the surfaces.
- the lead or lead-containing surfaces passivated according to the method of the invention are outstandingly suitable for subsequent coating with paints, varnishes and the like.
- the lead surfaces passivated in this way offer an outstandingly suitable reason for polyurethane coatings, but are also suitable for other post-treatment processes.
- a solution was prepared which contained 2 g. 1 ⁇ 1 technical chromium (III) ethanate (corresponding to 0.4 g. 1 ⁇ 1 Cr3+ and 0.1 g. 1 ⁇ 1 phosphoric acid (corresponding to 0.1 g. 1 ⁇ 1 PO43 ⁇ ) contained.
- the solution had a pH of 3.9.
- Leaded steel sheets which had previously been spray-treated with an alkaline cleaning solution at 55 ° C. for 60 seconds, were sprayed with the aforementioned solution for 60 seconds at 40 ° C. It was then rinsed with water and demineralized water and dried by blowing in compressed air.
- the sheets were then coated with a polyurethane varnish from Winkelmann.
- the sheets were then provided with a single cut in accordance with DIN 53167 and subjected to the salt spray test in accordance with DIN 50021 for a period of 240 h.
- the evaluation according to DIN 53167 showed an infiltration of ⁇ 3 mm.
- a solution was prepared that contained 4 g. 1 ⁇ 1 chromium (III) ethanate (corresponding to 0.8 g. 1 ⁇ 1 Cr3+) and 0.3 g. 1 ⁇ 1 phosphoric acid (corresponding to 0.3 g. 1 ⁇ 1 PO43 ⁇ ) contained.
- the solution had a pH of 3.5.
- Leaded fuel tanks of industrial design previously with an alkaline cleaning solution at 65 ° C for 3 minutes by immersion treatment were treated with the above solution for 2 minutes at 22 ° C in immersion.
- the containers were then rinsed with water and demineralized water and dried by blowing in compressed air.
- the containers were then coated with a polyurethane varnish from Winkelmann.
- the containers were then provided with a single cut in accordance with DIN 53167 and subjected to the salt spray test in accordance with DIN 50021 for a period of 240 h.
- the evaluation according to DIN 53167 showed an infiltration of ⁇ 3 mm.
- Leaded steel sheets were cleaned with an alkaline cleaning solution at 55 ° C. for 60 seconds by spraying. It was then rinsed with water and deionized water and dried by blowing in compressed air. The sheets were then coated with a polyurethane varnish from Winkelmann.
- the leaded steel sheets were then provided with a single cut in accordance with DIN 53167 and subjected to the salt spray test in accordance with DIN 50021 for a period of 240 h.
- the evaluation according to DIN 53167 showed an infiltration of> 20 mm.
- the comparative example illustrates that the method according to the invention brings about a significant improvement in corrosion protection.
Description
Die Erfindung betrifft ein Verfahren zur Passivierung von Blei- und bleihaltigen Oberflächen.The invention relates to a method for the passivation of lead and lead-containing surfaces.
Zahlreiche wertvolle spezifische Eigenschaften, wie hohe Korrosionsbeständigkeit, gute Verarbeitbarkeit, Beständigkeit gegen thermische Wechselbeanspruchung, gute Dämmeigenschaften gegen Schall und hohe Beständigkeit gegen Chemikalien, haben zu einem weiten Anwendungsspektrum von Blei- und bleihaltigen Legierungen geführt. So werden bleihaltige Werkstoffe im Bauwesen, im chemischen Apparatebau, im Strahlenschutz, in der Automobiltechnik und in anderen Bereichen in zunehmendem Maße verwendet.Numerous valuable specific properties, such as high corrosion resistance, good workability, resistance to thermal cycling, good insulation properties against noise and high resistance to chemicals, have led to a wide range of applications for lead and lead-containing alloys. For example, lead-containing materials are being used to an increasing extent in construction, chemical apparatus engineering, radiation protection, automotive engineering and other areas.
Einer der Gründe für die vielseitige Verwertbarkeit ist darin zu sehen, daß Blei- und bleihaltige Oberflächen bisher nicht gesondert gegen Korrosion geschützt werden mußten, da sich derartige Oberflächen an der Luft durch Ausbildung stabiler Überzüge aus Bleioxiden, alkalischen Bleicarbonaten, Bleisulfaten bzw. Bleisulfiden wechselnder Zusammensetzung selbst passivieren. Blei- und bleihaltige Oberflächen wurden bisher lediglich einer alkalischen Reinigung unterzogen, die ebenfalls zu einer für den Korrosionsschutz ausreichenden passivierten Oberfläche führte und eine ausreichende Grundlage für die Applikation weiterer Überzugsmittel, wie z.B. Lacke, abgab.One of the reasons for its versatility is that lead and lead-containing surfaces have not previously had to be specially protected against corrosion, since such surfaces are exposed to air in the form of stable coatings of lead oxides, alkaline lead carbonates, lead sulfates and lead sulfides of changing composition passivate yourself. Lead and Up to now, surfaces containing lead have only been subjected to alkaline cleaning, which likewise led to a passivated surface sufficient for corrosion protection and provided a sufficient basis for the application of further coating agents, such as lacquers.
Die relativ hohe Toxizität von Blei und gewissen Bleiverbindungen hat jedoch zu der Forderung geführt, den Korrosionsschutz für Blei- und bleihaltige Oberflächen wesentlich zu verbessern. Die Hersteller von Werkteilen mit Oberflächen, die aus Blei oder bleihaltigen Legierungen bestehen, hatten in der Folge hohe Auflagen hinsichtlich des Korrosionsschutzes der von ihnen gelieferten Werkteile zu erfüllen.However, the relatively high toxicity of lead and certain lead compounds has led to the requirement to significantly improve the corrosion protection for surfaces containing lead and lead. As a result, the manufacturers of workpieces with surfaces made of lead or alloys containing lead had to meet stringent requirements with regard to the corrosion protection of the workpieces they supplied.
Mit den gestiegenen Anforderungen an den Korrosionsschutz, die neue Techniken hinsichtlich der Passivierung von Blei- und bleihaltigen Oberflächen erforderlich machten stiegen auch die Anforderungen der Hersteller hinsichtlich der Lackhaftung auf Blei- und bleihaltigen Oberflächen. Die oben genannten Salze, die bei der Eigenpassivierung von Bleioberflächen an der Luft entstehen, sind in der Mehrzahl der Fälle nicht für eine langfristig ausreichende Haftung nachfolgend applizierter Überzugsmaterialien geeignet.With the increased requirements for corrosion protection, which made new techniques necessary for the passivation of lead and lead-containing surfaces, the requirements of the manufacturers with regard to paint adhesion on lead and lead-containing surfaces also increased. In most cases, the salts mentioned above, which are formed in the air in the course of self-passivation of lead surfaces, are not suitable for long-term sufficient adhesion of subsequently applied coating materials.
Die US-A-3 592 747 betrifft ein Verfahren zur Erzeugung von dekorativen, gegen Korrosion und Abrieb beständigen Schutzschichten auf Oberflächen, insbesondere Metalloberflächen. Bei diesem Verfahren wird zunächst auf der zu behandelnden Oberfläche ein lose-haftender, poröser Film ausgebildet. Nachfolgend bringt man auf diesen Film eine wäßrige Silicatlösung auf, trocknet diese und macht sie durch anschließendes Erhitzen unlöslich. Ein Beispiel dieser Patentschrift beschreibt die chemische Umwandlung einer Blei-Oberfläche. Hierbei wird die gereinigte Blei-Oberfläche für den Zeitraum von einer Minute bei 38 °C mit einer wäßrigen Lösung behandelt, die die folgende Zusammensetzung aufweist: 100 g Chromsäure, 60 ml einer 90 %igen Ameisensäure und 1000 ml Wasser. Der resultierende lose-haftende, poröse Film ist tief-gelb. Er wird anschließend mit einer wäßrigen Natriumsilicatlösung weiterbehandelt.US-A-3 592 747 relates to a method for producing decorative, corrosion and abrasion-resistant protective layers on surfaces, in particular metal surfaces. In this method, a loosely adhering, porous film is first formed on the surface to be treated. An aqueous silicate solution is subsequently applied to this film, dried and made insoluble by subsequent heating. An example of this patent describes the chemical conversion of a lead surface. Here, the cleaned lead surface is treated for a period of one minute at 38 ° C. with an aqueous solution which has the following composition: 100 g of chromic acid, 60 ml of 90% formic acid and 1000 ml of water. The resulting loose-adhering, porous film is deep yellow. It is then treated further with an aqueous sodium silicate solution.
Der vorliegenden Erfindung lag demgegenüber die Aufgabe zugrunde, ein Verfahren zur Verfügung zu stellen, daß zu einer Passivierung von Oberflächen von Blei oder von Legierungen auf der Basis von Blei führt, wobei die erzeugte Passivierung einen hohen Schutz gegen Korrosion gewährleistet und die so behandelten Oberflächen für die nachfolgende Applikation von Lacken und anderen Beschichtungsmitteln optimal vorbereitet.The present invention was based on the object of providing a method which leads to a passivation of surfaces of lead or of lead-based alloys, the passivation produced ensuring a high level of protection against corrosion and the surfaces thus treated for the subsequent application of paints and other coating agents is optimally prepared.
Die Erfindung betrifft dementsprechend ein Verfahren zur Passivierung von Oberflächen von Blei oder von Legierungen auf der Basis von Blei, bei welchem man die Oberflächen, gegebenenfalls nach einer entfettenden Reinigung, mit sauren, wäßrigen Lösungen, die Chrom-Ionen und Anionen einer organischen Carbonsäure enthalten, in Kontakt bringt,
dadurch gekennzeichnet, daß die sauren, wäßrigen Lösungen die folgende Zusammensetzung aufweisen:
- a) 0,01 bis 10 g·1⁻¹ an Chrom(III)-Ionen in Form von Chrom(III)-ethanat, und
- b) 0,001 bis 10 g·1⁻¹ an PO₄³⁻-Ionen in Form von Phosphorsäure.
characterized in that the acidic, aqueous solutions have the following composition:
- a) 0.01 to 10 g · 1⁻¹ of chromium (III) ions in the form of chromium (III) ethanate, and
- b) 0.001 to 10 g · 1⁻¹ of PO₄³⁻ ions in the form of phosphoric acid.
Wenn im Zusammenhang mit der vorliegenden Erfindung von "Blei-Oberflächen" und "bleihaltigen Oberflächen" die Rede ist, so hat dies - insbesondere im Hinblick auf die vorstehende Definition "Oberflächen von Blei oder von Legierungen auf der Basis von Blei" - die folgende Bedeutung:When referring to "lead surfaces" and "lead-containing surfaces" in connection with the present invention, this has the following meaning - in particular with regard to the above definition "surfaces of lead or of alloys based on lead" :
Unter "Blei-Oberflächen" werden im folgenden Oberflächen von Werkstücken verstanden, die zu 100 % aus Blei bestehen oder auch aus einem anderen Metall bestehen können, das mit einer elektrolytisch oder auf anderem Wege erzeugten Oberfläche aus metallischem Blei überzogen ist. Unter "bleihaltigen Oberflächen" werden im folgenden Oberflächen von Werkstücken verstanden, die zu 100 % aus einer binären oder auch höheren Legierung des Metalls Blei oder aus einem anderen Metall bestehen, das mit einer mehr oder weniger dünnen Oberfläche einer binären oder auch höheren bleihaltigen Mischung überzogen ist.In the following, “lead surfaces” are understood to mean surfaces of workpieces which consist 100% of lead or can also consist of another metal which is coated with an electrolytically or otherwise produced surface of metallic lead. In the following, "lead-containing surfaces" are understood to mean surfaces of workpieces which consist 100% of a binary or also higher alloy of the metal lead or of another metal which is coated with a more or less thin surface of a binary or also higher lead-containing mixture is.
Für das Verfahren gemäß der vorliegenden Erfindung werden wäßrige Lösungen verwendet, die Chrom(III)-Ionen in einer Menge von 0,01 bis 10 g . 1 ⁻¹ , bevorzugt in einer Menge von 0,02 bis 5 g . 1⁻¹ Anwendungslösung, enthalten. In der praktischen Anwendung haben sich Lösungen besonders bewährt, deren Gehalt an Chrom(III)-Ionen im Bereich von 0,4 bis 3 g . 1⁻¹ Anwendungslösung liegt.For the process according to the present invention, aqueous solutions are used which contain chromium (III) ions in an amount of 0.01 to 10 g. 1 ⁻¹, preferably in an amount of 0.02 to 5 g. 1⁻¹ application solution included. In practical use, solutions have proven particularly useful whose chromium (III) ion content is in the range from 0.4 to 3 g. 1⁻¹ application solution.
Erfindungsgemäß enthalten die Anwendungslösungen die Chrom(III)-Ionen in Form von Chrom(III)-ethanat (= Chrom(III)-acetat). Dieses Salz ist im Temperaturbereich des Verfahrens gut in Wasser löslich. Das Chrom(III)-ethanat ist im Sinne der Erfindung ferner dadurch von Vorteil, da das Anion als Puffer in den Anwendungslösungen wirkt und zudem einen Komplex mit dem Chrom(III)-Kation bildet, der eine zur Vermeidung von Umweltschäden der Passivierungslösung ausreichende Stabilität aufweist. Derartige Lösungen können dadurch erhalten werden, daß man Chrom(III)-Ionen in geeigneter Menge enthaltende feste oder flüssige Konzentrate in an sich bekannter Weise in Wasser löst.According to the invention, the application solutions contain the chromium (III) ions in the form of chromium (III) ethanate (= chromium (III) acetate). This salt is readily soluble in water in the temperature range of the process. The chromium (III) ethanate is also advantageous in the sense of the invention because the anion acts as a buffer in the application solutions and also forms a complex with the chromium (III) cation which has sufficient stability to avoid environmental damage to the passivation solution having. Such solutions can be obtained by dissolving chromium (III) ions in suitable amounts containing solid or liquid concentrates in water in a manner known per se.
Zur Herstellung der erfindungsgemäßen Behandlungslösungen kann Chrom(III)-ethanat in Analysequalität eingesetzt werden, was jedoch aufgrund der hohen Kosten als nicht vorteilhaft anzusehen ist. In der industriellen Anwendung wird technisches Chrom(III)-ethanat eingesetzt, dessen wäßrige Lösung in der Regel einen pH-Wert im Bereich von 3 bis 5 aufweist.Chromium (III) ethanate of analytical quality can be used to prepare the treatment solutions according to the invention, but this is not to be regarded as advantageous because of the high costs. Industrial chromium (III) ethanate is used in industrial applications, the aqueous solution of which generally has a pH in the range from 3 to 5.
Die wäßrigen, Chrom(III)-Ionen enthaltenden Anwendungslösungen weisen vorzugsweise einen pH-Wert im Bereich von 2 bis 6, insbesondere im Bereich von 3,2 bis 4,2 auf. Dieser pH-Wert kann sich durch Auflösen des technischen Chrom(III)-ethanats in Wasser unmittelbar einstellen. Sollte der pH-Wert nach Lösen des verwendeten Chrom(III)-ethanats in Wasser außerhalb des pH-Bereiches von 2 bis 6 liegen, so wird er durch Zugabe von Phosphorsäure auf den gewünschten Wert eingestellt.The aqueous application solutions containing chromium (III) ions preferably have a pH in the range from 2 to 6, in particular in the range from 3.2 to 4.2. This pH value can be established immediately by dissolving the technical chromium (III) ethanate in water. If, after dissolving the chromium (III) ethanate used in water, the pH is outside the pH range from 2 to 6, it is adjusted to the desired value by adding phosphoric acid.
Den Lösungen zur Passivierung von Blei- und bleihaltigen Oberflächen wird erfindungsgemäß Phosphat zugesetzt. Dies geschieht in der Weise, daß man den Lösungen vor der Anwendung Phosphorsäure in einer Menge zusetzt, daß der Phosphatgehalt der Anwendungslösungen im Bereich von 0,001 bis 10 g . 1⁻¹, bevorzugt im Bereich von 0,01 bis 5 g . 1⁻¹ Phosphat-Ionen in der Anwendungslösung liegt.According to the invention, phosphate is added to the solutions for the passivation of lead and lead-containing surfaces. This is done in such a way that phosphoric acid is added to the solutions in an amount such that the phosphate content of the application solutions is in the range from 0.001 to 10 g. 1⁻¹, preferably in the range of 0.01 to 5 g. 1⁻¹ phosphate ions in the application solution.
Das erfindungsgemäße Verfahren zur Passivierung von Blei- und bleihaltigen Oberflächen mittels sauren, wäßrigen Lösungen arbeitet im Temperaturbereich von 20 bis 50°C, bevorzugt im Bereich von 25 bis 40°C. Behandlungszeiten von ungefähr 1 Minute sind ausreichend, um selbst bei diesen Temperaturen eine hervorragende Passivierung der Blei- und bleihaltigen Oberflächen zu erreichen.The process according to the invention for the passivation of lead and lead-containing surfaces by means of acidic, aqueous solutions works in the temperature range from 20 to 50 ° C., preferably in the range from 25 to 40 ° C. Treatment times of approximately 1 minute are sufficient to achieve an excellent passivation of the lead and lead-containing surfaces even at these temperatures.
In der Praxis wird das erfindungsgemäße Verfahren so durchgeführt, daß mit einer alkalischen wäßrigen Lösung bei 55 bis 65°C während 60 bis 180 Sekunden durch Spritzbehandlung gereinigte Blei- oder bleihaltige Oberflächen gemäß dem vorliegenden Verfahren mit einer sauren, wäßrigen Lösung im Temperaturbereich von 20 bis 40°C behandelt werden. Für die Behandlung der Blei- oder bleihaltigen Oberflächen sind Spritzverfahren, Tauchverfahren oder andere, dem Fachmann bekannte Verfahren der Auftragung, wie z.B. Spritztauchen oder Fluten, für die Passivierung geeignet. Die Behandlungszeit beträgt im Regelfall 1 Minute. Die derart passivierten Blei- oder bleihaltigen Oberflächen werden mit vollentsalztem Wasser gespült und anschließend mit Druckluft getrocknet. Danach wird gefunden, daß sich auf den Oberflächen eine sichtbare, gleichmäßige Passivierungsschicht ausgebildet hat.In practice, the process according to the invention is carried out in such a way that, with an alkaline aqueous solution at 55 to 65 ° C. for 60 to 180 seconds, sprayed lead-cleaned or lead-containing surfaces according to the present process with an acidic, aqueous solution in the temperature range from 20 to 40 ° C to be treated. For the treatment of the lead or lead-containing surfaces, spray processes, immersion processes or other methods of application known to the person skilled in the art, such as e.g. Spray dipping or flooding, suitable for passivation. The treatment time is usually 1 minute. The passivated lead or lead-containing surfaces are rinsed with deionized water and then dried with compressed air. Then it is found that a visible, uniform passivation layer has formed on the surfaces.
Die entsprechend dem erfindungsgemäßen Verfahren passivierten Blei- oder bleihaltigen Oberflächen sind für eine anschließende Beschichtung mit Anstrichen, Lacken und dergleichen hervorragend geeignet. Insbesondere bieten die derart passivierten Bleioberflächen einen hervorragend geeigneten Grund für Polyurethanlacke, sind jedoch auch für andere Nachbehandlungsverfahren geeignet.The lead or lead-containing surfaces passivated according to the method of the invention are outstandingly suitable for subsequent coating with paints, varnishes and the like. In particular the lead surfaces passivated in this way offer an outstandingly suitable reason for polyurethane coatings, but are also suitable for other post-treatment processes.
Die Erfindung wird durch die nachstehenden Beispiele näher erläutert.The invention is illustrated by the examples below.
Es wurde eine Lösung hergestellt, die 2 g . 1⁻¹ technisches Chrom(III)-ethanat (entsprechend 0,4 g . 1⁻¹ Cr³⁺ und 0,1 g . 1⁻¹ Phosphorsäure (entsprechend 0,1 g . 1⁻¹ PO₄³⁻) enthielt. Die Lösung hatte einen pH-Wert von 3,9.A solution was prepared which contained 2 g. 1⁻¹ technical chromium (III) ethanate (corresponding to 0.4 g. 1⁻¹ Cr³⁺ and 0.1 g. 1⁻¹ phosphoric acid (corresponding to 0.1 g. 1⁻¹ PO₄³⁻) contained. The solution had a pH of 3.9.
Verbleite Stahlbleche, die zuvor mit einer alkalischen Reinigungslösung bei 55°C während 60 sec. durch Spritzbehandlung gereinigt worden waren, wurden mit der vorgenannten Lösung 60 sec. bei 40°C im Spritzen behandelt. Anschließend wurde mit Wasser und vollentsalztem Wasser gespült und durch Aufblasen von Preßluft getrocknet.Leaded steel sheets, which had previously been spray-treated with an alkaline cleaning solution at 55 ° C. for 60 seconds, were sprayed with the aforementioned solution for 60 seconds at 40 ° C. It was then rinsed with water and demineralized water and dried by blowing in compressed air.
Danach wurden die Bleche mit einem Polyurethanlack der Fa. Winkelmann beschichtet.The sheets were then coated with a polyurethane varnish from Winkelmann.
Anschließend wurden die Bleche mit einem Einzelschnitt nach DIN 53167 versehen und dem Salzsprühtest gemäß DIN 50021 während einer Zeitdauer von 240 h unterworfen. Die Auswertung nach DIN 53167 ergab eine Unterwanderung von <3 mm.The sheets were then provided with a single cut in accordance with DIN 53167 and subjected to the salt spray test in accordance with DIN 50021 for a period of 240 h. The evaluation according to DIN 53167 showed an infiltration of <3 mm.
Die Beurteilung des Blasengrades nach DIN 53209 ergab m0/g0.The assessment of the degree of bubbles according to DIN 53209 resulted in m0 / g0.
Es wurde eine Lösung hergestellt, die 4 g . 1⁻¹ Chrom-(III)-ethanat (entsprechend 0,8 g . 1⁻¹ Cr³⁺) und 0,3 g . 1⁻¹ Phosphorsäure (entsprechend 0,3 g . 1⁻¹ PO₄³⁻) enthielt. Die Lösung hatte einen pH-Wert von 3,5.A solution was prepared that contained 4 g. 1⁻¹ chromium (III) ethanate (corresponding to 0.8 g. 1⁻¹ Cr³⁺) and 0.3 g. 1⁻¹ phosphoric acid (corresponding to 0.3 g. 1⁻¹ PO₄³⁻) contained. The solution had a pH of 3.5.
Verbleite Kraftstoffbehälter industriemäßiger Ausführung, die zuvor mit einer alkalischen Reinigungslösung bei 65°C während 3 min durch Tauchbehandlung gereinigt worden waren, wurden mit der vorgenannten Lösung 2 min bei 22°C im Tauchen behandelt. Anschließend wurden die Behälter mit Wasser und vollentsalztem Wasser gespült und durch Aufblasen von Preßluft getrocknet.Leaded fuel tanks of industrial design, previously with an alkaline cleaning solution at 65 ° C for 3 minutes by immersion treatment were treated with the above solution for 2 minutes at 22 ° C in immersion. The containers were then rinsed with water and demineralized water and dried by blowing in compressed air.
Danach wurden die Behälter mit einem Polyurethanlack der Fa. Winkelmann beschichtet.The containers were then coated with a polyurethane varnish from Winkelmann.
Anschließend wurden die Behälter mit einem Einzelschnitt nach DIN 53167 versehen und dem Salzsprühtest gemäß DIN 50021 während einer Zeitdauer von 240 h unterworfen. Die Auswertung nach DIN 53167 ergab eine Unterwanderung von <3 mm.The containers were then provided with a single cut in accordance with DIN 53167 and subjected to the salt spray test in accordance with DIN 50021 for a period of 240 h. The evaluation according to DIN 53167 showed an infiltration of <3 mm.
Die Beurteilung des Blasengrades nach DIN 53209 ergab m0/g0.The assessment of the degree of bubbles according to DIN 53209 resulted in m0 / g0.
Verbleite Stahlbleche wurden mit einer alkalischen Reinigungslösung bei 55°C während 60 sec. durch Spritzen gereinigt. Anschließend wurde mit Wasser und mit vollentsalztem Wasser gespült und durch Aufblasen von Preßluft getrocknet. Danach wurden die Bleche mit einem Polyurethanlack der Fa. Winkelmann beschichtet.Leaded steel sheets were cleaned with an alkaline cleaning solution at 55 ° C. for 60 seconds by spraying. It was then rinsed with water and deionized water and dried by blowing in compressed air. The sheets were then coated with a polyurethane varnish from Winkelmann.
Anschließend wurden die verbleiten Stahlbleche mit einem Einzelschnitt nach DIN 53167 versehen und dem Salzsprühtest gemäß DIN 50021 während einer Zeitdauer von 240 h unterworfen. Die Auswertung nach DIN 53167 ergab eine Unterwanderung von >20 mm.The leaded steel sheets were then provided with a single cut in accordance with DIN 53167 and subjected to the salt spray test in accordance with DIN 50021 for a period of 240 h. The evaluation according to DIN 53167 showed an infiltration of> 20 mm.
Die Beurteilung des Blasengrades nach DIN 53209 ergab m5/g5.The assessment of the degree of bubbles according to DIN 53209 resulted in m5 / g5.
Das Vergleichsbeispiel veranschaulicht, daß das erfindungsgemäße Verfahren eine deutliche Verbesserung des Korrosionsschutzes erbringt.The comparative example illustrates that the method according to the invention brings about a significant improvement in corrosion protection.
Claims (5)
- A process for passivating surfaces of lead or alloys based on lead, in which the surfaces are contacted, optionally after a degreasing treatment, with acidic aqueous solutions containing chromium ions and anions of an organic carboxylic acid, characterized in that the acidic aqueous solutions have the following composition:a) 0.01 to 10 g · 1⁻¹ chromium(III) ions in the form of chromium (III) ethanate,b) 0.001 to 10 g · 1⁻¹ PO₄³⁻ ions in the form of phosphoric acid.
- A process as claimed in claim 1, characterized in that the solutions contain 0.02 to 5 g · 1⁻¹ chromium(III) ions.
- A process as claimed in claim 1 or 2, characterized in that the solutions have a pH value in the range from 2 to 6 and preferably in the range from 3.2 to 4.2.
- A process as claimed in claims 1 to 3, characterized in that the solutions contain 0.01 to 5 g · 1⁻¹ PO₄³⁻ ions.
- A process as claimed in claims 1 to 4, characterized in that the surfacesa) are cleaned with an alkaline cleaning solution,b) treated with the acidic aqueous solutions at 20 to 40°C by spraying or dipping and thenc) rinsed with water or deionized or low-salt water and dried.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3429532 | 1984-08-10 | ||
| DE19843429532 DE3429532A1 (en) | 1984-08-10 | 1984-08-10 | METHOD FOR PASSIVATING LEAD AND LEAD-BASED SURFACES |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0171043A2 EP0171043A2 (en) | 1986-02-12 |
| EP0171043A3 EP0171043A3 (en) | 1988-06-08 |
| EP0171043B1 true EP0171043B1 (en) | 1991-05-15 |
Family
ID=6242814
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP85109735A Expired - Lifetime EP0171043B1 (en) | 1984-08-10 | 1985-08-02 | Passivating process for lead and lead-containing surfaces |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0171043B1 (en) |
| JP (1) | JPS6148575A (en) |
| CA (1) | CA1261716A (en) |
| DE (2) | DE3429532A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4135524A1 (en) * | 1991-10-28 | 1993-04-29 | Gc Galvano Consult Gmbh | Chrome plating of zinc@, cadmium@ and their alloys - using aq. soln. of chromium (III) oxalate complex, at acidic pH to form blue corrosion-resistant coating |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9409811D0 (en) * | 1994-05-17 | 1994-07-06 | Imi Yorkshire Fittings | Improvements in copper alloy water fittings |
| WO2018209348A1 (en) | 2017-05-12 | 2018-11-15 | Chemeon Surface Technology, Llc | pH STABLE TRIVALENT CHROMIUM COATING SOLUTIONS |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB118182A (en) * | 1917-10-04 | 1918-08-22 | Edwin Ebenezer Burnett | Depositing Chromium upon Metals, particularly Iron, Chemically. |
| US3592747A (en) * | 1966-08-17 | 1971-07-13 | Samuel L Cohn & Charles C Cohn | Method of forming a decorative and protective coating on a surface |
| DE2031358C3 (en) * | 1970-06-25 | 1981-10-15 | Gerhard Collardin GmbH, 5000 Köln | Process for the production of protective layers on aluminum, iron and zinc by means of acidic solutions containing complex fluorides |
| GB1461244A (en) * | 1974-06-17 | 1977-01-13 | Lubrizol Corp | Treatment of metal surfaces with trivalent chromium solutions |
| EP0034040A1 (en) * | 1980-02-06 | 1981-08-19 | BNF Metals Technology Centre | Method of producing conversion coatings |
| GB2117414B (en) * | 1982-03-26 | 1985-11-13 | Usui Kokusai Sangyo Kk | Ferrous substrates hot dip coated with lead alloy |
-
1984
- 1984-08-10 DE DE19843429532 patent/DE3429532A1/en not_active Withdrawn
-
1985
- 1985-07-16 CA CA000486844A patent/CA1261716A/en not_active Expired
- 1985-08-02 EP EP85109735A patent/EP0171043B1/en not_active Expired - Lifetime
- 1985-08-02 DE DE8585109735T patent/DE3582833D1/en not_active Expired - Fee Related
- 1985-08-08 JP JP60175628A patent/JPS6148575A/en active Pending
Non-Patent Citations (2)
| Title |
|---|
| Handbuch der Galvanotechnik, Band III, Seite 140 * |
| Ullmann, Bd. 9, Seite 618 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4135524A1 (en) * | 1991-10-28 | 1993-04-29 | Gc Galvano Consult Gmbh | Chrome plating of zinc@, cadmium@ and their alloys - using aq. soln. of chromium (III) oxalate complex, at acidic pH to form blue corrosion-resistant coating |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3582833D1 (en) | 1991-06-20 |
| CA1261716A (en) | 1989-09-26 |
| DE3429532A1 (en) | 1986-02-20 |
| EP0171043A2 (en) | 1986-02-12 |
| EP0171043A3 (en) | 1988-06-08 |
| JPS6148575A (en) | 1986-03-10 |
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