EP0214571B1 - Process for forming conversion layers on zinc and/or zinc alloys - Google Patents
Process for forming conversion layers on zinc and/or zinc alloys Download PDFInfo
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- EP0214571B1 EP0214571B1 EP86111976A EP86111976A EP0214571B1 EP 0214571 B1 EP0214571 B1 EP 0214571B1 EP 86111976 A EP86111976 A EP 86111976A EP 86111976 A EP86111976 A EP 86111976A EP 0214571 B1 EP0214571 B1 EP 0214571B1
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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
- C23C22/37—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 hexavalent chromium compounds
- C23C22/38—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 hexavalent chromium compounds containing also phosphates
Definitions
- the invention relates to a var procedure for producing conversion layers on surfaces made of zinc or zinc alloys by means of aqueous acidic chromating solutions which contain chromium VI, chromium III and phosphate.
- drying processes i.e. Processes in which the chromating solution is dried without rinsing water at ambient temperature or in particular at an elevated temperature are becoming increasingly important.
- the advantage of such methods is, in particular, that no rinsing water is produced and that the conversion layers obtained in this way impart excellent corrosion resistance.
- Another advantage is that the treatment solutions e.g. by adding zinc or reducing chromium VI to chromium III less than those in which the conversion layer is in constant contact with the solution.
- the object of the invention is to provide a method for producing conversion layers on surfaces made of zinc or zinc alloys, the chromating solution of which has a longer service life, which leads to excellent conversion layers with regard to corrosion protection and adhesion promotion for a possibly subsequently applied lacquer and which is nevertheless simple to carry out .
- the method is suitable for the treatment of workpieces coated with solid zinc or solid zinc alloys, e.g. galvanized steel sheet or strip.
- chromic acid is introduced as such in the simplest way.
- the chromium-III ions can be added using suitable salts, but particularly advantageously by reducing chromium-VI using e.g. Oxalic acid, tannic acid, starch, alcohol, hydrazine or citric acid can be added.
- the phosphate content can be adjusted by adding phosphoric acid, ammonium phosphate and the like.
- the fluorozirconate content can be measured by adding ammonium hexafluorozirconate or the free acid.
- the concentrations of the active constituents of the chromating solution are critical insofar as the conversion layers produced do not have the required quality at a chromic acid concentration below 10 g / l, and at a concentration above 100 g / l the paint adhesion decreases due to an excessively high layer weight. In the case of chromium concentrations below 1 g / 1, the corrosion protection in particular decreases. It should also be noted that only certain varnishes can then be applied, i.e. the otherwise universal type of painting is partially lost. At concentrations above 21 g / 1, it is difficult to avoid the formation of precipitates in the chromating solution.
- the phosphate. that is built into the conversion layer is responsible in particular for the uniform appearance of the conversion layer and the excellent adhesion for a subsequently applied lacquer. If its concentration is below 0.1 g / l, the aforementioned effects are only present to a small extent. At concentrations above 4 g / l, the proportion of phosphate in the conversion layer increases sharply, which is associated with reduced corrosion resistance. The fluorozirconate ion intensifies the pickling attack on the zinc surface. Its ability to complexly bind metal ions is likely to be decisive for increasing the service life of the chromating solution or for its ability to form conversion layers of excellent quality over a longer period of time.
- the chromium VI chromium III weight ratio also determines the uniformity of the conversion layers produced, but is also responsible for the long service life of the chromating solution and the universal type of coating. When leaving the area, these advantages no longer exist. Even the weight ratios of chrome Acid: fluorozirconate and phosphate: fluorozirconate are critical insofar as the favorable results with regard to corrosion resistance, adhesion promotion and universal paintability are lost when the design rule is left.
- the metal surface is brought into contact with a chromating solution in which the weight ratio of chromic acid: fluorozirconate is set to (10 to 40): 1.
- the corrosion resistance and the adhesion promotion of the conversion layer produced by the method according to the invention can be further improved if, according to a preferred embodiment of the invention, the surface is brought into contact with a chromating solution which additionally contains 0.1 to 200 g / l of silicate or silica. With lower contents, the improvement achieved is only very slight, with higher contents, the layer weight increases considerably, which reduces the paint adhesion. The best results are achieved if, according to a further advantageous embodiment of the invention, the metal surface is brought into contact with a chromating solution in which the weight ratio of chromic acid: silica is set to (10 to 0.5): 1.
- the chromating solution is usually used at a temperature that ranges from ambient to 50 ° C.
- the contact with the surface consisting of zinc or a zinc alloy is best done by roller application, spraying or dipping. Any excess chromating solution should be removed as soon as possible, for example using pinch rollers. In this way, it can be achieved in a particularly simple manner that a specific and constant layer weight results.
- a particularly favorable embodiment of the invention provides for the metal surface to be brought into contact with the phosphating solution in such a way that, after drying, a layer weight of 10 to 200 mg / m 2 , preferably 15 to 100 mg / m 2 (calculated as Cr) , results.
- Excess chromating solution removed using squeeze rollers can be returned to the treatment bath and thereby reused.
- drying is carried out without intermediate rinsing. This can be done at ambient temperature or at elevated temperature, e.g. in a convection oven.
- the service life of the chromating solution is practically unlimited and the conversion layers produced are of excellent quality.
- meaningful means, within the usual process sequence, degreasing / cleaning, rinsing water, applying the chromating solution and drying by thorough rinsing to ensure that as little contamination as possible gets into the chromating solution.
- a certain enrichment, particularly of zinc ions cannot be avoided, an excess can be removed by known ion exchange processes.
- Oiled sheets of hot-dip galvanized steel were treated after the process step alkaline degreasing, water rinsing, squeezing with rollers, roller application of the chromating solution at room temperature and drying.
- the compositions of the chromating solutions used for this are given in Table 1 below.
- the layer weights produced with all chromating solutions were 20 to 25 mglm 2 (calculated as Cr).
- the coating is first scratched with a cutter at a distance of 1 mm to the metal surface, so that a grid with several scratch marks lying at an angle of 90 ° is created.
- the test sheet is first dented slowly by pressing in a ball until a bulge with a height of 7 mm is created.
- a falling body with a weight of 1 kg and a punch diameter of 12.7 mm is dropped on the test sheet from a height of 30 cm. The top and back of the deformed area are evaluated.
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Description
Die Erfindung betrifft ein Varfahren zur Erzeugung von Konversionsschichten auf Oberflächen aus Zink oder Zinklegierungen mittels wässriger saurer Chromatierungslösungen, die Chrom-VI, Chrom-III und Phosphat enthalten.The invention relates to a var procedure for producing conversion layers on surfaces made of zinc or zinc alloys by means of aqueous acidic chromating solutions which contain chromium VI, chromium III and phosphate.
Bei der Erzeugung von Konversionsschichten auf Metalloberflächen mit Hilfe von Chromatierungslösungen erlangen sogenannte Auftrockenverfahren, d.h. Verfahren, bei denen die Chromatierungslösung ohne Wasserspülung bei Umgebungstemperatur oder insbesondere erhöhter Temperatur aufgetrocknet wird, zunehmend an Bedeutung. Der Vorzug derartiger Verfahren liegt insbesondere darin, dass kein Spülwasser anfällt und dass die so erhaltenen Konversionsschichten einen hervorragenden Korrosionswiderstand vermitteln. Ein weiterer Vorteil ist dadurch gegeben, dass sich die Behandlungslösungen z.B. durch Eintrag von Zink oder Reduktion von Chrom-VI zu Chrom-III weniger stark verändern als diejenigen, bei denen die Ausbildung der Konversionsschicht in ständigem Kontakt mit der Lösung erfolgt.When generating conversion layers on metal surfaces with the aid of chromating solutions, so-called drying processes, i.e. Processes in which the chromating solution is dried without rinsing water at ambient temperature or in particular at an elevated temperature are becoming increasingly important. The advantage of such methods is, in particular, that no rinsing water is produced and that the conversion layers obtained in this way impart excellent corrosion resistance. Another advantage is that the treatment solutions e.g. by adding zinc or reducing chromium VI to chromium III less than those in which the conversion layer is in constant contact with the solution.
Dennoch lässt es sich auch bei Auftrockenverfahren nicht gänzlich vermeiden, dass z.B. durch den Vorgang des Abquetschens überschüssiger Behandlungslösung von der Metalloberfläche Ionen aus der Metalloberfläche in die Lösung gelangen. In gleicher Weise findet auch eine gewisse Anreicherung von durch Reduktion gebildeten Chrom-III-Ionen statt.Nevertheless, even with drying processes, it cannot be completely avoided that e.g. by squeezing excess treatment solution from the metal surface ions get into the solution from the metal surface. In the same way, a certain accumulation of chromium III ions formed by reduction takes place.
Die Folge der vorstehend geschilderten Effekte ist, dass mit zunehmender Alterung der Chromatierungslösung die hiermit erzeugen Konversionsschichten nicht mehr die Qualität besitzen, die anfänglich mit einer frischen Chromatierungslösung erhalten wurde. Ein Neuansatz des Behandlungsbades in gewissen zeitlichen Abständen ist daher unvermeidlich.The consequence of the effects described above is that with increasing aging of the chromating solution, the conversion layers produced herewith no longer have the quality that was initially obtained with a fresh chromating solution. A new preparation of the treatment bath at certain intervals is therefore inevitable.
Aufgabe der Erfindung ist es, ein Verfahren zur Erzeugung von Konversionsschichten auf Oberflächen aus Zink oder Zinklegierungen bereitzustellen, dessen Chromatierungslösung eine längere Standzeit besitzt, das zu hervorragenden Konversionsschichten hinsichtlich Korrosionsschutz und Haftvermittlung für einen gegebenenfalls anschliessend aufgebrachten Lack führt und das dennoch einfach in der Durchführung ist.The object of the invention is to provide a method for producing conversion layers on surfaces made of zinc or zinc alloys, the chromating solution of which has a longer service life, which leads to excellent conversion layers with regard to corrosion protection and adhesion promotion for a possibly subsequently applied lacquer and which is nevertheless simple to carry out .
Die Aufgabe wird gelöst, indem das Verfahren der eingangs genannten Art entsprechend der Erfindung derart ausgestaltet wird, dass man die Metalloberfläche mit einer Chromatierungslösung in Kontakt bringt, die
- 10 bis 100 g/l Chromsäure (ber. als Cr03)
- 1 bis 21 g/I Chrom-Ionen (ber. als Cr)
- 0,1 bis 4 g/I Phosphationen (ber. als P04) und
- 0,1 bis 4 g/I Fluorozirkonationen (ber. als ZrFs)
enthält, in der das Gewichtsverhältnis
- von Chrom-VI: Chrom-III auf (1,5 bis 5) : 1
- von Chromsäure: Fluorozirkonat auf (5 bis 100) : 1 und
- von Phosphat: Fluorozirkonat auf (0,5 bis 2) : 1 eingestellt ist und man die Chromatierungslösung anschliessend auftrocknet.
- 10 to 100 g / l chromic acid (calculated as Cr0 3 )
- 1 to 21 g / I chromium ions (calculated as Cr)
- 0.1 to 4 g / l phosphate ions (calc. As P0 4 ) and
- 0.1 to 4 g / l fluorozirconate ions (calculated as ZrFs)
contains in which the weight ratio
- from Chromium VI: Chromium III to (1.5 to 5): 1
- of chromic acid: fluorozirconate on (5 to 100): 1 and
- of phosphate: fluorozirconate is set to (0.5 to 2): 1 and the chromating solution is then dried.
Das Verfahren ist zur Behandlung von Werkstücken geeignet, die aus massivem Zink bzw. massiven Zinklegierungen beschichtet sind, z.B. verzinktes Stahlblech oder -band.The method is suitable for the treatment of workpieces coated with solid zinc or solid zinc alloys, e.g. galvanized steel sheet or strip.
Zum Ansatz der Chromatierungslösung wird Chromsäure in einfachster Weise als solche eingebracht. Die Chrom-III-Ionen können über geeignete Salze, mit besonderem Vorteil jedoch durch Reduktion von Chrom-VI mittels z.B. Oxalsäure, Tanninsäure, Stärke, Alkohol, Hydrazin oder Zitronensäure, zugeführt werden. Der Phosphatgehalt kann durch Zugabe von Phosphorsäure, Ammonphosphat und dergl. eingestellt werden. Die Bemessung der Fluorozirkonatgehaltes kann durch Eintrag von Ammoniumhexafluorozirkonat oder der freien Säure erfolgen.To prepare the chromating solution, chromic acid is introduced as such in the simplest way. The chromium-III ions can be added using suitable salts, but particularly advantageously by reducing chromium-VI using e.g. Oxalic acid, tannic acid, starch, alcohol, hydrazine or citric acid can be added. The phosphate content can be adjusted by adding phosphoric acid, ammonium phosphate and the like. The fluorozirconate content can be measured by adding ammonium hexafluorozirconate or the free acid.
Bei der Zugabe der Badbestandteile sollte darauf geachtet werden, dass ein Eintrag von Alkaliionen möglichst unterbleibt.When adding the bath components, care should be taken to ensure that alkali ions are not introduced as far as possible.
Die Konzentrationen der wirksamen Bestandteile der Chromatierungslösung sind insofern kritisch, als bei einer Chromsäurekonzentration unter 10 g/I die erzeugten Konversionsschichten nicht die erforderliche Qualität besitzen, bei einer Konzentration über 100 g/I infolge eines zu hohen Schichtgewichtes die Lackhaftung sinkt. Bei Chromkonzentrationen unter 1 g/1 lässt insbesondere der Korrosionsschutz nach. Auch ist festzustellen, dass dann nur bestimmte Lacke aufgebracht werden können, d.h. die sonst gegebene universelle Art der Lackierung geht teilweise verloren. Bei Konzentrationen über 21 g/1 bereitet es Schwierigkeiten, die Bildung von Niederschlägen in der Chromatierungslösung zu vermeiden.The concentrations of the active constituents of the chromating solution are critical insofar as the conversion layers produced do not have the required quality at a chromic acid concentration below 10 g / l, and at a concentration above 100 g / l the paint adhesion decreases due to an excessively high layer weight. In the case of chromium concentrations below 1 g / 1, the corrosion protection in particular decreases. It should also be noted that only certain varnishes can then be applied, i.e. the otherwise universal type of painting is partially lost. At concentrations above 21 g / 1, it is difficult to avoid the formation of precipitates in the chromating solution.
Das Phosphat. das mit in die Konversionsschicht eingebaut wird, ist insbesondere für das gleichmässige Aussehen der Konversionsschicht und die hervorragende Haftvermittlung für einen anschliessend aufgebrachten Lack verantwortlich. Sofern dessen Konzentration unter 0,1 g/l liegt, sind die vorgenannten Effekte nur in geringem Masse vorhanden. Bei Konzentrationen über 4 g/I nimmt der Anteil des Phosphates in der Konversionsschicht stark zu, was mit einem verminderten Korrosionswiderstand verbunden ist. Das Fluorozirkonat-lon intensiviert den Beizangriff auf der Zinkoberfläche. Seine Fähigkeit, Metallionen komplex zu binden, dürfte massgeblich für die Erhöhung der Standzeit der Chromatierungslösung bzw. für deren Fähigkeit, über einen längeren Zeitraum Konversionsschichten von hervorragender Qualität zu bilden, sein. Bei Konzentrationen unter 0,1 g/l ist diese Wirkung nicht hinreichend ausgeprägt, bei Konzentrationen über 4 g/I ist der Beizangriff auf die Zinkoberfläche sehr stark. Dadurch gelangen zu grosse Zinkmengen in die Chromatierungslösung, wodurch der Vorteil der erhöhten Standzeit verlorengeht.The phosphate. that is built into the conversion layer is responsible in particular for the uniform appearance of the conversion layer and the excellent adhesion for a subsequently applied lacquer. If its concentration is below 0.1 g / l, the aforementioned effects are only present to a small extent. At concentrations above 4 g / l, the proportion of phosphate in the conversion layer increases sharply, which is associated with reduced corrosion resistance. The fluorozirconate ion intensifies the pickling attack on the zinc surface. Its ability to complexly bind metal ions is likely to be decisive for increasing the service life of the chromating solution or for its ability to form conversion layers of excellent quality over a longer period of time. At concentrations below 0.1 g / l, this effect is not sufficiently pronounced; at concentrations above 4 g / l, the pickling attack on the zinc surface is very strong. As a result, excessive amounts of zinc get into the chromating solution, which means that the advantage of increased service life is lost.
Das Gewichtsverhältnis Chrom-VI: Chrom-III bestimmt ebenfalls die Gleichmässigkeit der erzeugten Konversionsschichten, ist aber auch für die hohe Standzeit der Chromatierungslösung und die universelle Art der Lackierung verantwortlich. Beim Verlassen des Bereiches sind diese Vorzüge nicht mehr gegeben. Auch die Gewichtsverhältnisse von Chromsäure: Fluorozirkonat und von Phosphat: Fluorozirkonat sind insofern kritisch, als beim Verlassen der Bemessungsregel die günstigen Ergebnisse hinsichtlich Korrosionswiderstand, Haftvermittlung und universeller Lackierbarkeit verlorengehen.The chromium VI: chromium III weight ratio also determines the uniformity of the conversion layers produced, but is also responsible for the long service life of the chromating solution and the universal type of coating. When leaving the area, these advantages no longer exist. Even the weight ratios of chrome Acid: fluorozirconate and phosphate: fluorozirconate are critical insofar as the favorable results with regard to corrosion resistance, adhesion promotion and universal paintability are lost when the design rule is left.
Besonders günstige Ergebnisse werden erzielt, wenn man entsprechend einer vorteilhaften Weiterbildung der Erfindung die Metalloberfläche mit einer Chromatierungslösung in Kontakt bringt, in der das Gewichtsverhältnis von Chromsäure: Fluorozirkonat auf (10 bis 40) : 1 eingestellt ist.Particularly favorable results are achieved if, according to an advantageous development of the invention, the metal surface is brought into contact with a chromating solution in which the weight ratio of chromic acid: fluorozirconate is set to (10 to 40): 1.
Der Korrosionswiderstand und die Haftvermittlung der mit dem erfindungsgemässen Verfahren erzeugten Konversionsschicht lassen sich weiter verbessern, wenn entsprechend einer bevorzugten Ausgestaltung der Erfindung die Oberfläche mit einer Chromatierungslösung in Kontakt gebracht wird, die zusätzlich 0,1 bis 200 g/I Silikat bzw. Kieselsäure enthält. Bei geringeren Gehalten ist die erzielte Verbesserung nur sehr geringfügig, bei höheren Gehalten steigt das Schichtgewicht beträchtlich an, wodurch die Lackhaftung verringert wird. Die besten Resultate werden erzielt, wenn man gemäss einer weiteren vorteilhaften Ausführungsform der Erfindung die Metalloberfläche mit einer Chromatierungslösung in Kontakt bringt, in der das Gewichtsverältnis von Chromsäure: Kieselsäure auf (10 bis 0,5) : 1 eingestellt ist.The corrosion resistance and the adhesion promotion of the conversion layer produced by the method according to the invention can be further improved if, according to a preferred embodiment of the invention, the surface is brought into contact with a chromating solution which additionally contains 0.1 to 200 g / l of silicate or silica. With lower contents, the improvement achieved is only very slight, with higher contents, the layer weight increases considerably, which reduces the paint adhesion. The best results are achieved if, according to a further advantageous embodiment of the invention, the metal surface is brought into contact with a chromating solution in which the weight ratio of chromic acid: silica is set to (10 to 0.5): 1.
Schliesslich ist es zweckmässig, die Metalloberfläche mit einer Chromatierungslösung in Kontakt zu bringen, deren pH-Wert im Bereich von 0,6 bis 4 liegt.Finally, it is expedient to bring the metal surface into contact with a chromating solution whose pH is in the range from 0.6 to 4.
Der Einsatz der Chromatierungslösung erfolgt üblicherweise bei einer Temperatur, die etwa von Umgebungstemperatur bis 50°C reicht. Der Kontakt mit der aus Zink oder einer Zinklegierung bestehenden Oberfläche erfolgt am zweckmässigsten durch Rollenauftrag, Spritzen oder Tauchen. Eventuelle überschüssige Chromatierungslösung sollte möglichst unverzüglich, z.B. mittels Quetschrollen, entfernt werden. Hierdurch lässt sich in besonders einfacher Weise erreichen, dass ein bestimmtes und konstantes Schichtgewicht resultiert. Eine besonders günstige Ausfürungsform der Erfindung sieht vor, die Metalloberfläche mit der Phosphatierungslösung derart in Kontakt zu bringen, dass nach dem Auftrocknen ein Schichtgewicht von 10 bis 200 mg/m2, vorzugsweise von 15 bis 100 mg/m2 (ber. als Cr), resultiert.The chromating solution is usually used at a temperature that ranges from ambient to 50 ° C. The contact with the surface consisting of zinc or a zinc alloy is best done by roller application, spraying or dipping. Any excess chromating solution should be removed as soon as possible, for example using pinch rollers. In this way, it can be achieved in a particularly simple manner that a specific and constant layer weight results. A particularly favorable embodiment of the invention provides for the metal surface to be brought into contact with the phosphating solution in such a way that, after drying, a layer weight of 10 to 200 mg / m 2 , preferably 15 to 100 mg / m 2 (calculated as Cr) , results.
Die z.B. unter Verwendung von Abquetschrollen entfernte überschüssige Chromatierungslösung kann dem Behandlungsbad wieder zugeführt und dadurch wiederverwendet werden.The e.g. Excess chromating solution removed using squeeze rollers can be returned to the treatment bath and thereby reused.
Im Anschluss an die Applikation der Chromatierungslösung wird ohne Zwischenspülung getrocknet. Dies kann bei Umgebungstemperatur oder bei erhöhter Temperatur, z.B. im Umluftofen, erfolgen.Following the application of the chromating solution, drying is carried out without intermediate rinsing. This can be done at ambient temperature or at elevated temperature, e.g. in a convection oven.
Bei sinnvoller Anwendung des erfindungsgemäsen Verfahrens sind die Standzeit der Chromatierungslösung praktisch unbegrenzt und die erzeugten Konversionsschichten von hervorragender Qualität. Sinnvoll bedeutet hierbei zum einen, innerhalb des üblichen Verfahrensablaufes Entfetten/Reinigen, Wasserspülen, Applizieren der Chromatierungslösung und Trocknen durch gründliches Spülen Sorge dafür zu tragen, dass möglichst wenig Verunreinigungen in die Chromatierungslösung gelangt. Zum anderen sollte beim In-Kontakt-Bringen mit der Chromatierungslösung darauf geachtet werden, dass möglichst keine überschüssige Chromatierungslösung aufgebracht wird oder - falls dies nicht gelingt - überschüssige Chromatierungslösung möglichst schnell entfernt wird, damit praktisch kein durch den Beizangriff gelöstes Zink bzw. gebildetes Chrom-lll in die wieder zu entfernende Lösung gelangt. Sollte sich dennoch eine gewisse Anreicherung insbesondere von Zinkionen nicht vermeiden lassen, kann durch an sich bekannte Ionenaustauscher-Verfahren ein Überschuss entfernt werden.If the method according to the invention is used sensibly, the service life of the chromating solution is practically unlimited and the conversion layers produced are of excellent quality. On the one hand, meaningful means, within the usual process sequence, degreasing / cleaning, rinsing water, applying the chromating solution and drying by thorough rinsing to ensure that as little contamination as possible gets into the chromating solution. On the other hand, when bringing the chromating solution into contact, care should be taken to ensure that no excess chromating solution is applied or, if this does not succeed, that excess chromating solution is removed as quickly as possible, so that practically no zinc or chromium formed as a result of the pickling attack lll get into the solution to be removed. However, if a certain enrichment, particularly of zinc ions, cannot be avoided, an excess can be removed by known ion exchange processes.
Die Erfindung wird anhand der folgenden Beispiele beispielsweise und näher erläutert.The invention is illustrated by the following examples, for example and in more detail.
Eingeölte Bleche aus feuerverzinktem Stahl wurden nach dem Verfahrensgang alkalische Entfettung, Wasserspülung, Abquetschen mit Rollen, Rollenauftrag der Chromatierungslösung bei Raumtemperatur und Trocknen behandelt. Die Zusammensetzungen der hierfür verwendeten Chromatierungslösungen sind in der nachfolgenden Tabelle 1 angegeben. Die mit sämtlichen Chromatierungslösungen erzeugten Schichtgewichte lagen bei 20 bis 25 mglm2 (ber. als Cr).Oiled sheets of hot-dip galvanized steel were treated after the process step alkaline degreasing, water rinsing, squeezing with rollers, roller application of the chromating solution at room temperature and drying. The compositions of the chromating solutions used for this are given in Table 1 below. The layer weights produced with all chromating solutions were 20 to 25 mglm 2 (calculated as Cr).
Tabelle 2 enthält Angaben über den mit den Konversionsschichten erzielten Korrosionswiderstand und die Lackhaftung. Dabei ist in Spalte 2 die nach 48- bzw. 72stündigem Salzsprühtest ermittelte Korrosion, bezogen auf die gesamte Fläche, in Prozent wiedergegeben. In der Spalte 3 sind die bezüglich der Lackhaftung erzielten Testergebnisse aufgeführt. Die Prüfbleche waren zu deren Ermittlung mit einem Melamin-Alkydlack von 25 11m Dicke versehen worden. Die Bewertung geschah durch Ermittlung der Lackentfernung nach dem Aufkleben und Abreissen eines Klebebandes mit den Noten 5 bis 1. Hierbei bedeuten
- 5 keine Lackentfernung
- 4 Lackentfernung bis 10% der Gesamtfläche
- 3 Lackentfernung von 11 bis 30% der Gesamtfläche
- 2 Lackentfernung von 31 bis 50% der Gesamtfläche
- Lackentfernung von 51 % und mehr der gesamten Fläche.
- 5 no paint removal
- 4 Paint removal up to 10% of the total area
- 3 Paint removal from 11 to 30% of the total area
- 2 Paint removal from 31 to 50% of the total area
- Paint removal of 51% and more of the entire area.
Beim Gitterschnitt wird der Überzug zuvor mit einem Schneidegerät im Abstand von 1 mm bis zum metallischen Untergrund angeritzt, so dass ein Gitter mit mehreren im Winkel von 90° aufeinanderliegenden Ritzspuren entsteht. Im Erichsen-Test wird das Prüfblech zuvor durch Eindrücken einer Kugel langsam verbeult, bis eine Wölbung mit einer Höhe von 7 mm entsteht. Bei der Schlagtiefung lässt man aus einer Höhe von 30 cm einen Fallkörper mit einem Gewicht von 1 kg und einem Stempeldurchmesser von 12,7 mm auf das Prüfblech fallen. Bewertet werden Ober- und Rückseite des verformten Bereiches.In the case of a cross cut, the coating is first scratched with a cutter at a distance of 1 mm to the metal surface, so that a grid with several scratch marks lying at an angle of 90 ° is created. In the Erichsen test, the test sheet is first dented slowly by pressing in a ball until a bulge with a height of 7 mm is created. In the impact recess, a falling body with a weight of 1 kg and a punch diameter of 12.7 mm is dropped on the test sheet from a height of 30 cm. The top and back of the deformed area are evaluated.
In Spalte 4 ist die Lackunterwanderung lackierter und mit einem Kreuzschnitt versehener Bleche nach 144stündiger Salzsprühbehandlung angegeben. Zur Bestimmung wurde im Bereich der Ritzstelle Klebeband aufgepresst und anschliessend abgerissen. Die Zahlenangaben verstehen sich als von der Ritzstelle ausgehend nach einer Seite gemessen.Column 4 shows the undermining of the lacquered and cross-cut sheet metal 144 hour salt spray treatment indicated. For the determination, adhesive tape was pressed on in the area of the scratch point and then torn off. The figures are understood to be measured on one side from the scratch point.
In einem weiteren Versuch wurde durch kontinuierliche Behandlung von Blech in den Chromatierungslösungen gemäss Beispiel 1 und Vergleichsbeispiel 1 der Grad der Zinkanreicherung und insbesondere deren Auswirkung auf den Korrosionswiderstand bei einer Salzsprühbehandlung von 48 bis 72 Stunden untersucht. Die Ergebnisse sind in Tabelle 3 niedergelegt.
Schliesslich wurde bei einem weiteren Versuch der Einfluss der Veränderung der wirksamen Badbestandteile auf den Chromgehalt in der Konversionsschicht uind auf den Korrosionswiderstand bei der Salzprühprüfung von 48 bzw. 72 Stunden Dauer untersucht. Die erhaltenen Ergebnisse finden sich in Tabelle 4.
Bei sämtlichen Prüfungen zeigte sich, das die nach dem erfindungsgemässen Verfahren erzeugten Konversionsschichten von hervorragender Qualität hinsichtlich Korrosionswiderstand und Haftvermittlung bei anschliessender Lackierung sind. Auch wird deutlich, dass die innerhalb des erfindungsgemässen Verfahrens zum Einsatz kommenden Chromatierungslösungen einen beträchtlichen Zinkgehalt tolerieren, ohne dass damit eine wesentliche Verschlechterung des Korrosionswiderstandes verbunden wäre.In all of the tests, it was found that the conversion layers produced by the process according to the invention are of excellent quality with regard to corrosion resistance and adhesion promotion with subsequent painting. Also will It is clear that the chromating solutions used in the process according to the invention tolerate a considerable zinc content without being associated with a significant deterioration in the corrosion resistance.
Claims (6)
in which the weight ratio is adjusted
and thereafter the chromating solution is dried in situ.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60194940A JPS6256580A (en) | 1985-09-05 | 1985-09-05 | Chromating solution for galvanized steel sheet |
| JP194940/85 | 1985-09-05 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0214571A1 EP0214571A1 (en) | 1987-03-18 |
| EP0214571B1 true EP0214571B1 (en) | 1989-01-18 |
Family
ID=16332863
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP86111976A Expired EP0214571B1 (en) | 1985-09-05 | 1986-08-29 | Process for forming conversion layers on zinc and/or zinc alloys |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US4749418A (en) |
| EP (1) | EP0214571B1 (en) |
| JP (1) | JPS6256580A (en) |
| AU (1) | AU584454B2 (en) |
| CA (1) | CA1274156A (en) |
| DE (2) | DE3661845D1 (en) |
| GB (1) | GB2180263B (en) |
| NZ (1) | NZ217245A (en) |
| ZA (1) | ZA866712B (en) |
Families Citing this family (30)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6352338A (en) * | 1987-05-29 | 1988-03-05 | Mitsubishi Electric Corp | Disk reproducing device |
| GB2215740B (en) * | 1988-02-08 | 1992-06-03 | Brent Chemicals Int | Composition and process for treating metal surfaces |
| JPH01249331A (en) * | 1988-03-31 | 1989-10-04 | Toyo Kohan Co Ltd | Manufacture of metallic sheet coated with polyester resin superior in processability |
| JPH0735587B2 (en) * | 1988-06-30 | 1995-04-19 | 日本鋼管株式会社 | Manufacturing method of high corrosion resistant surface treated steel sheet |
| JPH0230771A (en) * | 1988-07-19 | 1990-02-01 | Nkk Corp | Production of surface-treated steel sheet having high corrosion resistance |
| JPH02243772A (en) * | 1989-03-17 | 1990-09-27 | Nisshin Steel Co Ltd | Chromating solution ensuring high corrosion resistance for galvanized steel sheet and chromating method |
| JPH0753911B2 (en) * | 1989-04-07 | 1995-06-07 | 日本パーカライジング株式会社 | Chromate treatment method for galvanized steel sheet |
| JP2879344B2 (en) * | 1989-04-07 | 1999-04-05 | 富山化学工業株式会社 | Anti-inflammatory preparation containing 3-formylamino-7-methylsulfonylamino-6-phenoxy-4H-1-benzopyran-4-one or a salt thereof |
| JPH07100873B2 (en) * | 1989-09-27 | 1995-11-01 | 日本パーカライジング株式会社 | Chromate coating solution for zinc-based plated steel sheet |
| CA2019861C (en) * | 1990-06-26 | 1995-10-17 | Hiroaki Kawamura | Tin-plated steel sheet with a chromium bilayer and a copolyester resin laminate and method |
| JP2628782B2 (en) * | 1990-10-08 | 1997-07-09 | 日本パーカライジング株式会社 | Chromate treatment method for galvanized steel sheet |
| LT3218B (en) | 1993-03-27 | 1995-04-25 | Chemijos Inst | Method for coating zinc alloy by chromium plating |
| JP3288152B2 (en) * | 1993-08-14 | 2002-06-04 | 日本パーカライジング株式会社 | Method for producing galvanized steel sheet with excellent resistance to blackening and white rust |
| JPH09157864A (en) * | 1995-11-30 | 1997-06-17 | Nippon Parkerizing Co Ltd | Chromate treating solution composition for metallic material and treatment thereby |
| US6149735A (en) * | 1995-11-30 | 2000-11-21 | Henkel Corporation | Chromate treatment bath composition and process for application to metals |
| DE19615664A1 (en) | 1996-04-19 | 1997-10-23 | Surtec Produkte Und Systeme Fu | Chromium (VI) free chromate layer and process for its production |
| US7314671B1 (en) | 1996-04-19 | 2008-01-01 | Surtec International Gmbh | Chromium(VI)-free conversion layer and method for producing it |
| CA2252559C (en) * | 1996-04-26 | 2006-06-06 | Henkel Corporation | Chromate passivating and storage stable concentrate solutions therefor |
| WO1999008806A1 (en) | 1997-08-21 | 1999-02-25 | Henkel Corporation | Process for coating and/or touching up coatings on metal surfaces |
| DE19740248A1 (en) * | 1997-09-12 | 1999-03-18 | Henkel Kgaa | Aqueous chromating or post-passivating solution |
| KR100370472B1 (en) * | 1998-12-02 | 2003-04-10 | 주식회사 포스코 | Cr Solution for Coating Steel Sheets |
| US6527841B2 (en) * | 2000-10-31 | 2003-03-04 | The United States Of America As Represented By The Secretary Of The Navy | Post-treatment for metal coated substrates |
| US6375726B1 (en) * | 2000-10-31 | 2002-04-23 | The United States Of America As Represented By The Secretary Of The Navy | Corrosion resistant coatings for aluminum and aluminum alloys |
| DE102004032561B3 (en) * | 2004-07-05 | 2006-02-09 | Heraeus Electro-Nite International N.V. | Container for molten metal and use of the container |
| US20060240191A1 (en) * | 2005-04-21 | 2006-10-26 | The U.S. Of America As Represented By The Secretary Of The Navy | Composition and process for preparing chromium-zirconium coatings on metal substrates |
| KR20110020237A (en) | 2008-04-25 | 2011-03-02 | 헨켈 아게 운트 코 카게아아 | Trichrome passivates for treating galvanized steel |
| US8273190B2 (en) | 2009-05-29 | 2012-09-25 | Bulk Chemicals, Inc. | Method for making and using chromium III salts |
| US20110070429A1 (en) * | 2009-09-18 | 2011-03-24 | Thomas H. Rochester | Corrosion-resistant coating for active metals |
| US8425692B2 (en) | 2010-05-27 | 2013-04-23 | Bulk Chemicals, Inc. | Process and composition for treating metal surfaces |
| US10435806B2 (en) | 2015-10-12 | 2019-10-08 | Prc-Desoto International, Inc. | Methods for electrolytically depositing pretreatment compositions |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL70371C (en) * | 1948-07-12 | 1900-01-01 | ||
| US3076734A (en) * | 1960-07-01 | 1963-02-05 | Acme Steel Co | Protective coatings on metals |
| US3278343A (en) * | 1963-03-12 | 1966-10-11 | Amchem Prod | Conversion coating of magnesium alloy surfaces |
| DE1277646B (en) * | 1963-06-27 | 1968-09-12 | Metallgesellschaft Ag | Process for increasing the corrosion resistance of surfaces made of aluminum and aluminum alloys |
| US3382111A (en) * | 1965-04-26 | 1968-05-07 | Pennsalt Chemicals Corp | Coating metal |
| US3562011A (en) * | 1968-04-26 | 1971-02-09 | Gen Electric | Insulating coating comprising an aqueous mixture of the reaction product of chromium nitrate and sodium chromate,phosphoric acid and colloidal silica and method of making the same |
| JPS499022B1 (en) * | 1970-12-11 | 1974-03-01 | ||
| JPS6039751B2 (en) * | 1982-08-12 | 1985-09-07 | 新日本製鐵株式会社 | Chromate treatment method for zinc-coated steel |
| JPS6039169A (en) * | 1983-08-12 | 1985-02-28 | Nippon Light Metal Co Ltd | Hydrophilic surface treating agent for metal |
-
1985
- 1985-09-05 JP JP60194940A patent/JPS6256580A/en active Granted
-
1986
- 1986-08-08 US US06/894,595 patent/US4749418A/en not_active Expired - Fee Related
- 1986-08-18 NZ NZ217245A patent/NZ217245A/en unknown
- 1986-08-25 AU AU61815/86A patent/AU584454B2/en not_active Ceased
- 1986-08-29 EP EP86111976A patent/EP0214571B1/en not_active Expired
- 1986-08-29 DE DE8686111976T patent/DE3661845D1/en not_active Expired
- 1986-08-29 DE DE19863629382 patent/DE3629382A1/en not_active Withdrawn
- 1986-09-03 CA CA000517392A patent/CA1274156A/en not_active Expired - Fee Related
- 1986-09-03 ZA ZA866712A patent/ZA866712B/en unknown
- 1986-09-25 GB GB8621414A patent/GB2180263B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| NZ217245A (en) | 1988-10-28 |
| GB2180263A (en) | 1987-03-25 |
| GB8621414D0 (en) | 1986-10-15 |
| US4749418A (en) | 1988-06-07 |
| AU6181586A (en) | 1987-03-12 |
| AU584454B2 (en) | 1989-05-25 |
| DE3629382A1 (en) | 1987-03-05 |
| EP0214571A1 (en) | 1987-03-18 |
| JPS6256580A (en) | 1987-03-12 |
| JPH0419313B2 (en) | 1992-03-30 |
| ZA866712B (en) | 1987-11-25 |
| DE3661845D1 (en) | 1989-02-23 |
| GB2180263B (en) | 1989-08-16 |
| CA1274156A (en) | 1990-09-18 |
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