EP3140438B1 - Zinc-plated workpiece with improved adhesion for cover layers - Google Patents

Zinc-plated workpiece with improved adhesion for cover layers Download PDF

Info

Publication number
EP3140438B1
EP3140438B1 EP15726512.5A EP15726512A EP3140438B1 EP 3140438 B1 EP3140438 B1 EP 3140438B1 EP 15726512 A EP15726512 A EP 15726512A EP 3140438 B1 EP3140438 B1 EP 3140438B1
Authority
EP
European Patent Office
Prior art keywords
zinc
voltage
pores
time interval
workpiece
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
EP15726512.5A
Other languages
German (de)
French (fr)
Other versions
EP3140438A1 (en
Inventor
Mark-Daniel GERNGROSS
Jürgen CARSTENSEN
Rainer Adelung
Helmut FÖLL
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Christian Albrechts Universitaet Kiel
Original Assignee
Christian Albrechts Universitaet Kiel
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Christian Albrechts Universitaet Kiel filed Critical Christian Albrechts Universitaet Kiel
Publication of EP3140438A1 publication Critical patent/EP3140438A1/en
Application granted granted Critical
Publication of EP3140438B1 publication Critical patent/EP3140438B1/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25FPROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00Electrolytic etching or polishing
    • C25F3/02Etching

Definitions

  • the invention relates to a galvanized workpiece having polycrystalline zinc at least on parts of the workpiece surface.
  • the invention further relates to a method for producing a galvanized workpiece with improved adhesion for cover layers.
  • the protective passivation layer has the disadvantage of reduced adhesion to polymers, paints or other metallic films to be applied as a cover layers on a galvanized workpiece surface.
  • Adhesion can be improved by providing adhesion promoting chemicals, either as a separate interlayer or as a component of the overcoat to be applied. But in addition to the cost of the primer usually additional work steps are required, and the coating result is not always satisfactory. For example, delamination may occur over time when the thermal expansion coefficients of the workpiece and the paint are very different and the painted workpiece is subject to high temperature variations.
  • trenches, pores or local elevations on the workpiece surface can be structures which can be penetrated, filled or surrounded by a flowable polymer or lacquer, so that the subsequently curing polymer or lacquer film is fixed as a result of mechanical anchoring.
  • PTFE polytetrafluoroethylene
  • the etched chromium layer plays the role of a bonding agent.
  • contiguous network patterns of grooves are to be produced, as can be seen in FIGS. 6 and 7 of the document. It may be assumed that the deposited chromium layer is polycrystalline and that the grooves form by etching along the grain boundaries.
  • Intergranular etching of metal surfaces to improve the adhesion of polymers is also the subject of DE 601 28 364 T2 , which also proposes an immersion plating step.
  • the galvanizing of a workpiece can be done by galvanic deposition, flame spraying or by dip coating in a molten zinc - also: hot dip galvanizing.
  • Dip coating is the most widely used industrial process for corrosion protection of steel. He will both on finished parts - galvanizing with coating thicknesses in the range 50-150 micrometers - as well as on endless steel strips - strip galvanizing with coating thicknesses up to about 20 micrometers - applied. Strip-galvanized steel sheets are generally still cut after cutting, punched and formed, whereby the coating is damaged in places. It is therefore common to provide such galvanized workpieces with other cover layers, not least also to restore the corrosion protection.
  • galvanized workpiece is also used for such workpieces that attain their final shape only after being coated with zinc. It is only important that at least parts of their surface have a zinc layer.
  • the coating is a polycrystalline zinc layer on the workpiece surface, whereby the zinc crystallites can reach particle sizes of millimeters to centimeters.
  • the etching of depressions along the grain boundaries does not provide sufficient space for a robust anchoring of cover layers on the galvanized workpiece with very large particle sizes.
  • the object is achieved by providing a galvanized workpiece, which has polycrystalline zinc with particle sizes greater than 20 micrometers, at least on parts of the workpiece surface, characterized by irregularly distributed, penetrating into the zinc grains, different diameter, conical pores.
  • the subclaims are directed to advantageous embodiments of the galvanized workpiece and to a method for its production.
  • a conical pore in the sense of the present invention is a pore whose pore diameter at the pore approach - on the workpiece surface - assumes a maximum and decreases monotonically towards the pore tip - in the interior of the zinc layer.
  • the pore diameter never increases with the etching depth, but it decreases or at best remains piecewise constant.
  • the structures according to the invention are not created by intergranular etching, but by etching into the zinc crystallites, including zinc grains.
  • the pores penetrate into the zinc grains and penetrate into the interior of the zinc grains.
  • etching conditions can be found in which, firstly, the pore etching speed along a crystal axis differs approximately ten times from the etching speeds along a crystal axis - this can be termed the "fast etching direction" of the zinc grain secondly, crystal defects such as grain boundaries and dislocation nests are not preferentially etched.
  • the prior art knows deep, largely constant diameter in the micrometer range having channel-like or conical pores, for example, of monocrystalline semiconductors, in particular silicon wafers. These so-called macropores can penetrate almost the entire wafer if, for example, they are electrochemically etched in n-type silicon from one wafer side, while the other wafer side is illuminated. The illumination serves to provide sufficient free charge carriers at the pore tips. By contrast, the pore walls are hardly etched because there are no free charge carriers available there. The pore wall stability is therefore most likely to be found in semiconductors and also not along arbitrary crystal axes.
  • the fast etching direction is a property of the zinc grain, but can also be affected by the etching electrolyte. However, it is not readily foreseeable in any of the zinc grains which direction the fast etching direction will face.
  • zinc grains with different orientations and thus also a different direction of the rapid etching direction with respect to the workpiece surface form.
  • adjacent zinc grains have quite different crystal orientations in the finished zinc layer. Therefore, the fast etch directions with respect to the workpiece surface at quite different angles are also with respect to the surface of the workpiece. In particular, the fast etching direction is almost never perpendicular to the workpiece surface.
  • the pore structure of the galvanized workpiece according to the invention thus typically comprises side by side in a random arrangement in the wall of the same zinc grain penetrating, parallel, conical pores, of which typically only a few are directed perpendicular to the workpiece surface.
  • the diameter of the pores which has its maximum at the pore approach and should preferably be in the interval between 100 nanometers and 15 microns, more preferably between 1 and 5 microns, varies along the wall of each individual zinc grain, ie each grain is both of wide and deep as well as at the same time interspersed by less wide and less deep pores.
  • the depth to diameter ratio - also: aspect ratio - exceeds the value of 3
  • the pores penetrate so deeply into the grain, which is a part of the pore space of the zinc grain wall on which the pores attach, hidden.
  • the pore tip is no longer visible from the surface of the workpiece formed by the zinc grain walls because the pore has grown obliquely. This is certainly the case with larger aspect ratios, preferably greater than about 10.
  • Hidden pore space undercuts the workpiece surface, thereby providing greater resistance to peeling, e.g. a polymer film, which is applied in liquid form to the galvanized workpiece, also penetrates into the pore space and then cured.
  • the direction in which the pores undercut the workpiece surface varies from zinc grain to zinc grain.
  • a covering layer which is toothed with the zinc layer locally in different directions along the surface of the material in particular sets forces which are suitable for displacing the covering layer on the surface to be of greater resistance.
  • temperature-induced expansion changes of the workpiece relative to the cover layer at many points of the workpiece surface lead to increased adhesion of the cover layer, namely where the locally acting forces press the cover layer deeper into the hidden pore space.
  • the cover layer has barbs in practice, and these have local directions along the entire workpiece surface in each case in a direction dependent on the zinc grain present there.
  • the pore etching takes place in an electrochemical etching cell with a potassium chloride-containing, aqueous electrolyte.
  • the temperature is controlled and kept constant by a thermostat.
  • a square wave voltage is applied between the zinc layer and the electrode in the electrolyte, i. a temporal voltage curve, which is described by a rectangular function.
  • the square-wave voltage is periodic and preferably has a predetermined number of periods.
  • a first voltage is applied for a first time interval and a second voltage for an immediately subsequent second time interval, the time period from the beginning of the first to the end of the second time interval being the period of the periodic square voltage.
  • the nucleation of the pores should preferably be done by applying a third voltage once for a third time interval before applying the periodic square wave voltage.
  • a polycrystalline, rolled, 100 micron thick zinc foil (Zn content 99.95%) is etched.
  • the electrolyte contains 0.1 mol / liter of potassium chloride.
  • the temperature is chosen to be 50 ° C.
  • the first voltage is 0 V
  • the length of the first time interval is 4.6 s
  • the second voltage is -1 V
  • the length of the second time interval is 0.8 s
  • the third voltage is 0.5 V
  • the length of the second third time interval has been determined to be 1 s.
  • the total etching time is 10 min.
  • the etching parameters must be adjusted so as to suppress preferential etching of the grain boundaries. This can e.g. be achieved by extending the second time interval compared to the first time interval. In the case of large zinc grains, preferential etching of the grain boundaries plays a negligible role.
  • the specific etching parameters must be adapted and optimized to the specific zinc etch incident, but this is within the skill of the artisan and given him as necessary experimentation to find a favorable Is to expect working point. Usually, such tests are only to be carried out once for series production.
  • Fig. 1 shows the achieved pore structure.
  • Fig. 1 a It can be seen that the pores have been formed in a random distribution and with different pore diameters. Since all pores should become deeper and wider at the same time as the etch time increases, it can be assumed that not all visible pores are nucleated at the same time, ie during the third time interval, but some may only be nucleated during any period of the subsequent square wave. However, shows Fig. 1 a) also a random distribution of pore density along the surface. Closely adjacent pores do not inevitably grow together, but can certainly interfere with each other in their broadening, as can be seen from the excerpt from the enlargement Fig. 1 b) can suspect. In Fig.
  • the steps are subsequently simply wet-chemical with a weak acid, e.g. Citric acid, dissolve. They do not consist of zinc oxide, but of zinc metal, which is oxidized on its surface - by ambient air.
  • a weak acid e.g. Citric acid
  • They do not consist of zinc oxide, but of zinc metal, which is oxidized on its surface - by ambient air.
  • This is a useful distinguishing feature of the prior art. Namely, it is well known to etch in zinc surfaces by first oxidizing the zinc and then etching into the semiconductor zinc oxide. The zinc oxide can then be completely or partially removed with a weak acid, for example, corresponding steps on the pore walls.
  • the etching is carried out directly in the metal. That is, on each free zinc metal surface quickly forms an oxide layer is inevitable and not further problematic. However, through-oxidation of the zinc layer to a predetermined depth to propel the pores to that depth does not occur. It would also be counterproductive to practically remove zinc plating for this purpose.
  • pore depths of between about 3 and 50 microns appear sufficient to provide good anchorage of cover layers.
  • the conical pores at any point should not traverse the entire thickness of the zinc coating, because this would both weaken the anti-corrosion effect of the zinc layer and possibly lead to the replacement of the galvanizing of the workpiece.
  • FIG. 2 a A look at the sectional sketch in Fig. 2 a) are intended to illustrate the particularly favorable effect of the generated pore structure for the anchoring of cover layers.
  • the workpiece At the bottom (black) is the workpiece with a layer of zinc arranged on top of it, which here is very much made up of three zinc crystallites.
  • the sketch represents a cross section to the galvanized workpiece surface. In the individual crystallites are each juxtaposed several parallel pores (recesses) etched into it. The pore shape is different in each crystallite, resulting in pores in all directions along the galvanized surface. In every crystallite the Fig. 2 a) there is covered pore space.
  • the real pore structure of a zinc workpiece is in Fig. 2b ) shown in supervision. You can see many individual areas parallel to each other grown pores. The orientation of the pores with respect to the surface of the zinc workpiece is very different in adjacent regions depending on the orientation of the zinc crystallites with respect to the surface of the zinc workpiece.
  • FIG. 2c Figure 3 shows the photograph of an actual vertical section through the porous zinc foil described above.
  • This image is unexpectedly difficult to interpret, because you can barely make out the expected pore channels. This is due to the simple fact that it is very difficult to make the cut exactly along the fast etching direction of any zinc grain because it can not be determined beforehand.
  • monolithic semiconductors which typically cleave along certain planes, which afford a nice view of the etching geometry, are in Fig. 2c) at most difficult to identify small areas with pore walls of the etched pores in the image plane. Their parallel growth is, however, recognizable by the section.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electroplating Methods And Accessories (AREA)

Description

Die Erfindung betrifft ein verzinktes Werkstück, das wenigstens auf Teilen der Werkstückoberfläche polykristallines Zink aufweist. Die Erfindung betrifft weiter ein Verfahren zur Erzeugung eines verzinkten Werkstücks mit verbesserter Haftung für Deckschichten.The invention relates to a galvanized workpiece having polycrystalline zinc at least on parts of the workpiece surface. The invention further relates to a method for producing a galvanized workpiece with improved adhesion for cover layers.

Bekanntlich werden rotrostanfällige Werkstücke aus Eisen oder Stahl, z.B. Karosserieteile von Automobilen, großflächig mit Zinkmetall beschichtet, kurz: verzinkt, um dem Durchrosten vorzubeugen. Das an sich unedle Zinkmetall bildet auf seiner Oberfläche unter Raumluftbedingungen sehr schnell eine Passivierungsschicht aus Zinkoxid oder Zinkkarbonat, die gut auf dem Zinkmetall haftet und die chemische Stabilität der verzinkten gegenüber einer unbehandelten Werkstückoberfläche deutlich erhöht.As is well known, workpieces made of red or iron or steel, e.g. Body parts of automobiles, extensively coated with zinc metal, in short: galvanized to prevent rusting. The zinc metal, which is inherently base, quickly forms on its surface under ambient air conditions a passivation layer of zinc oxide or zinc carbonate, which adheres well to the zinc metal and significantly increases the chemical stability of the galvanized surface compared to an untreated workpiece surface.

Die schützende Passivierungsschicht hat jedoch den Nachteil eines verringerten Haftvermögens für Polymere, Lacke oder auch weitere metallische Filme, die als Deckschichten auf eine verzinkte Werkstückoberfläche aufgetragen werden sollen.However, the protective passivation layer has the disadvantage of reduced adhesion to polymers, paints or other metallic films to be applied as a cover layers on a galvanized workpiece surface.

Die Haftung kann durch das Vorsehen haftvermittelnder Chemikalien, entweder als eigene Zwischenschicht oder als Komponente der aufzubringenden Deckschicht, verbessert werden. Doch neben den Kosten für die Haftvermittler fallen gewöhnlich zusätzliche Arbeitsschritte an, und das Beschichtungsergebnis ist nicht immer zufriedenstellend. Beispielsweise kann es mit der Zeit zu Lackablösungen kommen, wenn sich die thermischen Ausdehnungskoeffizienten des Werkstücks und des Lacks sehr unterscheiden und das lackierte Werkstück hohen Temperaturschwankungen ausgesetzt ist.Adhesion can be improved by providing adhesion promoting chemicals, either as a separate interlayer or as a component of the overcoat to be applied. But in addition to the cost of the primer usually additional work steps are required, and the coating result is not always satisfactory. For example, delamination may occur over time when the thermal expansion coefficients of the workpiece and the paint are very different and the painted workpiece is subject to high temperature variations.

Es ist grundsätzlich bekannt, dass eine Aufrauhung der metallischen Werkstückoberfläche hilfreich sein kann, die Haftung von Deckschichten zu verbessern. Insbesondere können Gräben, Poren oder lokale Erhöhungen auf der Werkstückoberfläche Strukturen sein, die sich von einem fließfähigen Polymer oder Lack durchsetzen, auffüllen oder umschließen lassen, so dass der anschließend aushärtende Polymer- oder Lackfilm infolge einer mechanischen Verankerung fixiert ist. Selbst sehr schlecht haftende Polymere wie etwa Polytetrafluorethylen (PTFE) lassen sich so mechanisch beanspruchbar mit Metalloberflächen verbinden.It is generally known that a roughening of the metallic workpiece surface can be helpful in improving the adhesion of cover layers. In particular, trenches, pores or local elevations on the workpiece surface can be structures which can be penetrated, filled or surrounded by a flowable polymer or lacquer, so that the subsequently curing polymer or lacquer film is fixed as a result of mechanical anchoring. Even very poorly adhering polymers such as polytetrafluoroethylene (PTFE) can be so mechanically bondable to metal surfaces.

Beispielsweise ist der DE 1811264 A1 (1968 ) zu entnehmen, wie ein metallischer Kolben einer Tieftemperaturexpansionsvorrichtung mit PTFE überzogen wird, indem in eine zunächst auf dem Kolben abgeschiedene Chromschicht elektrochemisch eine große Anzahl Löcher oder Rinnen geätzt wird, so dass das hiernach aufgetragene PTFE wenigstens diese Vertiefungen befüllt und mechanisch verankert wird. In der DE 1811264 A1 geht es um eine Funktionsbeschichtung, die die Reibung des Kolbens vermindern und sein Verkanten im Zylinder vermeiden soll. Die geätzte Chromschicht spielt dabei die Rolle eines Haftvermittlers. Bevorzugt sollen zusammenhängende Netzwerkmuster von Rinnen erzeugt werden, wie zu sehen in den Figuren 6 und 7 der Druckschrift. Man darf annehmen, dass die abgeschiedene Chromschicht polykristallin ist und dass sich die Rinnen durch Ätzen entlang der Korngrenzen bilden.For example, the DE 1811264 A1 (1968 ) to disclose how a metallic piston of a cryogenic expansion device is coated with PTFE by electrochemically etching a large number of holes or grooves in a chromium layer initially deposited on the piston, so that the subsequently applied PTFE fills and mechanically anchors at least these recesses. In the DE 1811264 A1 It is about a functional coating, which should reduce the friction of the piston and avoid its tilting in the cylinder. The etched chromium layer plays the role of a bonding agent. Preferably, contiguous network patterns of grooves are to be produced, as can be seen in FIGS. 6 and 7 of the document. It may be assumed that the deposited chromium layer is polycrystalline and that the grooves form by etching along the grain boundaries.

Intergranulares Ätzen von Metalloberflächen zur Haftverbesserung von Polymeren ist auch Gegenstand der DE 601 28 364 T2 , die darüber hinaus noch einen Immersionsplattierungsschritt vorschlägt.Intergranular etching of metal surfaces to improve the adhesion of polymers is also the subject of DE 601 28 364 T2 , which also proposes an immersion plating step.

Das Verzinken eines Werkstücks kann durch galvanische Abscheidung, Flammspritzen oder auch durch Tauchbeschichten in einer Zinkschmelze - auch: Feuerverzinken - erfolgen. Das Tauchbeschichten ist der am weitesten verbreitete industrielle Prozess zum Korrosionsschutz von Stahl. Er wird sowohl auf Fertigteile - Stückverzinken mit Überzugsdicken im Bereich 50-150 Mikrometer - als auch auf Endlosstahlbänder - Bandverzinken mit Überzugsdicken bis etwa 20 Mikrometer - angewandt. Bandverzinkte Stahlbleche werden nach dem Verzinken grundsätzlich noch geschnitten, gestanzt und umgeformt, wobei der Überzug stellenweise beschädigt wird. Es ist daher gängig, derart verzinkte Werkstücke mit weiteren Deckschichten zu versehen, nicht zuletzt auch, um den Korrosionsschutz wieder herzustellen.The galvanizing of a workpiece can be done by galvanic deposition, flame spraying or by dip coating in a molten zinc - also: hot dip galvanizing. Dip coating is the most widely used industrial process for corrosion protection of steel. He will both on finished parts - galvanizing with coating thicknesses in the range 50-150 micrometers - as well as on endless steel strips - strip galvanizing with coating thicknesses up to about 20 micrometers - applied. Strip-galvanized steel sheets are generally still cut after cutting, punched and formed, whereby the coating is damaged in places. It is therefore common to provide such galvanized workpieces with other cover layers, not least also to restore the corrosion protection.

In der vorliegenden Beschreibung wird die Bezeichnung verzinktes Werkstück auch für solche Werkstücke benutzt, die erst nach dem Überziehen mit Zink ihre endgültige Form erlangen. Wesentlich ist nur, dass wenigstens Teile ihrer Oberfläche eine Zinkschicht aufweisen.In the present specification, the term galvanized workpiece is also used for such workpieces that attain their final shape only after being coated with zinc. It is only important that at least parts of their surface have a zinc layer.

Typischerweise ist der Überzug eine polykristalline Zinkschicht auf der Werkstückoberfläche, wobei die Zinkkristallite Korngrößen von Millimeter bis Zentimeter erreichen können. Das Ätzen von Vertiefungen entlang der Korngrenzen bietet bei sehr großen Korngrößen zu wenig Raum für eine robuste Verankerung von Deckschichten auf dem verzinkten Werkstück.Typically, the coating is a polycrystalline zinc layer on the workpiece surface, whereby the zinc crystallites can reach particle sizes of millimeters to centimeters. The etching of depressions along the grain boundaries does not provide sufficient space for a robust anchoring of cover layers on the galvanized workpiece with very large particle sizes.

Die Erfindung stellt sich daher die Aufgabe, die Haftung von Deckschichten auf verzinkten Werkstücken zu verbessern.The invention therefore has the task of improving the adhesion of outer layers on galvanized workpieces.

Die Aufgabe wird gelöst durch das Bereitstellen eines verzinkten Werkstücks, das wenigstens auf Teilen der Werkstückoberfläche polykristallines Zink mit Korngrößen größer als 20 Mikrometer aufweist, gekennzeichnet durch unregelmäßig verteilte, in die Zinkkörner eindringende, verschiedene Durchmesser aufweisende, konische Poren.The object is achieved by providing a galvanized workpiece, which has polycrystalline zinc with particle sizes greater than 20 micrometers, at least on parts of the workpiece surface, characterized by irregularly distributed, penetrating into the zinc grains, different diameter, conical pores.

Die Unteransprüche sind auf vorteilhafte Ausgestaltungen des verzinkten Werkstücks und auf ein Verfahren zu dessen Herstellung gerichtet.The subclaims are directed to advantageous embodiments of the galvanized workpiece and to a method for its production.

Eine konische Pore im Sinne der vorliegenden Erfindung ist eine Pore, deren Porendurchmesser am Porenansatz - auf der Werkstückoberfläche - ein Maximum annimmt und zur Porenspitze - im Innern der Zinkschicht - hin monoton abnimmt. Der Porendurchmesser nimmt mit der Ätztiefe niemals zu, sondern er nimmt ab oder bleibt allenfalls stückweise konstant.A conical pore in the sense of the present invention is a pore whose pore diameter at the pore approach - on the workpiece surface - assumes a maximum and decreases monotonically towards the pore tip - in the interior of the zinc layer. The pore diameter never increases with the etching depth, but it decreases or at best remains piecewise constant.

Im Unterschied zum Stand der Technik werden die erfindungsgemäßen Strukturen nicht durch intergranulares Ätzen, sondern durch Ätzen in die Zinkkristallite - auch: Zinkkörner - geschaffen. Die Poren dringen dabei in die Zinkkörner ein und stoßen ins Innere der Zinkkörner vor. Dies ist nur möglich und zweckdienlich, weil sich überraschend gezeigt hat, dass man Ätzbedingungen finden kann, bei denen sich erstens die Porenätzgeschwindigkeit entlang einer Kristallachse etwa um den Faktor Zehn von den Ätzgeschwindigkeiten senkrecht dazu unterscheidet - man kann diese als "schnelle Ätzrichtung" des Zinkkorns bezeichnen - und zweitens Kristalldefekte wie Korngrenzen und Versetzungsnester nicht bevorzugt geätzt werden.In contrast to the prior art, the structures according to the invention are not created by intergranular etching, but by etching into the zinc crystallites, including zinc grains. The pores penetrate into the zinc grains and penetrate into the interior of the zinc grains. This is only possible and expedient because it has surprisingly been found that etching conditions can be found in which, firstly, the pore etching speed along a crystal axis differs approximately ten times from the etching speeds along a crystal axis - this can be termed the "fast etching direction" of the zinc grain secondly, crystal defects such as grain boundaries and dislocation nests are not preferentially etched.

Der Stand der Technik kennt tiefe, weitgehend gleichbleibende Durchmesser im Mikrometerbereich aufweisende, kanalartige oder auch konische Poren beispielsweise von monokristallinen Halbleitern, insbesondere Silizium-Wafern. Diese sogenannten Makroporen können annähernd den gesamten Wafer durchdringen, wenn man sie z.B. in n-Typ Silizium von der einen Waferseite her elektrochemisch ätzt, während die andere Waferseite beleuchtet wird. Die Beleuchtung dient dabei der Bereitstellung ausreichender freier Ladungsträger an den Porenspitzen. Die Porenwände werden hingegen kaum geätzt, weil dort keine freien Ladungsträger verfügbar sind. Die Porenwandstabilität ist deshalb am ehesten bei Halbleitern gegeben und auch dort nicht entlang beliebiger Kristallachsen. In Metallen mit frei beweglichen Elektronen ist die Möglichkeit, tiefe konische Poren in Kristallite zu ätzen, für den Fachmann unerwartet, da er zunächst von keiner Porenwandstabilität ausgehen kann. Sie zeigt sich aber bei Zink gleichwohl insoweit, als dass die Ätzgeschwindigkeiten entlang verschiedener Kristallrichtungen stark unterschiedlich sind.The prior art knows deep, largely constant diameter in the micrometer range having channel-like or conical pores, for example, of monocrystalline semiconductors, in particular silicon wafers. These so-called macropores can penetrate almost the entire wafer if, for example, they are electrochemically etched in n-type silicon from one wafer side, while the other wafer side is illuminated. The illumination serves to provide sufficient free charge carriers at the pore tips. By contrast, the pore walls are hardly etched because there are no free charge carriers available there. The pore wall stability is therefore most likely to be found in semiconductors and also not along arbitrary crystal axes. In metals with freely mobile electrons, the ability to etch deep conical pores in crystallites is unexpected to those skilled in the art, as it can initially assume no pore wall stability. However, it does show up in the case of zinc to the extent that the etching rates vary greatly along different crystal directions.

Innerhalb eines einzelnen Zinkkorns verlaufen die Poren, die in dieses Zinkkorn eindringen, parallel. Die schnelle Ätzrichtung ist eine Eigenschaft des Zinkkorns, kann aber auch durch den Ätzelektrolyten beeinflusst werden. Es ist jedoch bei keinem der Zinkkörner ohne weiteres vorhersehbar, in welche Richtung die schnelle Ätzrichtung weist. Beim Verzinken des Werkstückes bilden sich Zinkkörner mit unterschiedlichen Orientierungen und damit auch einer unterschiedlichen Richtung der schnellen Ätzrichtung in Bezug auf die Werkstückoberfläche. Typischerweise weisen benachbarte Zinkkörner in der fertigen Zinkschicht recht unterschiedliche Kristall-Orientierungen auf. Daher befinden sich die schnellen Ätzrichtungen in Bezug auf die Werkstückoberfläche unter recht unterschiedlichen Winkeln ebenfalls in Bezug auf die Oberfläche des Werkstücks. Insbesondere verläuft die schnelle Ätzrichtung fast nie senkrecht zur Werkstückoberfläche.Within a single grain of zinc, the pores that penetrate into this zinc grain are parallel. The fast etching direction is a property of the zinc grain, but can also be affected by the etching electrolyte. However, it is not readily foreseeable in any of the zinc grains which direction the fast etching direction will face. During galvanizing of the workpiece, zinc grains with different orientations and thus also a different direction of the rapid etching direction with respect to the workpiece surface form. Typically, adjacent zinc grains have quite different crystal orientations in the finished zinc layer. Therefore, the fast etch directions with respect to the workpiece surface at quite different angles are also with respect to the surface of the workpiece. In particular, the fast etching direction is almost never perpendicular to the workpiece surface.

Die Porenstruktur des erfindungsgemäßen verzinkten Werkstücks umfasst insofern typischerweise nebeneinander in zufälliger Anordnung in die Wand desselben Zinkkorns eindringende, parallel verlaufende, konische Poren, von denen typischerweise nur wenige senkrecht zur Werkstückoberfläche gerichtet sind. Der Durchmesser der Poren, der sein Maximum am Porenansatz aufweist und vorzugsweise im Intervall zwischen 100 Nanometer und 15 Mikrometer, besonders bevorzugt zwischen 1 und 5 Mikrometer, liegen soll, variiert dabei entlang der Wand eines jeden einzelnen Zinkkorns, d.h. jedes Korn wird sowohl von breiten und tiefen als auch gleichzeitig von weniger breiten und weniger tiefen Poren durchsetzt. Wenn das Tiefen- zu Durchmesserverhältnis - auch: Aspektverhältnis - etwa den Wert 3 übersteigt, dringen die Poren so tief in das Korn ein, das ein Teil des Porenraumes von der Zinkkornwand, an der die Poren ansetzen, verdeckt ist. In anderen Worten: die Porenspitze ist von der Oberfläche des Werkstücks, die durch die Zinkkornwände gebildet wird, nicht mehr sichtbar, da die Pore schräg gewachsen ist. Dies ist erst recht der Fall bei größeren Aspektverhältnissen, vorzugsweise größer als etwa 10.The pore structure of the galvanized workpiece according to the invention thus typically comprises side by side in a random arrangement in the wall of the same zinc grain penetrating, parallel, conical pores, of which typically only a few are directed perpendicular to the workpiece surface. The diameter of the pores, which has its maximum at the pore approach and should preferably be in the interval between 100 nanometers and 15 microns, more preferably between 1 and 5 microns, varies along the wall of each individual zinc grain, ie each grain is both of wide and deep as well as at the same time interspersed by less wide and less deep pores. If the depth to diameter ratio - also: aspect ratio - exceeds the value of 3, the pores penetrate so deeply into the grain, which is a part of the pore space of the zinc grain wall on which the pores attach, hidden. In other words, the pore tip is no longer visible from the surface of the workpiece formed by the zinc grain walls because the pore has grown obliquely. This is certainly the case with larger aspect ratios, preferably greater than about 10.

Mit zunehmender Ätztiefe steigt der Anteil des verdeckten Porenraumes. Verdeckter Porenraum hinterschneidet die Werkstückoberfläche und bietet dadurch einen größeren Widerstand gegen das Abziehen z.B. eines Polymerfilmes, der in flüssiger Form auf das verzinkte Werkstück aufgetragen wird, auch in den Porenraum eindringt und danach aushärtet.With increasing etch depth, the proportion of hidden pore space increases. Hidden pore space undercuts the workpiece surface, thereby providing greater resistance to peeling, e.g. a polymer film, which is applied in liquid form to the galvanized workpiece, also penetrates into the pore space and then cured.

Von besonderer Bedeutung ist hier, dass die Richtung, in der die Poren die Werkstückoberfläche hinterschneiden, von Zinkkorn zu Zinkkorn variiert. Ein entlang der Werkstoffoberfläche jeweils lokal in verschiedene Richtungen mit der Zinkschicht verzahnte Deckschicht setzt insbesondere Kräften, die zur Verschiebung der Deckschicht auf der Oberfläche geeignet sind, einen größeren Widerstand entgegen. Unter anderem führen temperaturbedingte Ausdehnungsänderungen des Werkstücks gegenüber der Deckschicht an vielen Stellen der Werkstückoberfläche zu einer erhöhten Haftung der Deckschicht, nämlich dort, wo die lokal angreifenden Kräfte die Deckschicht tiefer in den verdeckten Porenraum pressen. Die Deckschicht besitzt durch ihre Verankerung in den konischen, nicht senkrecht zur Werkstückoberfläche verlaufenden Poren praktisch Widerhaken, und diese weisen entlang der gesamten Werkstückoberfläche lokal jeweils in eine vom dort vorliegenden Zinkkorn abhängige Richtung.Of particular importance here is that the direction in which the pores undercut the workpiece surface varies from zinc grain to zinc grain. A covering layer which is toothed with the zinc layer locally in different directions along the surface of the material in particular sets forces which are suitable for displacing the covering layer on the surface to be of greater resistance. Among other things, temperature-induced expansion changes of the workpiece relative to the cover layer at many points of the workpiece surface lead to increased adhesion of the cover layer, namely where the locally acting forces press the cover layer deeper into the hidden pore space. By virtue of its anchoring in the conical pores, which are not perpendicular to the surface of the workpiece, the cover layer has barbs in practice, and these have local directions along the entire workpiece surface in each case in a direction dependent on the zinc grain present there.

Dem Fachmann ist nun ersichtlich, wie ein mit den erfindungsgemäßen Merkmalen versehenes verzinktes Werkstück eine bessere Verankerung und damit Haftung von Deckschichten auf dem Zinküberzug ermöglicht. Im Folgenden wird das Erzeugen eines erfindungsgemäß verzinkten Werkstücks beschrieben, und eine im Labor erzeugte poröse Zinkfolie wird vorgestellt. Dazu dienen auch die folgenden Figuren. Dabei zeigt:

Fig. 1
Elektronenmikroskop-Aufnahmen einer porösen Zinkfolie in der Aufsicht in zwei Vergrößerungen;
Fig. 2
a) Schematisch senkrechter Schnitt durch die poröse Zinkfolie, b) Elektronenmikroskop-Aufnahmen einer porösen Zinkfolie in der Aufsicht und c) eine Elektronenmikroskop-Aufnahme eines senkrechten Schnittes durch eine poröse Zinkfolie.
The person skilled in the art will now see how a galvanized workpiece provided with the features according to the invention enables a better anchoring and thus adhesion of cover layers on the zinc coating. In the following, the production of a galvanized workpiece according to the invention is described, and a porous zinc foil produced in the laboratory is presented. The following figures are also used for this purpose. Showing:
Fig. 1
Electron micrographs of a porous zinc foil in the plan view in two magnifications;
Fig. 2
a) Schematic vertical section through the porous zinc foil, b) electron micrographs of a porous zinc foil in plan view, and c) an electron micrograph of a vertical section through a porous zinc foil.

Das Porenätzen erfolgt in einer elektrochemischen Ätzzelle mit einem Kaliumchlorid enthaltenden, wässrigen Elektrolyten. Die Temperatur wird dabei kontrolliert und durch einen Thermostaten konstant gehalten. Zwischen Zinkschicht und Elektrode im Elektrolyten wird eine Rechteckspannung angelegt, d.h. ein zeitlicher Spannungsverlauf, der durch eine Rechteckfunktion beschrieben ist.The pore etching takes place in an electrochemical etching cell with a potassium chloride-containing, aqueous electrolyte. The temperature is controlled and kept constant by a thermostat. A square wave voltage is applied between the zinc layer and the electrode in the electrolyte, i. a temporal voltage curve, which is described by a rectangular function.

Die Rechteckspannung ist periodisch und weist vorzugsweise eine vorbestimmte Anzahl von Perioden auf. Dabei wird für ein erstes Zeitintervall eine erste Spannung und für ein unmittelbar anschließendes zweites Zeitintervall eine zweite Spannung angelegt wird, wobei die Zeitspanne vom Beginn des ersten bis zum Ende des zweiten Zeitintervalls die Periodendauer der periodischen Rechteckspannung ist.The square-wave voltage is periodic and preferably has a predetermined number of periods. In this case, a first voltage is applied for a first time interval and a second voltage for an immediately subsequent second time interval, the time period from the beginning of the first to the end of the second time interval being the period of the periodic square voltage.

Es ist sehr vorteilhaft, das Porenätzen mit einem Nukleationsschritt einzuleiten, der die ersten Vertiefungen in zufälliger Verteilung auf der Werkstückoberfläche erzeugt. Die Nukleation der Poren soll vorzugsweise durch einmaliges Anlegen einer dritten Spannung für ein drittes Zeitintervall vor dem Anlegen der periodischen Rechteckspannung erfolgen.It is very advantageous to initiate pore etching with a nucleation step that creates the first pits in random distribution on the workpiece surface. The nucleation of the pores should preferably be done by applying a third voltage once for a third time interval before applying the periodic square wave voltage.

Der Porenätzvorgang erfolgt in jedem Zinkkorn vorwiegend entlang der eingangs genannten schnellen Ätzrichtung des Zinkkorns. Ein wesentlicher Grund, warum dies bei der hier vorgestellten Zinkätzung möglich ist, ist das periodische Umschalten von kathodischen auf anodischen Spannungen, was bei der Wahl des Elektrolyten zur Bildung einer genau definierten Zinkoxidbedeckung auf Porenwänden und Bereichen mit Kristalldefekten führt, die diese gegen eine präferentielle Ätzung schützen.The pore etching process takes place in each zinc grain predominantly along the aforementioned rapid etching direction of the zinc grain. A major reason why this is possible with the zinc etch presented here is the periodic switching from cathodic to anodic stresses, which in the choice of the electrolyte to form a well-defined zinc oxide coverage on Pore walls and areas with crystal defects that protect them against a preferential etching.

Als Ausführungsbeispiel wird eine polykristalline, gewalzte, 100 Mikrometer dicke Zinkfolie (Zn-Anteil 99,95 %) geätzt. Der Elektrolyt enthält 0,1 mol/Liter Kaliumchlorid. Die Temperatur wird zu 50 °C gewählt. Die erste Spannung ist zu 0 V, die Länge des ersten Zeitintervalls zu 4,6 s, die zweite Spannung zu -1 V, die Länge des zweiten Zeitintervalls zu 0,8 s, die dritte Spannung zu 0,5 V und die Länge des dritten Zeitintervalls zu 1 s bestimmt worden. Die Gesamt-Ätzdauer beträgt 10 min.As an exemplary embodiment, a polycrystalline, rolled, 100 micron thick zinc foil (Zn content 99.95%) is etched. The electrolyte contains 0.1 mol / liter of potassium chloride. The temperature is chosen to be 50 ° C. The first voltage is 0 V, the length of the first time interval is 4.6 s, the second voltage is -1 V, the length of the second time interval is 0.8 s, the third voltage is 0.5 V, and the length of the second third time interval has been determined to be 1 s. The total etching time is 10 min.

Im Fall von einer polykristallinen Zinkschicht mit vielen kleineren Zinkkörnern und damit vielen Korngrenzen müssen die Ätzparameter dahingehend angepasst werden, dass eine präferentielle Ätzung der Korngrenzen unterdrückt wird. Dies kann z.B. dadurch erreicht werden, dass das zweite Zeitintervall im Vergleich zum ersten Zeitintervall ausgedehnt wird. Im Fall von großen Zinkkörnern spielt eine präferentielle Ätzung der Korngrenzen eine vernachlässigbare Rolle.In the case of a polycrystalline zinc layer having many smaller zinc grains and thus many grain boundaries, the etching parameters must be adjusted so as to suppress preferential etching of the grain boundaries. This can e.g. be achieved by extending the second time interval compared to the first time interval. In the case of large zinc grains, preferential etching of the grain boundaries plays a negligible role.

Neben dem präferentiellen Ätzen von Korngrenzen kann es z.B. bei mechanisch stark verformten Zinkoberflächen auch zu einer präferentiellen Ätzung von Defektstrukturen, z.B. von Versetzungen / Versetzungsnestern etc. kommen. Dies könnte auf die gleiche Art unterdrückt werden, wie im vorher beschriebenen Fall. Im Fall von Zinkkörnern in Zentimeter oder im Extremfall von einkristallinem Zink ist die Anzahl an Nukleationskeimen für das Wachstum von Poren möglicherweise zu gering. Eine Erhöhung der Anzahl an Nukleationskeimen könnte z.B. durch eine Erhöhung der dritten Spannung erreicht werden.Besides the preferential etching of grain boundaries, it may e.g. for mechanically strongly deformed zinc surfaces also leads to a preferential etching of defect structures, e.g. come from dislocations / Versetzungsnestern etc. This could be suppressed in the same way as in the previously described case. In the case of zinc grains in centimeters or, in extreme cases, monocrystalline zinc, the number of nucleation nuclei may be too small for the growth of pores. An increase in the number of nucleation germs could e.g. be achieved by increasing the third voltage.

Daher müssen die konkreten Ätzparameter auf den konkreten Zinkätzeinzelfall angepasst und optimiert werden, was aber zum Können des Fachmanns zählt und ihm als erforderliches Experimentieren zum Auffinden eines günstigen Arbeitspunktes zuzumuten ist. Gewöhnlich sind solche Untersuchungen für eine Serienfertigung nur einmalig durchzuführen.Therefore, the specific etching parameters must be adapted and optimized to the specific zinc etch incident, but this is within the skill of the artisan and given him as necessary experimentation to find a favorable Is to expect working point. Usually, such tests are only to be carried out once for series production.

Fig. 1 zeigt die erzielte Porenstruktur. Aus Fig. 1 a) ist ersichtlich, dass die Poren in zufälliger Verteilung und mit verschieden großen Porendurchmessern gebildet worden sind. Da alle Poren mit steigender Ätzzeit tiefer und zugleich breiter am Porenansatz werden sollten, kann man annehmen, dass nicht alle sichtbaren Poren zur selben Zeit - also während des dritten Zeitintervalls - nukleiert sind, sondern manche womöglich erst während irgendeiner Periode der anschließenden Rechteckspannung. Allerdings zeigt Fig. 1 a) auch eine zufällige Verteilung der Porendichte entlang der Oberfläche. Dicht benachbart liegende Poren wachsen keineswegs zwangsläufig zusammen, sondern können sich durchaus gegenseitig in ihrer Verbreiterung behindern, wie man auch anhand der Ausschnittvergrößerung in Fig. 1 b) vermuten kann. In Fig. 1 b) ist auf jeden Fall die konische Verjüngung der Poren von außen nach innen gut zu erkennen. Darüber hinaus sieht man den gestuften Verlauf der Porenwände insbesondere entlang einer Ebene, die von links unten nach rechts oben im Bild verläuft und in beiden gezeigten Poren sichtbar ist. Anscheinend handelt es sich hier um eine Kristallebene, die dem Ätzangriff besonders hohen Widerstand entgegensetzt. Fig. 1 shows the achieved pore structure. Out Fig. 1 a) It can be seen that the pores have been formed in a random distribution and with different pore diameters. Since all pores should become deeper and wider at the same time as the etch time increases, it can be assumed that not all visible pores are nucleated at the same time, ie during the third time interval, but some may only be nucleated during any period of the subsequent square wave. However, shows Fig. 1 a) also a random distribution of pore density along the surface. Closely adjacent pores do not inevitably grow together, but can certainly interfere with each other in their broadening, as can be seen from the excerpt from the enlargement Fig. 1 b) can suspect. In Fig. 1 b) In any case, the conical rejuvenation of the pores from the outside to the inside is easy to recognize. In addition, one sees the stepped course of the pore walls, in particular along a plane which runs from bottom left to top right in the image and is visible in both pores shown. Apparently, this is a crystal plane, which offers the etching attack particularly high resistance.

Im Zusammenhang mit den gestuften Porenwänden ist anzumerken, dass sich die Stufen nachträglich einfach nasschemisch mit einer schwachen Säure, z.B. Zitronensäure, auflösen lassen. Sie bestehen nicht aus Zinkoxid, sondern aus Zinkmetall, das an seiner Oberfläche - durch Raumluft - oxidiert ist. Dies stellt ein nützliches Unterscheidungsmerkmal zum Stand der Technik dar. Es ist nämlich durchaus bekannt, in Zinkoberflächen zu ätzen, indem man das Zink zunächst oxidiert und danach in den Halbleiter Zinkoxid hineinätzt. Das Zinkoxid lässt sich danach mit einer schwachen Säure ganz oder teilweise entfernen, also beispielsweise auch entsprechende Stufen an den Porenwänden.In connection with the stepped pore walls, it should be noted that the steps are subsequently simply wet-chemical with a weak acid, e.g. Citric acid, dissolve. They do not consist of zinc oxide, but of zinc metal, which is oxidized on its surface - by ambient air. This is a useful distinguishing feature of the prior art. Namely, it is well known to etch in zinc surfaces by first oxidizing the zinc and then etching into the semiconductor zinc oxide. The zinc oxide can then be completely or partially removed with a weak acid, for example, corresponding steps on the pore walls.

Im Falle der vorliegenden Erfindung erfolgt das Ätzen unmittelbar in das Metall. Dass sich auf jeder freien Zinkmetallfläche schnell eine Oxidschicht bildet, ist unvermeidlich und nicht weiter problematisch. Doch ein Durchoxidieren der Zinkschicht bis zu einer vorbestimmten Tiefe, um die Poren in diese Tiefe voranzutreiben, findet nicht statt. Es wäre auch kontraproduktiv, die Verzinkung zu diesem Zweck praktisch wieder abzutragen.In the case of the present invention, the etching is carried out directly in the metal. That is, on each free zinc metal surface quickly forms an oxide layer is inevitable and not further problematic. However, through-oxidation of the zinc layer to a predetermined depth to propel the pores to that depth does not occur. It would also be counterproductive to practically remove zinc plating for this purpose.

Im Übrigen erscheinen Porentiefen zwischen ungefähr 3 und 50 Mikrometer als ausreichend, um eine gute Verankerung von Deckschichten zu erreichen. Selbstverständlich sollen die konischen Poren an keiner Stelle die gesamte Dicke des Zinküberzugs durchqueren, denn dies würde sowohl die Korrosionsschutzwirkung der Zinkschicht schwächen als auch unter Umständen zur Ablösung der Verzinkung vom Werkstück führen.Incidentally, pore depths of between about 3 and 50 microns appear sufficient to provide good anchorage of cover layers. Of course, the conical pores at any point should not traverse the entire thickness of the zinc coating, because this would both weaken the anti-corrosion effect of the zinc layer and possibly lead to the replacement of the galvanizing of the workpiece.

Ein Blick auf die Schnittskizze in Fig. 2 a) sollen den besonders günstigen Effekt der erzeugten Porenstruktur für die Verankerung von Deckschichten verdeutlichen. Gezeichnet ist unten (schwarz) das Werkstück mit darauf angeordneter Zinkschicht, die hier stark vereinfacht aus drei Zinkkristalliten gebildet wird. Die Skizze stellt einen Querschnitt zur verzinkten Werkstückoberfläche dar. In die einzelnen Kristallite sind jeweils mehrere nebeneinander angeordnete, parallel verlaufende Poren (Aussparungen) hineingeätzt. Der Porenverlauf ist in jedem Kristallit anders ausgerichtet, sodass sich entlang der verzinkten Oberfläche Porenverläufe in alle möglichen Richtungen ergeben. In jedem Kristallit der Fig. 2 a) existiert verdeckter Porenraum. Denkt man sich auf die Porenöffnungen einfallendes, paralleles Licht in die Skizze, so wäre der verdeckte Porenraum jener Anteil, in den das Licht aufgrund von Abschattung nicht eintreten könnte. Material einer Deckschicht, das beim Auftragen - gewöhnlich in flüssiger Form - bis in den verdeckten Porenraum gelangt, bildet bei Verfestigung Widerhaken sowohl gegen das Abziehen als auch gegen das seitliche Verschieben gegenüber der Werkstückoberfläche.A look at the sectional sketch in Fig. 2 a) are intended to illustrate the particularly favorable effect of the generated pore structure for the anchoring of cover layers. At the bottom (black) is the workpiece with a layer of zinc arranged on top of it, which here is very much made up of three zinc crystallites. The sketch represents a cross section to the galvanized workpiece surface. In the individual crystallites are each juxtaposed several parallel pores (recesses) etched into it. The pore shape is different in each crystallite, resulting in pores in all directions along the galvanized surface. In every crystallite the Fig. 2 a) there is covered pore space. If one thinks of the pore openings incident, parallel light in the sketch, so the hidden pore space would be the proportion in which the light could not occur due to shading. Material of a cover layer, which reaches the concealed pore space during application, usually in liquid form, forms barbs during solidification both against the removal and against the lateral displacement relative to the workpiece surface.

Die reale Porenstruktur eines Zinkwerkstückes ist in Fig. 2b) in Aufsicht dargestellt. Man erkennt viele einzelne Bereiche mit parallel zueinander gewachsenen Poren. Die Orientierung der Poren in Bezug auf die Oberfläche des Zinkwerkstückes ist in benachbarten Bereichen stark unterschiedlich abhängig von der Orientierung der Zinkkristallite in Bezug auf die Oberfläche des Zinkwerkstückes.The real pore structure of a zinc workpiece is in Fig. 2b ) shown in supervision. You can see many individual areas parallel to each other grown pores. The orientation of the pores with respect to the surface of the zinc workpiece is very different in adjacent regions depending on the orientation of the zinc crystallites with respect to the surface of the zinc workpiece.

Die Fig. 2 c) zeigt die Aufnahme eines tatsächlichen senkrechten Schnitts durch die oben beschriebene, poröse Zinkfolie. Dieses Bild ist unerwartet schwer zu deuten, weil man die erwarteten Porenkanäle kaum ausmachen kann. Dies liegt an der einfachen Tatsache, dass es sehr schwierig ist, den Schnitt genau entlang der schnellen Ätzrichtung irgendeines Zinkkorns auszuführen, weil man diese nicht zuvor bestimmen kann. Im Unterschied zu typisch leicht entlang bestimmter Ebenen spaltbaren, monolithischen Halbleitern, die einen schönen Blick auf die Ätzgeometrie gewähren, sind in Fig. 2 c) allenfalls mit Mühe kleine Bereiche mit Porenwänden der geätzten Poren in der Bildebene auszumachen. Ihr paralleles Wachstum ist allerdings anhand des Schnitts erkennbar.The Fig. 2c) Figure 3 shows the photograph of an actual vertical section through the porous zinc foil described above. This image is unexpectedly difficult to interpret, because you can barely make out the expected pore channels. This is due to the simple fact that it is very difficult to make the cut exactly along the fast etching direction of any zinc grain because it can not be determined beforehand. In contrast to monolithic semiconductors which typically cleave along certain planes, which afford a nice view of the etching geometry, are in Fig. 2c) at most difficult to identify small areas with pore walls of the etched pores in the image plane. Their parallel growth is, however, recognizable by the section.

Claims (9)

  1. A zinc-plated workpiece which has at least on parts of the workpiece surface polycrystalline zinc having grain sizes of greater than 20 micrometres, characterised by irregularly distributed conical pores which penetrate into the zinc grain walls and are of different diameters.
  2. A zinc-plated workpiece according to Claim 1, characterised in that the pores run in parallel within an individual zinc grain.
  3. A zinc-plated workpiece according to one of the preceding claims, characterised in that the pores have a ratio of depth to diameter of at least 3, preferably of at least 10.
  4. A zinc-plated workpiece according to one of the preceding claims, characterised in that the pores on the workpiece surface have diameters from the range of between 100 nanometres and 15 micrometres, preferably from the range of 1 micrometre to 5 micrometres.
  5. A zinc-plated workpiece according to one of the preceding claims, characterised in that at least part of the pore space etched into the zinc grains is covered by the zinc grain walls which form the workpiece surface.
  6. A method for producing a zinc-plated workpiece according to one of the preceding claims, characterised by electrochemical etching of the zinc-plated workpiece surface in an aqueous potassium chloride containing electrolyte at a predetermined temperature with the application of a periodic square-wave voltage.
  7. A method according to Claim 6, characterised in that for a first time interval a first voltage and for a second, directly succeeding, time interval a second voltage, is applied, the amount of time from the beginning of the first until the end of the second time interval being the period of the periodic square-wave voltage.
  8. A method according to one of Claims 6 or 7, characterised in that the nucleation of the pores takes place by one-time application of a third voltage for a third time interval prior to the application of the periodic square-wave voltage.
  9. A method according to Claims 6 to 8, characterised in that the electrolyte contains 0.1 mol/litre potassium chloride, the predetermined temperature is selected to be around 50°C and the first voltage is determined at 0 V, the length of the first time interval at 4.6 s, the second voltage at -1 V, the length of the second time interval at 0.8 s, the third voltage at 0.5 V and the length of the third time interval at 1 s.
EP15726512.5A 2014-05-06 2015-04-08 Zinc-plated workpiece with improved adhesion for cover layers Active EP3140438B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102014106276.0A DE102014106276A1 (en) 2014-05-06 2014-05-06 Galvanized workpiece with improved adhesion for surface layers
PCT/DE2015/100150 WO2015169278A1 (en) 2014-05-06 2015-04-08 Zinc-plated workpiece with improved adhesion for cover layers

Publications (2)

Publication Number Publication Date
EP3140438A1 EP3140438A1 (en) 2017-03-15
EP3140438B1 true EP3140438B1 (en) 2018-06-06

Family

ID=53276677

Family Applications (1)

Application Number Title Priority Date Filing Date
EP15726512.5A Active EP3140438B1 (en) 2014-05-06 2015-04-08 Zinc-plated workpiece with improved adhesion for cover layers

Country Status (3)

Country Link
EP (1) EP3140438B1 (en)
DE (1) DE102014106276A1 (en)
WO (1) WO2015169278A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102018109531A1 (en) 2018-04-20 2019-10-24 Christian-Albrechts-Universität Zu Kiel Adhesive joining device and adhesive joining method for a metallic surface

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE370195C (en) * 1921-10-09 1923-02-28 Elek Scher Zuender G M B H Fab Process to make metals and thin metal sheets or foils, in particular those made of copper or zinc, adhesive on fiber materials
GB1202337A (en) 1967-11-27 1970-08-12 Tokyo Shibaura Electric Co A method of coating a metal body with a plastics material and a metal body coated with a plastics material
JPS5443463B2 (en) * 1972-07-18 1979-12-20
US6506314B1 (en) 2000-07-27 2003-01-14 Atotech Deutschland Gmbh Adhesion of polymeric materials to metal surfaces
DE202006013555U1 (en) * 2006-09-01 2006-12-21 Zeschky Galvanik Gmbh & Co. Kg Zinc-plated cast iron pivot bearing for automobile front suspensions has a crystalline zinc coating

Non-Patent Citations (1)

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

Also Published As

Publication number Publication date
DE102014106276A1 (en) 2015-11-12
WO2015169278A1 (en) 2015-11-12
EP3140438A1 (en) 2017-03-15

Similar Documents

Publication Publication Date Title
EP2892663B1 (en) Flat product made of metal material, in particular a steel material, use of such a flat product, and roll and method for producing such flat products
EP3416760B1 (en) Planishing roll, method for planishing a flat product therewith and flat product therefrom
EP1781841A1 (en) Surface comprising a microstructure that reduces adhesion and associated production method
EP1843864B1 (en) Component with a coating for reducing the wettability of the surfaces and method for production thereof
DE102010030465B4 (en) Method for producing a sheet metal part from a high-strength steel sheet material with an electrolytically applied zinc-nickel coating
DE102005039614A1 (en) Anodic oxide layer and method of anodization
EP2576862B1 (en) Method for cold gas spraying a layer comprising a metallic and a polymeric structural phase
WO2021052818A1 (en) Sheet steel having a deterministic surface structure
DE102015016259A1 (en) Method for producing a plastic-metal hybrid component
DE102019214133A1 (en) Sheet steel with a deterministic surface structure
EP3140438B1 (en) Zinc-plated workpiece with improved adhesion for cover layers
EP1927419A1 (en) Grid comprising netted wires having a thick tinning
DE3413060A1 (en) METHOD AND DEVICE FOR LAYING A PIPE IN THE GROUND UNDER WATER
DE112015004652T5 (en) DEVICE AND METHOD FOR ATTACHING A POLYMER ON A SUBSTRATE
EP3400323B1 (en) Self-lubricating electrolytically deposited phosphate coating
EP2644311A1 (en) Method for welding using a laser
WO2017144407A1 (en) Roller, in particular skin pass roller, and skin passed flat product
DE102012109812A1 (en) Anodizing and anodizing
DE102004010212B4 (en) Coating system for corrosion protection and its use
DE102020202896A1 (en) Application / scoop roller and process for its manufacture
EP3232070B1 (en) Self-cutting thread insert and method for its production
DE102021119589A1 (en) Sheet metal with a deterministic surface structure
EP1846593A1 (en) Surface with a wettability-reducing microstructure and method for the production thereof
DE102004014871A1 (en) piston ring
WO2022228601A1 (en) Composite polymer structure having an aluminum polymer anchoring layer, and etching method

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20160909

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent

Extension state: BA ME

DAV Request for validation of the european patent (deleted)
DAX Request for extension of the european patent (deleted)
GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: GRANT OF PATENT IS INTENDED

INTG Intention to grant announced

Effective date: 20171221

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE PATENT HAS BEEN GRANTED

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

Free format text: NOT ENGLISH

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

Ref country code: AT

Ref legal event code: REF

Ref document number: 1006178

Country of ref document: AT

Kind code of ref document: T

Effective date: 20180615

REG Reference to a national code

Ref country code: IE

Ref legal event code: FG4D

Free format text: LANGUAGE OF EP DOCUMENT: GERMAN

REG Reference to a national code

Ref country code: DE

Ref legal event code: R096

Ref document number: 502015004553

Country of ref document: DE

REG Reference to a national code

Ref country code: NL

Ref legal event code: MP

Effective date: 20180606

REG Reference to a national code

Ref country code: LT

Ref legal event code: MG4D

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: ES

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

Ref country code: SE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

Ref country code: NO

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180906

Ref country code: FI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

Ref country code: BG

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180906

Ref country code: LT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

Ref country code: CY

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180907

Ref country code: RS

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

Ref country code: HR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

Ref country code: LV

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: RO

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

Ref country code: CZ

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

Ref country code: SK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

Ref country code: EE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

Ref country code: IS

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20181006

Ref country code: PL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

Ref country code: SM

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

REG Reference to a national code

Ref country code: DE

Ref legal event code: R097

Ref document number: 502015004553

Country of ref document: DE

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed

Effective date: 20190307

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

Ref country code: SI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

REG Reference to a national code

Ref country code: BE

Ref legal event code: MM

Effective date: 20190430

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LU

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20190408

Ref country code: MC

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LI

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20190430

Ref country code: CH

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20190430

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: BE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20190430

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: TR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20190408

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: PT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20181008

REG Reference to a national code

Ref country code: DE

Ref legal event code: R082

Ref document number: 502015004553

Country of ref document: DE

Representative=s name: HEESCHEN, SVEN, DIPL.-PHYS., DE

REG Reference to a national code

Ref country code: AT

Ref legal event code: MM01

Ref document number: 1006178

Country of ref document: AT

Kind code of ref document: T

Effective date: 20200408

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: HU

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT; INVALID AB INITIO

Effective date: 20150408

Ref country code: MT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20200408

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: MK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20180606

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20230417

Year of fee payment: 9

Ref country code: DE

Payment date: 20230418

Year of fee payment: 9

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20230420

Year of fee payment: 9