EP0462073A2 - Electrolyte for producing thin black conversion layers on light metals - Google Patents
Electrolyte for producing thin black conversion layers on light metals Download PDFInfo
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- EP0462073A2 EP0462073A2 EP91810453A EP91810453A EP0462073A2 EP 0462073 A2 EP0462073 A2 EP 0462073A2 EP 91810453 A EP91810453 A EP 91810453A EP 91810453 A EP91810453 A EP 91810453A EP 0462073 A2 EP0462073 A2 EP 0462073A2
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
- C25D11/026—Anodisation with spark discharge
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
- C25D11/04—Anodisation of aluminium or alloys based thereon
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
- C25D11/04—Anodisation of aluminium or alloys based thereon
- C25D11/14—Producing integrally coloured layers
Definitions
- the invention relates to electrolytes for producing uniformly thin, matte black conversion layers as functional surfaces of components or groups made of light metal materials or their alloys by the process of anodic oxidation with spark discharge (ANOF).
- ANOF anodic oxidation with spark discharge
- they represent a coating variant especially for complex shaped construction parts or groups and are therefore particularly suitable for use in optical precision device construction.
- a number of electrolytes for producing conversion layers by means of the ANOF process on lightweight materials, especially on valve metals such as Ti, Ta, Zr, Nb or AI, are known from the specialist and patent literature (see PS-DD 229 163, PS-DD 236 978 , PS-DD 142 360, PS-EP 0 280 886).
- electrolytes are used which mainly contain subgroup elements which are bound as hydroxo, amino or complexone complexes.
- PS-DD 229 163 describes electrolyte solutions for producing black or gray-black conversion layers on light metals, such as Al.
- electrolyte solutions mainly contain fluorides as NaF or NH4F, dihydrogen phosphates as NaH2PO4, tetraborates as Borax Na2B4O7 and chromates as well as other foreign additives.
- fluorides as NaF or NH4F
- dihydrogen phosphates as NaH2PO4
- tetraborates as Borax Na2B4O7
- chromates as well as other foreign additives.
- the disadvantage here is that the use of fluorides necessitates special work, environmental protection and disposal measures.
- the PS-DD 257 275 refers to decorative coatings, inter alia, on titanium materials which are produced by means of the ANOF process and an electrolyte consisting of NaF, NaH2PO4, Na2B4O7 and potassium hexacyanoferrate-K4 [Fe [CN] 6] are produced.
- this solution contains the great problems of health and environmental protection due to the toxic cyanide-containing electrolyte.
- the black color is achieved only through the use of hexacyanoferrate, which, like the black iron-aluminum spinel, forms a tita spinel and only serves decorative purposes.
- PS-DD 236 978 describes solar-selective absorption layers which consist of dark-colored, chromadotized oxide layers on valve metals such as Ti, Ta, Zr, Nb, Al and which are also produced by means of an electrolyte containing fluoride and dihydrogen phosphate, tetraborate and chromate in the ANOF process .
- These electrolytes also have the already mentioned disadvantage of fluoride content and the layers obtained with them also have such a rough surface structure effect that when used, for example as a functional surface for complexly shaped structural parts or assemblies, there is such abrasion that dimensional accuracy is no longer guaranteed .
- these layers have a high ABsorption capacity ⁇ , they also record multiple reflections of the incident radiation due to the rough surface structure effect, which emits its energy in the form of heat to the absorption layer and transfers it to the collector body. In relation to the optical absorption ⁇ , a very low thermal emission ⁇ is achieved.
- the aim of the invention is to provide an easy-to-use electrolyte for the production of uniformly thin, matte black conversion layers as functional surfaces of components or groups, which open up a large amount of constructive freedom even in the case of complicatedly shaped structural parts or groups.
- the invention has for its object to develop a low-pollutant, environmentally friendly electrolyte that enables the production of optically black layers with a layer thickness ⁇ 10 microns and almost the same optical absorption and thermal emissivity using the ANOF process.
- the object is achieved by an electrolyte for producing thin black conversion layers on light metals or their alloys by means of anodic oxidation with spark discharge in that the electrolyte consists of an aqueous solution which contains potassium dihydrogen phosphate, potassium chromate, acetates, ammonium citrate and ethylenediamine.
- mol / l potassium dihydrogen phosphate 0.03 to 0.08 mol / l potassium chromate; Acetations in concentrations from 0.08 to 0.5 mol / l; 0.1 to 0.3 mol / l ammonium citrate and 0.5 to 0.9 mol / l ethylenediamine mixed to form an aqueous solution.
- An advantageous embodiment of the solution consists in that the ions of the copper acetate are used as acetations.
- An essential result of the use of the electrolyte according to the invention is that it can be used to produce the thin black conversion layers by the light metal or its alloys using plasma-chemical anodic oxidation in an aqueous electrolyte at a current density of 0.005 to 0.05 A. cm ⁇ 2 and a voltage of 100 - 200 V is coated.
- a degreased and alkaline pickled sheet made of AlMg 5 was also made using plasma-chemical anodic oxidation with spark discharge in an already known aqueous electrolyte, consisting of a 4.5% by volume ammoniacal solution with 0.5 mol / l KH2PO4; 0.1 mol / l K2crO4 and 0.35 mol / l Cu [CH3COO] 2 at a current density of 0.045 A. cm ⁇ 2 coated.
- a deep black colored conversion layer is also obtained in the one-step process.
- the new electrolyte gives a conversion layer of approximately 4 ⁇ m in thickness. It is therefore about 30% of the layer thickness of conventional black ANOF layers. This is particularly advantageous for constructive solutions in which coatings have to be applied without changing the fit tolerances. Even thread fits up to H6 tolerances are manageable. The release of particles when fitting parts is minimized. The good spreading capacity of cylindrical parts up to an inner diameter / length ratio of 1:10.
- the reflectance at 540 nm is 6% and is therefore comparable to conventional black ANOF layers.
- the roughness number is 1.6 ⁇ m, while for conventional black ANOF layers it is 5.4 ⁇ m - with the same initial roughness of 0.7 ⁇ m.
- the layers obtained therefore have a lower particle generation and are therefore suitable as a coating variant for complexly shaped construction parts or assemblies with higher requirements for their dimensional accuracy.
- the dielectric strength test is to be understood here as a laboratory method for determining the current / voltage curve up to the breakdown of the layer under high vacuum conditions (10 ⁇ 2Pa). The results obtained show that the dielectric strength is maintained or even increases slightly as the layer thickness decreases due to the specific morphology of the layer. However, it would have been assumed that the dielectric strength of layers of chemically similar composition decreases with decreasing layer thickness (see Kahle, M.-Elektro Isoliertechnik, VEB Verlagtechnik, Berlin, 1988).
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Abstract
Description
Die Erfindung betrifft Elektrolyte zur Erzeugung gleichmässig dünner mattschwarzer Konversionsschichten als Funktionsflächen von Bauteilen bzw. -gruppen aus Leichtmetallwerkstoffen oder deren Legierungen nach dem Verfahren der anodischen Oxidation unter Funkenentladung (ANOF). Sie stellen in ihrer Anwendung eine Beschichtungsvariante besonders für kompliziert geformte Konstruktionsteile oder -gruppen dar und sind daher besonders für den Einsatz im optischen Präzisisionsgerätebau geeignet.The invention relates to electrolytes for producing uniformly thin, matte black conversion layers as functional surfaces of components or groups made of light metal materials or their alloys by the process of anodic oxidation with spark discharge (ANOF). In their application they represent a coating variant especially for complex shaped construction parts or groups and are therefore particularly suitable for use in optical precision device construction.
Aus der Fach- und Patentliteratur sind eine Anzahl Elektrolyte zur Erzeugung von Konversionsschichten mittels ANOF-Verfahren auf Leichtgewichtswerkstoffen, speziell auf Ventilmetallen, wie Ti, Ta, Zr, Nb oder AI bekannt (s. PS-DD 229 163, PS-DD 236 978, PS-DD 142 360, PS-EP 0 280 886). Hierbei werden Elektrolyte verwendet, die vorwiegend Nebengruppenelemente enthalten, die als Hydroxo-, Amino- oder Komplexonkomplexe gebunden sind. Beispielsweise beschreibt die PS-DD 229 163 Elektrolytlösungen zur Erzeugung schwarzer bzw. grau-schwarzer Konversionsschichten auf Leichtmetallen, wie AI. Diese Elektrolytlösungen enthalten hauptsächlichst Fluoride als NaF oder NH₄F, Dihydrogenphosphate als NaH₂PO₄, Tetraborate als Borax Na₂B₄O₇ und Chromate sowie andere Fremdzusätze. Nachteilig ist dabei, dass durch die Verwendung der Fluoride besondere Arbeits-, Umweltschutz- und Entsorgungsmassnahmen erforderlich sind.A number of electrolytes for producing conversion layers by means of the ANOF process on lightweight materials, especially on valve metals such as Ti, Ta, Zr, Nb or AI, are known from the specialist and patent literature (see PS-DD 229 163, PS-DD 236 978 , PS-DD 142 360, PS-EP 0 280 886). Here electrolytes are used which mainly contain subgroup elements which are bound as hydroxo, amino or complexone complexes. For example, PS-DD 229 163 describes electrolyte solutions for producing black or gray-black conversion layers on light metals, such as Al. These electrolyte solutions mainly contain fluorides as NaF or NH₄F, dihydrogen phosphates as NaH₂PO₄, tetraborates as Borax Na₂B₄O₇ and chromates as well as other foreign additives. The disadvantage here is that the use of fluorides necessitates special work, environmental protection and disposal measures.
Die PS-DD 257 275 verweist auf dekorative Ueberzüge u.a. auf Titanwerkstoffen, die mittels ANOF-Verfahren und einem Elektrolyten, bestehend aus NaF, NaH₂PO₄, Na₂B₄O₇ und Kaliumhexacyanoferrat-K₄ [Fe[CN]₆] hergestellt werden. Neben den bereits erwähnten Nachteilen der Fluoridhaltigkeit des Elektrolyten birgt diese Lösung in sich die grosse Problematik des Gesundheits- und Umweltschutzes aufgrund des toxisch wirkenden cyanidhaltigen Elektrolyten. Die schwarze Farbe wird lediglich durch den Einsatz des Hexacyanoferrats erzielt, was ähnlich dem schwarzen Eisen-Aluminiumspinell ein Tita-Spinell bildet und lediglich dekorative Zwecke erfüllt.The PS-DD 257 275 refers to decorative coatings, inter alia, on titanium materials which are produced by means of the ANOF process and an electrolyte consisting of NaF, NaH₂PO₄, Na₂B₄O₇ and potassium hexacyanoferrate-K₄ [Fe [CN] ₆] are produced. In addition to the already mentioned disadvantages of the fluoride content of the electrolyte, this solution contains the great problems of health and environmental protection due to the toxic cyanide-containing electrolyte. The black color is achieved only through the use of hexacyanoferrate, which, like the black iron-aluminum spinel, forms a tita spinel and only serves decorative purposes.
Die PS-DD 236 978 beschreibt solarselektive Absorptionsschichten, die aus dunkelgefärbten, chromadotierten Oxidschichten auf Ventilmetallen, wie Ti, Ta, Zr, Nb, Al bestehen und die ebenfalls mittels eines fluoridhaltigen und Dihydrogenphosphat, Tetraborat sowie Chromat enthaltenen Elektrolyten im ANOF-Verfahren erzeugt werden. Diese Elektrolyten besitzen auch den bereits erwähnten Nachteil der Fluoridhaltigkeit und die damit erzielten Schichten weisen ausserdem einen derart rauhen Oberflächenstruktureffekt auf, dass bei ihrer Anwendung beispielsweise als Funktionsfläche für kompliziert geformte Konstruktionsteile oder Baugruppen ein solcher Abrieb zu verzeichnen ist, dass eine Masshaltigkeit nicht mehr gegeben ist. Diese Schichten besitzen zwar ein hohes ABsorptionsvermögen α, verzeichnen jedoch ebenfalls, bedingt durch den rauhen Oberflächenstruktureffekt, Mehrfachreflexionen der einfallenden Strahlung, die dabei ihre Energie in Form von Wärme an die Absorptionsschicht abgibt und diese auf den Kollektorkörper übertragen wird. Es wird im Verhältnis zur optischen Absorption α eine sehr geringe thermische Emission ε erzielt.PS-DD 236 978 describes solar-selective absorption layers which consist of dark-colored, chromadotized oxide layers on valve metals such as Ti, Ta, Zr, Nb, Al and which are also produced by means of an electrolyte containing fluoride and dihydrogen phosphate, tetraborate and chromate in the ANOF process . These electrolytes also have the already mentioned disadvantage of fluoride content and the layers obtained with them also have such a rough surface structure effect that when used, for example as a functional surface for complexly shaped structural parts or assemblies, there is such abrasion that dimensional accuracy is no longer guaranteed . Although these layers have a high ABsorption capacity α, they also record multiple reflections of the incident radiation due to the rough surface structure effect, which emits its energy in the form of heat to the absorption layer and transfers it to the collector body. In relation to the optical absorption α, a very low thermal emission ε is achieved.
Seit kurzem sind cyanid- und fluoridfreie und damit verbunden gesundheits- und umweltfreundliche Elektrolyte zur Erzeugung feimattierter, tiefschwarzer Konversionsschichten mit nahezu gleichem optischen Absorptions- und thermischen Emissionsvermögen auf Leichtmetallen oder deren Legierungen bekannt, die mittels ANOF-Verfahren realisiert werden. Die so erzeugten Schichten sind 10 ... 12 µm stark, garantieren damit eine grosse Anwendungsbreite, sind jedoch für Konstruktionsteile (z.B. Passungen, Gewinde) mit höheren Anforderungen an Masshaltigkeit als Funktionsflächen nicht geeignet. Da der Elektrolyt u.a. aus einer 2 bis 6-volumenprozentigen ammoniakalischen Lösung besteht, tritt eine deutliche Geruchsbelästigung auf, die erhöhte Anforderungen an die Produktionstechnologie stellt.Recently, cyanide and fluoride-free and associated health and environmentally friendly electrolytes for the production of finely matted, deep black conversion layers known with almost the same optical absorption and thermal emissivity on light metals or their alloys, which are realized using the ANOF process. The layers produced in this way are 10 ... 12 µm thick, thus guaranteeing a wide range of applications, but are not suitable for structural parts (eg fits, threads) with higher requirements for dimensional accuracy than functional surfaces. Since the electrolyte consists, among other things, of a 2 to 6 volume percent ammoniacal solution, there is a significant odor nuisance, which places increased demands on the production technology.
Das Ziel der Erfindung liegt in der Bereitstellung eines einfach zu handhabenden Elektrolyten zur Erzeugung gleichmässig dünner mattschwarzer Konversionsschichten als Funktionsflächen von Bauteilen bzw. -gruppen, die auch bei kompliziert geformten Konstruktionsteilen oder -gruppen einen grossen konstruktiven Spielraum eröffnen.The aim of the invention is to provide an easy-to-use electrolyte for the production of uniformly thin, matte black conversion layers as functional surfaces of components or groups, which open up a large amount of constructive freedom even in the case of complicatedly shaped structural parts or groups.
Der Erfindung liegt die Aufgabe zugrunde, einen schadstoffarmen, umweltfreundlichen Elektrolyten zu entwickeln, der die Herstellung optisch schwarzer Schichten mit einer Schichtdicke <10 µm und nahezu gleichem optischen Absorptions- und thermischen Emissionsvermögen mittels ANOF-Verfahren ermöglicht.The invention has for its object to develop a low-pollutant, environmentally friendly electrolyte that enables the production of optically black layers with a layer thickness <10 microns and almost the same optical absorption and thermal emissivity using the ANOF process.
Erfindungsgemäss wird die Aufgabe durch einen Elektrolyt zur Erzeugung dünner schwarzer Konversionsschichten auf Leichtmetallen oder deren Legierungen mittels anodischer Oxidation unter Funkenentladung dadurch gelöst, dass der Elektrolyt aus einer wässrigen Lösung besteht, die Kaliumdihydrogenphosphat, Kaliumchromat, Acetationen, Ammoniumcitrat und Ethylendiamin enthält. Zur Herstellung des Elektrolyten werden 0,4 bis 0,7 mol/l Kaliumdihydrogenphosphat; 0,03 bis 0,08 mol/l Kaliumchromat; Acetationen in Konzentrationen von 0,08 bis 0,5 mol/l; 0,1 bis 0,3 mol/l Ammoniumcitrat und 0,5 bis 0,9 mol/l Ethylendiamin zu einer wässrigen Lösung vermischt. Eine vorteilhafte Ausgestaltung der Lösung besteht darin, dass als Acetationen die Ionen des Kupferacetats verwendet werden. Ein wesentliches Ergebnis der Anwendung des erfindungsgemässen Elektrolyten besteht darin, dass mit ihm die dünnen schwarzen Konversionsschichten hergestellt werden können, indem das Leichtmetall oder dessen Legierungen mittels plasmachemischer anodischer Oxidation in einem wässrigen Elektrolyten bei einer Stromdichte von 0,005 bis 0,05 A . cm⁻² und einer Spannung von 100 - 200 V beschichtet wird.According to the invention, the object is achieved by an electrolyte for producing thin black conversion layers on light metals or their alloys by means of anodic oxidation with spark discharge in that the electrolyte consists of an aqueous solution which contains potassium dihydrogen phosphate, potassium chromate, acetates, ammonium citrate and ethylenediamine. To produce the electrolyte, 0.4 to 0.7 mol / l potassium dihydrogen phosphate; 0.03 to 0.08 mol / l potassium chromate; Acetations in concentrations from 0.08 to 0.5 mol / l; 0.1 to 0.3 mol / l ammonium citrate and 0.5 to 0.9 mol / l ethylenediamine mixed to form an aqueous solution. An advantageous embodiment of the solution consists in that the ions of the copper acetate are used as acetations. An essential result of the use of the electrolyte according to the invention is that it can be used to produce the thin black conversion layers by the light metal or its alloys using plasma-chemical anodic oxidation in an aqueous electrolyte at a current density of 0.005 to 0.05 A. cm⁻² and a voltage of 100 - 200 V is coated.
Die Vorteile der Lösung ergeben sich im wesentlichen dadurch, dass ein Elektrolyt entwickelt wurde,
- der die Herstellung optisch schwarzer Schichten mit einer Schichtdicke <10 µm und nahezu gleichem optischen Absorptions- und thermischen Emissionsvermögen ermöglicht,
- Welcher ammoniak-, cyanid- und fluoridfrei und daher gesundheits- und umweltfreundlich ist, d.h. es sind keine zusätzlichen Umweltschutz- und arbeitsschutztechnischen Massnahmen erforderlich,
- bei dessen Anwendung im ANOF-Verfahren eine Konversionsschicht erreicht wird, die im Vergleich zu den bisherig bekannten, im ANOF-Verfahren erzielten Konversionsschichten eine wesentlich geringere Rauhzahl und damit eine geringere Partikelgenerierung besitzt,
- durch dessen Einsatz im ANOF-Verfahren somit eine Beschichtungsvariante für kompliziert geformte Konstruktionsteile oder Baugruppen mit höheren Anforderungen an ihre Masshaltigkeit gegeben ist,
- der ein Schichtsystem erzeugt, welches eine sehr gute Thermovakuumstabilität, verbunden mit einer hohen Langzeitstabilität durch eine minimale Abgabe flüchtiger Bestandteile des Schichtsystems ermöglicht. Damit werden funktionsbeeinträchtigende Kontaminationserscheinungen in Baugruppen, beispielsweise in optischen Systemen, ausgeschlossen.
- that enables the production of optically black layers with a layer thickness of <10 µm and almost the same optical absorption and thermal emissivity,
- Which is free of ammonia, cyanide and fluoride and is therefore health and environmentally friendly, ie no additional environmental and occupational safety measures are required,
- when it is used in the ANOF process, a conversion layer is achieved which, in comparison to the previously known conversion layers achieved in the ANOF process, has a significantly lower roughness number and thus less particle generation,
- its use in the ANOF process thus provides a coating variant for complexly shaped construction parts or assemblies with higher requirements for their dimensional accuracy,
- which produces a layer system which has a very good thermal vacuum stability combined with a high Long-term stability enabled by a minimal release of volatile components of the layer system. This eliminates the effects of contamination in assemblies, for example in optical systems, which impair functionality.
Die Erfindung soll nachfolgend an einem Beispiel erläutert werden.The invention will be explained below using an example.
Ein entfettetes und alkalisch gebeiztes Blech aus AlMg 5 wird in einem Elektrolysebad, bestehend aus einer wässrigen Lösung aus 0,59 mol/l=80 g/l KH₂PO₄; 0,05 mol/l=10 g/l K₂CrO₄, 0,35 mol/ml=70 g/l Cu[CH₃COO]₂ . H₂O; 0,22 mol/l=50 g/l NH₄ . citrat und 0,38 ml/l=100 ml Ethylendiamin als Anode geschaltet und mit Hilfe der anodischen Oxidation unter Funkenentladung bei einer Stromdichte von 0,05A . cm⁻² und bei einer Spannung von 170V beschichtet. Man erhält eine tiefschwarze, matte Konversionsschicht.A degreased and alkaline pickled sheet of AlMg 5 is in an electrolysis bath consisting of an aqueous solution of 0.59 mol / l = 80 g / l KH₂PO₄; 0.05 mol / l = 10 g / l K₂CrO₄, 0.35 mol / ml = 70 g / l Cu [CH₃COO] ₂. H₂O; 0.22 mol / l = 50 g / l NH₄. citrate and 0.38 ml / l = 100 ml ethylenediamine switched as anode and with the help of anodic oxidation with spark discharge at a current density of 0.05A. cm⁻² and coated at a voltage of 170V. A deep black, matt conversion layer is obtained.
Im Vergleich dazu wurde ebenfalls ein entfettetes und alkalisch gebeiztes Blech aus AlMg 5 mittels plasmachemischer anodischer Oxidation unter Funkenentladung in einem bereits bekannten wässrigen Elektrolyten, bestehend aus einer 4,5-volumenprozentigen ammoniakalischen Lösung mit 0,5 mol/l KH₂PO₄; 0,1 mol/l K₂crO₄ und 0,35 mol/l Cu[CH₃COO]₂ bei einer Stromdichte von 0,045 A . cm⁻² beschichtet.In comparison, a degreased and alkaline pickled sheet made of AlMg 5 was also made using plasma-chemical anodic oxidation with spark discharge in an already known aqueous electrolyte, consisting of a 4.5% by volume ammoniacal solution with 0.5 mol / l KH₂PO₄; 0.1 mol / l K₂crO₄ and 0.35 mol / l Cu [CH₃COO] ₂ at a current density of 0.045 A. cm⁻² coated.
Man erhält auch im Einstufenprozess eine tiefschwarz gefärbte Konversionsschicht.A deep black colored conversion layer is also obtained in the one-step process.
Die signifikanten Unterschiede beider Lösungen sind in Tabelle 1 dargestellt:
Es ist zu entnehmen, dass man mit dem neuen Elektrolyten eine Konversionsschicht von ca. 4 µm Schichtdicke erhält. Sie beträgt somit etwa 30 % der Schichtdicke von konventionellen schwarzen ANOF-Schichten. Die ist besonders für konstruktive Lösungen vorteilhaft, bei denen Beschichtungen ohne Veränderungen der Passungstoleranzen erfolgen müssen. So sind selbst Gewindepassungen bis H6-Toleranzen beherrschbar. Das Freisetzen von Partikeln beim Einpassen von Teilen wird minimiert. Das gute Streuvermögen von zylinderförmigen Teilen bis zu einem Innendurchmesser-/Längenverhältnis 1:10.It can be seen that the new electrolyte gives a conversion layer of approximately 4 µm in thickness. It is therefore about 30% of the layer thickness of conventional black ANOF layers. This is particularly advantageous for constructive solutions in which coatings have to be applied without changing the fit tolerances. Even thread fits up to H6 tolerances are manageable. The release of particles when fitting parts is minimized. The good spreading capacity of cylindrical parts up to an inner diameter / length ratio of 1:10.
Die Remission bei 540 nm beträgt 6 % und ist damit mit herkömmlichen schwarzen ANOF-Schichten vergleichbar.The reflectance at 540 nm is 6% and is therefore comparable to conventional black ANOF layers.
Die Rauhigkeit (Rz) . Rauhzahl beträgt 1,6 µm, während sie für konventionelle schwarze ANOF-Schichten 5,4 µm beträgt - bei gleicher Ausgangsrauhigkeit von 0,7 µm. Die erzielten Schichten besitzen deshalb eine geringere Partikelgenerierung und sind deshalb als Beschichtungsvariante für kompliziert geformte Konstruktionsteile oder Baugruppen mit höheren Anforderungen an ihre Masshaltigkeit geeignet.The roughness (R z ). The roughness number is 1.6 µm, while for conventional black ANOF layers it is 5.4 µm - with the same initial roughness of 0.7 µm. The layers obtained therefore have a lower particle generation and are therefore suitable as a coating variant for complexly shaped construction parts or assemblies with higher requirements for their dimensional accuracy.
Die Prüfung der Durchschlagfestigkeit ist hier zu verstehen als labormässige Methode zur Ermittlung des Strom-/Spannungsverlaufes bis zum Durchschlag der Schicht unter Hochvakuumbedingungen (10⁻²Pa). Die ermittelten Ergebnisse zeigen, dass mit abnehmender Schichtdicke aufgrund der spezifischen Morphologie der Schicht die Durchschlagfestigkeit erhalten bleibt, bzw. sich sogar etwas erhöht. Anzunehmen wäre jedoch gewesen, dass bei Schichten chemisch ähnlicher Zusammensetzung sich die Durchschlagfestigkeit mit abnehmender Schichtdicke verringert (s. Kahle, M.-Elektrische Isoliertechnik, VEB Verlag Technik, Berlin, 1988).The dielectric strength test is to be understood here as a laboratory method for determining the current / voltage curve up to the breakdown of the layer under high vacuum conditions (10⁻²Pa). The results obtained show that the dielectric strength is maintained or even increases slightly as the layer thickness decreases due to the specific morphology of the layer. However, it would have been assumed that the dielectric strength of layers of chemically similar composition decreases with decreasing layer thickness (see Kahle, M.-Elektro Isoliertechnik, VEB Verlag Technik, Berlin, 1988).
Weiterhin tritt beim Beschichtungsprozess durch die Verwendung eines ammoniakfreien Elektrolyten keinerlei Geruchsbelästigung auf. Ein anschliessendes Spülen mit ammoniakalischer wässriger Lösung entfällt.Furthermore, there is no odor nuisance in the coating process due to the use of an ammonia-free electrolyte. A subsequent rinsing with ammoniacal aqueous solution is not necessary.
Claims (8)
0,4 bis 0,7 mol/l Kaliumdihydrogenphosphat,
0,3 bis 0,08 mol/l Kaliumchromat,
0,08 bis 0,5 mol/l Acetationen,
0,1 bis 0,3 mol/l Ammoniumcitrat,
0,5 bis 0,9 mol/l Ethylendiamin
enthält.Electrolyte according to claim 1, characterized in that the aqueous solution
0.4 to 0.7 mol / l potassium dihydrogen phosphate,
0.3 to 0.08 mol / l potassium chromate,
0.08 to 0.5 mol / l acetate ions,
0.1 to 0.3 mol / l ammonium citrate,
0.5 to 0.9 mol / l ethylenediamine
contains.
0,59 mol/l KH₂PO₄,
0,05 mol/l K₂CrO₄,
0,35 mol/l Cu[CH₃COO]₂,
0,22 mol/l Ammoniumcitrat,
0,38 mol/l Ethylendiamin,
enthält.Electrolyte according to claim 3, characterized in that the aqueous solution
0.59 mol / l KH₂PO₄,
0.05 mol / l K₂CrO₄,
0.35 mol / l Cu [CH₃COO] ₂,
0.22 mol / l ammonium citrate,
0.38 mol / l ethylenediamine,
contains.
55 bis 97 g Kaliumdihydrogenphosphat,
60 bis 1,6 g Kaliumchromat,
26 bis 100 g Cu[CH₃COO]₂·H₂O,
22 bis 68 g Ammoniumcitrat,
131 bis 237 ml Ethylendiamin,
aufgelöst werden.Process for the production of electrolytes according to one of claims 2 to 4, characterized in that per liter of water
55 to 97 g of potassium dihydrogen phosphate,
60 to 1.6 g of potassium chromate,
26 to 100 g Cu [CH₃COO] ₂ · H₂O,
22 to 68 g ammonium citrate,
131 to 237 ml of ethylenediamine,
be resolved.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DD341637 | 1990-06-14 | ||
| DD34163790A DD295198B5 (en) | 1990-06-14 | 1990-06-14 | Electrolyte for producing thin black conversion coatings on light metals |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0462073A2 true EP0462073A2 (en) | 1991-12-18 |
| EP0462073A3 EP0462073A3 (en) | 1993-01-20 |
| EP0462073B1 EP0462073B1 (en) | 1994-11-30 |
Family
ID=5619162
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP91810453A Expired - Lifetime EP0462073B1 (en) | 1990-06-14 | 1991-06-13 | Electrolyte for producing thin black conversion layers on light metals |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US5094727A (en) |
| EP (1) | EP0462073B1 (en) |
| DD (1) | DD295198B5 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1996033300A1 (en) * | 1995-04-18 | 1996-10-24 | Harbin Huanya Micro - Arc Co. Ltd. | Process for producing ceramic layer by plasma enhanced electrolysis and product thereof |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6245436B1 (en) * | 1999-02-08 | 2001-06-12 | David Boyle | Surfacing of aluminum bodies by anodic spark deposition |
| DE102008026557A1 (en) | 2008-06-03 | 2009-12-17 | Königsee Implantate und Instrumente zur Osteosynthese GmbH | Electrochemically produced, biodegradation-stable, ductile and adherent titanium oxide surface layer on titanium or titanium-based alloys |
| DE102008026558B4 (en) | 2008-06-03 | 2010-04-01 | Königsee Implantate und Instrumente zur Osteosynthese GmbH | Electrochemical immersion process in an aqueous electrolyte to produce a biologically degradable surface layer on bases of titanium or titanium-based alloys |
| CN103088387B (en) * | 2012-12-13 | 2016-04-20 | 陕西华银科技有限公司 | Copper oxide/aluminum oxide composite catalyst and preparation method thereof and special micro-arc oxidation electrolyte |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3870925D1 (en) * | 1987-02-02 | 1992-06-17 | Friebe & Reininghaus Ahc | METHOD FOR PRODUCING DECORATIVE COATINGS ON METALS. |
-
1990
- 1990-06-14 DD DD34163790A patent/DD295198B5/en not_active IP Right Cessation
-
1991
- 1991-04-25 US US07/691,629 patent/US5094727A/en not_active Expired - Lifetime
- 1991-06-13 EP EP91810453A patent/EP0462073B1/en not_active Expired - Lifetime
Non-Patent Citations (1)
| Title |
|---|
| METALLOBERFLäCHE Bd. 40, Nr. 12, Dezember 1986, Seiten 539 - 540 KURZE 'beschichten durch anodische oxidation unter funkenentladungen (anof)' * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1996033300A1 (en) * | 1995-04-18 | 1996-10-24 | Harbin Huanya Micro - Arc Co. Ltd. | Process for producing ceramic layer by plasma enhanced electrolysis and product thereof |
| CN1034522C (en) * | 1995-04-18 | 1997-04-09 | 哈尔滨环亚微弧技术有限公司 | Plasma enhanced electrochemical surface ceramic method and product prepared by same |
Also Published As
| Publication number | Publication date |
|---|---|
| US5094727A (en) | 1992-03-10 |
| EP0462073B1 (en) | 1994-11-30 |
| DD295198B5 (en) | 1996-06-27 |
| EP0462073A3 (en) | 1993-01-20 |
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