DE722921C - Process for the electrolytic production of corrosion-preventing coatings on zinc, cadmium and their alloys - Google Patents
Process for the electrolytic production of corrosion-preventing coatings on zinc, cadmium and their alloysInfo
- Publication number
- DE722921C DE722921C DES139479D DES0139479D DE722921C DE 722921 C DE722921 C DE 722921C DE S139479 D DES139479 D DE S139479D DE S0139479 D DES0139479 D DE S0139479D DE 722921 C DE722921 C DE 722921C
- Authority
- DE
- Germany
- Prior art keywords
- zinc
- cadmium
- corrosion
- alloys
- electrolytic production
- 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.)
- Expired
Links
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 title claims description 11
- 239000011701 zinc Substances 0.000 title claims description 11
- 229910052725 zinc Inorganic materials 0.000 title claims description 10
- 238000000034 method Methods 0.000 title claims description 7
- 229910052793 cadmium Inorganic materials 0.000 title claims description 6
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 title claims description 6
- 229910045601 alloy Inorganic materials 0.000 title claims description 5
- 239000000956 alloy Substances 0.000 title claims description 5
- 238000000576 coating method Methods 0.000 title claims description 3
- 238000004519 manufacturing process Methods 0.000 title claims description 3
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical class [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 claims description 4
- 229910002651 NO3 Inorganic materials 0.000 claims description 3
- 239000003513 alkali Substances 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 claims description 2
- 229910001963 alkali metal nitrate Inorganic materials 0.000 claims 1
- -1 nitrate ions Chemical class 0.000 claims 1
- 239000010410 layer Substances 0.000 description 6
- 238000005260 corrosion Methods 0.000 description 5
- 230000007797 corrosion Effects 0.000 description 5
- 239000011241 protective layer Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 229910001297 Zn alloy Inorganic materials 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- QLOKJRIVRGCVIM-UHFFFAOYSA-N 1-[(4-methylsulfanylphenyl)methyl]piperazine Chemical compound C1=CC(SC)=CC=C1CN1CCNCC1 QLOKJRIVRGCVIM-UHFFFAOYSA-N 0.000 description 1
- 241000234435 Lilium Species 0.000 description 1
- 206010037867 Rash macular Diseases 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- KRVSOGSZCMJSLX-UHFFFAOYSA-L chromic acid Substances O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 description 1
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000004040 coloring Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 239000003925 fat Substances 0.000 description 1
- AWJWCTOOIBYHON-UHFFFAOYSA-N furo[3,4-b]pyrazine-5,7-dione Chemical compound C1=CN=C2C(=O)OC(=O)C2=N1 AWJWCTOOIBYHON-UHFFFAOYSA-N 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 239000004922 lacquer Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000011253 protective coating Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 235000010344 sodium nitrate Nutrition 0.000 description 1
- 239000004317 sodium nitrate Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 239000001993 wax Substances 0.000 description 1
- 150000003752 zinc compounds Chemical class 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Classifications
-
- 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
- C25D11/38—Chromatising
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Treatment Of Metals (AREA)
Description
Verfahren zur elektrolytischen Erzeugung korrosionsverhindernder Überzüge auf Zink, Kadmium und deren Legierungen überzugsschichten auf Zink oder Kadmium werden vielfach zum Schutz gegen Rostbildung verwendet, allerdings werden diese Metalle und ihre Legierungen ebenfalls durch die Atmosphärilien angegriffen. Man hat daher schon mehrfach versucht, auf Gegenständen oder Schichten aus Zink und/oder Kadnju m bzw. zink- oder kadmiumreichen Legierungen Schutzschichten aufzubringen, die :eine Korrosion verhindern oder mindestens stark einschränken.Process for the electrolytic production of corrosion-preventing coatings on zinc, cadmium and their alloys coating layers on zinc or cadmium are often used to protect against rust formation, but these are Metals and their alloys also attacked by the atmospheric lilies. Man has therefore tried several times on objects or layers made of zinc and / or Apply protective layers of cadnju m or alloys rich in zinc or cadmium, which: prevent or at least severely limit corrosion.
Man hat zu diesem Zweck verschiedene Verfahren vorgeschlagen, die im wesentlichen darauf abzi.elen"eine Schicht zu bilden, welche schwer. lösliche imd widerstandsfähige Zinkverbindungen, @evtl. gemischt mit Zinkoxyd, enthalten. Die Mehrzahl der Verfahren sind rein chemischer Art. Das Zink wird in bestimmte Lösungen ,getaucht und überzieht sich unter der Einwirkung dieser Lösungen mit einer Schutzschicht. Sowohl diese chemischen Verfahre. als auch die Versuche, durch elektrolytische Behandlung brauchbare korrosionsfeste Schichten zu erhalten, führten bis jetzt zu keinem befriedigenden Ergebnis. Die ausgebildeten Schichten waren nicht gleichmäßig, sondern fleckig, und neben Stellen, die einwandfreien Schutz aufwiesen, konnte man immer auch solche finden, bei denen das Grundmetall zu Tage trat.Various methods have been proposed for this purpose, which essentially aimed at forming a layer which is difficult to dissolve imd resistant zinc compounds, @evtl. mixed with zinc oxide. The majority of the procedures are purely chemical in nature. The zinc is used in certain Solutions, submerged and covered with a under the action of these solutions Protective layer. Both these chemical processes. as well as the attempts by electrolytic Treatment to obtain usable corrosion-resistant layers has so far led to no satisfactory result. The formed layers were not even, but blotchy, and next to places that had perfect protection, you could always find those where the base metal came to light.
In weiterer Ausbildung der Verfahren, bei welchen Lösungen angewendet werden, die sechswertiges Chrom enthalten, gelang es nun, Arbeitsbedingungen festzustellen, bei deren Einhaltung Schutzschichten erreicht werden, die an Gleichmäßigkeit und Dauerhaftigkeit die bis jetzt bekannten weit überragen.In further training of the procedures in which solutions are used containing hexavalent chromium, it has now been possible to determine working conditions at compliance with which protective layers are achieved, which in terms of uniformity and durability far surpass those known up to now.
Erfindungsgemäß wird die elektrolytische Behandlung mehrere Minuten lang, vorzugsweise bei Zimmertemperatur, anodisch in einem Bad durchgeführt, welches ungefähr q.o bis 5o% Alkalichromate und ungefähr 2 bis 6% Alkalinitrate enthält. Überraschenderweise ließen sich mit Bichromaten und Zusatz von freien Säuren bzw. deren Salzen, mit Ausnahme von freier Salpetersäure bzw. deren. Salzen, keine gleich guten Ergebnisse erzielen. Die Stromstärke während der Behandlung wird zweckmäßig anfänglich ungefähr zwischen o,q. und o,ß A/dm° gehalten. Die erzeugten Schichten sind sehr dicht. Sie zeigen hohe Korrosionsbeständigkeit und gutes Anfärbevermögen. Der Korrosionsschutz-vv:ert kann durch Verwendung geeigneter Nachdichtungsmittel, z. B. Ölen, Fetten, Wachsen, Lacken, anorganischen Niederschlägen usw., noch verbessert werden. Eine Messung des pH-Wertes des verwendeten Elektrolyten ergab, daß dieser ganz schwach alkalisch ist. Ausführungsbeispiel Ein Zinkblech wurde in einer wäßrigen Lösung, welche 450/0 Kalium:chromat und 2% Natriumnitrat enthält, 2o Minuten lang bei einer Stromdichte von o,5 A/dm2 anodisch behandelt. Der erhaltene gelblichgrün gefärbte Schutzüberzug ist mechanisch und chemisch sehr widerstandsfähig. Er ist völlig gleichmäßig über die Oberfläche verteilt und läßt sich- gut anfärben. Die verwendete Elektrolytösung weist dann einen pH-Wert von rund 9 auf. Als Material für die Aufhängevorrichtung haben sich Zink bzw. Zinklegierungen bewährt.According to the invention, the electrolytic treatment takes several minutes long, preferably at room temperature, carried out anodically in a bath, which contains approximately q.o to 5o% alkali chromates and approximately 2 to 6% alkali nitrates. Surprisingly, with bichromates and the addition of free acids or their salts, with the exception of free nitric acid or their. Salts, none of the same get good results. The strength of the current during the treatment becomes appropriate initially roughly between o, q. and o, ß A / dm ° held. The layers created are very dense. They show high corrosion resistance and good coloring properties. Corrosion protection can be achieved by using suitable re-sealing agents, z. B. oils, fats, waxes, lacquers, inorganic precipitates, etc., still improved will. A measurement of the pH of the electrolyte used showed that this is very weakly alkaline. Embodiment A zinc sheet was in an aqueous Solution containing 450/0 potassium chromate and 2% sodium nitrate for 20 minutes treated anodically at a current density of 0.5 A / dm2. The yellowish green obtained colored protective coating is mechanically and chemically very resistant. He is evenly distributed over the surface and easy to stain. the The electrolyte solution used then has a pH value of around 9. As material Zinc or zinc alloys have proven themselves for the suspension device.
Die Schichtdicke ist von der Behandlungsdauer abhängig, doch ergab sich, daß bei eitler Behandlungsdauer von länger als 2o...Minuten die Dicke der Schicht nicht mehr proportional der Zeit, sondern langsamer zunahm. Wird durch längere Benutzungsdauer das Bad erschöpft, so kann es durch Zugabe von Chromat und Nitrat wieder regeneriert werden. Dabei empfiehlt @es sich, evtl. am Boden auftretende Zinkniederschläge abzufiltern. Werden die Nitratkonzentrationen wesentlich über die angegebenen hinaus erhöht, so treten Anfressungen auf. Steigt bei längerer Behandlungsdauer der pii-Wert des Bades allmählich an, dann ist es möglich, wieder den gewünschten pH-Wert dadurch herzustellen, daß man eine ganz geringe Menge Salpetersäure oder Chromsäure zusetzt.The layer thickness depends on the duration of the treatment, but it was found that if the treatment lasts longer than 20 ... minutes, the thickness of the Shift no longer proportional to time, but increased more slowly. Will go through longer Duration of use the bath exhausts, so it can by adding chromate and nitrate can be regenerated again. It is recommended to avoid any occurrences on the floor To filter out zinc deposits. The nitrate concentrations are significantly above the specified beyond increases, then corrosion occurs. Increases with longer duration of treatment the pii value of the bath gradually increases, then it is possible to get back to the desired level Establish pH by adding a very small amount of nitric acid or Chromic acid adds.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DES139479D DE722921C (en) | 1939-12-08 | 1939-12-08 | Process for the electrolytic production of corrosion-preventing coatings on zinc, cadmium and their alloys |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DES139479D DE722921C (en) | 1939-12-08 | 1939-12-08 | Process for the electrolytic production of corrosion-preventing coatings on zinc, cadmium and their alloys |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| DE722921C true DE722921C (en) | 1942-07-28 |
Family
ID=7541108
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| DES139479D Expired DE722921C (en) | 1939-12-08 | 1939-12-08 | Process for the electrolytic production of corrosion-preventing coatings on zinc, cadmium and their alloys |
Country Status (1)
| Country | Link |
|---|---|
| DE (1) | DE722921C (en) |
-
1939
- 1939-12-08 DE DES139479D patent/DE722921C/en not_active Expired
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