EP0083571B1 - Verfahren zur Korrosionsverhütung von Aluminiumteilen - Google Patents

Verfahren zur Korrosionsverhütung von Aluminiumteilen Download PDF

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Publication number
EP0083571B1
EP0083571B1 EP19830300018 EP83300018A EP0083571B1 EP 0083571 B1 EP0083571 B1 EP 0083571B1 EP 19830300018 EP19830300018 EP 19830300018 EP 83300018 A EP83300018 A EP 83300018A EP 0083571 B1 EP0083571 B1 EP 0083571B1
Authority
EP
European Patent Office
Prior art keywords
magnetite
aluminium
circulating water
water
component
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
Application number
EP19830300018
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English (en)
French (fr)
Other versions
EP0083571A1 (de
Inventor
Ronald William Elkington
David Francis Fletcher
Albert Harold Carter
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.)
Rio Tinto Alcan International Ltd
Original Assignee
Alcan International Ltd Canada
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 Alcan International Ltd Canada filed Critical Alcan International Ltd Canada
Publication of EP0083571A1 publication Critical patent/EP0083571A1/de
Application granted granted Critical
Publication of EP0083571B1 publication Critical patent/EP0083571B1/de
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
    • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
    • C23F11/18—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using inorganic inhibitors

Definitions

  • the present invention relates to the inhibition of corrosion in circulating water systems which include aluminium or aluminium alloy components; it is particularly advantageous when used in the operation of heating systems employing hot water radiators made of aluminium alloys.
  • Aluminium and its alloys have a number of attractions as materials for the construction of hot water radiators, for example their light weight and good heat emissivity characteristics.
  • Such radiators may be manufactured in various ways, for example by casting methods, by fabrication from sheet or plate, or by assembly of suitable extruded sections.
  • the alloy used is generally an aluminium-silicon alloy, for example AI-11 % Si.
  • commercially pure aluminium (99.5%) can be used but its mechanical strengths and other properties are generally inadequate and alloys of aluminium are preferred.
  • alloys of the aluminium-magnesium silicide group such as AA 6063 are much preferred.
  • aluminium and its alloys may undergo pitting corrosion when in contact with potable water drawn from domestic supplies and subjected to the temperature cycles normally encountered in radiators; in particular such pitting corrosion is liable to occur when the system includes copper-containing components so as to provide a source of copper ions in the water.
  • British Patent Specification GB-A-2013168 describes a method of inhibiting a corrosion of a body of e.g. aluminium im the presence of water by adding to the water ferrous sulphate and an organic polymer, preferably in the presence of a reducing or chelating agent, so as to deposit an even layer of ferric hydroxide on the body.
  • Such protective film could be formed on aluminium surfaces in general and were not confined to high silicon alloys of the type involved in the initial experiment.
  • Such films can, for example, be developed on the internal surfaces of radiators assembled from extruded sections made in alloy AA 6063 and other common extrusion alloys.
  • the magnetite particles were of a size less than 0.1 pm, i.e. of colloidal dimensions and presumably originated from some colloidal solution and originated with some chance source of iron in contact with the water.
  • Some domestic hot water radiator systems to-day are free of iron components.
  • chance sources of iron such as the water heating jacket of the boiler, exist, but may not give rise to colloidal particles of magnetite incorporated into the Bayerite film under the operating conditions.
  • a method of reducing corrosion of the surface of an aluminium or aluminium alloy component in contact with circulating water comprises providing on the surface a protective oxide layer containing finely divided particles of magnetite.
  • a source of colloidal magnetite is introduced into the circulating water so as to form on the surface of the component the protective film of magnetite.
  • colloidal magnetite may be introduced into the circulating water, preferably at a concentration of from 500 ppm to 10000 ppm. Below 500 ppm, the protective film may be developed only slowly or to an insufficient extent. Amounts above 10000 ppm contaminate the circulating water without providing sufficient compensating advantages.
  • the method of the invention may be used to pre-treat the component before it comes in contact with the circulating water.
  • the source of colloidal magnetite is introduced into the circulating water at substantially the same time as the component, whereby there is formed on the surface thereof a protective layer of hydrated alumina containing the finely divided particles of magnetite.
  • the most convenient route for applying the treatment to an aluminium radiator in situ in a heating system is to dose the water in the radiator system with a magnetite-bearing material in colloidal form or in at least such a fine state of suspension that it can only remain in a settled out condition when entrapped in the growing layer of Bayerite on the surface of aluminium in contact with the water.
  • magnetite of an average particle size of about 0.2 11m was dispersed in water at a temperature of 70 to 75°C and circulated through an aluminium alloy pipe in the presence of a copper gauze. It was found that such magnetite was quickly absorbed into the Bayerite layer on the internal surface of the pipe. It was found that the dark-coloured Bayerite layer was highly protective and after a test under these conditions over a three month period the aluminium surface was found to be essentially free from pitting.
  • a surface active agent is also introduced into the circulating water in order to assist dispersion of the colloidal magnetite in the water.
  • a surface active agent is also introduced into the circulating water in order to assist dispersion of the colloidal magnetite in the water.
  • the method of this invention is effective to reduce or prevent such galvanic corrosion, but only after a period of, perhaps, a few days when a protective layer comprising finely divided particles of magnetite has been formed. Prior to formation of this protective layer, galvanic corrosion may still occur.
  • a supplementary corrosion inhibitor may be included in the circulating water. Copper passivators are well known, and can be used in conventional amounts as supplementary corrosion inhibitors. Examples are sodium mercaptobenzthiazole (smbt) and benztriazole.
  • colloidal magnetite may be mixed with the surface active agent and/or the supplementary corrosion inhibitor before adding the mixture to the circulating water.
  • the colloidal magnetite optionally in admixture with other ingredients, may be added to the circulating water as a paste, or as capsules or tablets.
  • the mixture is in the form of capsules coated with water-soluble gelatin.
  • An aluminium coupon was directly connected to a copper coupon of equal area and immersed in Banbury tapwater at 70°C.
  • the galvanic current generated by the AI/Cu cell was recorded, and represents a measure of the galvanic corrosion taking place.
  • Example 1 The comparative experiments of Example 1 were repeated using a test-rig system which simulates the actual use of an aluminium radiator in a circulating water system containing also copper pipes and brass fittings.
  • the test-rig experiments confirmed the results of the beaker tests.
  • the radiators were examined after one month's exposure in the simulated central heating system; previous experience had been that, after one month, some galvanic corrosion would have been observable in the absence of a copper passivator.
  • the radiator which had been exposed to water containing 1 g/litre magnetite and 0.5 g/litre smbt showed no signs of corrosion whatsoever. Furthermore the test sample was covered with a very good black film which was determined to comprise hydrated alumina containing embedded therein the colloidal particles of magnetite.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)

Claims (10)

1. Verfahren zum Verhindern der Korrosion an der Oberfläche einer Aluminium- oder Aluminiumlegierungskomponente im Kontakt mit zurkulierendem Wasser, dadurch gekennzeichnet, dass man auf der Oberfläche eine Schutzoxidschicht, enthaltend feinteilige Teilchen von Magnetit, ausbildet.
2. Verfahren gemäss Anspruch 1, worin, die Komponente eine Aluminium-Silicium-Legierung oder eine Legierung der Aluminium-Magnesium-Silicid-Gruppe ist.
3. Verfahren gemäss Anspruch 1 oder Anspruch 2, worin die Komponente ein Heisswasserradiator in einem Heizsystem ist.
4. Verfahren gemäss einem der Ansprüche 1 bis 3, worin eine Quelle für kolloidalen Magnetit in das Zirkulationswasser so eingeführt wird, dass es auf der Oberfläche den Schutzfilm aus Magnetit bildet.
5. Verfahren gemäss Anspruch 4, worin die Quelle des kolloidalen Magnetits in das Zirkulationswasser im wesentlichen zur gleichen Zeit wie die Komponente eingeführt wird, wodurch auf der Oberfläche der Komponente eine Schutzschicht aus hydratisiertem Aluminiumoxid, enthaltend die feinteiligen Teilchen von Magnetit, gebildet wird.
6. Verfahren gemäss einem der Ansprüche 1 bis 5, worin der kolloidale Magnetit in das Zirkulationswasser in einer Konzentration von 500 ppm bis 10.000 ppm eingeführt wird.
7. Verfahren gemäss Anspruch 6, worin ein oberflächenaktives Mittel ebenfalls in das Zirkulationswasser eingeführt wird, um die Dispergierung des Magnetits in dem Wasser zu unterstützen.
8. Verfahren gemäss einem der Ansprüche 1 bis 7, worin ein zusätzlicher Korrosionsinhibitor zur Unterdrückung einer galvanischen Korrosion der Komponente in Gegenwart von Kupfer oder einer Kupferlegierung inkorporiert wird.
9. Verfahren gemäss einem der Ansprüche 6 bis 8, worin in das Zirkulationswasser wenigstens eine Kapsel oder Tablette aus kolloidalem Magnetit und gewünschtenfalls auch dem oberflächenaktiven Mittel und/oder dem zusätzlichen Inhibitor eingeführt wird.
10. Verfahren gemäss Anspruch 9, worin die Kapsel mit wasserlöslicher Gelatine beschichtet ist.
EP19830300018 1982-01-06 1983-01-05 Verfahren zur Korrosionsverhütung von Aluminiumteilen Expired EP0083571B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8200291 1982-01-06
GB8200291 1982-01-06

Publications (2)

Publication Number Publication Date
EP0083571A1 EP0083571A1 (de) 1983-07-13
EP0083571B1 true EP0083571B1 (de) 1986-04-16

Family

ID=10527484

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19830300018 Expired EP0083571B1 (de) 1982-01-06 1983-01-05 Verfahren zur Korrosionsverhütung von Aluminiumteilen

Country Status (3)

Country Link
EP (1) EP0083571B1 (de)
DE (1) DE3362966D1 (de)
GB (1) GB2114113B (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2583582A1 (fr) * 1985-06-18 1986-12-19 Int Fuel Cells Corp Installation productrice d'energie electrique a pile a combustible utilisant une solution aqueuse
FR2583581A1 (fr) * 1985-06-18 1986-12-19 Int Fuel Cells Corp Installation productrice d'energie electrique a pile a combustible utilisant une solution aqueuse et procede de commande de son fonctionnement
EP0285318A1 (de) * 1987-03-24 1988-10-05 Alcan International Limited Korrosionsinhibierung in einer wässrigen Wärmeübertragungsvorrichtung
EP0206974A3 (de) * 1985-06-17 1988-11-17 International Fuel Cells Corporation Eine wässrige Lösung gebrauchender Apparat
US4885141A (en) * 1987-05-22 1989-12-05 Alcan International Limited Water treatment in aqueous heat transfer apparatus

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4670357A (en) * 1985-06-17 1987-06-02 International Fuel Cells Corporation Fuel cell powerplant employing an aqueous solution
US4923767A (en) * 1985-06-18 1990-05-08 International Fuel Cells Fuel cell power plants employing an aqueous solution

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1087475A (fr) * 1953-08-03 1955-02-24 Condensation Application Mec Procédé et dispositif de protection de cuivre et d'alliages de cuivre en contact avec de l'eau salée, en particulier pour les condenseurs tubulaires
FR1204092A (fr) * 1957-10-08 1960-01-22 Ca Atomic Energy Ltd Perfectionnements à la protection des alliages d'aluminium contre la corrosion
US3578508A (en) * 1967-04-12 1971-05-11 Martin B Pearlman Treatment of ferrous metal surfaces to prevent corrosion
FR2048116A5 (en) * 1969-06-02 1971-03-19 Borg Service Protection of copper in salt - water
US3968313A (en) * 1971-05-10 1976-07-06 Pearlman Martin B Surface treatment
JPS5140538B1 (de) * 1971-05-28 1976-11-04

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0206974A3 (de) * 1985-06-17 1988-11-17 International Fuel Cells Corporation Eine wässrige Lösung gebrauchender Apparat
FR2583582A1 (fr) * 1985-06-18 1986-12-19 Int Fuel Cells Corp Installation productrice d'energie electrique a pile a combustible utilisant une solution aqueuse
FR2583581A1 (fr) * 1985-06-18 1986-12-19 Int Fuel Cells Corp Installation productrice d'energie electrique a pile a combustible utilisant une solution aqueuse et procede de commande de son fonctionnement
EP0285318A1 (de) * 1987-03-24 1988-10-05 Alcan International Limited Korrosionsinhibierung in einer wässrigen Wärmeübertragungsvorrichtung
US4885141A (en) * 1987-05-22 1989-12-05 Alcan International Limited Water treatment in aqueous heat transfer apparatus

Also Published As

Publication number Publication date
GB2114113A (en) 1983-08-17
EP0083571A1 (de) 1983-07-13
GB8300120D0 (en) 1983-02-09
GB2114113B (en) 1985-01-09
DE3362966D1 (en) 1986-05-22

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