EP0482614B1 - Procédé de passivation contrÔlée des parois intérieures d'un système de refroidissement en acier au carbone et utilisation du procédé pour le control de la passivation et du qualité de l'eau de refroidissement - Google Patents

Procédé de passivation contrÔlée des parois intérieures d'un système de refroidissement en acier au carbone et utilisation du procédé pour le control de la passivation et du qualité de l'eau de refroidissement Download PDF

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Publication number
EP0482614B1
EP0482614B1 EP91118080A EP91118080A EP0482614B1 EP 0482614 B1 EP0482614 B1 EP 0482614B1 EP 91118080 A EP91118080 A EP 91118080A EP 91118080 A EP91118080 A EP 91118080A EP 0482614 B1 EP0482614 B1 EP 0482614B1
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Prior art keywords
passivation
process according
coolant fluid
corrosion
oxygen
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EP91118080A
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German (de)
English (en)
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EP0482614B2 (fr
EP0482614A1 (fr
Inventor
Enno Dr. c/o Nalco Europe Sàrl Buss
Donald A. C/O Nalco Chemical Company Johnson
Gerhard Dr. Bohnsack
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ChampionX LLC
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Nalco Chemical Co
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • 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
    • C23F15/00—Other methods of preventing corrosion or incrustation
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/60—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using alkaline aqueous solutions with pH greater than 8
    • C23C22/62—Treatment of iron or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/68—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous solutions with pH between 6 and 8

Definitions

  • the invention relates to a simple and economical method for the controlled passivation of the inner walls of an air-open and / or closed cooling circuit system made of carbon steel with an oxygen-containing circulating therein as well as an aqueous cooling liquid containing alkali and alkaline earth bicarbonate, and the application of this method for electrochemical control and determination of the passivation state the metallic surfaces of the cooling liquid system, which come into contact with the aqueous cooling liquid, and for checking the quality of the cooling liquid, in particular water.
  • open-air and / or closed cooling circuit system means a cooling system containing an aqueous cooling liquid, primarily water, the metallic surfaces of which come into contact with the aqueous cooling liquid are subject to corrosion.
  • a cooling system can be a cooling circuit system that is open to air and / or a closed cooling circuit system.
  • Corrosion a practically ubiquitous problem, is known to be the disadvantageous and quality-reducing change in the surface of the material that usually originates from the surface of a metallic material and is caused by chemical or electrochemical attacks on the corrosive medium flowing around this material in most cases.
  • electrolytic solutions including water
  • melts or gases can be considered as a corrosive medium.
  • immersion, splash water and drip corrosion The corrosion damage to be borne annually in the industrialized countries reaches DM 100 per inhabitant and more. For the area of the (old) Federal Republic, the costs were estimated at 30 billion DM or about 2.5% of the gross national product. Avoiding or at least reducing corrosion damage is therefore of paramount importance.
  • corrosion inhibition focuses primarily on carbon steel substrates, the most corrosion-sensitive material in a cooling circuit.
  • active corrosion protection measures such as the modification of the material, the removal and blocking of particularly aggressive corrosive constituents and the use of corrosion inhibitor additives
  • passive corrosion protection measures such as the application of coatings, protective layers, foils and the like, can be applied to those sensitive to corrosion Surfaces to prevent contact between the metallic material and the corrosive medium as much as possible.
  • Passive corrosion protection measures i.e. Methods for forming passive corrosion protection layers on steel substrates are e.g. already known from US Pat. No. 3,817,795.
  • the method described therein comprises contacting the steel substrate with an aqueous electrolyte solution, removing the steel substrate from the aqueous electrolyte solution and drying it in an oxygen-containing gas atmosphere, and repeating this process several times until the periodically repeated measurement of the electrode potential of the steel substrate in contact with the aqueous electrolyte solution assumes a stable value compared to a saturated calomel electrode, which is higher than 0 mV in the presence of water.
  • the object of the invention was therefore to passivate the inner walls of a cooling circuit system made of (economical) carbon steel with a circulating, oxygen-containing and alkali and alkaline earth bicarbonate-containing aqueous cooling liquid in a controlled manner.
  • the pH of the cooling liquid is preferably set to a value in the range from 8.5 to 9.5.
  • the adjustment of the oxygen content of the cooling liquid is preferably carried out by introducing air or oxygen or by adding H202.
  • An Ag / AgCl or an Hg / Hg 2 Cl 2 electrode is preferably used as the reference electrode.
  • the measurement of the resting electrochemical potential is preferably carried out at a temperature in the range from 5 to 95 ° C., in particular in the range from 25 to 40 ° C.
  • Another conventional corrosion inhibitor can preferably be added to the cooling liquid.
  • the present invention relates to the use of the method described above for determining the passivation state of the metallic contact surfaces in aqueous cooling liquid systems and for checking the quality of the cooling liquid, in particular water.
  • the passivation state of metallic contact surfaces in aqueous cooling systems can be easily determined, the corrosion inhibition can be effectively controlled and the quality of the cooling water, in particular of water in general, can be checked easily and quickly. It has been shown that the current passivation state in an aqueous cooling system and in particular in a cooling water circulation system can be determined in a very simple and reliable manner if a measuring device with a measuring electrode is arranged in the system and the surface state of this measuring electrode is measured their rest potential against a reference electrode. It has been shown that there is a direct correlation between the corrosion rate and the rest potential, the almost ideal passivation state corresponding to a characteristic value of the rest potential.
  • the attached drawing shows the dependence of the corrosion rate (measured in 0.025 mm / day) as it occurs under varying conditions of alkalinity, the oxygen and chloride concentration in an air-open cooling water circuit system on the resting potential of the measuring electrode (measured in mV).
  • the invention enables the operator of a cooling tower system to control and control the operation of his unit in such a way that the chemical conditions can be adjusted with the aim of producing an optimal passivation layer on the metallic surfaces.
  • the current state is determined here by means of a display by means of a single parameter, the resting potential of the measuring electrode. This makes it possible to simplify the entire corrosion monitoring method considerably.
  • the method according to the invention can also be used to evaluate corrosion inhibition methods which are used to effectively form a passivation layer on the metal surfaces.
  • the basic concept of corrosion inhibition is to keep the solubility of the corrosion products as low as possible. Since the primary corrosion products of iron in water systems are iron hydroxide (Fe (OH) 2 ) or iron carbonate (FeC0 3 ), an increase in the pH value leads to a reduction in the solubility of the iron compounds.
  • Fe (OH) 2 iron hydroxide
  • FeC0 3 iron carbonate
  • chromate To inhibit cooling water corrosion, chromate was first used as the oxidizing agent. It is an excellent corrosion inhibitor, but the use of this oxidizing anodic corrosion inhibitor is not harmless because a certain minimum concentration is required to avoid extensive localized corrosion. This minimum concentration is also referred to as the "dangerous inhibitor concentration".
  • the primary oxidizing agent ie the primary corrosion inhibitor
  • the primary corrosion inhibitor is dissolved oxygen, which because of its low solubility is normally also present in the dangerous inhibitor concentration.
  • the minimum concentration of the oxidizing agent for anodic corrosion inhibition by means of oxidation depends strongly on the kinetics of the oxidation reaction. The oxidation must take place very close to the metal surface in order to achieve a permanent and even covering of the metal surface. For this reason, the magnitude of the dangerous inhibitor concentration also depends on the amount of the corrosion product that has to be oxidized. In the case of the oxygen saturation, this concentration is less than 10- 7 mol / I of Fe (II).
  • the reaction products of the redox reactions are Fe (III) oxyhydrates, since Fe (II) does not exist in the presence of oxygen under these conditions.
  • the Fe (III) oxyhydrate forms a thin but very effective passivation layer containing phosphonates.
  • the anodic passivation described above which prevents anodic iron dissolution, leads to a measurable change in the resting potential.
  • the passivation layer formed has the electron conductivity properties of a semiconductor, which gives it cathodic activity. Because of its cathodic reaction on the passivation layers, oxygen causes an increase in the metal potential, which is answered by the iron solution reaction. However, if the passivation layer is sufficiently impermeable to ions, iron dissolution is prevented and the reaction rate drops to negligible values. Since these conditions are entirely due to the prevention of iron dissolution (anodic inhibition), the potential is increased if the corrosion rates are reduced. In order to determine and control the conditions under which this passivation layer forms and the passivation is maintained, the resting potential of an iron electrode in the cooling water is measured according to the invention.
  • a measuring electrode made of carbon steel is combined with a reference electrode, preferably an Ag / AgCl electrode, and the resting potential is measured.
  • a reference electrode preferably an Ag / AgCl electrode
  • Another suitable reference electrode is the calomel electrode. If, under these conditions, a resting potential of more than -300 mV (eg more than -250 mV) is reached, the dissolution on the iron electrode and the mild steel surfaces that are in contact with the cooling water is due to the corrosion process minimal. In contrast, a corrosive iron electrode typically has a rest potential of around -500 mV.
  • ferrous metal surfaces can be transferred analogously to other metals.
  • carbon steel and other steel alloys come into consideration as metallic materials.
  • the method according to the invention also opens up a method for determining the water quality.
  • the method according to the invention can also be integrated into any corrosion inhibition method, it being possible to use corrosion inhibitors which are known per se and, if appropriate, further water treatment agents, since the resting potential measurement allows a broad approximation to the "ideal" passivation state. Likewise, it enables testing and evaluation of newly developed corrosion inhibitors in a simple manner.
  • the material of the measuring electrode corresponds to the composition of the metallic material which is at risk of corrosion
  • immediate and current information about the passivation state of the metal surface is obtained via the measurement of the resting potential.
  • the measuring arrangement with measuring electrode can also be arranged in multiple copies, so that the entire state of corrosion can be determined in an aqueous coolant system.
  • the pH of the water system is adjusted to values from 8.0 to 10.5 and preferably from 8.5 to 9.5.
  • the passivation is greatest under these alkalinity conditions.
  • the operator of a cooling water circuit is thus enabled by the invention to keep the corrosion state close to the ideal passivation or to take appropriate measures when the measured resting potential increases (i.e. in the case of more negative values).
  • the oxygen concentration in an open-air cooling water circulation system should be set to a value in the range of 1 to 50 mg / I, which in certain cases can also be achieved by adding oxygen (air or pure oxygen) or by adding H 2 0 2 can be reached.
  • the resting potential measurement is preferably carried out at temperatures in the range from 5 ° C. to 95 ° C. and preferably from 25 ° C. to 40 ° C. Temperatures outside this range are, however, often predetermined in the operating state by the corresponding water-containing cooling system.
  • the method according to the invention is also suitable here for controlled passivation and current determination of the passivation state.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
  • Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)

Claims (9)

1. Procédé pour la passivation contrôlée des parois intérieures d'un système de circuit de refroidissement en acier de carbone ouvert à l'air et/ou fermé, avec un liquide aqueux de refroidissement contenant de l'oxygène et du bicarbonate alcalin et alcalin-terreux circulant dans ce circuit,
caractérisé en ce que
a) on ajoute au liquide de refroidissement un ou plusieurs acides phosphoniques dans une concentration de 1 à 20 mg/I de liquide de refroidissement,
b) qu'on règle la concentration en oxygène du liquide de refroidissement à une valeur contenue dans la gamme de 1 à 50 mg/1, qu'on règle le pH du liquide de refroidissement à une valeur contenue dans la gamme de 8,0 à 10,5 et qu'on règle la concentration en carbonate à une valeur loin au-dessus de la saturation en bicarbonate de calcium, pour maintenir minimale la solubilité du produit primaire de corrosion (FeC03 ou Fe-(OH)2), et
c) qu'on mesure la passivation résultante des parois intérieures du système de circuit de refroidissement en tant que changement dans le temps du potentiel de repos électrochimique entre une électrode de mesure en acier de carbone plongeant dans le liquide de refroidissement et une électrode de référence en direction électropositive respectivement anodique, les conditions de la concentration d'oxygène, du pH et de la concentration de carbonate étant accordées entre elles de telle façon qu'un changement maximal du potentiel de repos en direction électropositive respectivement anodique est obtenu correspondant à une passivation maximale.
2. Procédé selon la revendication 1, caractérisé en ce que le pH du liquide de refroidissement est réglé à une valeur dans la gamme entre 8,5 et 9,5.
3. Procédé selon la revendication 1 ou 2, caractérisé en ce que le réglage du contenu en oxygène du liquide de refroidissement est obtenu par admission d'air ou d'oxygène ou par l'addition de H202.
4. Procédé selon l'une des revendications 1 à 3, caractérisé en ce qu'on utilise comme électrode de référence une électrode Ag/AgCl ou Hg/Hg2 Cl2.
5. Procédé selon l'une des revendications 1 à 4, caractérisé en ce que la mesure du potentiel de repos électrochimique est réalisée à une température dans la gamme entre 5 et 95 ° C.
6. Procédé selon la revendication 5, caractérisé en ce que la mesure du potentiel de repos électrochimique est réalisée à une température dans la gamme entre 25 et 40 ° C.
7. Procédé selon l'une des revendications 1 à 6, caractérisé en ce que l'on ajoute au liquide de refroidissement un autre inhibiteur de corrosion classique.
8. Utilisation du procédé selon l'une des revendications 1 à 7 pour la détermination de l'état de passivation des surfaces métalliques de contact dans des systèmes de liquide de refroidissement aqueux.
9. Utilisation du procédé selon l'une des revendications 1 à 7 pour tester la qualité du liquide de refroidissement, en particulier de l'eau.
EP91118080A 1990-10-23 1991-10-23 Procédé de passivation contrÔlée des parois intérieures d'un système de refroidissement en acier au carbone Expired - Lifetime EP0482614B2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4033686 1990-10-23
DE4033686 1990-10-23

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EP0482614A1 EP0482614A1 (fr) 1992-04-29
EP0482614B1 true EP0482614B1 (fr) 1995-12-27
EP0482614B2 EP0482614B2 (fr) 1999-03-31

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EP91118080A Expired - Lifetime EP0482614B2 (fr) 1990-10-23 1991-10-23 Procédé de passivation contrÔlée des parois intérieures d'un système de refroidissement en acier au carbone

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EP (1) EP0482614B2 (fr)
AT (1) ATE132205T1 (fr)
DE (2) DE59107150D1 (fr)
ES (1) ES2082092T5 (fr)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH691479A5 (de) 1996-12-06 2001-07-31 Siemens Ag Oberflächenbehandlung von Stahl.
DE102017107529A1 (de) * 2017-04-07 2018-10-11 Lisa Dräxlmaier GmbH Verfahren zur Korrosionsinhibierung von Metallen und Temperierungssystem für ein metallisches Werkzeug

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3483133A (en) * 1967-08-25 1969-12-09 Calgon C0Rp Method of inhibiting corrosion with aminomethylphosphonic acid compositions
US3817795A (en) * 1968-01-16 1974-06-18 Belge Etude De La Corrosion Ce Process for treating a metal or alloy by means of an electrolyte
US3891568A (en) * 1972-08-25 1975-06-24 Wright Chem Corp Method and composition for control of corrosion and scale formation in water systems
US3992318A (en) * 1973-10-09 1976-11-16 Drew Chemical Corporation Corrosion inhibitor
US3935125A (en) * 1974-06-25 1976-01-27 Chemed Corporation Method and composition for inhibiting corrosion in aqueous systems
US4209487A (en) * 1975-06-02 1980-06-24 Monsanto Company Method for corrosion inhibition
US4105581A (en) * 1977-02-18 1978-08-08 Drew Chemical Corporation Corrosion inhibitor
US4149969A (en) * 1977-03-23 1979-04-17 Amax Inc. Process and composition for inhibiting corrosion of metal parts in water systems
US4317744A (en) * 1979-04-25 1982-03-02 Drew Chemical Corporation Corrosion inhibitor
EP0049706B1 (fr) * 1980-10-10 1987-04-01 Nippon Kinzoku Co., Ltd. Procédé et appareil pour la fabrication en continu d'une pellicule décorative colorée sur un ruban d'acier inoxydable
DE3504925A1 (de) * 1985-02-13 1986-08-14 Kraftwerk Union AG, 4330 Mülheim Verfahren und einrichtung zum schutz von dampferzeugern, insbesondere von kernreaktoren
DE3635411A1 (de) * 1986-10-17 1988-04-21 Dietz Josef Sauerstoffanreicherung von trinkwasser

Also Published As

Publication number Publication date
ATE132205T1 (de) 1996-01-15
DE4135029A1 (de) 1992-04-30
DE59107150D1 (de) 1996-02-08
EP0482614B2 (fr) 1999-03-31
ES2082092T3 (es) 1996-03-16
ES2082092T5 (es) 1999-08-16
EP0482614A1 (fr) 1992-04-29
DE4135029C2 (fr) 1993-05-13

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