EP0340077B1 - Process for increasing the corrosion resistance of metallic materials - Google Patents

Process for increasing the corrosion resistance of metallic materials Download PDF

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EP0340077B1
EP0340077B1 EP89401071A EP89401071A EP0340077B1 EP 0340077 B1 EP0340077 B1 EP 0340077B1 EP 89401071 A EP89401071 A EP 89401071A EP 89401071 A EP89401071 A EP 89401071A EP 0340077 B1 EP0340077 B1 EP 0340077B1
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process according
metallic material
alloy
atmosphere
nitrogen
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EP0340077A1 (en
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Roger Berneron
Pierre De Gelis
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Institut de Recherches de la Siderurgie Francaise IRSID
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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
    • 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
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/36—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases using ionised gases, e.g. ionitriding

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  • the present invention relates to a method for improving the corrosion resistance of metallic materials such as stainless steels, ordinary steels, low-alloy steels, carbon steels, processing steels, refractory steels, nickel-based alloys and based on cobalt, aluminum and its alloys, titanium and its alloys, zirconium and its alloys, zinc and its alloys, copper and its alloys.
  • metallic materials such as stainless steels, ordinary steels, low-alloy steels, carbon steels, processing steels, refractory steels, nickel-based alloys and based on cobalt, aluminum and its alloys, titanium and its alloys, zirconium and its alloys, zinc and its alloys, copper and its alloys.
  • the present invention therefore relates to a method for improving the corrosion resistance of a metallic material according to which the metallic material maintained at a temperature below 100 ° C is subjected to a surface treatment by plasma at low temperature, at a pressure of 1 to 103 Pa, in an atmosphere comprising at least one gas chosen from oxygen, ozone, nitrogen, hydrogen, air, carbon dioxide , carbon monoxide, nitrogen oxides, water, flue gases and mixtures thereof with neutral gas.
  • low temperature plasma or "cold" plasma is generally meant a plasma obtained by glow discharge in a low pressure atmosphere (less than 103 Pa).
  • the discharge is obtained in an enclosure between an anode and the negatively polarized metallic material which serves as a cathode.
  • the metallic material to be treated is maintained in practice at a temperature below 100 ° C., for example through the use of a cathode and an anode cooled by a circulation of water.
  • the molecules of the gas are dissociated, excited or ionized; in the electrical discharge thus created, a low energy plasma scans the surface of the material and the various gaseous species react with the surface atoms according to their chemical affinity. A large number of elements disappear from the treated surface depending on whether the gases are oxidizing or reducing. After treatment, the surface is generally passive vis-à-vis the atmosphere, that is to say, conventional pollution elements C, S, P O, ...
  • reaction products for the most part, certainly in gaseous form, are evacuated by pumping and others, positively charged can redeposit on the cathode, for example calcium, but without, however, disturbing the surface.
  • neutral gas means rare gases such as argon, neon and helium.
  • Particularly suitable gas atmospheres are N2 / O2 mixtures, including air, carbon dioxide, N2 / H2, H2 / Ar.
  • Processing times can be from about 1 second to 10 minutes. It is advantageous to operate at voltages from 100 to 5000 V.
  • results indicated above can be obtained by electric or electromagnetic fields generated by the conventional techniques of "cold" plasma usually used for physical vapor deposition (magnetron, ion or electron guns, conventional ionic deposits) or thermochemical treatments by ion bombardment.
  • the metallic materials treated can in particular be martensitic, ferritic, austenitic and austenoferritic stainless steels, ordinary or low-alloy steels, carbon steels, treatment steels, refractory steels, nickel-based alloys and cobalt-based alloys. ; aluminum and its alloys, titanium and its alloys, zirconium and its alloys, zinc and its alloys, copper and its alloys ...
  • Figure 1 shows an analysis curve by luminescent discharge spectrometry (SDL) of untreated stainless steel.
  • FIG. 2 presents, for comparison, an SDL analysis curve of the same material in FIG. 1 after treatment under N2 / O2 according to the method of the invention.
  • the material was subjected to a plasma treatment under the following conditions: pressure 103 Pa imposed intensity 100 mA, voltage 250 V with a duration of 4 minutes, the material serving as cathode as well as the anode being cooled by a circulation of water.
  • the gas used was a 80/20 N2 / O2 mixture.
  • an argon atmosphere was used.
  • the material was examined before and after treatment.
  • the corrosion resistance was also evaluated by the drop test.
  • This test consists in depositing for 5 minutes a drop of the following solution 17 ml FeCl3 at 28% 2.5 ml HCl 5 g NaCl 188.5 ml distilled water After visual examination, the attack on the metal is rated from 1 to 3 in increasing order of attack on the metal.
  • Tests were carried out similar to those carried out in Example 1 on a ferritic stainless steel containing 17% Cr and 1% Mo (reference FMo). The conditions are the same, except with CO2 where the voltage has been chosen equal to 400 V so that the discharge can be established.
  • the resistance to corrosion was also evaluated by electrochemical measurements of pitting potential (Ep) in medium chlorinated medium (0.02 M NaCl). A potential scan is carried out from the free potential (Ec) at the speed of 10 mV / min. The appearance of a current indicates the formation of pitting. Pitting detection threshold: 100 uA.
  • the sheets having undergone a N2-O2 treatment exhibit numerous pitting.
  • Luminescent discharge spectrometry (SDL) measurements make it possible to analyze the elementary surface composition of a treated material and compare it with the composition of an untreated reference material.
  • Figure 1 shows different characteristic curves determining the surface concentrations of elements such as C, P, S, N2, Si and Mn.
  • FIG. 2 shows the characteristic curves of the same elements noted, in SDL, on the same material treated by the method according to the invention.
  • the treatment removes surface contaminants from the material such as for example P and Si.
  • the treatment is limited to the passivated layer in the case of stainless steels (50 to 100 A). There is no nitriding, no carburizing, no implantation (as the analysis by SDL proves).
  • the treatment consists of a modification of the surface state: passivation and / or amorphization.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
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  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
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Abstract

PCT No. PCT/FR89/00176 Sec. 371 Date Dec. 14, 1989 Sec. 102(e) Date Dec. 14, 1989 PCT Filed Apr. 18, 1989 PCT Pub. No. WO89/10424 PCT Pub. Date Nov. 2, 1989.A subject of the invention is a process for improving the corrosion resistance of a metallic material, characterized in that the metallic material is subjected cold to a surface treatment by a low-temperature plasma, at a pressure of 1 to 103 Pa in an atmosphere comprising at least one gas chosen from the following; oxygen, ozone, nitrogen, hydrogen, air, carbon dioxide, carbon monoxide, the oxides of nitrogen, water, combustion gases and mixtures of these with a neutral gas.

Description

La présente invention concerne un procédé pour améliorer la résistance à la corrosion de matériaux métalliques tels que les aciers inoxydables, les aciers ordinaires, les aciers faiblement alliés, les aciers au carbone, les aciers de traitement, les aciers réfractaires, les alliages à base nickel et à base cobalt, l'aluminium et ses alliages, le titane et ses alliages, le zirconium et ses alliages, le zinc et ses alliages, le cuivre et ses alliages.The present invention relates to a method for improving the corrosion resistance of metallic materials such as stainless steels, ordinary steels, low-alloy steels, carbon steels, processing steels, refractory steels, nickel-based alloys and based on cobalt, aluminum and its alloys, titanium and its alloys, zirconium and its alloys, zinc and its alloys, copper and its alloys.

Les traitements, de la surface de matériaux métalliques se font jusqu'à présent par des réactions chimiques classiques (oxydation, réduction, traitements de conversion.The treatments of the surface of metallic materials have hitherto been carried out by conventional chemical reactions (oxidation, reduction, conversion treatments.

Il est par ailleurs connu de soumettre la surface de matériaux métalliques à un traitement superficiel par plasma dans une atmosphère consituée par un gaz rare tel que l'argon. Dans un tel traitement la surface du matériau métallique polarisé négativement est bombardé par des ions tels que Ar⁺, ce qui provoque un arrachement des atomes superficiels et une érosion préférentielle et conduit à une très grande réactivité vis-à-vis de l'atmosphère et à une augmentation de la rugosité.It is also known to subject the surface of metallic materials to a surface plasma treatment in an atmosphere consisting of a rare gas such as argon. In such a treatment, the surface of the negatively polarized metallic material is bombarded with ions such as Ar⁺, which causes tearing of the surface atoms and preferential erosion and leads to a very high reactivity with respect to the atmosphere and an increase in roughness.

On a maintenant trouvé que si l'on remplace le gaz neutre monatomique par certains gaz de type moléculaire, oxydants ou réducteurs, il est possible, par un traitement superficiel par plasma à base température (c'est-à-dire à température ambiante), d'améliorer la résistance à la corrosion de matériaux métalliques.We have now found that if we replace the neutral atomic gas by certain gases of molecular type, oxidizing or reducing, it is possible, by a surface treatment with plasma at low temperature (i.e. at room temperature) , to improve the corrosion resistance of metallic materials.

La présente invention a en conséquence pour objet un procédé pour améliorer la résistance à la corrosion d'un matériau métallique selon lequel on soumet le matériau métallique maintenu à une température inférieure à 100°C à un traitement superficiel par plasma à basse température, à une pression de 1 à 10³ Pa, dans une atmosphère comprenant au moins un gaz choisi parmi l'oxygène, l'ozone, l'azote, l'hydrogène, l'air, le gaz carbonique, le monoxyde de carbone, les oxydes d'azote, l'eau, les gaz de combustion et les mélanges de ceux-ci avec un gaz neutre.The present invention therefore relates to a method for improving the corrosion resistance of a metallic material according to which the metallic material maintained at a temperature below 100 ° C is subjected to a surface treatment by plasma at low temperature, at a pressure of 1 to 10³ Pa, in an atmosphere comprising at least one gas chosen from oxygen, ozone, nitrogen, hydrogen, air, carbon dioxide , carbon monoxide, nitrogen oxides, water, flue gases and mixtures thereof with neutral gas.

Par plasma à basse température ou plasma "froid" on désigne généralement un plasma obtenu par décharge luminescente dans une atmosphère à faible pression (inférieure à 10³ Pa). La décharge est obtenue dans une enceinte entre une anode et le matériau métallique polarisé négativement qui sert de cathode. Le matériau métallique à traiter est maintenu en pratique à une température inférieure à 100°C, par exemple grâce à l'utilisation d'une cathode et d'une anode refroidies par une circulation d'eau.By low temperature plasma or "cold" plasma is generally meant a plasma obtained by glow discharge in a low pressure atmosphere (less than 10³ Pa). The discharge is obtained in an enclosure between an anode and the negatively polarized metallic material which serves as a cathode. The metallic material to be treated is maintained in practice at a temperature below 100 ° C., for example through the use of a cathode and an anode cooled by a circulation of water.

Sous l'influence du champ électrique, les molécules du gaz sont dissociées, excitées ou ionisées ; dans la décharge électrique ainsi créée, un plasma de basse énergie balaie la surface du matériau et les diverses espèces gazeuses réagissent avec les atomes de surface suivant leur affinité chimique. Un grand nombre d'éléments disparaissent de la surface traitée selon que les gaz sont oxydants ou réducteurs. Après traitement, la surface est généralement passive vis-à-vis de l'atmosphère, c'est-à-dire, des éléments de pollution classiques C, S, P O,...Under the influence of the electric field, the molecules of the gas are dissociated, excited or ionized; in the electrical discharge thus created, a low energy plasma scans the surface of the material and the various gaseous species react with the surface atoms according to their chemical affinity. A large number of elements disappear from the treated surface depending on whether the gases are oxidizing or reducing. After treatment, the surface is generally passive vis-à-vis the atmosphere, that is to say, conventional pollution elements C, S, P O, ...

Une des caractéristiques les plus intéressantes d'un nettoyage par plasma moléculaire est de ne pas changer la rugosité superficielle du matériau même sur des couches à bas point de fusion étant donné la température du plasma. En effet il n'y a pas d'érosion avec un gaz moléculaire, alors que l'érosion est importante avec les gaz rares.One of the most interesting characteristics of a cleaning by molecular plasma is that it does not change the surface roughness of the material even on layers with low melting point given the plasma temperature. Indeed there is no erosion with a molecular gas, while erosion is significant with rare gases.

Les produits de réaction, pour une grande part, certainement sous forme gazeuse, sont évacués par le pompage et d'autres, chargés positivement peuvent se redéposer sur la cathode, par exemple le calcium, mais sans toutefois, perturber la surface.The reaction products, for the most part, certainly in gaseous form, are evacuated by pumping and others, positively charged can redeposit on the cathode, for example calcium, but without, however, disturbing the surface.

Dans la présente invention on entend par gaz neutre des gaz rares tels que l'argon, le néon et l'hélium.In the present invention, neutral gas means rare gases such as argon, neon and helium.

Des atmosphères gazeuses qui conviennent en particulier sont des mélanges N₂/O₂, y compris l'air, le gaz carbonique, N₂/H₂, H₂/Ar.Particularly suitable gas atmospheres are N₂ / O₂ mixtures, including air, carbon dioxide, N₂ / H₂, H₂ / Ar.

Les temps de traitement peuvent être d'environ 1 seconde à 10 minutes. On opère avantageusement sous des tensions de 100 à 5000 V.Processing times can be from about 1 second to 10 minutes. It is advantageous to operate at voltages from 100 to 5000 V.

Il est certain que les résultats précédemment indiqués peuvent être obtenus par des champs électriques ou électromagnétiques générés par les techniques classiques de plasma "froid" habituellement utilisés pour les dépôts physiques en phase vapeur (magnétron, canons à ions ou à électrons, dépôts ioniques classiques) ou les traitements thermochimiques par bombardement ionique.It is certain that the results indicated above can be obtained by electric or electromagnetic fields generated by the conventional techniques of "cold" plasma usually used for physical vapor deposition (magnetron, ion or electron guns, conventional ionic deposits) or thermochemical treatments by ion bombardment.

Les matériaux métalliques traités peuvent être notamment des aciers inoxydables martensitiques, ferritiques, austénitiques et austénoferritiques, des aciers ordinaires ou faiblement alliés, des aciers au carbone, des aciers de traitement, des aciers réfractaires, des alliages à base de nickel et à base de cobalt; l'aluminium et ses alliages, le titane et ses alliages, le zirconium et ses alliages, le zinc et ses alliages, le cuivre et ses alliages ...The metallic materials treated can in particular be martensitic, ferritic, austenitic and austenoferritic stainless steels, ordinary or low-alloy steels, carbon steels, treatment steels, refractory steels, nickel-based alloys and cobalt-based alloys. ; aluminum and its alloys, titanium and its alloys, zirconium and its alloys, zinc and its alloys, copper and its alloys ...

La figure 1 présente une courbe d'analyse par spectrométrie à décharge luminescente (SDL) d'un acier inoxydable non traité.Figure 1 shows an analysis curve by luminescent discharge spectrometry (SDL) of untreated stainless steel.

La figure 2 présente, à titre de comparaison, une courbe d'analyse par SDL du même matériau de la fig. 1 après traitement sous N₂/O₂ selon le procédé de l'invention.FIG. 2 presents, for comparison, an SDL analysis curve of the same material in FIG. 1 after treatment under N₂ / O₂ according to the method of the invention.

Les exemples suivants, non limitatifs, illustrent la présente invention.The following nonlimiting examples illustrate the present invention.

Exemple 1 :Example 1:

On a effectué des essais sur un acier inoxydable ferritique à 17% de chrome.Tests were carried out on a 17% chromium ferritic stainless steel.

Le matériau a été soumis à un traitement par plasma dans les conditions suivantes : pression 10³ Pa intensité imposée 100 mA, tension 250 V avec une durée de 4 minutes, le matériau servant de cathode ainsi que l'anode étant refroidis par une circulation d'eau.The material was subjected to a plasma treatment under the following conditions: pressure 10³ Pa imposed intensity 100 mA, voltage 250 V with a duration of 4 minutes, the material serving as cathode as well as the anode being cooled by a circulation of water.

Le gaz utilisé a été un mélange N₂/O₂ 80/20. A titre de comparaison on a utilisé une atmosphère d'argon.The gas used was a 80/20 N₂ / O₂ mixture. For comparison, an argon atmosphere was used.

On a examiné avant et après traitement le matériau.The material was examined before and after treatment.

On a par ailleurs évalué la résistance à la corrosion par le test à la goutte.The corrosion resistance was also evaluated by the drop test.

Ce test consiste à déposer pendant 5 minutes une goutte de la solution suivante
17 ml FeCl₃ à 28%
2,5 ml HCl
5 g NaCl
188,5 ml d'eau distillée
   Après examen visuel on cote l'attaque du métal de 1 à 3 dans un ordre croissant d'attaque du métal.

Figure imgb0001
This test consists in depositing for 5 minutes a drop of the following solution
17 ml FeCl₃ at 28%
2.5 ml HCl
5 g NaCl
188.5 ml distilled water
After visual examination, the attack on the metal is rated from 1 to 3 in increasing order of attack on the metal.
Figure imgb0001

Exemple 2 : Example 2 :

On a effectué des essais similaires à ceux effectués à l'exemple 1 sur un acier inoxydable ferritique contenant 17% Cr et 1% Mo (référence FMo). Les conditions étant les mêmes, sauf avec CO₂ où la tension a été choisie égale à 400 V pour que la décharge puisse être établie.Tests were carried out similar to those carried out in Example 1 on a ferritic stainless steel containing 17% Cr and 1% Mo (reference FMo). The conditions are the same, except with CO₂ where the voltage has been chosen equal to 400 V so that the discharge can be established.

Les résultats sont donnés dans le tableau II.

Figure imgb0002
The results are given in Table II.
Figure imgb0002

Exemple 3Example 3

On effectue des essais similaires à ceux effectués à l'exemple 1 sur un acier inoxydable ferritique à 17% de chrome et 1% de molybdène dans les conditions suivantes :

  • a) Traitement par l'argon pour comparaison,
  • b) Traitement par N₂ + O₂ (80/20)
   On a examiné avant et après traitement le matériau.Tests similar to those carried out in Example 1 are carried out on a ferritic stainless steel with 17% chromium and 1% molybdenum under the following conditions:
  • a) Argon treatment for comparison,
  • b) Treatment with N₂ + O₂ (80/20)
The material was examined before and after treatment.

On a par ailleurs évalué la résistance à la corrosion par des mesures électrochimiques de potentiel de piqûres (Ep) en milieu moyennement chloruré (NaCl 0,02 M). On effectue un balayage en potentiel depuis le potentiel libre (Ec) à la vitesse de 10 mV/mn. L'apparation d'un courant indique la formation de piqûres. Seuil de détection des piqûres : 100 uA.The resistance to corrosion was also evaluated by electrochemical measurements of pitting potential (Ep) in medium chlorinated medium (0.02 M NaCl). A potential scan is carried out from the free potential (Ec) at the speed of 10 mV / min. The appearance of a current indicates the formation of pitting. Pitting detection threshold: 100 uA.

Les résultats sont donnés dans le tableau III. La comparaison avec l'acier non traité montre une très faible amélioration de la résistance à la corrosion avec le traitement par l'argon et une nette amélioration dans le cas du traitement par N₂ + O₂. (La résistance à la corrosion est d'autant plus grande que le potentiel de piqûre est élevé).

Figure imgb0003
The results are given in Table III. The comparison with untreated steel shows a very slight improvement in corrosion resistance with the argon treatment and a marked improvement in the case of treatment with N₂ + O₂. (The higher the pitting potential, the higher the corrosion resistance).
Figure imgb0003

Exemple 4Example 4

Un essai de traitement a été réalisé comme à l'exemple 1 sur des tôles nues en acier doux et traitées sous une tension de 400 volts avec un courant de 200 mA dans différents gaz sous une pression de 10³ Pa.

  • 5 mn sous plasma froid N₂/H₂ (90/10)
  • 5 mn sous plasma froid N₂/O₂ (80/20)
   Les tôles ont été laissées à l'air ambiant.A treatment test was carried out as in Example 1 on bare sheets of mild steel and treated under a voltage of 400 volts with a current of 200 mA in different gases at a pressure of 10³ Pa.
  • 5 min under cold plasma N₂ / H₂ (90/10)
  • 5 min under cold plasma N₂ / O₂ (80/20)
The sheets were left in the ambient air.

Après 5 mois on observe des disparités importantes :
   Les tôles traitées par N₂-H₂ ne présentent aucune amorce de rouille.After 5 months there are significant disparities:
The sheets treated with N₂-H₂ do not show any rust onset.

Les tôles ayant subi un traitement N₂-O₂ présentent de nombreuses piqûres.The sheets having undergone a N₂-O₂ treatment exhibit numerous pitting.

La référence simplement dégraissée au chlorotène est attaquée sur quasiment toute sa surface.The simply defatted reference to chlorotene is attacked on almost its entire surface.

Ces résultats mettent en évidence l'efficacité du traitement réducteur vis-à-vis d'une corrosion dans le cas d'une exposition simple à l'air.These results demonstrate the effectiveness of the reducing treatment against corrosion in the case of simple exposure to air.

Analyse comparative par spectrométrie à décharge luminescente sur un acier inoxydableComparative analysis by glow discharge spectrometry on stainless steel

Des mesures par spectrométrie à décharge luminescente (SDL) permettent d'analyser la composition élémentaire, en surface, d'un matériau traité et de la comparer avec la composition d'un matériau de référence non traité.Luminescent discharge spectrometry (SDL) measurements make it possible to analyze the elementary surface composition of a treated material and compare it with the composition of an untreated reference material.

La figure 1 présente différentes courbes caractéristiques déterminant les concentrations en surface d'éléments comme par exemple C, P, S, N₂, Si et Mn.Figure 1 shows different characteristic curves determining the surface concentrations of elements such as C, P, S, N₂, Si and Mn.

On remarque, sur les courbes caractéristiques d'un matériau non traité une forte concentration en C, P, S, Si et Mn caractérisée par des pics émis dès la première seconde de l'analyse SDL.We note, on the characteristic curves of an untreated material, a high concentration of C, P, S, Si and Mn characterized by peaks emitted from the first second of the SDL analysis.

La figure 2 présente les courbes caractéristiques des mêmes éléments relevées, en SDL, sur un même matériau traité par le procédé selon l'invention.FIG. 2 shows the characteristic curves of the same elements noted, in SDL, on the same material treated by the method according to the invention.

On remarque que les pics de concentrations émis dès la première seconde de l'analyse SDL sont beaucoup moins intenses.We note that the concentration peaks emitted from the first second of the SDL analysis are much less intense.

On en déduit que le traitement élimine les contaminants de surface du matériau comme par exemple P et Si.It is deduced therefrom that the treatment removes surface contaminants from the material such as for example P and Si.

Le traitement est limité à la couche passivée dans le cas des aciers inoxydables (50 à 100 A). Il n'y a ni nitruration, ni cémentation, ni implantation (comme le prouve l'analyse par SDL). Le traitement consiste en une modification de l'état de surface : passivation et/ou amorphisation.The treatment is limited to the passivated layer in the case of stainless steels (50 to 100 A). There is no nitriding, no carburizing, no implantation (as the analysis by SDL proves). The treatment consists of a modification of the surface state: passivation and / or amorphization.

Claims (13)

  1. Process for improving the corrosion resistance of a metallic material, according to which the metallic material, kept at a temperature less than 100°C, is subjected to a surface treatment by a low temperature plasma, at a pressure of from 1 to 10³ Pa in an atmosphere comprising at least one gas chosen from oxygen, ozone, nitrogen, hydrogen, air, carbon dioxide, carbon monoxide, the nitrogen oxides, water, combustion gases and mixtures of these with a neutral gas.
  2. Process according to claim 1, characterised in that the treatment time is from 1 second to 10 minutes.
  3. Process according to claim 1 or claim 2, characterised in that the operating voltage is from 100 to 5000 V.
  4. Process according to claim 1, characterised in that the atmosphere is composed of a mixture of oxygen and nitrogen.
  5. Process according to claim 1, characterised in that the atmosphere is composed of carbon dioxide.
  6. Process according to any one of claims 1 to 5, characterised in that the metallic material is stainless steel.
  7. Process according to any one of claims 1 to 5, characterised in that the metallic material is ordinary or weakly alloyed steel, carbon steel, heat-treatable steel or refractory steel.
  8. Process according to any one of claims 1 to 5, characterised in that the metallic material is of aluminium or an aluminium alloy.
  9. Process according to any one of claims 1 to 5, characterised in that the metallic material is of titanium or a titanium alloy.
  10. Process according to any one of claims 1 to 5, characterised in that the metallic material is of zirconium or a zirconium alloy.
  11. Process according to any one of claims 1 to 5, characterised in that the metallic material is of zinc or a zinc alloy.
  12. Process according to any one of claims 1 to 5, characterised in that the metallic material is a nickel-based or cobalt-based alloy.
  13. Process according to any one of claims 1 to 5, characterised in that the metallic material is of copper or a copper alloy.
EP89401071A 1988-04-18 1989-04-18 Process for increasing the corrosion resistance of metallic materials Expired - Lifetime EP0340077B1 (en)

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FR8805091 1988-04-18
FR8805091A FR2630133B1 (en) 1988-04-18 1988-04-18 PROCESS FOR IMPROVING THE CORROSION RESISTANCE OF METAL MATERIALS

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DE68908249T2 (en) 1993-11-25
ES2044161T3 (en) 1994-01-01
ATE92975T1 (en) 1993-08-15
EP0340077A1 (en) 1989-11-02
JPH03500550A (en) 1991-02-07
KR960015540B1 (en) 1996-11-18
MX171779B (en) 1993-11-15
FR2630133A1 (en) 1989-10-20
KR900700649A (en) 1990-08-16
DE68908249D1 (en) 1993-09-16
WO1989010424A1 (en) 1989-11-02
US5062900A (en) 1991-11-05
CA1331745C (en) 1994-08-30
FR2630133B1 (en) 1993-09-24

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