EP0159222A1 - Process for the surface treatment of iron or cast iron parts by ionic bombardment - Google Patents

Process for the surface treatment of iron or cast iron parts by ionic bombardment Download PDF

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Publication number
EP0159222A1
EP0159222A1 EP85400442A EP85400442A EP0159222A1 EP 0159222 A1 EP0159222 A1 EP 0159222A1 EP 85400442 A EP85400442 A EP 85400442A EP 85400442 A EP85400442 A EP 85400442A EP 0159222 A1 EP0159222 A1 EP 0159222A1
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EP
European Patent Office
Prior art keywords
parts
ionic
nitriding
treatment
carried out
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EP85400442A
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German (de)
French (fr)
Inventor
Yves Pourprix
Roger Dumas
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Automobiles Peugeot SA
Automobiles Citroen SA
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Automobiles Peugeot SA
Automobiles Citroen SA
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Publication of EP0159222A1 publication Critical patent/EP0159222A1/en
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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
    • 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
    • C23C8/38—Treatment of ferrous surfaces
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D7/00—Modifying the physical properties of iron or steel by deformation
    • C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
    • C21D7/04—Modifying the physical properties of iron or steel by deformation by cold working of the surface
    • 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
    • C23F17/00—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

Definitions

  • the present invention relates to a method of surface treatment of steel or cast iron parts, in particular of cylindrical parts, with a view to giving these parts resistance to wear and corrosion.
  • the main treatment processes currently used for this purpose are nitriding, chromium plating and other electrolytic deposits, boriding, chromizing, oxidation.
  • the hard chromium plating often used in these applications exhibits a limited corrosion resistance due to the micro-cracks which characterize it. In addition, it requires complex and expensive operations with a final superfinishing operation.
  • Variants have been proposed for nitriding in a salt bath, comprising in the final phase an oxidation in an oxidizing bath, followed by running in and a new oxidation.
  • the corrosion resistance obtained is generally satisfactory, but the intermediate lapping is difficult to carry out and, moreover, the quantity of material extracted by lapping is not reproducible, which makes the results dispersed.
  • the present invention aims to provide a surface treatment method which is easy to carry out and which makes it possible to obtain good resistance to corrosion.
  • the subject of the present invention is a method of surface treatment of steel or cast iron parts to give these parts resistance to wear and corrosion, characterized in that the surface of the parts with ionic nitriding, ionic oxynitriding and ionic oxidation.
  • the three successive operations can be carried out in the same ionization enclosure by successively using a nitriding gas, a mixture of nitriding gas and oxidizing gas and an oxidizing gas.
  • the method according to the invention makes it possible to obtain a layer of iron nitrides (Fe 2-3 N) and a layer of iron oxide of Fe304 type, these layers being separated by a transition layer in which layers are progressively passed.
  • iron nitrides with Fe 3 O 4 type oxide iron nitrides with Fe 3 O 4 type oxide.
  • a surface hardening operation is advantageously carried out after the three operations under ion bombardment, which has the effect of compressing the layers formed by ion bombardment.
  • This surface hardening can be carried out in particular by roller burnishing in the case of cylindrical parts.
  • the method according to the present invention can be implemented on these annealed or tempered steel parts, in gray cast iron or in spheroidal graphite cast iron.
  • the first phase of the process is ion nitriding.
  • This phase can be carried out in a conventional manner in an enclosure containing a nitriding gas under reduced pressure.
  • the parts to be treated are arranged in the heart of the enclosure which serves as an anode.
  • the parts to be treated constitute the cathode.
  • a voltage of a few hundred volts is applied between the anode and the cathode.
  • the parts to be treated are bombarded with nitrogen ions.
  • the nitriding gas can be a gaseous mixture based on nitrogen and hydrogen or ammonia, for example a gaseous mixture containing 80% by weight of nitrogen, 2 to 6% by weight of methane, the rest being l 'hydrogen.
  • the pressure can be of the order of 1.5 to 4.10 2 Pa.
  • the temperature can be from 550 to 600 ° C.
  • the treatment time can be around 15 to 60 minutes depending on the parts to be treated and the desired nitriding thickness.
  • the thickness of the nitride layer obtained can be approximately 10 to 30 microns.
  • the procedure is the same as for the first phase, but an oxidizing gas can be added to the nitriding gas which can be 0 2 , C0 2 or H 2 0.
  • the content of oxidizing gas is advantageously from 0.5 to 2% by weight (expressed in oxygen).
  • the temperatures and pressures can be the same as for the first phase.
  • the duration of treatment can vary from 30 to 120 minutes.
  • the thickness of the intermediate layer obtained can be from 2 to 10 microns.
  • an oxidizing gas is introduced into the enclosure.
  • This gas can be 0 2 , CO 2 , H 2 0 or a mixture of these gases.
  • This third phase can be carried out under glow discharge, the temperature conditions and pressure then being the same as for the first two phases.
  • the duration of the treatment can be approximately 10 to 20 minutes.
  • This third phase can also be carried out in the absence of glow discharge, under a pressure of 1.5 to 2.10 Pa for a period of 15 to 20 minutes, the oxidizing gas being introduced continuously and pumped continuously.
  • the quantity of oxidizing gas used can represent from 50 to 100 Nl per m 2 of surface to be treated.
  • the room temperature drops to around 450 ° C.
  • the thickness of the Fe 3 0 4 type oxide layer obtained can be from 0.5 to 4 microns.
  • the parts can then be cooled under a nitrogen atmosphere.
  • the parts thus obtained can have a roughness less than or equal to 1 micron.
  • the surface condition can be improved by the surface hardening operation.
  • this work hardening can be carried out by roller burnishing at the pass under a pressure of 2 to 5.10 6 Pa and with an advance of 1 mm per revolution.
  • This operation which maintains the entire coating layers compresses these layers and makes it possible to obtain a roughness of less than 0.4 microns.
  • the work hardening pressure is adjusted according to the desired final roughness.
  • XC38 steel cylinder rods having a diameter of 12 mm are treated by the method according to the invention.
  • the rods are placed in an ionization enclosure, the rods being maintained under a voltage of -400 V relative to the walls of the enclosure.
  • a gaseous mixture comprising 80% by weight of nitrogen, 3% by weight of methane and 17% by weight of hydrogen is introduced into the enclosure.
  • the pressure is 2.10 2 P a.
  • the temperature is 575 ° C.
  • the duration of the treatment is 30 minutes.
  • the duration of the treatment is 90 minutes.
  • Water vapor is then introduced into the enclosure at a pressure of 1.5 ⁇ 10 3 Pa.
  • the duration of the treatment is 20 minutes.
  • a coating comprising a compact layer of iron nitride Fe 2-3 N with a thickness of about 18 microns, a porous layer consisting of a mixture of iron nitride and Fe 3 0 4 with a thickness d '' about 5 microns and a surface layer of black appearance of Fe 3 0 4 of 1 to 2 microns.
  • the coating thus obtained has a roughness of the order of 1 micron.
  • the parts are subjected to a corrosion test of the marine atmosphere type.
  • the parts are treated by carrying out only the first nitriding phase.
  • the parts thus treated exhibit generalized corrosion after 90 days.
  • Example 2 The procedure is as in Example 1, but the cylinder rods thus treated are further subjected to roller burnishing on the parade under a pressure of 4.10 6 Pa with an advance of 1 mm per revolution. A surface roughness of about 0.2 microns is obtained.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)

Abstract

The treatment, which endows these parts with resistance to wear and to corrosion, is characterised in that the surface of the parts is subjected successively to ionic nitriding, ionic oxynitriding and ionic oxidation.

Description

La présente invention concerne un procédé de traitement superficiel de pièces en acier ou en fonte, notamment de pièces cylindriques, en vue de conférer à ces pièces une résistance à l'usure et à la corrosion.The present invention relates to a method of surface treatment of steel or cast iron parts, in particular of cylindrical parts, with a view to giving these parts resistance to wear and corrosion.

Les principaux procédés de traitement actuellement utilisés à cet effet sont la nitruration, le chromage et autres dépôts électrolytiques, la boruration, la chromisation, l'oxydation.The main treatment processes currently used for this purpose are nitriding, chromium plating and other electrolytic deposits, boriding, chromizing, oxidation.

Par les traitements de type chromisation ou boruration, on obtient de hautes caractéristiques en résistance à l'usure, mais leur mise en oeuvre impose des températures élevées, souvent incompatibles avec la structure et la stabilité dimensionnelle des pièces à traiter.By chrome-plating or boriding-type treatments, high resistance to wear characteristics are obtained, but their implementation requires high temperatures, often incompatible with the structure and dimensional stability of the parts to be treated.

Le chromage dur souvent utilisé dans ces applications présente une tenue à la corrosion limitée du fait des micro-fissures qui le caractérisent. De plus, il impose des opérations complexes et onéreuses avec une opération de superfinition finale.The hard chromium plating often used in these applications exhibits a limited corrosion resistance due to the micro-cracks which characterize it. In addition, it requires complex and expensive operations with a final superfinishing operation.

La nitruration classique réalisée en bain de sel ou la nitruration ionique permet d'obtenir des couches de nitrures de fer Fe4N ou Fe 2-3 N ayant de bonnes caractéristiques en frottement, mais une résistance à la corrosion limitée et présentant de plus un médiocre état de surface imposant généralement une opération finale de superfinition.Conventional nitriding carried out in a salt bath or ionic nitriding makes it possible to obtain layers of iron nitrides Fe 4 N or Fe 2-3 N having good friction characteristics, but limited corrosion resistance and moreover having a poor surface finish generally requiring a final superfinishing operation.

Des variantes ont été proposées pour la nitruration en bain de sel, comportant en phase finale une oxydation en bain oxydant, suivie d'un rodage et d'une nouvelle oxydation. La tenue en corrosion obtenue est généralement satisfaisante, mais le rodage intermédiaire est d'une mise en oeuvre difficile et, de plus, la quan- tite de matière extraite par rodage n'est pas reproductible, ce qui rend les résultats dispersés.Variants have been proposed for nitriding in a salt bath, comprising in the final phase an oxidation in an oxidizing bath, followed by running in and a new oxidation. The corrosion resistance obtained is generally satisfactory, but the intermediate lapping is difficult to carry out and, moreover, the quantity of material extracted by lapping is not reproducible, which makes the results dispersed.

La présente invention vise à fournir un procédé de traitement superficiel qui soit d'une mise en oeuvre aisée et qui permette d'obtenir une bonne résistance à la corrosion.The present invention aims to provide a surface treatment method which is easy to carry out and which makes it possible to obtain good resistance to corrosion.

A cet effet, la présente invention a pour objet un procédé de traitement superficiel de pièces en acier ou en fonte pour conférer à ces pièces une résistance à l'usure et à la corrosion, caractérisé en ce que l'on soumet successivement la surface des pièces à une nitruration ionique, à une oxynitruration ionique et à une oxydation ionique.To this end, the subject of the present invention is a method of surface treatment of steel or cast iron parts to give these parts resistance to wear and corrosion, characterized in that the surface of the parts with ionic nitriding, ionic oxynitriding and ionic oxidation.

En pratique, les trois opérations successives peuvent être effectuées dans la même enceinte d'ionisation en utilisant successivement un gaz nitrurant, un mélange de gaz nitrurant et de gaz oxydant et un gaz oxydant.In practice, the three successive operations can be carried out in the same ionization enclosure by successively using a nitriding gas, a mixture of nitriding gas and oxidizing gas and an oxidizing gas.

Le procédé selon l'invention permet d'obtenir une couche de nitrures de fer (Fe2-3N) et une couche d'oxyde de fer de type Fe304, ces couches étant séparées par une couche de transition dans laquelle on passe progressivement des nitrures de fer à l'oxyde de type Fe3O4.The method according to the invention makes it possible to obtain a layer of iron nitrides (Fe 2-3 N) and a layer of iron oxide of Fe304 type, these layers being separated by a transition layer in which layers are progressively passed. iron nitrides with Fe 3 O 4 type oxide.

Pour améliorer l'état de surface ainsi que la résistance à la corrosion, on effectue avantageusement, après les trois opérations sous bombardement ionique, une opération d'écrouissage superficiel qui a pour effet de comprimer les couches formées par bombardement ionique.To improve the surface condition as well as the resistance to corrosion, a surface hardening operation is advantageously carried out after the three operations under ion bombardment, which has the effect of compressing the layers formed by ion bombardment.

Cet écrouissage superficiel peut être effectué notamment par galetage au défilé dans le cas de pièces cylindriques.This surface hardening can be carried out in particular by roller burnishing in the case of cylindrical parts.

Le procédé selon la présente invention peut être mis en oeuvre sur ces pièces ei aciers recuits ou trempés revenus, en fonte grise ou en fonte à graphite sphéroidal.The method according to the present invention can be implemented on these annealed or tempered steel parts, in gray cast iron or in spheroidal graphite cast iron.

Ainsi que cela a été indiqué précédemment, la première phase du procédé est une nitruration ionique. Cette phase peut être effectuée de manière classique dans une enceinte contenant un gaz nitrurant sous pression réduite. Les pièces à traiter sont disposées au coeur de l'enceinte qui sert d'anode. Les pièces à traiter constituent la cathode. Une tension de quelques centaines de volts est appliquée entre l'anode et la cathode. Les pièces à traiter reçoivent un bombardement d'ions d'azote.As indicated above, the first phase of the process is ion nitriding. This phase can be carried out in a conventional manner in an enclosure containing a nitriding gas under reduced pressure. The parts to be treated are arranged in the heart of the enclosure which serves as an anode. The parts to be treated constitute the cathode. A voltage of a few hundred volts is applied between the anode and the cathode. The parts to be treated are bombarded with nitrogen ions.

Le gaz nitrurant peut être un mélange gazeux à base d'azote et d'hydrogène ou d'ammoniac, par exemple un mélange gazeux contenant 80 % en poids d'azote, 2 à 6 % en poids de méthane, le reste étant de l'hydrogène. La pression peut être de l'ordre de 1,5 à 4.102 Pa. La température peut être de 550 à 600°C.The nitriding gas can be a gaseous mixture based on nitrogen and hydrogen or ammonia, for example a gaseous mixture containing 80% by weight of nitrogen, 2 to 6% by weight of methane, the rest being l 'hydrogen. The pressure can be of the order of 1.5 to 4.10 2 Pa. The temperature can be from 550 to 600 ° C.

La durée de traitement peut être d'environ 15 à 60 minutes selon les pièces à traiter et l'épaisseur de nitruration souhaitée.The treatment time can be around 15 to 60 minutes depending on the parts to be treated and the desired nitriding thickness.

L'épaisseur de la couche de nitrure obtenue peut être d'environ 10 à 30 microns.The thickness of the nitride layer obtained can be approximately 10 to 30 microns.

Dans la seconde phase, on opère comme pour la première phase, mais on ajoute au gaz nitrurant un gaz oxydant qui peut être 02, C02 ou H20. La teneur en gaz cxydant est avantageusement de 0,5 à 2 % en poids (exprimé en oxygène). Les températures et les pressions peuvent être les mêmes que pour la première phase. La durée de traitement peut varier de 30 à 120 minutes.In the second phase, the procedure is the same as for the first phase, but an oxidizing gas can be added to the nitriding gas which can be 0 2 , C0 2 or H 2 0. The content of oxidizing gas is advantageously from 0.5 to 2% by weight (expressed in oxygen). The temperatures and pressures can be the same as for the first phase. The duration of treatment can vary from 30 to 120 minutes.

L'épaisseur de la couche intermédiaire obtenue peut être de 2 à 10 microns.The thickness of the intermediate layer obtained can be from 2 to 10 microns.

Dans la troisième phase, on introduit dans l'enceinte un gaz oxydant. Ce gaz peut être 02, CO2, H 20 ou un mélange de ces gaz.In the third phase, an oxidizing gas is introduced into the enclosure. This gas can be 0 2 , CO 2 , H 2 0 or a mixture of these gases.

Cette troisième phase peut être réalisée sous décharge luminescente, les conditions de température et de pression étant alors les mêmes que pour les deux premières phases. La durée du traitement peut être d'environ 10 à 20 minutes.This third phase can be carried out under glow discharge, the temperature conditions and pressure then being the same as for the first two phases. The duration of the treatment can be approximately 10 to 20 minutes.

Cette troisième phase peut être également réalisée en l'absence de décharge luminescente, sous une pression de 1,5 à 2.10 Pa pendant une durée de 15 à 20 minutes, le gaz oxydant étant introduit en continu et pompé en continu. La quantité de gaz oxydant utilisé peut représenter de 50 à 100 Nl par m2 de surface à traiter.This third phase can also be carried out in the absence of glow discharge, under a pressure of 1.5 to 2.10 Pa for a period of 15 to 20 minutes, the oxidizing gas being introduced continuously and pumped continuously. The quantity of oxidizing gas used can represent from 50 to 100 Nl per m 2 of surface to be treated.

Au cours de cette troisième phase, la température des pièces descend jusqu'à environ 450°C.During this third phase, the room temperature drops to around 450 ° C.

L'épaisseur de la couche d'oxyde de type Fe304 obtenue peut être de 0,5 à 4 microns.The thickness of the Fe 3 0 4 type oxide layer obtained can be from 0.5 to 4 microns.

Après cette troisième phase, on peut éventuellement effectuer dans la même enceinte un décapage ionique sous faible pression d'azote (par exemple sous une pression d'azote d'environ 0,5.102 Pa) pendant 10 à 20 minutes, afin d'éliminer de la surface des pièces les particules non adhérentes.After this third phase, it is optionally possible to carry out in the same enclosure an ion pickling under low nitrogen pressure (for example under a nitrogen pressure of approximately 0.5 × 10 2 Pa) for 10 to 20 minutes, in order to eliminate non-adherent particles from the surface of the parts.

Les pièces peuvent être ensuite refroidies sous atmosphère d'azote.The parts can then be cooled under a nitrogen atmosphere.

Les pièces ainsi obtenues peuvent avoir une rugosité inférieure ou égale à 1 micron.The parts thus obtained can have a roughness less than or equal to 1 micron.

L'état de surface peut être amélioré par l'opération d'écrouissage superficiel. Dans le cas de pièces cylindriques, cet écrouissage peut être effectué par galetage au défilé sous une pression de 2 à 5.106 Pa et avec une avance de 1 mm par tour.The surface condition can be improved by the surface hardening operation. In the case of cylindrical parts, this work hardening can be carried out by roller burnishing at the pass under a pressure of 2 to 5.10 6 Pa and with an advance of 1 mm per revolution.

Cette opération qui maintient l'intégralité des couches de revêtement comprime ces couches et permet d'obtenir une rugosité inférieure à 0,4 microns.This operation which maintains the entire coating layers compresses these layers and makes it possible to obtain a roughness of less than 0.4 microns.

La pression d'écrouissage est réglée en fonction de la rugosité finale souhaitée.The work hardening pressure is adjusted according to the desired final roughness.

Les exemples suivants illustrent la présente invention.The following examples illustrate the present invention.

EXEMPLE 1EXAMPLE 1

On traite des tiges de vérin en acier XC38, ayant un diamètre de 12mm par le procédé selon l'invention.XC38 steel cylinder rods having a diameter of 12 mm are treated by the method according to the invention.

A cet effet, on place les tiges dans une enceinte d'ionisation, les tiges étant maintenues sous une tension de -400 V par rapport aux parois de l'enceinte.For this purpose, the rods are placed in an ionization enclosure, the rods being maintained under a voltage of -400 V relative to the walls of the enclosure.

On introduit dans l'enceinte un mélange gazeux comprenant 80 % en poids d'azote, 3 % en poids de méthane et 17 % en poids d'hydrogène. La pression est de 2.102 Pa. La température est de 575°C. La durée du traitement est de 30 minutes.A gaseous mixture comprising 80% by weight of nitrogen, 3% by weight of methane and 17% by weight of hydrogen is introduced into the enclosure. The pressure is 2.10 2 P a. The temperature is 575 ° C. The duration of the treatment is 30 minutes.

On introduit ensuite 2 % en poids d'oxygène dans l'enceinte. La durée du traitement est de 90 minutes.Then introduced 2% by weight of oxygen into the enclosure. The duration of the treatment is 90 minutes.

On introduit ensuite dans l'enceinte de la vapeur d'eau sous une pression de 1,5.103Pa. La durée du traitement est de 20 minutes.Water vapor is then introduced into the enclosure at a pressure of 1.5 × 10 3 Pa. The duration of the treatment is 20 minutes.

On obtient un revêtement comprenant une couche compacte de nitrure de fer Fe2-3N d'une épaisseur d'environ 18 microns, une couche poreuse constituée d'un mélange de nitrure de fer et de Fe304 d'une épaisseur d'environ 5 microns et une couche superficielle d'aspect noir de Fe304 de 1 à 2 microns.A coating is obtained comprising a compact layer of iron nitride Fe 2-3 N with a thickness of about 18 microns, a porous layer consisting of a mixture of iron nitride and Fe 3 0 4 with a thickness d '' about 5 microns and a surface layer of black appearance of Fe 3 0 4 of 1 to 2 microns.

Le revêtement ainsi obtenu a une rugosité de l'ordre de 1 micron.The coating thus obtained has a roughness of the order of 1 micron.

Les pièces sont soumises à un test de corrosion de type atmosphère marine.The parts are subjected to a corrosion test of the marine atmosphere type.

Au bout de 90 jours on n'observe pratiquement pas de piqûres.After 90 days there are practically no bites.

A titre comparatif, on traite les pièces en n'effectuant que la première phase de nitruration. Dans le même test de corrosion, les pièces ainsi traitées présentent une corrosion généralisée au bout de 90 jours.By way of comparison, the parts are treated by carrying out only the first nitriding phase. In the same corrosion test, the parts thus treated exhibit generalized corrosion after 90 days.

EXEMPLE 2EXAMPLE 2

On opère comme à l'exemple 1, mais on soumet en outre les tiges de vérins ainsi traitées à un galetage au défilé sous une pression de 4.106 Pa avec une avance de 1 mm par tour. On obtient une rugosité de surface d'environ 0,2 micron.The procedure is as in Example 1, but the cylinder rods thus treated are further subjected to roller burnishing on the parade under a pressure of 4.10 6 Pa with an advance of 1 mm per revolution. A surface roughness of about 0.2 microns is obtained.

Claims (7)

1. Procédé de traitement superficiel de pièces en acier ou en fonte pour conférer à ces pièces une résistance à l'usure et à la corrosion, caractérisé en ce que l'on soumet successivement la surface des pièces à une nitruration ionique, à une oxynitruration ionique et à une oxydation ionique.1. A method of surface treatment of steel or cast iron parts to give these parts resistance to wear and corrosion, characterized in that the surface of the parts is successively subjected to ionic nitriding, to oxynitriding ionic ionic oxidation. 2. Procédé selon la revendication 1, caractérisé en ce qu'on effectue les trois opérations successives dans la même enceinte en utilisant successivement un gaz nitrurant, un mélange de gaz nitrurant et de gaz oxydant et un gaz oxydant.2. Method according to claim 1, characterized in that the three successive operations are carried out in the same enclosure using successively a nitriding gas, a mixture of nitriding gas and oxidizing gas and an oxidizing gas. 3. Procédé selon la revendication 1 ou la revendication 2, caractérisé en ce que pour l'oxynitruration ionique on ajoute au gaz nitrurant de 0,5 à 2 % en poids de gaz oxydant, ce pourcentage étant exprimé en oxygène.3. Method according to claim 1 or claim 2, characterized in that for ion oxynitriding is added to the nitriding gas from 0.5 to 2% by weight of oxidizing gas, this percentage being expressed in oxygen. 4. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que les conditions et les durées de traitement sont réglées de façon à déposer une couche de nitrure de 10 à 30 microns, une couche intermédiaire de 2 à 10 microns et une couche d'oxyde de 0,5 à 4 microns.4. Method according to any one of the preceding claims, characterized in that the conditions and the treatment times are adjusted so as to deposit a layer of nitride of 10 to 30 microns, an intermediate layer of 2 to 10 microns and a layer 0.5 to 4 micron oxide. 5. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce qu'on effectue un décapage ionique juste après l'opération d'oxydation ionique.5. Method according to any one of the preceding claims, characterized in that an ionic stripping is carried out just after the ionic oxidation operation. 6. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que l'on effectue ensuite un écrouissage superficiel.6. Method according to any one of the preceding claims, characterized in that a surface hardening is then carried out. 7. Procédé selon la revendication 6 pour le traitement des pièces cylindriques, caractérisé en ce que l'on effectue le traitement d'écrouissage superficiel par galetage au défilé.7. Method according to claim 6 for the treatment of cylindrical parts, characterized in that one performs the surface hardening treatment by roller burnishing in the process.
EP85400442A 1984-03-12 1985-03-07 Process for the surface treatment of iron or cast iron parts by ionic bombardment Withdrawn EP0159222A1 (en)

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FR8403768 1984-03-12
FR8403768A FR2560892B1 (en) 1984-03-12 1984-03-12 METHOD FOR THE SURFACE TREATMENT OF STEEL OR CAST IRON PARTS BY ION BOMBING

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FR2630133A1 (en) * 1988-04-18 1989-10-20 Siderurgie Fse Inst Rech PROCESS FOR IMPROVING THE CORROSION RESISTANCE OF METAL MATERIALS
EP0753599A1 (en) * 1995-07-11 1997-01-15 METAPLAS IONON Oberflächenveredelungstechnik GmbH Method and apparatus for producing corrosion and wear resistant protective coatings on iron based substrates
WO2017122044A1 (en) 2016-01-13 2017-07-20 Ion Heat S.A.S Equipment for ion nitriding/nitrocarburizing treatment comprising two furnace chambers with shared resources, able to run glow discharge treatment continuously between the two chambers

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FR2588281B1 (en) * 1985-10-08 1991-08-16 Air Liquide HEAT TREATMENT PROCESS FOR PRODUCING CORROSION RESISTANT STEEL PARTS
GB2208658B (en) * 1987-07-17 1992-02-19 Lucas Ind Plc Manufacture of corrosion resistant steel components
FR2999608A1 (en) * 2012-12-13 2014-06-20 Peugeot Citroen Automobiles Sa Heat treating a cast part e.g. tension disk or braking drum, of braking system of vehicle i.e. car, comprises ion nitriding a cast part to form a surface layer of iron nitride on cast part with specific amount of thickness

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FR2630133A1 (en) * 1988-04-18 1989-10-20 Siderurgie Fse Inst Rech PROCESS FOR IMPROVING THE CORROSION RESISTANCE OF METAL MATERIALS
EP0340077A1 (en) * 1988-04-18 1989-11-02 Institut De Recherches De La Siderurgie Francaise (Irsid) Process for increasing the corrosion resistance of metallic materials
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US5062900A (en) * 1988-04-18 1991-11-05 Institut De Recherches De La Siderurgie Francaise Process for the improvement of the corrosion resistance of metallic materials
US5679411A (en) * 1995-07-10 1997-10-21 Metaplas Ionon Oberflachenveredelungstechnik Gmbh Method for producing a corrosion and wear resistant coating on iron materials
EP0753599A1 (en) * 1995-07-11 1997-01-15 METAPLAS IONON Oberflächenveredelungstechnik GmbH Method and apparatus for producing corrosion and wear resistant protective coatings on iron based substrates
WO2017122044A1 (en) 2016-01-13 2017-07-20 Ion Heat S.A.S Equipment for ion nitriding/nitrocarburizing treatment comprising two furnace chambers with shared resources, able to run glow discharge treatment continuously between the two chambers

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FR2560892B1 (en) 1986-10-31

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