EP0638661B1 - Verfahren zur Verbesserung des Verschleissfestigkeit und Korrosionswiderstand von Eisenmetalgegenständen - Google Patents

Verfahren zur Verbesserung des Verschleissfestigkeit und Korrosionswiderstand von Eisenmetalgegenständen Download PDF

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EP0638661B1
EP0638661B1 EP94401716A EP94401716A EP0638661B1 EP 0638661 B1 EP0638661 B1 EP 0638661B1 EP 94401716 A EP94401716 A EP 94401716A EP 94401716 A EP94401716 A EP 94401716A EP 0638661 B1 EP0638661 B1 EP 0638661B1
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bath
parts
salts
oxygenated
corrosion
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French (fr)
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EP0638661A1 (de
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Jean Polti
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Centre Stephanois de Recherches Mecaniques Hydromecanique et Frottement SA
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Centre Stephanois de Recherches Mecaniques Hydromecanique et Frottement SA
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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
    • C23C8/40—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 liquids, e.g. salt baths, liquid suspensions
    • C23C8/42—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 liquids, e.g. salt baths, liquid suspensions only one element being applied
    • C23C8/48—Nitriding
    • C23C8/50—Nitriding of ferrous surfaces
    • 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
    • C23C22/70—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 melts
    • C23C22/72—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
    • 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
    • C23C8/80—After-treatment

Definitions

  • the present invention relates to a method for improving the resistance to wear and corrosion of ferrous metal parts, making it possible to guarantee a high degree of reproducibility of the results whatever the type of parts treated.
  • thermochemical diffusion treatments and in particular those designated by nitriding, is known for improving the wear resistance of ferrous metal parts.
  • Patent FR 2 306 268 from 1976 describes an oxidizing salt bath composed of alkali hydroxides, optionally with an alkali nitrate in an amount of 2 to 20% by weight.
  • This salt bath at preferred operating temperatures of 200 to 300 ° C, is essentially intended to simultaneously achieve controlled cooling of ferrous metal parts nitrides, leaving a cyanate / cyanide nitriding bath, and the destruction by oxidation of the cyanides entrained by the parts.
  • Patent FR 2,525,637 of 1982 describes a process for treating ferrous metal parts in an oxidizing salt bath to improve their resistance to corrosion, parts containing sulfur.
  • This document teaches to immerse the parts in an oxidizing bath, comprising alkali hydroxides, nitrates and / or alkali nitrites and possibly alkali carbonates, with in addition from 0.5 to 15% by weight of a strong oxidant, in the species of oxygenated alkali metal salts whose normal redox potential compared to the hydrogen reference electrode is less than or equal to - 1 volt.
  • Bichromates, permanganates, peroxycarbonates, iodates and periodates are cited as oxygenated salts, the alkali metals being sodium and potassium.
  • the process described in this patent is further characterized in that an oxygen-containing gas is injected into the salt bath and in that the weight content of the bath in insoluble particles is kept at less than 3%.
  • This process provides even better performance. It not only improves the corrosion resistance of the parts this time by a factor of almost 4, but also does not alter their resistance to wear and fatigue and even improve their anti-seizure properties in dry friction.
  • EP-A-0 497 663 describes a process aimed at improving the corrosion resistance of ferrous metal parts which have undergone nitriding and oxidation in a bath corresponding to the teaching of FR-A-2 525 637, by depositing on the surface of the treated parts, a coating of a polymer, for example FEP (fluoroethylene-propylene), having a thickness of 3 to 20 ⁇ m.
  • FEP fluoroethylene-propylene
  • the subject of the present invention is a process, associating thermochemical diffusion and passivation by oxidation, making it possible to substantially improve the wear and corrosion resistance of parts made of ferrous metals, while guaranteeing a high degree of reproducibility , therefore a minimum dispersion.
  • the invention covers any composition containing other alkali metal salts than sodium, taken alone or in mixtures, and the percentages of which are converted into sodium salts are those indicated above.
  • concentrations will be expressed in% by weight corresponding to the sodium salts and designated by the expression “sodium unit”, which will serve to "normalize” the different mixtures, regardless of the associated metal cation (for example Na + , K + , Li + ).
  • the temperature of the bath is between 350 and 550 ° C. and preferably between 450 and 530 ° C., and the duration of immersion of the parts in the bath is greater than 10 minutes.
  • composition according to the invention is, from a qualitative point of view, of the same type as that cited in the patent FR 2 525 637 previously mentioned. In quantitative terms, however, it stands out in a very significant way. This can be explained as follows.
  • the improvement in the wear resistance is due to the nitrided layer essentially while the improvement in the corrosion resistance depends on both the nitrided layer and the oxidized layer: both providing anodic protection.
  • the effectiveness of this protection depends directly on the integrity of the barrier layer: it is sought to have an oxidized, continuous and waterproof surface layer.
  • the nature of the layer forming in the oxidizing bath is known and consists essentially of iron oxide type Fe 3 O 4 , which is perfectly inert. It was therefore not a question of doing better in terms of the nature of the layer but of finding a solution to guarantee its sealing.
  • the oxidizing bath composition which is the subject of the present application differs from known baths by the fact that it combines a percentage of powerful oxidizing salt which is clearly lower than that cited in patent FR 2 525 637, in combination with nitrates and also different hydroxides.
  • the cationic species of the bath are only defined by the nature of the corresponding metals, namely the alkali metals. It is indeed of little importance that one or more cations are present and in the case where at least two cations are present simultaneously, the relationships between them have only a slight influence.
  • composition according to the invention makes it possible to reconcile all of the criteria listed above.
  • thermochemical treatment prior to oxidation produces on the surface of the parts a layer mainly composed of nitrides and / or carbonitrides, with also free iron in a minority proportion essentially present at the level of the defects of the layer. previous. It is probably this free iron which is responsible for the poor resistance to corrosion of parts that are simply nitrided, or carbonitrided.
  • Nitrates are, however, oxidizing agents of medium activity and if they are capable of oxidizing the free iron present in the layer, they would not however be powerful enough to destabilize the nitrides or carbonitrides.
  • Too much oxidizing agent on the other hand would lead to a weakening of the layer by the effect of the residual stresses of which it is the seat with the appearance of cracks, corrosion and scaling, detrimental to its tribological properties.
  • the presence of carbonates would go in the direction of a moderation of these oxidation reactions.
  • the temperature of the bath below a certain threshold, fixed by the carbonate content of the bath, it does not make it possible to achieve sufficient fluidity of the molten salts, which on the practical level leads to significant consumption. of salts by removal with the charges of parts, as well as a significant decantation at the bottom of the crucible. Too high a temperature leads to premature degeneration of the bath, with a concomitant decrease in its effectiveness.
  • the oxidation operation which is carried out according to reactions in heterogeneous liquid / solid phase, acts primarily and preferentially on the outer part of the nitrided, sulfonitrided or carbonitrided layer. It is therefore understandable that the morphology and the degree of porosity of this layer can have a significant influence on the intensity levels and on the kinetics of the reactions.
  • Parts made of non-alloy steel with 0.38% carbon were used, which were first subjected to a sulfonitriding treatment according to the teachings of the patents FR 2 171 993 and FR 2 271 307, by immersion for 90 minutes in a salt bath containing by weight 37% of cyanate ions and 17% of carbonate ions, the rest being alkaline cations K + , Na + and Li + , with in addition 10 to 15 ppm of S 2- ions.
  • the temperature of the molten salts was 570 ° C.
  • Friction tests the test pieces in this case were rings with a diameter of 35 mm and parallelepipedic plates with dimensions 30 x 18 x 8 mm. The friction test is carried out dry, pressing the ring against the large face of the plate, with a regularly increasing load from the initial value of 10 daN and with a sliding speed of 0.55 m / s. The results obtained are summarized in the following table:
  • Example 1 The other operating conditions, as regards the prior nitriding, the duration of immersion of the parts in the oxidizing bath, and the final washing / drying operations, were the same as in Example 1.
  • results obtained were qualified according to two reproducibility criteria, taking into account one of the color of the parts, the other of their resistance to corrosion in standardized salt spray.
  • the color it can go from dark black (which is the optimum sought, for reasons of presentation of the treated parts), to reddish brown (which one seeks to avoid).
  • Example 2 The procedure was as in Example 1, but varying from 0 to 1% the content of the oxidizing bath in Cr 2 O 7 2- anions.
  • the introduction into the dichromate bath makes it possible to find a regular black color of the parts and there is concomitantly an increase in the corrosion potential above 1000 mV / DHW.
  • the effect begins with 0.05% Cr 2 O 7 2- anion in the bath.
  • the optimal influence is obtained with 0.2% Cr 2 O 7 2- ; beyond 0.2%, no further improvement is observed up to 0.5%; more than 0.5% of Cr 2 O 7 2- leads to a weakening of the layer which tends to flake.
  • Example 2 As in Example 2, the results obtained were qualified, on the one hand by the color regularity of the treated parts, on the other hand by their resistance to corrosion with standardized salt spray:
  • the carbonate content of the bath increases. This is due to the fact that when leaving the preliminary nitriding bath, the parts carry with them salts of said bath, which are composed essentially of carbonates and alkaline cyanates. These in turn transform into carbonates by reaction with the oxidizing salts.
  • thermochemical diffusion is carried out by ionic or gas route it is the same, except that the conduct of the oxidizing bath is modified compared to what was described in Example 5: in this case in fact it there is no longer the entrainment of the nitriding salts; the carbonation of the oxidizing bath, as well as its drop in level, are slower.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Powder Metallurgy (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Coating With Molten Metal (AREA)
  • Electroplating Methods And Accessories (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
  • Luminescent Compositions (AREA)

Claims (5)

  1. Verfahren zur Verbesserung der Korrosionsbeständigkeit und Verschleißfestigkeit von Eisenmetallgegenständen, wobei man die Gegenstände, die der vorhergehenden thermochemischen Diffusion entweder von der Art Nitrierung oder Sulfonitrierung oder Carbonitrierung unterworfen waren, in ein Bad geschmolzener Salze, die aus Carbonaten, Nitraten, Hydroxyden sowie sauerstoffhaltigen Salzen von Alkalimetallen, ausgewählt aus den Bichromaten, Chromaten, Permanganaten, Peroxycarbonaten, lodaten und Periodaten bestehen, eintaucht, dadurch gekennzeichnet, daß die relativen Gewichtsmengen der Anionen von Carbonaten, Nitraten und Hydroxyden, ausgedrückt für die Natriumsalze und entsprechend der aktiven Phase, d. h. der Badflüssigkeit, wie folgt sind: 11 ≺ CO 3   2- ≺ 23
    Figure imgb0009
     19 ≺ NO 3   - ≺ 37
    Figure imgb0010
     6 ≺ OH - ≺ 19
    Figure imgb0011
     während die Gewichtsmenge der sauerstoffhaltigen Salze der Alkalimetalle, ausgedrückt in Äquivalenten von Cr2O7 2- wie folgt ist: 0,05 ≺ sauerstoffhaltige Anionen ≺ 0,5
    Figure imgb0012
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Temperatur des Bads zwischen 350 und 550°C liegt.
  3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Temperatur des Bads zwischen 450 und 550°C liegt.
  4. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Dauer des Eintauchens der Stücke im Bad über 10 Minuten ist.
  5. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß man die thermochemische Diffusion so durchführt, daß man auf der Oberfläche des Stücks eine Schicht erhält, welche im Kontakt mit dem Substrat einen kompakten Teil von einer Dicke zwischen 6 und 12 µm zeigt und auf dem Äußeren einen feinporösen Teil mit einer Dicke zwischen 3 und 6 µm, wobei der mittlere Durchmesser der Poren zwischen 0,1 und 2 µm liegt.
EP94401716A 1993-08-10 1994-07-26 Verfahren zur Verbesserung des Verschleissfestigkeit und Korrosionswiderstand von Eisenmetalgegenständen Expired - Lifetime EP0638661B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9309814A FR2708941B1 (fr) 1993-08-10 1993-08-10 Procédé pour améliorer la résistance à l'usure et à la corrosion de pièces en métaux ferreux.
FR9309814 1993-08-10

Publications (2)

Publication Number Publication Date
EP0638661A1 EP0638661A1 (de) 1995-02-15
EP0638661B1 true EP0638661B1 (de) 1997-01-22

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EP94401716A Expired - Lifetime EP0638661B1 (de) 1993-08-10 1994-07-26 Verfahren zur Verbesserung des Verschleissfestigkeit und Korrosionswiderstand von Eisenmetalgegenständen

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EP (1) EP0638661B1 (de)
JP (1) JP3083453B2 (de)
KR (1) KR100273924B1 (de)
CN (1) CN1054891C (de)
AT (1) ATE148178T1 (de)
BR (1) BR9403101A (de)
CA (1) CA2129162C (de)
DE (1) DE69401551T2 (de)
ES (1) ES2097012T3 (de)
FR (1) FR2708941B1 (de)
MY (1) MY111901A (de)
PL (1) PL177228B1 (de)
TW (1) TW259815B (de)

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FR2731232B1 (fr) * 1995-03-01 1997-05-16 Stephanois Rech Procede de traitement de surfaces ferreuses soumises a des sollicitations elevees de frottement
JP4487340B2 (ja) 1999-07-21 2010-06-23 日本精工株式会社 転がり軸受用保持器の製造方法
TW557330B (en) 2000-11-29 2003-10-11 Parker Netsushori Kogyo Kk Improved salt bath nitrogenating method for corrosion-resistant iron material and iron units
DE10124933A1 (de) * 2001-05-21 2002-11-28 Endress & Hauser Gmbh & Co Kg Anordnung aus einem metallischen Deckel und einem metallischem Gehäuse eines Meßgerätes und Verfahren zu deren Herstellung
EP2757423B1 (de) * 2013-01-17 2018-07-11 Omega SA Bauteil für Uhrwerk
CN103451595B (zh) * 2013-09-02 2015-09-23 中国科学院金属研究所 镁合金表面熔盐氧碳硫共渗耐腐蚀陶瓷涂层及制备和应用
CN113897579A (zh) * 2021-09-30 2022-01-07 成都工具研究所有限公司 一种316l不锈钢工件低温qpq处理工艺

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US2639244A (en) * 1950-07-15 1953-05-19 Remington Arms Co Inc Metal finishing method
DE2934113C2 (de) * 1979-08-23 1985-05-09 Degussa Ag, 6000 Frankfurt Verfahren zur Erhöhung der Korrosionsbeständigkeit nitrierter Bauteile aus Eisenwerkstoffen
FR2525637B1 (fr) * 1982-04-23 1986-05-09 Stephanois Rech Mec Procede de traitement de pieces en metal ferreux en bain de sels oxydant, pour ameliorer leur resistance a la corrosion, les pieces contenant du soufre
JPH0234793A (ja) * 1988-07-26 1990-02-05 Kobe Steel Ltd スケール密着性の優れた加工用高強度熱延鋼板の製造方法
FR2672059B1 (fr) * 1991-01-30 1995-04-28 Stephanois Rech Mec Procede pour conferer a des pieces en metal ferreux, nitrurees puis oxydees, une excellente resistance a la corrosion tout en conservant les proprietes acquises de friction.

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ATE148178T1 (de) 1997-02-15
TW259815B (de) 1995-10-11
ES2097012T3 (es) 1997-03-16
KR100273924B1 (ko) 2000-12-15
CN1054891C (zh) 2000-07-26
FR2708941B1 (fr) 1995-10-27
DE69401551D1 (de) 1997-03-06
JPH0776766A (ja) 1995-03-20
JP3083453B2 (ja) 2000-09-04
EP0638661A1 (de) 1995-02-15
KR950006020A (ko) 1995-03-20
MY111901A (en) 2001-02-28
FR2708941A1 (fr) 1995-02-17
CA2129162A1 (fr) 1995-02-11
PL177228B1 (pl) 1999-10-29
CA2129162C (fr) 2000-12-12
CN1101684A (zh) 1995-04-19
PL304595A1 (en) 1995-02-20
BR9403101A (pt) 1995-04-11
DE69401551T2 (de) 1997-07-03

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