EP0516899A1 - Procédé de nitration d'acier - Google Patents

Procédé de nitration d'acier Download PDF

Info

Publication number
EP0516899A1
EP0516899A1 EP91305033A EP91305033A EP0516899A1 EP 0516899 A1 EP0516899 A1 EP 0516899A1 EP 91305033 A EP91305033 A EP 91305033A EP 91305033 A EP91305033 A EP 91305033A EP 0516899 A1 EP0516899 A1 EP 0516899A1
Authority
EP
European Patent Office
Prior art keywords
gas
fluoriding
nitriding
steel
chamber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP91305033A
Other languages
German (de)
English (en)
Other versions
EP0516899B1 (fr
Inventor
Akira Yoshino
Haruo Senbokuya
Masaaki Tahara
Kenzo Kitano
Teruo Minato
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Air Water Inc
Original Assignee
Daido Sanso Co Ltd
Daido Hoxan Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Daido Sanso Co Ltd, Daido Hoxan Inc filed Critical Daido Sanso Co Ltd
Priority to DK91305033.2T priority Critical patent/DK0516899T3/da
Priority to EP91305033A priority patent/EP0516899B1/fr
Priority to DE69113789T priority patent/DE69113789T2/de
Priority to AT91305033T priority patent/ATE129023T1/de
Priority to ES91305033T priority patent/ES2082138T3/es
Priority to CN91104154.0A priority patent/CN1032375C/zh
Publication of EP0516899A1 publication Critical patent/EP0516899A1/fr
Application granted granted Critical
Publication of EP0516899B1 publication Critical patent/EP0516899B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • C23C8/02—Pretreatment of the material to be coated
    • 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
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • 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
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/18—After-treatment
    • 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
    • C23C8/08—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 only one element being applied
    • C23C8/24—Nitriding
    • C23C8/26—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
    • 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
    • C23C8/34—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 more than one element being applied in more than one step

Definitions

  • the present invention relates to a method of nitriding steel for nitrogen case-hardening of steel which comprises subjecting a steel work to a special pretreatment that is conducive to a deep and uniform nitride layer or case.
  • nitriding gas nitriding, gas soft nitriding
  • RX gas carbon source-containing gas
  • the organic and inorganic stain components adhering to the steel surface are destroyed by the activated fluorine atoms to leave a clean steel surface and, at the same time, the passivation film, inclusive of the oxide film, on the steel surface is converted to a fluoride film to cover and protect the steel surface.
  • the steel work is then nitrided.
  • the above fluoride film is destroyed and removed by introducing a mixed gas composed of a nitrogen source-containing nitriding gas (e.g. NH3 gas) and H2 gas into the furnace under heating.
  • a nitrogen source-containing nitriding gas e.g. NH3 gas
  • the present invention has as its object to provide a method of nitriding steel which is capable of forming a uniform and deep nitride case at low cost.
  • the present invention is directed, in a first aspect, to a method of nitriding steel characterized by fluoriding a steel work in heated condition under a blanket of a fluorine gas-inert gas mixture and, then, nitriding the same work in heated condition under a blanket of nitriding gas and, in a second aspect, to a method of nitriding steel characterized by fluoriding a steel work in heated condition under a blanket of a fluorine gas-nitrogen trifluoride gas-inert gas mixture and, then, nitriding the same work in heated condition under a blanket of nitriding gas.
  • the inventors of the present invention performed a series of investigations for the cost reduction of a nitriding process using NF3 as a fluoriding gas and found that fluorine gas (F2) which was not formerly considered to be suited for fluoriding at the stage of development of the above-mentioned basic invention employing NF3 as the fluoriding gas actually has excellent fluoriding activity and that fluorine gas achieves fluoriding at a considerably lower temperature than NF3.
  • the present invention is based on the above finding.
  • the first aspect of this invention in this application is directed to a fluoriding process employing a mixture of F2 and an inert gas such as N2.
  • substantial fluoriding can be accomplished at a comparatively low temperature in the range of about 150°C to about 300°C, preferably about 200°C to about 250°C.
  • the second aspect of the invention is concerned with a fluoriding process employing a mixed gas composed of an inert gas such as N2, F2 and NF3.
  • fluoriding can be accomplished at a temperature in the range of about 200°C to about 400°C, preferably about 250°C to about 300°C, which is lower than the temperature required for the prior process using NF3 as the fluoriding gas, although this temperature is slightly higher than that required for the first-mentioned process employing a mixed gas composed of N2 and F2 as the fluoriding gas. It was, thus, found that there is a temperature difference of as mush as 100°C to 150°C between the fluoriding temperature in the case of using F2 alone (F2 + N2) and the fluoriding temperature in the case of using NF3 alone (NF3 + N2).
  • fluoriding can be performed at a temperature beyond the above-mentioned range, for example about 500°C at the maximam, if desired.
  • F2 gas fluorine gas
  • F2 gas not only a general F2 gas which is formed by a melting electrolytic method and the like, but also F2 gas which is formed by thermal-cracking by introducing a F-containing composed such as BF3, CF4, HF, SF6, C2F4, WF4 , CHF3 , SiF4 into a thermal-cracking apparatus may be used.
  • F2 used in this invention includes such F2 formed by thermal-cracking.
  • either (1) a mixed gas of N2 + F2 or (2) a mixed gas of N2 + F2 + NF3 is employed for fluoriding as mentioned above.
  • the concentration of F2 is set at 0.05 to 20% (by volume; the same applies hereinafter).
  • the drawback of F2 is that since it is highly reactive, control of fluoriding is difficult at a high concentration. Thus, though F2 is rather easy to control at a concentration not exceeding 1%, prolonged treatment is required for sufficient case hardening of steel. Therefore, the preferred F2 concentration is 3 to 10%.
  • the preferred concentration of F2 is 1 to 5% and that of NF3 is 1 to 20%.
  • the proportions of F2 and NF3 depend on the scheduled fluoriding time and temperature.
  • the ratio of F2 to NF3 in the ternary gaseous mixture is determined in consideration of this disadvantage and the cost of the fluoriding gas.
  • the substrate steel for the present invention includes a variety of steels such as carbon steel, stainless steel and so on. These steels are not limited in shape or the like and may be in the form of plate or coil or even in the processed shape of a screw or the like.
  • the substrate steel for the present invention is not limited to said steels, either, but includes alloys of said steels and alloys based on said steels and supplemented with other metals.
  • the substrate steel is either treated using (A) a first heat treating furnace for fluoriding and a second treating furnace for nitriding or (B) in a single heat treating apparatus having both a fluoriding chamber and a nitriding chamber.
  • the process may for example comprise the following steps.
  • fluoriding is performed in said heat treating furnace for fluoriding in the following manner.
  • the steel work to be case-hardened is placed in the first heat treating furnace for fluoriding and heated to a temperature of 150-300°C, preferably 200-250°C.
  • fluorine gas (F2 + N2 ) is introduced into the heating furnace and the steel work is maintained at the same temperature as above in an atmosphere of said fluorine gas for about 10 to 120 minutes, preferably for about 20 to 90 minutes, and for still better results for about 30 to 60 minutes.
  • a cracking apparatus is disposed in front of the heat furnace or in the vicinity of the heat furnace. After thermal-cracking the above-mentioned compound, formed F2 is mixed with N2 and the mixture is introduced into the heat furnace. By this procedure, the passivation film (mainly composed of oxide) on the steel surface is converted to a fluoride film.
  • This reaction proceeds for example in accordance with the following reaction formulas. FeO + F2 ⁇ FeF2 + 1/2O2 Cr2O3 + 2F2 ⁇ 2CrF2 + 3/2O2
  • the above treatments are each carried out using a heat treating furnace such as, for example, the one illustrated in Fig. 1.
  • the reference numeral 1 indicates a bell-shaped outer cover and 2 indicates a cylindrical inner cover which is covered with said outer cover.
  • a frame structure 10 Integrally disposed on top of said outer cover 1 is a frame structure 10 having an engaging means 10a for engaging the hook of a crane or the like.
  • a cover structure 11 Integrally disposed on top of said inner cover 2 is a cover structure 11 having an engaging means 11a for engaging the hook of a crane or the like.
  • Formed within said inner cover 2 is a fluoriding chamber and the space between the two covers 1 and 2 constitutes a heating chamber.
  • the reference numeral 3 indicates steel works which are charged into and taken out from said inner cover 2.
  • the steel works 3 are mounted on a platform 15 having a center hole 14 and staged up in the space between a first cylindrical wire-mesh member 16 extending upwards from said center hole 14 and a second cylindrical wire-mesh member 17a extending upwards from the periphery of said platform 15 through interposed porous dividers 17b each having a center hole.
  • the reference numeral 4 indicates a port for installation of a burner as formed in the peripheral wall in the lower part of said outer cover 1, and 4a indicates an exhaust port formed in the top wall of the outer cover 1.
  • the reference numeral 5 indicates a base and 6 indicates a fan for circulation of the furnace atmosphere.
  • the reference numeral 7 indicates a heat exchanger which is disposed in a pipe 7a extending downwardly from the base of said inner cover 2.
  • the reference numeral 8 indicates a circulation blower for forced cooling which is installed in the pipe 7a downstreams of said heat exchanger 7, while a pipe for introducing fluorine gas into the inner cover 2 is indicated at 9.
  • Indicated at 12a is an exhaust gas pipe for withdrawal of spent gas, from the inner cover 2, which is bifurcated in an intermediate position, with one of branch pipes 17 being equipped with a valve 18 and the other branch pipe 19 being equipped with a valve 20 and a vacuum pump 21.
  • the reference numeral 12 indicates an antipollution device which is connected to the terminal end of said exhaust gas pipe 12a.
  • This antipollution device 12 comprises a transverse pair of activated carbon columns 22, a heater coil 23 wound round the periphery of each column, and a fin-type heat exchanger 24 and functions in such a manner that the spent gas introduced into the activated carbon column 22 is converted to harmless CF4 by thermal reaction of residual F2 etc. with the activated carbon and fed to the fin-type heat exchanger 24 for cooling.
  • a scrubber disposed in a pipe 25 extending from said heat exchanger 24.
  • This scrubber 13 contains water and functions to thoroughly treat the spent gas harmless for release into the atmosphere by reducing the spent gas from the pipe 25 into bubbles so as to dissolve the HF fraction (which is by-produced by reaction of F2 with H2O and H2 in inner cover 2) of the spent gas in the water.
  • fluoriding is performed as follows.
  • the hook of a crane or the like (not shown) is engaged with the engaging means 10a and 11a of said outer cover 1 and inner cover 2 to suspend the outer cover 1 and inner cover 2 with the crane or the like.
  • the substrate steel 3 is set up on the platform 15 as illustrated and the outer cover 1 and inner cover 2 are lowered to the original positions (the condition shown in Fig. 1).
  • the heat of the flame is radiated from a burner (not shown) set in the burner hole 4 into the heating chamber formed between the outer cover 1 and inner cover 2, whereby the steel work 3 in the inner cover 2 is heated.
  • a fluorine-containing gas such as NF3 is introduced into the inner cover 2 from its bottom through a pipe 9 for fluoriding.
  • the duration of this fluoriding is generally about 30 to 60 minutes as mentioned hereinbefore.
  • nitriding is performed as follows.
  • the steel work 3 after the above fluoriding treatment is covered with a fluoride film, it remains intact without surface oxidation even if it is exposed to the atmosphere such as air.
  • the steel work in this condition is either stored or immediately subjected to nitriding in said second heating furnace for nitriding.
  • This second heating furnace for nitriding is similar in construction with the first heating furnace described above.
  • the inner cover 2 and outer cover 1 of this second heating furnace A' are suspended up, the steel work 3 is then stacked, and the inner cover 2 and outer cover 1 are lowered into the original positions.
  • the heat of a flame is radiated from a burner into the space between the inner cover 2 and outer cover 1 to heat the steel work in the inner cover 2 at a nitriding temperature of 480-700°C.
  • NH3 gas or a mixed gas composed of NH3 and a carbon source-containing gas is introduced into the furnace from the bottom of the heating furnace through a pipe 9 and the steel work is maintained in this condition for about 120 minutes or more.
  • said fluoride film is reduced or destroyed by H2 or a small amount of water (by-produced in the course of nitriding reaction), for example in accordance with the following reaction, formulas, to give rise to an active steel surface.
  • the film may be destroyed by introducing a mixed gas of N2 and H2 or H2 gas prior to introduction of the nitriding gas. Rather, this practice is preferred in that the trouble due to by-production of ammonium fluoride can be avoided.
  • the active nitrogen derived from the nitriding gas acts to penetrate and diffuse into the steel work.
  • an ultrahard compound layer (nitride layer) containing nitrides such as CrN, Fe2N, Fe3N and Fe4N is formed uniformly and to a sufficient depth, followed by formulation of a hard diffusion layer of N atoms, and the above-mentioned compound layer and diffusion layer constitute the entire nitride case.
  • a furnace of the structure illustrated in Fig. 2 In the case of performing both fluoriding and nitriding in a single heat treating furnace (B), a furnace of the structure illustrated in Fig. 2, for instance, is employed.
  • 1' indicates a furnace and 2' a metal basket which is loaded with steel work (not shown).
  • the reference numeral 3' indicates a heater, 5' an exhaust gas pipe, 6' a diabetic wall, 7' a door, 8' a fan, 10' a post, 12' a vacuum pump, and 13' a spent gas treating unit.
  • Indicated at 21' is a furnace body having an adiabatic wall, which is internally divided into compartments 23' and 24' by a partitioning wall or shutter 22' which can be freely opened and closed.
  • the shutter 22' is adapted to keep the two compartments 23' ,24' gas-tight and insulated against heat and free to open and close by sliding vertically as shown.
  • the reference numeral 23' indicates a fluoriding chamber, while a nitriding chamber is indicated at 24'.
  • Each of the fluoriding chamber 23' and nitriding chamber 24' is formed with a base 25' which accepts the metal basket 2'.
  • the base 25' consists of a pair of rails and it is so arranged that the metal basket 2' may slide on the rails selectively into the fluoriding chamber 23' or the nitriding chamber 24'.
  • the reference numeral 26' indicates a gas inlet pipe for introduction of fluoriding gas into the fluoriding chamber 23', while a temperature sensor probe is indicated at 27'.
  • the front opening of the fluoriding chamber 23' is releasably covered with a laterally-driven cover 7'.
  • the reference numeral 28' indicates a nitriding gas pipe for introduction of the nitriding gas into the nitriding chamber 24'.
  • nitriding is performed as follows. First, the basket 2' containing the steel work is set in the fluoriding chamber 23' and, in this condition, the internal temperature of the fluoriding chamber 23' is increased to heat the steel work to 150-300°C. Then, in this condition, the fluorine-containing gas (F2+N2) is introduced into the chamber for fluoriding for 30 to 60 minutes. Upon completion of fluoriding, the fluoriding chamber 23' is vented to exhaust the gas.
  • F2+N2 fluorine-containing gas
  • nitriding is performed as follows.
  • the shutter 22' mentioned above is opened to transfer the steel work and the metal basket 2', as a unit, to the nitriding chamber 24' and the shutter 22' is then closed.
  • the internal temperature of the nitriding chamber 24' is increased to heat the steel work to 480-600°C and H2 gas is introduced into the nitriding chamber 24' to hold the condition for 1 hour, whereby the fluoride film covering the steel surface is destroyed to expose the substrate surface of the work.
  • nitriding is conducted at that temperature for 4-5 hours introducing a nitriding gas, i.e.
  • a mixed gas composed of NH3, N2, H2, Co and CO2 into the nitriding chamber 24'.
  • the internal temperature is decreased to 350-450°C and, in this condition, cleaning is conducted for 1 hour by introducing a mixed gas composed of H2 and N2 or a mixed gas composed of N2, H2 and CO2.
  • the spent gas within the nitriding chamber 24 is exhausted. out and the shutter 22' is opened.
  • the steel work and the metal basket 2' are transferred, as a unit, to the fluoriding chamber 23' and the shutter wall 22' is closed, followed by cooling in that condition. This cooling is effected by introducing nitrogen gas from the gas inlet pipe 26' into the fluoriding chamber 23'.
  • the thus-treated steel work has a deep and uniform nitride case.
  • the heating of steel work for fluoriding may be carried out in the nitriding chamber 24' by heating the same. That is, the steel work is placed directly in the nitriding chamber 24' and heated therein. Then, the shutter 22' is opened and the work is transferred to the fluoriding chamber 23' for fluoriding. The steel work is then placed in the nitriding chamber 24' again for nitriding. In this case, preheating of the nitriding chamber 24' can be effected by utilizing the heat for fluoriding of steel work.
  • the steel surface exposed upon destruction of the fluoride film has been highly activated and the nitrogen atoms act on this activated steel surface to form an ultrahard nitride layer of great depth and uniformity.
  • the gas used for fluoriding is a mixed gas based on F2 and compared with the use of NF3, it is not only inexpensive but permits the use of a lower fluoriding temperature, thus helping reduce the cost of treatment in a substantial measure.
  • a plurality of austenitic stainless steel screws were manufactured and cleaned with trichloroethylene vapor.
  • the screws were charged into a first heating furnace (Fig. 1), in which they were sufficiently baked at 200°C as mentioned hereinbefore.
  • a mixed gas composed of 10% of F2 and the balance of N2 was introduced into the furnace at a rate equal to 5 times the internal volume of the furnace per unit time and the work was maintained for 60 minutes. Thereafter, some of the samples were taken out and the surface layer of each sample was examined. It was confirmed that a fluoride film had been formed all over the surface.
  • the samples subjected to the above fluoriding treatment were transferred to a second heating furnace A' and NH3 + 50% RX gas was introduced into the furnace for nitriding at 530°C for 6 hours. After completion of this treatment, the samples were air-cooled and taken out from the furnace.
  • the above procedure provided nitrogen case-hardened austenitic stainless steel screws.
  • Example 2 The procedure described in Example 1 was repeated except that the fluoriding gas was replaced with a mixed gas of N2 + NF3 (concentration 1%) and the fluoriding temperature was replaced with 410°C to provide nitrogen case-hardened austenitic stainless steel screws.
  • a plurality of automotive engine suction valves were manufactured and placed directly in a heating furnace A to raise their temperature at 280°C.
  • a mixed gas composed of N2 + 10% F2 + 8% NF3 was introduced at a rate equal to 10 times the internal volume of the furnace per unit time and the work was held for 30 minutes. Thereafter, some of the samples were taken out and the surface layer of each sample was examined. As a result, it was confirmed that a fluoride film had been formed throughout the surface.
  • the samples subjected to the above fluoriding treatment was transferred to a second heat treating furnace A' and heated to 570°C. In this condition, a nitriding gas of NH3 + 50% RX was introduced for 120 minutes. Thereafter, the samples were air-cooled and taken out from the furnace.
  • Fluoriding was carried out at 380°C using a blanket gas of NF3 gas (1%) + N2 under otherwise the same conditions as Example 2 to provide samples of an engine valve.
  • Example 2 was equivalent in quality to the product of Comparative Example 2.
  • the proportion of the cost of fluoriding gas in the cost of the product engine valve in Example 2 was lower by 40% as compared with the product of Comparative Example 2 obtained using NF3.
  • the heating and cooling time in the fluoriding step could be reduced by 75 minutes.
  • Fluoriding and nitriding were performed using a heat treating furnace having a fluoriding chamber and a nitriding chamber as shown in Fig. 2.
  • the respective treatments were carried out as previously described in the text of this specification and the conditions in each treatment were the same as in Example 1. The same result was obtained as that of Example 1.
  • Fluoriding and nitriding were performed using a heat treating furnace having a fluoriding chamber and a nitriding chamber as shown in Fig. 2.
  • the respective treatments were carried out as previously described in the text of the specification and conditions in each treatment were the same as in Example 2. The same result was obtained as that of Example 2.
  • the method of the present invention employing a mixed gas based on inexpensive fluorine gas for fluoriding permits a drastic reduction of treatment cost. Furthermore, since fluoriding can be accomplished at a temperature lower by 100-150°C than that of fluoriding with NF3, the thermal energy requirements are reduced and this also contributes remarkably to cost reduction. Particularly because fluoriding can be accomplished at such a comparatively low temperature, the cooling time following fluoriding can also be curtailed so that the whole process can be expedited. Furthermore, because fluorine gas has an intense odor, it is more amenable to leak detection than NF3 and the pollution problem associated with harmful F2 can be prevented with greater assurance.
  • this lower temperature for fluoriding brings forth further advantages design-wise in the case of a heat treating furnace (continuous furnace) having both a fluoriding chamber and a nitriding chamber.
  • a heat treating furnace continuous furnace having both a fluoriding chamber and a nitriding chamber.
  • the serviceable life of the seal packing for the shutter between the nitriding chamber and the fluoriding chamber is prolonged.
  • the fluorine gas used for fluoriding is highly corrosive, the aging of characteristics of the seal packing is less pronounced when the temperature of the fluoriding chamber is low, so that a longer packing life can be realized.
  • the simplification and longer lives of reinforcing and other members of the structure are the simplification and longer lives of reinforcing and other members of the structure.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Basic Packing Technique (AREA)
EP91305033A 1991-06-04 1991-06-04 Procédé de nitration d'acier Expired - Lifetime EP0516899B1 (fr)

Priority Applications (6)

Application Number Priority Date Filing Date Title
DK91305033.2T DK0516899T3 (da) 1991-06-04 1991-06-04 Fremgangsmåde til nitrering af stål
EP91305033A EP0516899B1 (fr) 1991-06-04 1991-06-04 Procédé de nitration d'acier
DE69113789T DE69113789T2 (de) 1991-06-04 1991-06-04 Verfahren der Nitrierung von Stahl.
AT91305033T ATE129023T1 (de) 1991-06-04 1991-06-04 Verfahren der nitrierung von stahl.
ES91305033T ES2082138T3 (es) 1991-06-04 1991-06-04 Metodo de nitruracion del acero.
CN91104154.0A CN1032375C (zh) 1991-06-04 1991-06-24 钢的氮化方法

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP91305033A EP0516899B1 (fr) 1991-06-04 1991-06-04 Procédé de nitration d'acier
CN91104154.0A CN1032375C (zh) 1991-06-04 1991-06-24 钢的氮化方法

Publications (2)

Publication Number Publication Date
EP0516899A1 true EP0516899A1 (fr) 1992-12-09
EP0516899B1 EP0516899B1 (fr) 1995-10-11

Family

ID=36781525

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91305033A Expired - Lifetime EP0516899B1 (fr) 1991-06-04 1991-06-04 Procédé de nitration d'acier

Country Status (6)

Country Link
EP (1) EP0516899B1 (fr)
CN (1) CN1032375C (fr)
AT (1) ATE129023T1 (fr)
DE (1) DE69113789T2 (fr)
DK (1) DK0516899T3 (fr)
ES (1) ES2082138T3 (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0744471A2 (fr) * 1995-05-25 1996-11-27 Daido Hoxan Inc. Procédé pour la nitruration d'acier
EP0802339A2 (fr) * 1996-04-16 1997-10-22 Koyo Seiko Co., Ltd. Cage de palier et son procédé de fabrication
ES2112786A1 (es) * 1995-03-01 1998-04-01 Srephanois De Rechercehes Meca Procedimiento de tratamiento de superficies ferreas sometidas a elevadas solicitaciones de frotamiento.
EP0877175A2 (fr) * 1997-05-09 1998-11-11 Koyo Seiko Co., Ltd. Procédé de fabrication d'un palier et palier sans oxydes sous le lubrifiant
WO2004029320A1 (fr) 2002-09-24 2004-04-08 Honda Giken Kogyo Kabushiki Kaisha Procede de nitruration d'un anneau metallique et appareil correspondant
WO2018086930A1 (fr) * 2016-11-08 2018-05-17 Robert Bosch Gmbh Procédé de traitement thermique d'une pièce à usiner constituée d'un acier fortement allié
WO2019057555A1 (fr) * 2017-09-19 2019-03-28 Bortec Gmbh & Co. Kg Procédé de prétraitement amélioré d'une surface d'un substrat métallique
US11193197B2 (en) 2018-06-11 2021-12-07 Swagelok Company Chemical activation of self-passivating metals
US11885027B2 (en) 2020-04-29 2024-01-30 Swagelok Company Activation of self-passivating metals using reagent coatings for low temperature nitrocarburization

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102517540B (zh) * 2011-12-20 2013-11-20 广东华南特种气体研究所有限公司 一种准分子激光气配置装置的钝化方法
KR102466065B1 (ko) 2014-07-31 2022-11-10 스와겔로크 컴패니 자가 부동태화 금속의 향상된 활성화
CN111843407B (zh) * 2020-07-29 2021-11-02 扬州大学 一种304不锈钢螺旋铰刀氮化装置及氮化加工方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2851387A (en) * 1957-05-08 1958-09-09 Chapman Valve Mfg Co Method of depassifying high chromium steels prior to nitriding
SU638635A1 (ru) * 1977-05-24 1978-12-28 Московский Автомобильно-Дорожный Институт Способ азотировани стальных деталей
EP0352061A2 (fr) * 1988-07-20 1990-01-24 Hashimoto Chemical Industries Co., Ltd. Matériau métallique avec film passivé par fluoration et appareil constitué par ce matériau
EP0408168A1 (fr) * 1989-07-10 1991-01-16 Daidousanso Co., Ltd. Procédé pour le prétraitement préalable de matériaux métalliques et procédé pour la nitruration d'acier

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5112030A (en) * 1990-10-01 1992-05-12 Daidousanso Co., Ltd. Heat treat furnace for fluorinating steel material

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2851387A (en) * 1957-05-08 1958-09-09 Chapman Valve Mfg Co Method of depassifying high chromium steels prior to nitriding
SU638635A1 (ru) * 1977-05-24 1978-12-28 Московский Автомобильно-Дорожный Институт Способ азотировани стальных деталей
EP0352061A2 (fr) * 1988-07-20 1990-01-24 Hashimoto Chemical Industries Co., Ltd. Matériau métallique avec film passivé par fluoration et appareil constitué par ce matériau
EP0408168A1 (fr) * 1989-07-10 1991-01-16 Daidousanso Co., Ltd. Procédé pour le prétraitement préalable de matériaux métalliques et procédé pour la nitruration d'acier

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2112786A1 (es) * 1995-03-01 1998-04-01 Srephanois De Rechercehes Meca Procedimiento de tratamiento de superficies ferreas sometidas a elevadas solicitaciones de frotamiento.
EP0744471A2 (fr) * 1995-05-25 1996-11-27 Daido Hoxan Inc. Procédé pour la nitruration d'acier
EP0744471A3 (fr) * 1995-05-25 1999-02-10 Daido Hoxan Inc. Procédé pour la nitruration d'acier
EP0802339A2 (fr) * 1996-04-16 1997-10-22 Koyo Seiko Co., Ltd. Cage de palier et son procédé de fabrication
EP0802339A3 (fr) * 1996-04-16 1997-11-12 Koyo Seiko Co., Ltd. Cage de palier et son procédé de fabrication
US5833373A (en) * 1996-04-16 1998-11-10 Koyo Seiko Co., Ltd. Bearing retainer and method of fabricating the same
EP0877175A2 (fr) * 1997-05-09 1998-11-11 Koyo Seiko Co., Ltd. Procédé de fabrication d'un palier et palier sans oxydes sous le lubrifiant
EP0877175A3 (fr) * 1997-05-09 1999-11-24 Koyo Seiko Co., Ltd. Procédé de fabrication d'un palier et palier sans oxydes sous le lubrifiant
WO2004029320A1 (fr) 2002-09-24 2004-04-08 Honda Giken Kogyo Kabushiki Kaisha Procede de nitruration d'un anneau metallique et appareil correspondant
EP1544317A1 (fr) * 2002-09-24 2005-06-22 Honda Giken Kogyo Kabushiki Kaisha Procede de nitruration d'un anneau metallique et appareil correspondant
EP1544317A4 (fr) * 2002-09-24 2008-09-03 Honda Motor Co Ltd Procede de nitruration d'un anneau metallique et appareil correspondant
WO2018086930A1 (fr) * 2016-11-08 2018-05-17 Robert Bosch Gmbh Procédé de traitement thermique d'une pièce à usiner constituée d'un acier fortement allié
WO2019057555A1 (fr) * 2017-09-19 2019-03-28 Bortec Gmbh & Co. Kg Procédé de prétraitement amélioré d'une surface d'un substrat métallique
US11492693B2 (en) 2017-09-19 2022-11-08 Bortec Gmbh Pre-treatment process of a surface of a metallic substrate
US11193197B2 (en) 2018-06-11 2021-12-07 Swagelok Company Chemical activation of self-passivating metals
US11649538B2 (en) 2018-06-11 2023-05-16 Swagelok Company Chemical activation of self-passivating metals
US11885027B2 (en) 2020-04-29 2024-01-30 Swagelok Company Activation of self-passivating metals using reagent coatings for low temperature nitrocarburization

Also Published As

Publication number Publication date
DE69113789D1 (de) 1995-11-16
DK0516899T3 (da) 1996-02-26
EP0516899B1 (fr) 1995-10-11
ATE129023T1 (de) 1995-10-15
CN1067929A (zh) 1993-01-13
CN1032375C (zh) 1996-07-24
DE69113789T2 (de) 1996-04-25
ES2082138T3 (es) 1996-03-16

Similar Documents

Publication Publication Date Title
US5254181A (en) Method of nitriding steel utilizing fluoriding
KR930003031B1 (ko) 강(鋼)의 질화방법
JP2501925B2 (ja) 金属材の前処理方法
EP0408168B1 (fr) Procédé pour le prétraitement préalable de matériaux métalliques et procédé pour la nitruration d'acier
EP0588458B1 (fr) Méthode pour la nitruration d'un acier à austénite inoxydable
EP0516899B1 (fr) Procédé de nitration d'acier
KR100858598B1 (ko) 금속부재 표면의 활성화 방법
KR100503838B1 (ko) 가스침탄로용부품및지그
EP0551702A1 (fr) Procédé de nitruration d'un alliage de nickel
EP0481136B1 (fr) Procédé de nitruration d'acier
EP0479409B1 (fr) Vis en acier inoxydable austénitique et méthode de sa fabrication
CA2043872C (fr) Procede de nitruration de l'acier
AU648081B2 (en) Method of nitriding steel
EP0515701B1 (fr) Procede de fabrication d'un vilebrequin
JP2881111B2 (ja) 鋼の窒化方法
US5194097A (en) Method of nitriding steel and heat treat furnaces used therein
JP2918716B2 (ja) 鋼材の窒化方法
JPS63759Y2 (fr)
KR950000306B1 (ko) 강의 질화 방법 및 그 것을 이용한 열처리로
RU2796338C1 (ru) Способ обработки поверхности детали из жаропрочной нержавеющей стали
JP2506227B2 (ja) 鋼の窒化方法およびそれに用いる熱処理炉
JP2918765B2 (ja) 表面が窒化硬化されたニッケル合金製品
US5194096A (en) Carburizing treatment of a steel with reduction of the hydrogen content in the carburized layer
RU2790841C1 (ru) Способ обработки поверхности жаропрочной нержавеющей стали
JPS6033188B2 (ja) 金属熱処理設備

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT CH DE DK ES FR GB IT LI NL SE

17P Request for examination filed

Effective date: 19930510

17Q First examination report despatched

Effective date: 19931027

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: DAIDO HOXAN INC.

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT CH DE DK ES FR GB IT LI NL SE

REF Corresponds to:

Ref document number: 129023

Country of ref document: AT

Date of ref document: 19951015

Kind code of ref document: T

REF Corresponds to:

Ref document number: 69113789

Country of ref document: DE

Date of ref document: 19951116

ITF It: translation for a ep patent filed
ET Fr: translation filed
REG Reference to a national code

Ref country code: DK

Ref legal event code: T3

REG Reference to a national code

Ref country code: CH

Ref legal event code: NV

Representative=s name: BOVARD AG PATENTANWAELTE

REG Reference to a national code

Ref country code: ES

Ref legal event code: FG2A

Ref document number: 2082138

Country of ref document: ES

Kind code of ref document: T3

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: AT

Payment date: 19980605

Year of fee payment: 8

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: ES

Payment date: 19980619

Year of fee payment: 8

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DK

Payment date: 19980629

Year of fee payment: 8

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19990604

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: ES

Free format text: THE PATENT HAS BEEN ANNULLED BY A DECISION OF A NATIONAL AUTHORITY

Effective date: 19990605

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DK

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19990630

REG Reference to a national code

Ref country code: DK

Ref legal event code: EBP

REG Reference to a national code

Ref country code: CH

Ref legal event code: PFA

Free format text: DAIDO HOXAN INC. TRANSFER- AIR WATER INC.

NLT1 Nl: modifications of names registered in virtue of documents presented to the patent office pursuant to art. 16 a, paragraph 1

Owner name: AIR WATER INC.

REG Reference to a national code

Ref country code: FR

Ref legal event code: CD

REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

REG Reference to a national code

Ref country code: ES

Ref legal event code: FD2A

Effective date: 20020204

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED.

Effective date: 20050604

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: CH

Payment date: 20070530

Year of fee payment: 17

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 20070607

Year of fee payment: 17

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

EUG Se: european patent has lapsed
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LI

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080630

Ref country code: CH

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080630

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080605

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20100709

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 20100616

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20100602

Year of fee payment: 20

Ref country code: GB

Payment date: 20100602

Year of fee payment: 20

REG Reference to a national code

Ref country code: DE

Ref legal event code: R071

Ref document number: 69113789

Country of ref document: DE

REG Reference to a national code

Ref country code: DE

Ref legal event code: R071

Ref document number: 69113789

Country of ref document: DE

REG Reference to a national code

Ref country code: NL

Ref legal event code: V4

Effective date: 20110604

REG Reference to a national code

Ref country code: GB

Ref legal event code: PE20

Expiry date: 20110603

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20110603

Ref country code: NL

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20110604

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20110605