EP0552460A1 - Procédé de traitement thermochimique de pièces par des impulsions à plasma - Google Patents

Procédé de traitement thermochimique de pièces par des impulsions à plasma Download PDF

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Publication number
EP0552460A1
EP0552460A1 EP19920121129 EP92121129A EP0552460A1 EP 0552460 A1 EP0552460 A1 EP 0552460A1 EP 19920121129 EP19920121129 EP 19920121129 EP 92121129 A EP92121129 A EP 92121129A EP 0552460 A1 EP0552460 A1 EP 0552460A1
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EP
European Patent Office
Prior art keywords
plasma
carbon
duration
pulse
workpiece
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
EP19920121129
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German (de)
English (en)
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EP0552460B1 (fr
Inventor
Albrecht Dr. Melber
Frank Dipl.-Ing. Schnatbaum
Prof. Dr.-Ing. Kyong-Tschong Rie
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.)
Leybold Durferrit GmbH
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Leybold Durferrit GmbH
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Publication of EP0552460A1 publication Critical patent/EP0552460A1/fr
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/36—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases using ionised gases, e.g. ionitriding
    • C23C8/38—Treatment of ferrous surfaces

Definitions

  • the invention relates to a method for hardening workpieces made of steel, in particular with at least one alloy element from the group Cr, Ni, Mn, Si and Mo, by carburizing the surface and subsequent quenching, the carburizing using a plasma discharge in a vacuum in the presence of gaseous gases Hydrocarbons at voltages between 200 and 2000 volts, preferably between 300 and 1000 volts, carried out and the plasma is generated by means of electrodes operated in a vacuum, of which the cathode serves as a workpiece holder and is operated in pulse mode.
  • US Pat. No. 4,900,371 discloses a plasma-pulse method of the type described in the introduction, in which the repetition time is 10 ms and the pulse and pause times are each 5 ms.
  • the specified parameters are intended to homogenize the gas and plasma distribution over the workpiece surface, but with the usual cathode voltages of 500 to 1000 V result in mass flows of carbon, which, without the activation of carbonless diffusion phases, also after a few minutes to supersaturate the surface area with carbon and would lead to undesirable carbide formation.
  • the invention is therefore based on the object of improving a method of the type specified at the outset such that with reproducible and simple process monitoring and control, even with irregularly shaped workpieces, a uniform hardness distribution is achieved and carbide formation on the surface is avoided without the interposition of a pronounced diffusion phase, that the carbon content on the surface of the workpiece can be set to any value between the carbon content of the core in the workpiece and the saturation limit of the material and that the glow discharge is reliably prevented from turning into an arc discharge.
  • the object is achieved to the full extent, that is, the method specified at the outset is improved in such a way that, with simpler process monitoring and control, carbide formation on the surface without the interposition of a pronounced diffusion phase does not occur, that the carbon content on the surface of the workpiece can be reproducibly set to any value between the carbon content of the core in the workpiece and its saturation limit and that a change in the glow discharge into an arc discharge is reliably prevented.
  • the mass flow m c of the carbon is reduced so that its solubility in austenite is not exceeded and no carbides can be formed.
  • the method according to the invention can be operated quasi-stationary with continuously pulsed plasma.
  • the oxidation-free carburizing of the surface by the plasma increases the fatigue strength, the warpage of the workpiece is reduced, and there are lower costs for the reworking of the workpieces.
  • the mean power after a start-up phase with the carbon content on the surface rising as quickly as possible before the said saturation limit is reached is reduced to a value at which the pulse operation continues to spread the carbon content below the saturation limit into the depth of the workpiece is continued.
  • the mass flow is then just as large as the migration in the workpiece through diffusion. This can speed up the process, i.e. the carburizing rate can be selected very high at the beginning, but is then adapted to the diffusion rate.
  • gases are suitable as gaseous hydrocarbon compounds: methane, ethane, propane, ethylene and propene.
  • a vacuum furnace 1 is shown with a furnace chamber 2, which is lined with a thermal insulation device 3.
  • a thermal insulation device 3 In front of the side walls 3a of the thermal insulation device 3 there is an electrode which is grounded and which serves as an anode 4 of the circuit.
  • a vertical support rod 6 is guided through the furnace ceiling 2a by means of an insulating bushing 5 and carries at its lower end a plate-shaped horizontal workpiece holder which also has an electrode function, i.e. serves as cathode 7. Only one of the workpieces 8 arranged on this workpiece holder is shown.
  • the power supply 9 is on Assigned to control unit 10, with which the electrical process parameters for influencing the plasma can be set.
  • Cathode 7 and workpieces 8 are surrounded concentrically by a resistance heating element 11 which is connected to a controllable current source 12.
  • the energy balance of the furnace and thus the workpiece temperature is determined by the losses on the one hand and by the sum of the energy contributions from the plasma and the radiation from the resistance heating element on the other.
  • a supply line 13 which comes from a controllable gas source 14 and through which the desired process gases or gas mixtures are supplied, opens into the furnace chamber 2.
  • the gas balance is determined by the gas supply, the consumption by the workpieces and possibly loss sinks, but not least by the influence of the vacuum pump 15, which is connected to the furnace chamber 2 via a suction line 16 and can also be designed as a pump set.
  • FIG. 2 shows a parameter representation of the dependence of the carbon concentration at different depths of the workpiece after a different process duration in the event that one of the processes according to the prior art (Gas carburization) without interrupting the carburization by a diffusion break.
  • the depth values in millimeters are plotted on the abscissa, starting from the workpiece surface, and the carbon concentration in percent by weight on the ordinate.
  • the individual curves apply (from bottom to top) for the process times of 0.5, 1, 2 and 4 hours plotted under the abscissa. It can be seen that the carbon concentration on the surface has already exceeded the saturation value after a process duration of 2 h, which is reflected in a decrease in hardness according to FIG. 3.
  • Figure 3 shows the hardness values belonging to Figure 2.
  • the abscissa has the same scale, and the associated hardness values in HV are plotted on the ordinate. It can be seen that the surface hardness reaches a peak value of 800 HV after 2 h with a steep drop to the depth, but already begins to decrease again after a process duration of 3 h due to carbide formation and drops to around 700 HV after 4 h. As the experiments continue, the situation deteriorates further, which is also generally known from the literature (for example EP-A2-0 288 680).
  • cylinder pins made of the steel alloy 16MnCr5 with a diameter of 20 mm were carburized in batches as substrates.
  • the device for removing the residual gases was evacuated to a pressure of 10 -3 mbar, whereupon a mixture of 15% argon, the rest of hydrogen was admitted to a pressure of 15 mbar.
  • the resistance heater By simultaneously operating the resistance heater and applying a negative voltage of 600 V to the substrates, they were cleaned by sputtering and heated to 900 ° C. The pretreatment lasted 60 minutes.
  • the gas atmosphere was then replaced by that of 5% methane, 80% hydrogen and 15% argon until a pressure of 15 mbar was reached.
  • the actual carburizing was then carried out by means of a pulse mode, in which the pulse voltage was set to 600 V and the ratio of pulse duration to pause duration was 0.07 at the power source.
  • the first phase of the treatment time was 240 min, the substrate temperature being kept at a constant 900 ° C. by adjusting the power of the resistance heater. Then the said ratio was reduced to 0.023 while the parameters were otherwise the same and the carburization was continued at 900 ° C. with a corresponding adjustment of the resistance heater power for a period of 90 minutes. Arc discharges never occurred during the entire process.
  • the cylinder pins were then inserted into the oil bath, which was kept at a temperature of 60 ° C., using a manipulator with the cylinder axis in a vertical position.
  • the hardening depth at 0.9 mm was 550 HVl. This fully met the demands made.
  • FIG. 5 The results of this experiment are shown in FIG. 5: The tooth profile (hatched) and the so-called plasma border (thick black line) are shown at the top right of the window, as are the measurement locations M1 and M2.
  • the plasma conforms extremely well to the tooth profile.
  • the measuring location M1 is in the tooth flank, the measuring location M2 on the tooth base.
  • the diagram shows the hardness "HVl" over the depth "t”.
  • Curve K1 shows the hardness curve at measuring point M1
  • curve K2 shows the hardness curve at measuring point M2. It can be seen that the measured values agree very well and that in particular the penetration depth "t" is essentially the same for M1 and M2, which is due to the good conformity of the plasma to the tooth profile.
  • the results of this experiment are shown in FIG. 6:
  • the (identical) tooth profile (hatched) and the so-called plasma seam (thick black line) are shown in the top right of the window, as are the measurement locations M3 and M4.
  • the plasma only clings to the tooth tip and is at a significantly greater distance from the tooth profile at the tooth base.
  • the measuring location M3 is on the tooth flank, the measuring location M4 on the tooth base.
  • the diagram shows the hardness "HVl" over the depth "t”.
  • Curve K3 shows the hardness curve at measuring point M3,
  • curve K4 shows the hardness curve at measuring point M4. It can be seen that the measured values deviate greatly from one another and that in particular the penetration depth "t" is significantly less with M4 than with M3, which is due to the lower conformity of the plasma in the foot area of the tooth profile.

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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)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Heat Treatment Of Articles (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
  • Arc Welding In General (AREA)
  • Manufacture And Refinement Of Metals (AREA)
EP92121129A 1992-01-20 1992-12-11 Procédé de traitement thermochimique de pièces par des impulsions à plasma Expired - Lifetime EP0552460B1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE4201325 1992-01-20
DE4201325 1992-01-20
DE4238993 1992-11-19
DE4238993A DE4238993C1 (fr) 1992-01-20 1992-11-19

Publications (2)

Publication Number Publication Date
EP0552460A1 true EP0552460A1 (fr) 1993-07-28
EP0552460B1 EP0552460B1 (fr) 1996-02-14

Family

ID=25911085

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92121129A Expired - Lifetime EP0552460B1 (fr) 1992-01-20 1992-12-11 Procédé de traitement thermochimique de pièces par des impulsions à plasma

Country Status (5)

Country Link
EP (1) EP0552460B1 (fr)
JP (1) JPH0657404A (fr)
AT (1) ATE134222T1 (fr)
DE (2) DE4238993C1 (fr)
ES (1) ES2083663T3 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0645461A1 (fr) * 1993-08-27 1995-03-29 Hughes Aircraft Company Procédé et dispositif de traitement thermique par réchauffage au moyen de plasma et d'électrons et au moyen d'un jet de refroidissement solide/gazeux
EP0695813A2 (fr) 1994-08-06 1996-02-07 ALD Vacuum Technologies GmbH Procédé pour la carburation de pièces carburables par des impulsions à plasma
WO2006050696A1 (fr) * 2004-11-09 2006-05-18 Schaeffler Kg Procede de traitement thermique d'un element en acier trempe resistant au fluage a chaud et element en acier trempe resistant au fluage a chaud

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05128675A (ja) * 1991-11-05 1993-05-25 Sony Corp カセツト・オートチエンジヤー
JPH09512306A (ja) * 1994-04-26 1997-12-09 イーゲンヴェルト ゲゼルシャフト ミット ベシュレンクテル ハフツング 固体表面への物質の添加による改質、特に物質の表面改質方法
DE102006040814A1 (de) * 2006-08-31 2008-03-06 Schaeffler Kg Verfahren zum Erzeugen einer hoch einsatzhärtbaren Wälzlagerkomponente

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE601847C (de) * 1933-04-01 1934-08-25 Siemens Schuckertwerke Akt Ges Verfahren zum Einbringen eines Stoffes in ein Metall
FR1053916A (fr) * 1950-08-03 1954-02-05 Berghaus Elektrophysik Anst Procédé pour la commande de décharges dans des gaz servant à effectuer des opérations industrielles et dispositif pour l'application de ce procédé
EP0062550A1 (fr) * 1981-03-13 1982-10-13 Innovatique S.A. Procédé de traitements thermochimiques de métaux par bombardement ionique
US4853046A (en) * 1987-09-04 1989-08-01 Surface Combustion, Inc. Ion carburizing

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8625912D0 (en) * 1986-10-29 1986-12-03 Electricity Council Thermochemical treatment
DE3714283C1 (de) * 1987-04-29 1988-11-24 Ipsen Ind Internat Gmbh Verfahren zur Gasaufkohlung von Stahl

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE601847C (de) * 1933-04-01 1934-08-25 Siemens Schuckertwerke Akt Ges Verfahren zum Einbringen eines Stoffes in ein Metall
FR1053916A (fr) * 1950-08-03 1954-02-05 Berghaus Elektrophysik Anst Procédé pour la commande de décharges dans des gaz servant à effectuer des opérations industrielles et dispositif pour l'application de ce procédé
EP0062550A1 (fr) * 1981-03-13 1982-10-13 Innovatique S.A. Procédé de traitements thermochimiques de métaux par bombardement ionique
US4853046A (en) * 1987-09-04 1989-08-01 Surface Combustion, Inc. Ion carburizing

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
METALLURGICAL TRANSACTIONS A Bd. 9A, Oktober 1978, US Seiten 1421 - 1429 WILLIAM L. GRUBE 'high-rate carburizing in a glow-discharge methane plasma' *
SURFACE AND COATINGS TECHNOLOGY Bd. 35, 1988, ELSEVIER SEQUOIA,LAUSANNE,CH Seiten 309 - 321 N.Y. PEHLIVANTURK 'plasma or ion carburizing of several steels' *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0645461A1 (fr) * 1993-08-27 1995-03-29 Hughes Aircraft Company Procédé et dispositif de traitement thermique par réchauffage au moyen de plasma et d'électrons et au moyen d'un jet de refroidissement solide/gazeux
US5833918A (en) * 1993-08-27 1998-11-10 Hughes Electronics Corporation Heat treatment by plasma electron heating and solid/gas jet cooling
EP0695813A2 (fr) 1994-08-06 1996-02-07 ALD Vacuum Technologies GmbH Procédé pour la carburation de pièces carburables par des impulsions à plasma
WO2006050696A1 (fr) * 2004-11-09 2006-05-18 Schaeffler Kg Procede de traitement thermique d'un element en acier trempe resistant au fluage a chaud et element en acier trempe resistant au fluage a chaud
CN100572567C (zh) * 2004-11-09 2009-12-23 谢夫勒两合公司 用来热处理由通透淬硬性的耐高温钢构成的构件的方法和由通透淬硬性的耐高温钢构成的构件

Also Published As

Publication number Publication date
DE4238993C1 (fr) 1993-07-01
EP0552460B1 (fr) 1996-02-14
JPH0657404A (ja) 1994-03-01
ES2083663T3 (es) 1996-04-16
ATE134222T1 (de) 1996-02-15
DE59205356D1 (de) 1996-03-28

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