EP0218916B1 - A process to form a sulphide case at the surface of a metal part - Google Patents

A process to form a sulphide case at the surface of a metal part Download PDF

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Publication number
EP0218916B1
EP0218916B1 EP86112510A EP86112510A EP0218916B1 EP 0218916 B1 EP0218916 B1 EP 0218916B1 EP 86112510 A EP86112510 A EP 86112510A EP 86112510 A EP86112510 A EP 86112510A EP 0218916 B1 EP0218916 B1 EP 0218916B1
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EP
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Prior art keywords
sulphurizing
sulphur
temperature
sulphide
substrate
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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.)
Expired - Lifetime
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EP86112510A
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German (de)
English (en)
French (fr)
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EP0218916A1 (en
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Yifei Zhang
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    • CCHEMISTRY; METALLURGY
    • C23COATING 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
    • C23CCOATING 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
    • C23C8/00Solid 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
    • C23C8/06Solid 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
    • C23C8/36Solid 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
    • C23C8/38Treatment of ferrous surfaces

Definitions

  • the present invention relates to a process for forming a sulphide case at the surface of a metal part or component, and more particularly relates to such a process used to form a sulphide case at the surface of metal parts by means of gas sulphurization.
  • Sulphurization is one of the surface-treating procedures used for metal parts or components. Since a ferrous sulphide case can be formed by sulphurization and ferrous sulphide is a form of solid lubricant, then if there is a sulphide case between two contacting surfaces of friction components, the coefficient of friction between them can be reduced. Furthermore, a sulphide case may separate the underlying metal of two friction components from direct contact with each other and thereby provide the surface of the components with a fine resistance to wear and to seizure. Therefore, in recent years the study of sulphurization has been further developed and had great attention paid to it.
  • the Huanan Polytechnic College has developed a sulphurizing process using a single gas instead of the said nitrosulphurization in which a sulphide is used as a medium and a special-purpose sulphurizing furnace is used to hold the temperature at 160°C or above.
  • a case containing ferrous sulphide (FeS) and iron disulphide (FeS2) forms at the surface of the part (see “Heat treatment of metals" Vol. 5, 1983), but there are some disadvantages relating to this process.
  • the medium is a sulphide, the sulphurizing atmosphere contains some other components beside sulphur, which has a detrimental influence on the quality of the case.
  • some sulphides are poisonous, such as H2S and not only ferrous sulphide but also iron disulphide is formed in the process , the former being favourable but the latter being detrimental to the resistance of the part to wear.
  • the treating temperature used in the process is rather high.
  • the solid sulphur which is loaded in a steel box, is also located on the cathode table along with the parts being treated so that it is difficult to control the sulphur-gasifying temperature and the gasifying quantity.
  • the parts and the solid sulphur are heated by an inert gas discharge, the inert gas being pumped out from the vacuum furnace after the temperature has been raised to the desirable level in order to leave the sulphur-containing gas in the furnace, thus making the operation complicated and expensive.
  • the process of the present invention is an improved and developed version of the solid sulphur-gasifying and sulphurizing process mentioned above.
  • One of the objects of the present invention is to carry out a sulphurizing process in which the solid sulphur is directly heated to gasify it, which overcomes the shortcomings mentioned above and produces a better sulphurizing quality than that resulting from other processes with a uniform and thick case comprising a unitary constituent.
  • a process for sulphurizing a metallic substrate held within a vacuum chamber comprising the steps of:
  • the keypoint of the gas sulphurizing is to produce a sulphur-containing gas.
  • the advantages resulting from the present process in which the sulphur-containing gas is made from pure solid sulphur, not from a sulphide by direct heating are that the component of the gas is unitary, and does not contain other components like a sulphide thus making the control and regulation of the process simple, and that the component (ferrous sulphide) of the sulphurized case at the surface is also unitary so that there is no influence or disturbance from other elements.
  • Sulphur is in a solid state under normal atmospheric pressure and has a boiling point of 441°C.
  • the boiling point is lowered at low pressure, for example the boiling point is 188.8°C at 1 torr (133.3 Pa), and is even less when the pressure decreases further.
  • parts or components located on a cathode table of a vacuum furnace can be sulphurized by means of heating and gasifying sulphur at low pressure (1 - 10 ⁇ 2 torr)(133.3 - 1.3 Pa), applying a direct voltage field to ionize the gasified sulphur and bombarding the cathode with the high-speed sulphur ions, thus sulphurizing the parts on the table.
  • the sulphur-containing gas is glow discharged under the action of a high voltage field of preferably 450 V - 1500 V and the duration of the discharge is preferably between 1 hour and 4 hours. Because of the glow discharge, the sulphurizing process is speeded up, the sulphurized case depth is increased and, in addition, the parts are heated solely by means of electron bombardment.
  • the temperature of the parts is controlled between 140°C and 300°C and is regulated by regulating the field voltage but in the prior art when the low voltages are used the parts are heated only by the inert gas in the chamber.
  • the means of heating and gasifying the sulphur is variable. For example, it may be carried out by means of a low voltage supply when sulphur is located on the cathode table, as in the prior art, or sulphur can be located in the furnace but not on the table, or it can be located outside the furnace.
  • the present invention also has the advantage that the gas-sulphurizing operation can be carried out following a carburizing, nitriding or carbonitriding process when the furnace temperature is lowered to the sulphurizing level. Thus the working hours and the energy resource consumption of the furnace can be reduced.
  • Figure 1 is a schematic diagram of equipment for carrying out a process according to the present invention.
  • a part 5 to be treated is located on a cathode table 4 in a reacting chamber 1 of a vacuum furnace.
  • the temperature of the part 5 is measured and controlled by a thermocouple 7 and a temperature meter 12.
  • Solid sulphur is loaded into a vaporizer 6 and the temperature of the vaporizer 6 is measured and controlled by a thermocouple 8 and a temperature meter 10.
  • the vaporizer 6 is heated by electric energy supplied from a low-voltage supply 11.
  • the vaporizer 6 shown in Figure 1 is located outside the reacting chamber 1 of the furnace but it could alternatively be located on the table 4 or still within the chamber 1 but off the cathode table 4.
  • a vacuum pump 16 is started and the air in the reacting chamber 1 is pumped out.
  • the pressure reaches about 10 ⁇ 2 torr (1.3 Pa)
  • the low voltage supply 11 is turned on and thus the temperature of the vaporizer 6 starts to rise.
  • solid sulphur will be gasified when the vaporizer 6 is heated to more than 140°C (the gasifying temperature of the solid sulphur ranges from 140°C to 200°C in this example).
  • the pressure in the chamber 1 gradually rises, the temperature of the 6 vaporizer being controlled by regulating the current supplied from the low-voltage supply 11.
  • the quantity of gas resulting from the sulphur gasifying process is regulated and controlled so that the pressure in the reacting chamber 1 is also controlled.
  • the pressure in the reacting chamber 1 is also controlled by regulating the relationship between the vaporizing speed and the pumping speed (i.e. the vacuum pump still keeps running).
  • a high voltage direct supply 3 (ranging between 0 and 1500 V) is turned on and the voltage controlled between 450 V and 1500 V.
  • a high voltage field is formed between the cathode table 4, the part 5 and an anode 2, which forms a plasma of ionized gaseous sulphur so that positive sulphur ions will bombard the cathode table 4 and the part 5 to create a glow discharge which raises the temperature of the part 5.
  • a case of sulphide is formed at the surface of the part 5.
  • the duration of the glow discharge is controlled between 1 hour and 4 hours and the temperature of the part 5 is controlled between 140°C and 300°C.
  • the temperature-controlling means is conventional.
  • the sulphurized rolling bearing was a 204 single-row radial ball bearing.
  • the bearing was subjected to a life test with a model 7501-type lever tester.
  • the testing conditions were: 2400 r/min, radial load 190 kg, no lubricant agent.
  • the bearing tested ran continuously for 200 hours without fatigue damage.
  • the same kind of bearing parts, ball, outer races, inner races and cages, not subjected to the sulphurizing process were all burnt when they ran for only 80 minutes, the shortest life being only 35 minutes. It was also found that the case depth of the sulphurized bearing was 120 ⁇ m, which is much greater than the case depth formed by other processes.
  • Ferrous sulphide is formed at the surface of the parts by means of the process and the case depth is generally between 100 and 120 ⁇ m.
  • the equipment described above is the basic equipment required. However, in order to make the equipment function properly, it should be equipped with some devices such as a vacuum gauge 9 for controlling pressure, a flow meter 19 for controlling flow, valves 13,14, and 18, a waste gas filter 17, a cold trap 15 for condensing reactant, a gas cylinder 20, and an observing window 21, which would all be known to those skilled in the art.
  • the present invention may be applied not only to parts made of steel or iron to form a ferrous sulphide case at the surface but also to parts made of other metal to form a different sulphide case at the surface, for example, to form NiS, NiS2 at the surface of parts made of Ni or Ni alloy, to form MoS2 at the surface of parts made of Mo and Mo alloy, to form CuS, CuS2 at the surface of parts made of Cu and Cu alloy, and to form CoS at the surface of parts made of Co and Co alloy.

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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)
  • Chemical Vapour Deposition (AREA)
EP86112510A 1985-09-10 1986-09-10 A process to form a sulphide case at the surface of a metal part Expired - Lifetime EP0218916B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN85106828A CN85106828B (zh) 1985-09-10 1985-09-10 金属零件表面形成硫化物层的方法及设备
CN85106828 1985-09-10

Publications (2)

Publication Number Publication Date
EP0218916A1 EP0218916A1 (en) 1987-04-22
EP0218916B1 true EP0218916B1 (en) 1991-12-27

Family

ID=4795305

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86112510A Expired - Lifetime EP0218916B1 (en) 1985-09-10 1986-09-10 A process to form a sulphide case at the surface of a metal part

Country Status (4)

Country Link
EP (1) EP0218916B1 (zh)
JP (1) JPS6289858A (zh)
CN (1) CN85106828B (zh)
DE (1) DE3683119D1 (zh)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH671407A5 (zh) * 1986-06-13 1989-08-31 Balzers Hochvakuum
FR2688010B1 (fr) * 1992-03-02 1995-02-24 Innovatique Sa Procede pour la formation, sur une piece d'acier ou d'alliage d'acier d'une couche superficielle en un compose sulfure presentant des proprietes antifriction.
CN1217438A (zh) * 1997-11-07 1999-05-26 张昕辉 金属基润滑耐磨功能梯度材料
CN1296515C (zh) * 2004-05-13 2007-01-24 上海交通大学 自辉光等离子体基离子注入或者注入且沉积装置
EP2210929B1 (en) 2007-10-31 2016-11-23 China Petroleum & Chemical Corporation A pre-passivation process for a continuous reforming apparatus
CN102505106A (zh) * 2011-12-30 2012-06-20 瓦房店轴承集团有限责任公司 风力发电主轴轴承的表面处理工艺
CN102776472A (zh) * 2012-07-23 2012-11-14 宁波市鸿博机械制造有限公司 提高汽车转向泵定子的耐磨性能的方法
CN103397305B (zh) * 2013-08-06 2015-08-26 深圳先进技术研究院 硒化/硫化处理装置
CN110408885B (zh) * 2019-08-27 2021-06-11 南京工程学院 一种车用轻型齿轮及其制造工艺

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1273518A (fr) * 1960-10-28 1961-10-13 Ass Elect Ind Perfectionnements aux appareils de vaporisation sous vide
GB1160895A (en) * 1965-08-25 1969-08-06 Rank Xerox Ltd Coating Surfaces by Vapour Deposition
GB1133397A (en) * 1966-09-08 1968-11-13 Hughes Aircraft Co Method for the rapid deposition of metallic films using a plasma of the material to be deposited
JPS5165039A (ja) * 1974-12-03 1976-06-05 Seiko Instr & Electronics Metsukihoho
US4039416A (en) * 1975-04-21 1977-08-02 White Gerald W Gasless ion plating
JPS5749219A (en) * 1980-09-08 1982-03-23 Ayao Wada Forming method for ionized thin film without necessity of direct gas plasma

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
Heat Treatment of Metals, Vol. 3, 1983, p. 6-9 *
Hubei-Mechanics, vol. 4, 1981, p.10-12 *
J. of China Textile Engineering Assoc., vol. 4, No. 2, 1983, p. 5-10 *

Also Published As

Publication number Publication date
DE3683119D1 (de) 1992-02-06
JPS6357501B2 (zh) 1988-11-11
CN85106828B (zh) 1987-09-09
CN85106828A (zh) 1987-03-11
JPS6289858A (ja) 1987-04-24
EP0218916A1 (en) 1987-04-22

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