EP0040023A1 - Gasaufkohlung - Google Patents

Gasaufkohlung Download PDF

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Publication number
EP0040023A1
EP0040023A1 EP81301882A EP81301882A EP0040023A1 EP 0040023 A1 EP0040023 A1 EP 0040023A1 EP 81301882 A EP81301882 A EP 81301882A EP 81301882 A EP81301882 A EP 81301882A EP 0040023 A1 EP0040023 A1 EP 0040023A1
Authority
EP
European Patent Office
Prior art keywords
gas
hydrocarbon
heat treatment
treatment chamber
air
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.)
Ceased
Application number
EP81301882A
Other languages
English (en)
French (fr)
Inventor
Alan Paterson
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 Products and Chemicals Inc
Original Assignee
Air Products and Chemicals 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 Air Products and Chemicals Inc filed Critical Air Products and Chemicals Inc
Publication of EP0040023A1 publication Critical patent/EP0040023A1/de
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—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
    • C23C8/20—Carburising
    • C23C8/22—Carburising of ferrous surfaces

Definitions

  • This invention relates to a method of gas carburizing.
  • carrier gas flowrates greater than R are employed hydrocarbon additions reduce the concentration of carbon dioxide and water in the furnace atmosphere and nominally raise the carbon potential of the atmosphere.
  • the ability of such atmospheres to provide carbon to the work is strictly limited and, in many cases, shallow and irregular cases are the best that can be obtained even after prolonged exposure to such atmospheres.
  • a method of gas carburizing using a carrier gas enriched with a hydrocarbon addition in a heat treatment chamber at or above 690°C wherein said carrier gas is formed by the partial or complete reaction of a rich mixture of a hydrocarbon selected from the group consisting of natural gas, methane, butane, propane and mixtures thereof together with air or oxygen-enriched air, characterized in that the volumetric ratio of said hydrocarbon to oxygen used to produce said carrier gas (discounting any hydrocarbon which does not react) is:
  • the present invention is applicable to both batch and semi-continuous carburizing furnaces.
  • Preferably D is between 2.5 and 10 and more preferably between 3 and 7.
  • the exothermic gas is preferably dried before being introduced into the heat treatment chamber as carrier gas.
  • said carrier gas is prepared by indirectly heating said air or oxygen-enriched air in said heat treatment chamber, mixing said heated air or oxygen enriched air with said hydrocarbon, reacting said mixture in a chamber within said heat treatment chamber and using the hot gas to preheat said air or oxygen-enriched air.
  • the carrier gas is prepared by premixing air or oxygen enriched air with said hydrocarbon, preheating said mixture, reacting said mixture in a chamber within but separate and distinct from said heat treatment chamber, and using the hot gas to preheat said mixture.
  • gas emerging from said chamber is at least partially dried before being introduced into said heat treatment chamber.
  • drying is carried out by withdrawing said gas from said chamber to a location outside the heat treatment chamber, cooling said gas to condense at least part of the water vapour therein, separating said condensed water from said gas and introducing the gas into the heat treatment chamber.
  • the hydrocarbon is natural gas or methane and said ratio of hydrocarbon to oxygen is between 1.0:1 and 1.35:1.
  • the ratio of hydrocarbon to oxygen is preferably between 2:1 and 2.6:1.
  • the present invention also provides an apparatus for producing a carrier gas for use in a method in accordance with the present invention, which apparatus comprises means mountable in said heat treatment chamber for heating air or oxygen enriched air, a chamber, and means for mixing said heated air or oxygen enriched air with a hydrocarbon selected from the group consisting of natural gas, methane, butane, propane and mixtures thereof in said chamber wherein said mixture can react and means for using the hot gas produced by said reaction to heat said air and/or oxygen enriched air.
  • a hydrocarbon selected from the group consisting of natural gas, methane, butane, propane and mixtures thereof in said chamber wherein said mixture can react and means for using the hot gas produced by said reaction to heat said air and/or oxygen enriched air.
  • the present invention further provides an apparatus for producing a carrier gas for use in a method in accordance with the present invention, which apparatus comprises an inner tube mountable in said heat treatment chamber for conveying a mixture of air or oxygen enriched air and hydrocarbon into the confines of said heat treatment chamber, a chamber downstream of said inner tube in which said mixture can combust, and an outer tube for directing the hot gas produced by said combustion along the outside of said inner tube to, in use, heat said mixture as it flows through said inner tube.
  • the apparatus includes means to dry the reacted mixture.
  • the means comprises means to cool said gas to condense water therefrom, and means to separate the remaining gas from said water.
  • the furnace 1 comprises a vestibule 2, a quench tank 3 and a heat treatment chamber 4 which is provided with a fan 5 and radient tubes 6 which maintain the heat treatment chamber 4 at approximately 925 0 C during carburizing.
  • a carrier gas comprising (by volume) was supplied to to the heat treatment chamber 4 through pipe 7.
  • the carrier gas was synthesised by the reaction of 1 volume of natural gas and 61 ⁇ 2 volumes air in an exothermic gas generator 8 and was subsequently dried to a dew point of 0°C using a refrigerator 90. Hydrocarbon addition was added from a pipe 10.
  • the carrier gas was formed by using an apparatus which is generally identified by reference numeral 11.
  • the apparatus 11 comprises an outer annular passageway 12 and an inner annular passageway 13 which are separated by a wall 14.
  • air is preheated by the hot gases in the heat treatment chamber as it flows from pipe 15 through outer annular passageway 11 and is then further heated as it flows along inner annular passageway 13 until it reaches holes 16 arranged circumjacent the outlet of a pipe 17 carrying hydrocarbon.
  • the preheated air or oxygen enriched air reacts with the hydrocarbon in chamber 18 to produce the carrier gas.
  • the dried carrier gas had an analysis of 17% H 2 , 11% CO, 4i% C0 2 and 2.3% H 2 0 (Dew Point 20°C) thereby raising RMAX to 203 scfh.
  • the nitrogen addition then became redundant and using a flow rate of 150 scfh almost identical metallurgical results were obtained.
  • apparatus 11 can be replaced with an apparatus which is generally identified by reference numeral 40.
  • the apparatus 40 comprises an inner tube 41 which conveys premixed air or oxygen enriched air and hydrocarbon to a chamber 42 where they combust.
  • the hot gas produced is directed along the outside of the inner tube 41 by an outer tube 43 and leaves via a pipe 44 from which it can either be fed directly into the heat treatment chamber or dried and fed to the heat treatment chamber as desired.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Hydrogen, Water And Hydrids (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
EP81301882A 1980-05-02 1981-04-28 Gasaufkohlung Ceased EP0040023A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8014712 1980-05-02
GB8104712A GB2076023B (en) 1980-05-02 1980-05-02 Gas carburising

Publications (1)

Publication Number Publication Date
EP0040023A1 true EP0040023A1 (de) 1981-11-18

Family

ID=10513185

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81301882A Ceased EP0040023A1 (de) 1980-05-02 1981-04-28 Gasaufkohlung

Country Status (3)

Country Link
EP (1) EP0040023A1 (de)
GB (1) GB2076023B (de)
ZA (1) ZA812877B (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994029491A1 (de) * 1993-06-03 1994-12-22 Loi Thermprocess Gmbh Verfahren und vorrichtung zum wärmebehandeln von werkstücken

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5259893A (en) * 1991-07-08 1993-11-09 Air Products And Chemicals, Inc. In-situ generation of heat treating atmospheres using a mixture of non-cryogenically produced nitrogen and a hydrocarbon gas
US5342455A (en) * 1991-07-08 1994-08-30 Air Products And Chemicals, Inc. In-situ generation of heat treating atmospheres using a mixture of non-cryogenically produced nitrogen and a hydrocarbon gas
US5827375A (en) * 1993-07-23 1998-10-27 Barbour; George E. Process for carburizing ferrous metal parts

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1382075A (en) * 1971-06-23 1975-01-29 Hayes Inc C I Methods for vacuum carburizing
US4006042A (en) * 1974-03-18 1977-02-01 Hawera Probst Kommanditgesellschaft Hartmetall-Werkzeugfabrik Ravensburg Method of and apparatus for hardening workpieces of steel
US4035203A (en) * 1973-12-21 1977-07-12 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Method for the heat-treatment of steel and for the control of said treatment
US4145232A (en) * 1977-06-03 1979-03-20 Union Carbide Corporation Process for carburizing steel
GB1544214A (en) * 1975-04-21 1979-04-19 Gen Atomic Co Method of coating items with pyrolytic carbon

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1382075A (en) * 1971-06-23 1975-01-29 Hayes Inc C I Methods for vacuum carburizing
USRE29881E (en) * 1971-06-23 1979-01-16 C. I. Hayes Inc. Method of vacuum carburizing
US4035203A (en) * 1973-12-21 1977-07-12 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Method for the heat-treatment of steel and for the control of said treatment
US4006042A (en) * 1974-03-18 1977-02-01 Hawera Probst Kommanditgesellschaft Hartmetall-Werkzeugfabrik Ravensburg Method of and apparatus for hardening workpieces of steel
GB1544214A (en) * 1975-04-21 1979-04-19 Gen Atomic Co Method of coating items with pyrolytic carbon
US4145232A (en) * 1977-06-03 1979-03-20 Union Carbide Corporation Process for carburizing steel

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994029491A1 (de) * 1993-06-03 1994-12-22 Loi Thermprocess Gmbh Verfahren und vorrichtung zum wärmebehandeln von werkstücken

Also Published As

Publication number Publication date
ZA812877B (en) 1982-04-28
GB2076023B (en) 1983-08-03
GB2076023A (en) 1981-11-25

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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

17P Request for examination filed

Effective date: 19810831

AK Designated contracting states

Designated state(s): AT BE CH DE FR IT LI LU NL SE

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

Free format text: STATUS: THE APPLICATION HAS BEEN REFUSED

18R Application refused

Effective date: 19841116

RIN1 Information on inventor provided before grant (corrected)

Inventor name: PATERSON, ALAN