WO2012152521A1 - Processus pour le traitement thermique de pièces moulées sous pression - Google Patents

Processus pour le traitement thermique de pièces moulées sous pression Download PDF

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Publication number
WO2012152521A1
WO2012152521A1 PCT/EP2012/056639 EP2012056639W WO2012152521A1 WO 2012152521 A1 WO2012152521 A1 WO 2012152521A1 EP 2012056639 W EP2012056639 W EP 2012056639W WO 2012152521 A1 WO2012152521 A1 WO 2012152521A1
Authority
WO
WIPO (PCT)
Prior art keywords
section
moulding
sintering
sintering section
evaporation
Prior art date
Application number
PCT/EP2012/056639
Other languages
English (en)
Inventor
Thomas Braun-Klabunde
Jens Mirschinka
Original Assignee
L'air Liquide,Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude
Air Liquide Deutschland G.M.B.H
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 L'air Liquide,Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude, Air Liquide Deutschland G.M.B.H filed Critical L'air Liquide,Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude
Publication of WO2012152521A1 publication Critical patent/WO2012152521A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • B22F3/1017—Multiple heating or additional steps
    • B22F3/1021—Removal of binder or filler
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/02—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity of multiple-track type; of multiple-chamber type; Combinations of furnaces
    • F27B9/028—Multi-chamber type furnaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/02—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity of multiple-track type; of multiple-chamber type; Combinations of furnaces
    • F27B9/029—Multicellular type furnaces constructed with add-on modules
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/04—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity adapted for treating the charge in vacuum or special atmosphere
    • F27B9/045—Furnaces with controlled atmosphere
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/04—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity adapted for treating the charge in vacuum or special atmosphere
    • F27B9/045—Furnaces with controlled atmosphere
    • F27B9/047—Furnaces with controlled atmosphere the atmosphere consisting of protective gases

Definitions

  • the present invention relates to a process for the heat treatment of a moulding, which has been pressed from a material powder and a pressing aid, in a continuous furnace.
  • the process is also referred to as sintering.
  • sintering first of all a moulding is pressed from a mixture of material powder, in particular metal or plastic powder, and a pressing aid.
  • the pressed moulding is also referred to as a green compact.
  • the moulding is heat-treated in a continuous furnace having an evaporation section and a sintering section.
  • the pressing aid first of all has to be removed from the moulding.
  • the moulding is heated to a temperature in the evaporation section at which the pressing aid evaporates.
  • the temperature of the moulding is increased to a temperature below the melting temperature of the material powder in the sintering section, in which case a bond is formed between the material powder particles by surface diffusion between the material powder particles and thus the moulding is bound.
  • Both the evaporation of the pressing aid and the sintering itself take place in a suitable gas atmosphere, with the composition of the gas being adapted to the requirements in the various sections.
  • the gases or gas mixtures are generally introduced counter to the conveying direction of the moulding.
  • an oxidizing atmosphere is set in the evaporation section, such that the gases which form during the evaporation of the pressing aid, for example hydrogen (H 2 ), carbon monoxide (CO) and hydrocarbons (C x H y ), can be oxidized.
  • humidified nitrogen (N 2 ) is fed into the evaporation section.
  • US 5,578,147 additionally discloses that the throughput rate of the mouldings or the furnace temperature is regulated during the evaporation process such that if possible all pressing aid constituents oxidize completely.
  • the conveyor belt of the continuous furnace which is regularly produced from high-alloy, heat-resistant steel, is carburized in the sintering section and decarburized again outside.
  • This intermittent carburization and decarburization of the conveyor belt leads to grain growth, depletion of alloying elements and embrittlement, which in turn can lead to considerable shortening of the service life of the conveyor belt and to loss of production, and this in turn leads to increased production costs.
  • the sintering process is impaired by the inevitable carburization of the metallic material powder.
  • an excessive formation of soot is observed in the sintering section, as too are a reduction in the density and an increase in the hardness and brittleness of the sintered mouldings.
  • a process for the heat treatment of at least one moulding which has been pressed from at least one material powder and at least one pressing aid, in a continuous furnace having an evaporation section and a sintering section, said process comprising at least the following steps: a) the moulding is introduced into the evaporation section,
  • the moulding is heated to a temperature which is suitable for the evaporation of the at least one pressing aid in the evaporation section, c) the moulding is conveyed from the evaporation section into the sintering section,
  • the moulding is heated to a temperature which lies below the melting temperature of the at least one material powder in the sintering section, e) at least one oxidizing gas is fed into the sintering section.
  • the material powder preferably comprises metallic powders, in particular powders of iron, copper, molybdenum, bronze and/or stainless steels with incorporated hard materials, for example tungsten carbide or titanium carbide.
  • the pressing aids preferably comprise stearates which contain a very high proportion of bound hydrocarbons.
  • Zinc stearate is used with particular preference as the pressing aid (see for example "Kieback, Bernd (Editor): Pulvermetallurgie. Technologien und Maschinenstoffe [Powder Metallurgy. Technologies and Materials], 2nd edition”).
  • the continuous furnace can be formed by a plurality of individual furnaces arranged in succession, in which case a temperature which is independent of the other furnaces can be set in each furnace.
  • the furnace can comprise precisely one furnace in which a predefinable temperature profile can be set, where the sections are defined by the temperatures which prevail during operation.
  • the individual sections of the furnace may also be separated from one another by skirts or the like, for example in order to reduce the gas exchange between the individual sections.
  • the mouldings are preferably conveyed from an inlet of the continuous furnace to an outlet of the continuous furnace with the aid of a conveying apparatus, e.g. a conveyor belt. The moulding therefore initially passes through the evaporation section and then the sintering section on the conveyor belt.
  • the sintering section of the continuous furnace is generally followed by cooling zones, in which the sintered moulding is cooled, usually in a protective gas atmosphere.
  • the temperature which prevails in step b) is at least so high that the pressing aid can evaporate completely, but not so high that a bond is formed with the material powder; in particular, the temperature in step b) is between 250°C and 700°C, preferably between 400°C and 6oo°C.
  • step d) The temperature which prevails in step d) is in particular so high that a bond is formed with the material powder, but the latter just does not melt; in particular, the temperature in step d) is between 8oo°C and 1500°C, preferably between iooo°C and 1300°C.
  • an oxidizing gas is fed into the sintering section.
  • the intention of the oxidizing gas is to oxidize the gaseous pressing aid constituents which have passed into the sintering section, such that carburization of the metallic materials in the sintering section is suppressed.
  • the carbon potential in the sintering section which is a measure of the possible carburization, is therefore lowered to a non-critical level, and is in particular above the soot limit.
  • the oxygen partial pressure is measured in the sintering section.
  • the oxygen partial pressure it is possible to determine in particular the carbon potential in the sintering section, and therefore the amount of oxidizing gas fed in in step e) can preferably be regulated depending on the carbon potential.
  • the oxygen partial pressure can be measured by means of known oxygen probes or known lambda probes. Therefore, the flow rate of the oxidizing gas fed in is increased or lowered until a predefined oxygen partial pressure is reached or until in particular a carbon potential of less than 0.2% is reached.
  • carbon dioxide (C0 2 ) is fed in as the oxidizing gas in step e).
  • a base gas comprising at least nitrogen (N 2 ), hydrogen (H 2 ) and/or methane (CH 4 ) to be fed into the continuous furnace counter to a conveying direction of the moulding.
  • the composition of the base gas can vary depending on the requirements in the individual sections of the continuous furnace. It is therefore preferable for a gas mixture of at most 5% oxidizing gas with base gas as the remainder to be fed into the sintering section, where the base gas in the sintering section comprises at most 2% methane, 3% to 10% hydrogen and remainder nitrogen.
  • the composition of the gas mixture depends on the nature of the mouldings, i.e. in particular on the geometry, on the material powder used, on the pressing aid used for the mouldings and on the conveying speed of the mouldings, and so on. It is particularly preferable for the pressing aid to be a stearate.
  • a further aspect of the invention proposes a continuous furnace for carrying out the process according to the invention, comprising an evaporation section, a sintering section, a conveying device for conveying the mouldings from an inlet to an outlet of the continuous furnace and at least one gas line for feeding gases into the sintering section.
  • the continuous furnace prefferably comprises a measuring sensor for measuring the oxygen partial pressure in the sintering section.
  • the continuous furnace prefferably comprise a control apparatus which is connected at least to the measuring sensor or a controllable valve in the at least one gas line.
  • a control apparatus which is connected at least to the measuring sensor or a controllable valve in the at least one gas line.
  • Fig. shows a continuous furnace for carrying out the process according to the invention.
  • the figure schematically shows a continuous furnace 2 having an evaporation section 3, a sintering section 4, a cooling section 7 and a conveying device 5 for conveying at least one moulding 1 through the continuous furnace 2 from an inlet 12 to an outlet 13.
  • the continuous furnace 2 furthermore comprises gas lines 6, by means of which gases or gas mixtures can be fed into the sections of the continuous furnace 2 via valves 10.
  • a measuring sensor 11 which is connected to a control apparatus 8 via a data line 9.
  • the control apparatus 8 is furthermore connected to the valves 10 for providing a gas atmosphere with a gas composition in the sections of the sintering furnace 2.
  • the moulding 1 which has been pressed from a material powder and a pressing aid passes through the continuous furnace 2 from the inlet 12 to the outlet 13.
  • the moulding 1 is first of all introduced into the evaporation section 3, where the pressing aid evaporates at temperatures of between 400°C and 6oo°C.
  • the moulding 1 passes into the sintering section 4, where the material powder is sintered at temperatures of between 1030°C and 1250°C.
  • the sintered moulding is cooled in the cooling section 7 with the supply of a protective gas atmosphere.
  • the constituents of the pressing aid evaporate in the evaporation section 3, in particular with the release of hydrogen, carbon monoxide and hydrocarbons.
  • carbon dioxide is added to the inherently reducing gas mixture of, for example, hydrogen and nitrogen in the sintering section 4.
  • the pressing aid constituents which have passed into the sintering section 4 are oxidized, and carburization of the metallic constituents and the deposition of soot in the system in the sintering section 4 are avoided.
  • the targeted introduction of an oxidizing gas into the sintering section 4 of a continuous furnace 2 makes it possible to suppress the deposition of soot in the system and the carburization of metallic materials, in particular of mouldings 1 in the sintering section 4.

Abstract

L'invention concerne un processus de traitement thermique d'au moins une pièce moulée 1, qui a été pressée à partir d'au moins un matériau en poudre et d'au moins un agent de compression, dans un four continu 2 comprenant une section 3 d'évaporation et une section 4 de frittage, ledit processus comportant au moins les étapes suivantes : a) la pièce moulée 1 est introduite dans la section 3 d'évaporation ; b) la pièce moulée 1 est chauffée jusqu'à une température qui convient pour l'évaporation du ou des agents de compression dans la section 3 d'évaporation ; c) la pièce moulée 1 est transportée de la section 3 d'évaporation dans la section 4 de frittage ; d) la pièce moulée 1 est chauffée jusqu'à une température située au-dessous de la température de fusion du ou des matériaux en poudre dans la section 4 de frittage ; e) au moins un gaz oxydant, en particulier du dioxyde de carbone, est amené dans la section 4 de frittage. Selon les enseignements de l'invention, l'introduction ciblée d'un gaz oxydant dans la section 4 de frittage d'un four continu 2 permet de limiter le dépôt de suie dans le système et la carburation des composants métalliques et de la pièce moulée 1 dans la section 4 de frittage.
PCT/EP2012/056639 2011-05-11 2012-04-12 Processus pour le traitement thermique de pièces moulées sous pression WO2012152521A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102011101264.1A DE102011101264B4 (de) 2011-05-11 2011-05-11 Verfahren zur Wärmebehandlung von gepressten Formteilen
DE102011101264.1 2011-05-11

Publications (1)

Publication Number Publication Date
WO2012152521A1 true WO2012152521A1 (fr) 2012-11-15

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DE (1) DE102011101264B4 (fr)
WO (1) WO2012152521A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3043135A1 (fr) * 2015-01-08 2016-07-13 Linde Aktiengesellschaft Appareil et procédé pour commander un processus de frittage
EP3042967A1 (fr) * 2015-01-08 2016-07-13 Linde Aktiengesellschaft Mélange de gaz et procédé pour commander un potentiel de carbone de l'atmosphère d'un four
JP2016527393A (ja) * 2013-07-01 2016-09-08 アイゼンマン ソシエタス オイロペア 焼結ワークピースを焼結する方法並びにこのための設備
CN112404449A (zh) * 2020-10-23 2021-02-26 中国科学技术大学 基于热冲击连续合成粉体材料的装置及方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5578147A (en) 1995-05-12 1996-11-26 The Boc Group, Inc. Controlled process for the heat treating of delubed material
EP0745446A1 (fr) * 1995-06-01 1996-12-04 Air Products And Chemicals, Inc. Atmosphères pour prolonger la vie des convoyeurs à bande en treillis utilisés pour fritter des composants en poudre métallique
US6303077B1 (en) * 1997-05-27 2001-10-16 Höganäs Ab Method of monitoring and controlling the composition of sintering atmosphere

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS589806B2 (ja) * 1977-03-30 1983-02-23 住友電気工業株式会社 粉末冶金用焼結炉
DE19960095A1 (de) * 1999-12-14 2001-07-05 Bosch Gmbh Robert Gesinterter weichmagnetischer Verbundwerkstoff und Verfahren zu dessen Herstellung
DE102009004829A1 (de) * 2009-01-13 2010-07-22 Gkn Sinter Metals Holding Gmbh Mischung zur Verhinderung von Oberflächenflecken

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5578147A (en) 1995-05-12 1996-11-26 The Boc Group, Inc. Controlled process for the heat treating of delubed material
EP0745446A1 (fr) * 1995-06-01 1996-12-04 Air Products And Chemicals, Inc. Atmosphères pour prolonger la vie des convoyeurs à bande en treillis utilisés pour fritter des composants en poudre métallique
US6303077B1 (en) * 1997-05-27 2001-10-16 Höganäs Ab Method of monitoring and controlling the composition of sintering atmosphere

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"Practical issues in the sintering of ferrous parts", METAL POWDER REPORT, MPR PUBLISHING SERVICES, SHREWSBURY, GB, vol. 49, no. 2, 1 February 1994 (1994-02-01), pages 26 - 30, XP024089131, ISSN: 0026-0657, [retrieved on 19940201], DOI: 10.1016/0026-0657(94)90421-9 *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016527393A (ja) * 2013-07-01 2016-09-08 アイゼンマン ソシエタス オイロペア 焼結ワークピースを焼結する方法並びにこのための設備
EP3043135A1 (fr) * 2015-01-08 2016-07-13 Linde Aktiengesellschaft Appareil et procédé pour commander un processus de frittage
EP3042967A1 (fr) * 2015-01-08 2016-07-13 Linde Aktiengesellschaft Mélange de gaz et procédé pour commander un potentiel de carbone de l'atmosphère d'un four
WO2016110450A1 (fr) * 2015-01-08 2016-07-14 Linde Aktiengesellschaft Mélange de gaz et procédé de régulation d'un potentiel de carbone d'une atmosphère de four
WO2016110449A1 (fr) * 2015-01-08 2016-07-14 Linde Aktiengesellschaft Appareil et procédé pour la commande d'un processus de frittage
CN107107197A (zh) * 2015-01-08 2017-08-29 林德股份公司 控制烧结过程的设备和方法
CN112404449A (zh) * 2020-10-23 2021-02-26 中国科学技术大学 基于热冲击连续合成粉体材料的装置及方法

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Publication number Publication date
DE102011101264A1 (de) 2012-11-15
DE102011101264B4 (de) 2022-05-19

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