EP1230415B1 - Method for nitro-carburization of metal workpieces - Google Patents
Method for nitro-carburization of metal workpieces Download PDFInfo
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- EP1230415B1 EP1230415B1 EP00962293A EP00962293A EP1230415B1 EP 1230415 B1 EP1230415 B1 EP 1230415B1 EP 00962293 A EP00962293 A EP 00962293A EP 00962293 A EP00962293 A EP 00962293A EP 1230415 B1 EP1230415 B1 EP 1230415B1
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- treatment
- carbon
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- temperature
- carbon dioxide
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- 238000000034 method Methods 0.000 title claims abstract description 32
- 239000002184 metal Substances 0.000 title abstract description 5
- 229910052751 metal Inorganic materials 0.000 title abstract description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 44
- 239000007789 gas Substances 0.000 claims abstract description 39
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 24
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 23
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 22
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 21
- 230000000694 effects Effects 0.000 claims abstract description 19
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000006243 chemical reaction Methods 0.000 claims abstract description 15
- 238000005255 carburizing Methods 0.000 claims abstract description 12
- 239000001257 hydrogen Substances 0.000 claims abstract description 7
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 7
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 7
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910002091 carbon monoxide Inorganic materials 0.000 claims abstract description 6
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 20
- 239000000852 hydrogen donor Substances 0.000 claims description 14
- 229910021529 ammonia Inorganic materials 0.000 claims description 10
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 9
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 6
- 239000000386 donor Substances 0.000 claims description 5
- 229930195733 hydrocarbon Natural products 0.000 claims description 4
- 150000002430 hydrocarbons Chemical class 0.000 claims description 4
- 239000004215 Carbon black (E152) Substances 0.000 claims description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 3
- 239000001301 oxygen Substances 0.000 claims description 3
- 229910052760 oxygen Inorganic materials 0.000 claims description 3
- 239000001294 propane Substances 0.000 claims description 3
- 239000012530 fluid Substances 0.000 claims description 2
- 239000003345 natural gas Substances 0.000 claims description 2
- 238000007865 diluting Methods 0.000 claims 1
- 150000002431 hydrogen Chemical class 0.000 claims 1
- 150000004767 nitrides Chemical class 0.000 abstract description 9
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 6
- 230000015572 biosynthetic process Effects 0.000 abstract description 5
- 238000005121 nitriding Methods 0.000 description 17
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 9
- 239000000203 mixture Substances 0.000 description 8
- 239000000126 substance Substances 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 3
- 238000005256 carbonitriding Methods 0.000 description 2
- 238000003763 carbonization Methods 0.000 description 2
- 238000003776 cleavage reaction Methods 0.000 description 2
- -1 ferrous metals Chemical class 0.000 description 2
- 230000007017 scission Effects 0.000 description 2
- 238000010744 Boudouard reaction Methods 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000003085 diluting agent Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 239000004071 soot Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
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
- C23C8/06—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
- C23C8/28—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 one step
- C23C8/30—Carbo-nitriding
Definitions
- the invention relates to a method for nitrocarburizing metallic workpieces, by placing the work pieces in a nitrogen, carbon monoxide and hydrogen containing treatment atmosphere at a treatment temperature in one Treatment room are treated, being used to generate the Treatment atmosphere carbon dioxide is used as a carbon donor.
- the nitrogen donor is basically ammonia (NH 3 ), while various gas mixtures such as air-hydrocarbon mixtures (endogas and exogas) and carbon dioxide are used as carbon donors. In the nitriding furnace, these gases react with the hydrogen present, with stationary carbon, nitrogen and oxygen activity depending on the thermal and chemical conditions.
- the atomic nitrogen produced during ammonia splitting reacts particularly easily with the metal to form nitrides upon contact with metal surfaces (hereinafter referred to as (N) ad ).
- Different nitride phases can form in connection with iron.
- nitride phases in the form of so-called ⁇ -nitride (Fe 2-3 N) and ⁇ '-nitride (Fe 4 N) or mixtures of these nitrides are preferred with regard to high hardness and wear resistance.
- the carbon dissolved in the nitride affects morphology, compactness, Pore hem and adhesion of the connection layer and its corrosion and Wear resistance.
- the carbon activity in turn depends on the one used Carbon donor. It falls in the order of propane, endogas, and exogas Carbon dioxide. Because the composition of the gas phase in the nitriding furnace has a significant influence on the result of nitrocarburization, it is beneficial if this is adjustable in the widest possible range.
- the carbon dioxide contents are usually between 4 and 10% by volume.
- K B denotes the constant of the Boudouard equilibrium.
- the maximum carbon activity is 1, which corresponds to the activity of pure graphite.
- K N nitriding index
- DE-C1 197 19 225 from which a method for controlling the nitriding index of a nitriding or nitrocarburizing atmosphere in a furnace system when using NH 3 as a nitrogen source is known.
- the known method is characterized in that the NH 3 gas throughput is kept constant and only the operating point of the prespattern in which the NH 3 split gas is generated is regulated.
- a high nitriding index requires a high ammonia content in the nitriding furnace, which in turn results in a high residual ammonia content in the furnace exhaust gas, which leaves the furnace unused.
- methanol does not cleave stoichiometrically, but undesirable cleavage products such as CH 4 and other higher hydrocarbons, CO 2 , aldehydes, ketones etc. are formed, some of which are toxic and corrosive when condensed.
- cleavage of the methanol strongly depends on the conditions of the boiler room and on the surface of the batch, so that the desired furnace gas composition cannot be reproduced. This has the further consequence that soot deposits on the batch material and the boiler room surface due to uncontrolled cracking reactions or that undesired carbides are formed.
- the invention is therefore based on the object, the known method for Nitrocarburizing metallic workpieces using carbon dioxide as Modify carbon donors so that the type and extent of nitride formation in are widely adjustable.
- This object is achieved in that a carbon dioxide-containing Gas flow introduced into a reactor upstream of the treatment room and therein by reaction with a hydrogen donor at a reaction temperature above the treatment temperature is modified to a carburizing gas that a higher carbon activity compared to the gas stream containing carbon dioxide at the treatment temperature.
- the carbon dioxide-containing cas stream is fed to a reactor modified in the direction of a higher carbon activity and then as Carbonization gas introduced into the treatment room.
- the process for nitrocarburizing metallic workpieces by the workpieces in a nitrogen, carbon monoxide and hydrogen containing Treatment atmosphere at one treatment temperature in one Treatment room are treated, being used to generate the Treatment atmosphere carbon dioxide is used as a carbon donor characterized in that a carbon dioxide-containing gas stream 1, 21 in a Treatment room 6, 27 upstream reactor 4, 24 initiated and therein Reaction with a hydrogen donor 2, 22 at a reaction temperature is modified to a carburizing gas 5, 25 above the treatment temperature, the one compared to the gas stream containing carbon dioxide 1, 21 higher Has carbon activity at the treatment temperature.
- a hydrocarbon-containing fluid is used as the hydrogen donor 2 used, in particular natural gas, propane or is used as a hydrogen donor Methane 2 used.
- Another method is called a hydrogen donor Ammonia 22 used.
- a splitting device 24 for ammonia is used in particular as a reactor.
- the carburizing gas 5, 25 is introduced into the Treatment room 6.27 moisture removed.
- the method there is preferably a regulation 9, 30 for the carbon activity provided in the treatment room 6, 27, in which the supply rate of a serves the hydrogen donor 2, 22 partial stream.
- the regulation 9.30 for the carbon activity includes a measurement of the oxygen activity 8, 29 and / or the carbon monoxide concentration in the treatment room 8.27.
- the Carbon dioxide-containing gas stream 1, 21, the carbonization gas 5.25 and / or the Partial stream for the hydrogen donor 2.22 becomes in particular a diluent gas 3, 23 added.
- the carburizing gas 25 is preferably introduced into the Treatment room 27 to a temperature in the range of the treatment temperature cooled.
- the carburizing gas 5 preferably has the introduction into the Treatment room 6 a temperature in the range of the reaction temperature.
- the treatment temperature is preferably in the range between 500 ° C and 700 ° C.
- the reaction temperature is preferably in the range between 800 and 1150 ° C.
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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)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
- Chemical Or Physical Treatment Of Fibers (AREA)
Abstract
Description
Die Erfindung betrifft ein Verfahren zum Nitrocarburieren metallischer Werkstücke, indem die Werkstücke in einer Stickstoff, Kohlenmonoxid und Wasserstoff enthaltenden Behandlungsatmosphäre bei einer Behandlungstemperatur in einem Behandlungsraum behandelt werden, wobei zur Erzeugung der Behandlungsatmosphäre Kohlendioxid als Kohlenstoffspender eingesetzt wird.The invention relates to a method for nitrocarburizing metallic workpieces, by placing the work pieces in a nitrogen, carbon monoxide and hydrogen containing treatment atmosphere at a treatment temperature in one Treatment room are treated, being used to generate the Treatment atmosphere carbon dioxide is used as a carbon donor.
Zum Nitrocarburieren von metallischen Werkstücken kommen verschiedene Gasgemische zum Einsatz. Stickstoffspender ist dabei grundsätzlich Ammoniak (NH3), während als Kohlenstoffspender verschiedene Gasgemische wie beispielsweise Luft- Kohlenwasserstoff-Gemische (Endogas und Exogas) sowie Kohlendioxid zum Einsatz kommen. Im Nitrierofen reagieren diese Gase mit vorhandenem Wasserstoff, wobei sich je nach thermischen und chemischen Bedingungen eine stationäre Kohlenstoff-, Stickstoff und Sauerstoffaktivität einstellt.Various gas mixtures are used to nitrocarburize metallic workpieces. The nitrogen donor is basically ammonia (NH 3 ), while various gas mixtures such as air-hydrocarbon mixtures (endogas and exogas) and carbon dioxide are used as carbon donors. In the nitriding furnace, these gases react with the hydrogen present, with stationary carbon, nitrogen and oxygen activity depending on the thermal and chemical conditions.
Der bei der Ammoniakspaltung entstehende atomare Stickstoff reagiert bei Kontakt
mit Metalloberflächen (im folgenden als (N)ad bezeichnet) besonders leicht mit dem
Metall unter Bildung von Nitriden. In Verbindung mit Eisen können sich
unterschiedliche Nitrid-Phasen bilden. Bei Stählen werden im Hinblick auf eine hohe
Härte und Verschleißfestigkeit beispielsweise Nitrid-Phasen in Form von
sogenanntem ε-Nitrid (Fe2-3N) und γ'-Nitrid (Fe4N) oder Gemische dieser Nitride
bevorzugt. Die bei der Nitridbildung von Fe-haltigen Metallen ablaufenden
Reaktionen lassen sich schematisch anhand folgender chemischer Gleichungen
beschreiben:
Der im Nitrid gelöste Kohlenstoff wirkt sich auf Morphologie, Kompaktheit, Porensaum und Haftung der Verbindungsschicht und deren Korrosions- und Verschleißbeständigkeit aus. Darüberhinaus hat es sich gezeigt, daß Art und Umfang der Nitridbildung durch die Kohlenstoffaktivität in der Nitrieratmosphäre wesentlich beeinflußt wird. Die Kohlenstoffaktivität wiederum hängt von dem eingesetzten Kohlenstoffspender ab. Sie fällt in der Reihenfolge Propan, Endogas, Exogas und Kohlendioxid ab. Da die Zusammensetzung der Gasphase im Nitrierofen somit wesentlichen Einfluß auf das Ergebnis der Nitrocarburierung hat, ist es günstig, wenn diese in möglichst weiten Bereichen einstellbar ist.The carbon dissolved in the nitride affects morphology, compactness, Pore hem and adhesion of the connection layer and its corrosion and Wear resistance. In addition, it has been shown that the type and scope nitride formation due to the carbon activity in the nitriding atmosphere being affected. The carbon activity in turn depends on the one used Carbon donor. It falls in the order of propane, endogas, and exogas Carbon dioxide. Because the composition of the gas phase in the nitriding furnace has a significant influence on the result of nitrocarburization, it is beneficial if this is adjustable in the widest possible range.
Bei den bekannten Gasgemischen liegen die Kohlendioxidgehalte üblicherweise
zwischen 4 und 10 Vol.-%. Das Kohlendioxid wird direkt in den Ofenraum des
Nitrierofens dosiert und reagiert dort teilweise mit Wasserstoff nach folgender
Reaktionsgleichung:
Üblicherweise wird der Nitrierofen permanent mit Frischgas durchströmt, so daß sich
in der Gasphase kein chemisches Gleichgewicht einstellt. Es ergibt sich dadurch eine
stationäre Kohlenstoffaktivität (ac,B), die im wesentlichen von konkreten
Gegebenheiten im Nitrierofen, wie etwa der Oberfläche der zu behandelnden
Werkstücke, der Nitriertemperatur, der Gaszusammensetzung und dem
Gasvolumenstrom abhängt und die von außen kaum zu regeln ist. Es pendelt sich
somit eine den vorherrschenden Gegebenheiten angepaßte Kohlenstoffaktivität (ac,B)
ein, die nach der Boudouard-Reaktion definiert werden kann:
KB bezeichnet dabei die Konstante des Boudouard-Gleichgewichts. Beim Einspeisen von Kohlendioxid direkt in den Nitrierofen stellt sich eine Kohlenstoffaktivität von maximal 1 ein, was einer Aktivität von reinem Graphit entspricht. Unter diesen Bedingungen kann die Bildung von ε-Nitrid (Fe2-3N) aber nur durch eine hohe Nitrierkennzahl (KN) von größer 1 realisiert werden. K B denotes the constant of the Boudouard equilibrium. When carbon dioxide is fed directly into the nitriding furnace, the maximum carbon activity is 1, which corresponds to the activity of pure graphite. Under these conditions, the formation of ε-nitride (Fe 2-3 N) can only be achieved by a high nitriding index (K N ) of greater than 1.
Im Hinblick hierauf ist auf die DE-C1 197 19 225 zu verweisen, aus der ein Verfahren für die Regelung der Nitrierkennzahl einer Nitrier- bzw. Nitrocarburieratmosphäre in einer Ofenanlage bei Einsatz von NH3 als Stickstoffquelle bekannt ist. Das bekannte Verfahren zeichnet sich dadurch aus, dass der NH3-Gasdurchsatz konstant gehalten wird, und lediglich der Arbeitspunkt des Vorspatters, in dem das NH3-Spaltgas erzeugt wird, geregelt wird. Eine hohe Nitrierkennzahl erfordert einen hohen Ammoniakgehalt im Nitrierofen, was wiederum einen hohen Rest-Ammoniakgehalt im Ofenabgas zur Folge hat, das ungenutzt den Ofen verläßt.With regard to this, reference is made to DE-C1 197 19 225, from which a method for controlling the nitriding index of a nitriding or nitrocarburizing atmosphere in a furnace system when using NH 3 as a nitrogen source is known. The known method is characterized in that the NH 3 gas throughput is kept constant and only the operating point of the prespattern in which the NH 3 split gas is generated is regulated. A high nitriding index requires a high ammonia content in the nitriding furnace, which in turn results in a high residual ammonia content in the furnace exhaust gas, which leaves the furnace unused.
Dieser Effekt stellt sich auch bei dem in der DE-A1 42 29 803 vorgeschlagenen Verfahren ein, wonach die Nitrierkennzahl für die Kontrolle einer Nitrier- bzw. Nitrocarburieratmosphäre eingesetzt wird, wobei die Nitrierkennzähl durch Messung des O2-Gehalts der Atmosphäre unter Einsatz einer O2-Sonde ermittelt wird.This effect also occurs in the process proposed in DE-A1 42 29 803, according to which the nitriding index is used to control a nitriding or nitrocarburizing atmosphere, the nitriding index being measured by measuring the O 2 content of the atmosphere using an O 2 probe is determined.
In der DE-A1 195 14 932 wird zur Erzeugung einer Carbonitrier- Atmosphäre vorgeschlagen, dem Ofen Kohlenwasserstoffe und eine oxidierende Komponente, wie Luft oder CO2, und Ammoniak direkt zuzuführen. Um einen geregelten, möglichst hohen CO-Gehalt in der Carbonitner-Atmosphäre zu erreichen, wird der CO-Gehalt gemessen und bei Erreichen einer vorgegebenen Untergrenze eine CO-bildende Substanz, wie Methanol, in den Ofenraum eingespeist Bei diesem Verfahren werden die CO-bildenden Komponenten wie Methanol oder CO2 somit direkt in den Behandlungsraum eingespeist. Beim Aufkohlen oder Carbonitrieren ist dies aufgrund der dabei herrschenden hohen Temperaturen effektiv, jedoch nicht bei den üblichen, relativ niedrigen Nitriertemperaturen von max. 580°C. Bei diesen niedrigeren Temperaturen spaltet Methanol nicht stöchiometrisch, sondern es bilden sich unerwünschte Spaltprodukte wie CH4 und andere höhere Kohlenwasserstoffe, CO2, Aldehyde, Ketone usw, die teilweise giftig und bei Kondensation ätzend sind. Zudem hängt die Spaltung des Methanols stark von den Gegebenheiten des Heizraumes und von der Chargenoberfläche ab, so dass die Reproduzierbarkeit der gewünschten Ofengaszusammensetzung nicht gegeben ist. Dies hat weiterhin zur Folge, dass sich durch unkontrollierten Spaltreaktionen Ruß auf dem Chargenmaterial und der Heizraumoberfläche abscheidet oder unerwünschte Carbide gebildet. In DE-A1 195 14 932 it is proposed to produce a carbonitriding atmosphere that hydrocarbons and an oxidizing component, such as air or CO 2 , and ammonia are fed directly to the furnace. In order to achieve a regulated, as high as possible CO content in the carbonitner atmosphere, the CO content is measured and a CO-forming substance, such as methanol, is fed into the furnace chamber when a predetermined lower limit is reached Components such as methanol or CO 2 are thus fed directly into the treatment room. When carburizing or carbonitriding, this is effective due to the high temperatures involved, but not at the usual, relatively low nitriding temperatures of max. 580 ° C. At these lower temperatures, methanol does not cleave stoichiometrically, but undesirable cleavage products such as CH 4 and other higher hydrocarbons, CO 2 , aldehydes, ketones etc. are formed, some of which are toxic and corrosive when condensed. In addition, the cleavage of the methanol strongly depends on the conditions of the boiler room and on the surface of the batch, so that the desired furnace gas composition cannot be reproduced. This has the further consequence that soot deposits on the batch material and the boiler room surface due to uncontrolled cracking reactions or that undesired carbides are formed.
Der Erfindung liegt daher die Aufgabe zugrunde, das bekannte Verfahren zum Nitrocarburieren metallischer Werkstücke unter Einsatz von Kohlendioxid als Kohlenstoffspender so zu modifizieren, daß Art und Umfang der Nitridbildung in weitem Rahmen einstellbar sind.The invention is therefore based on the object, the known method for Nitrocarburizing metallic workpieces using carbon dioxide as Modify carbon donors so that the type and extent of nitride formation in are widely adjustable.
Diese Aufgabe wird erfindungsgemaß dadurch gelöst, daß ein Kohlendioxid-haltiger Gasstrom in einen dem Behandlungsraum vorgeschalteten Reaktor eingeleitet und darin durch Reaktion mit einem Wasserstoffspender bei einer Reaktionstemperatur oberhalb der Behandlungstemperatur zu einem Kohlungsgas modifiziert wird, das eine im Vergleich zum Kohlendioxid-haltigen Gasstrom höhere Kohlenstoffaktivität bei der Behandlungstemperatur aufweist.This object is achieved in that a carbon dioxide-containing Gas flow introduced into a reactor upstream of the treatment room and therein by reaction with a hydrogen donor at a reaction temperature above the treatment temperature is modified to a carburizing gas that a higher carbon activity compared to the gas stream containing carbon dioxide at the treatment temperature.
Der Kohlendioxid-haltige Casstrom wird erfindungegemäß einem Reaktor zugeführt, darin in Richtung einer höheren Kohlenstoffaktivität modifiziert und anschließend als Kohlungsgas in den Behandlungsraum eingeleitet.According to the invention, the carbon dioxide-containing cas stream is fed to a reactor modified in the direction of a higher carbon activity and then as Carbonization gas introduced into the treatment room.
Das Verfahren wird anhand Fig. 1 und Fig. 2 erläutert.The method is explained with reference to FIGS. 1 and 2.
Das Verfahren zum Nitrocarburieren metallischer Werkstücke, indem die Werkstücke
in einer Stickstoff, Kohlenmonoxid und Wasserstoff enthaltenden
Behandlungsatmosphäre bei einer Behandlungstemperatur in einem
Behandlungsraum behandelt werden, wobei zur Erzeugung der
Behandlungsatmosphäre Kohlendioxid als Kohlenstoffspender eingesetzt wird, ist
dadurch gekennzeichnet, daß ein Kohlendioxid-haltiger Gasstrom 1, 21 in einen dem
Behandlungsraum 6, 27 vorgeschalteten Reaktor 4, 24 eingeleitet und darin durch
Reaktion mit einem Wasserstoffspender 2, 22 bei einer Reaktionstemperatur
oberhalb der Behandlungstemperatur zu einem Kohlungsgas 5, 25 modifiziert wird,
das eine im Vergleich zum Kohlendioxid-haltigen Gasstrom 1, 21 höhere
Kohlenstoffaktivität bei der Behandlungstemperatur aufweist.The process for nitrocarburizing metallic workpieces by the workpieces
in a nitrogen, carbon monoxide and hydrogen containing
Treatment atmosphere at one treatment temperature in one
Treatment room are treated, being used to generate the
Treatment atmosphere carbon dioxide is used as a carbon donor
characterized in that a carbon dioxide-containing
Bei dem Verfahren wird als Wasserstoffspender ein Kohlenwasserstoff-haltiges Fluid
2 eingesetzt, insbesondere wird als Wasserstoffspender Erdgas, Propan oder
Methan 2 eingesetzt. Bei einem anderen Verfahren wird als Wasserstoffspender
Ammoniak 22 eingesetzt.In the process, a hydrocarbon-containing fluid is used as the
Bei dem Verfahren, bei dem als Wasserstoffspender Ammoniak 22 eingesetzt wird,
wird als Reaktor insbesondere ein Spaltgerät 24 für Ammoniak eingesetzt.
Insbesondere wird bei dem Verfahren dem Kohlungsgas 5, 25 vor Einleitung in den
Behandlungsraum 6,27 Feuchtigkeit entzogen.In the process in which
Bei dem Verfahren ist vorzugsweise eine Regelung 9, 30 für die kohlenstoffaktivität
im Behandlungsraum 6, 27 vorgesehen, bei der als Stellgröße die Zufuhrrate eines
den Wasserstoffspender 2, 22 enthaltenden Teilstromes dient. Die Regelung 9,30
für die Kohlenstoffaktivität umfaßt eine Messung der Sauerstoffaktivität 8, 29
und/oder der Kohlenmonoxidkonzentration im Behandlungsraum 8,27. Dem
Kohlendioxid-haltigen Gasstrom 1, 21, dem Kohlungsgas 5,25 und/oder dem
Teilstrom für den Wasserstoffspender 2,22 wird insbesondere ein Verdünnungsgas
3, 23 beigemischt.In the method there is preferably a
Bei dem Verfahren wird vorzugsweise das Kohlungsgas 25 vor Einleitung in den
Behandlungsraum 27 auf eine Temperatur im Bereich der Behandlungstemperatur
abgekühlt.In the method, the
Bei dem Verfahren weist vorzugsweise das Kohlungsgas 5 bei Einleitung in den
Behandlungsraum 6 eine Temperatur im Bereich der Reaktionstemperatur auf.In the method, the
Bei dem Verfahren liegt die Behandlungstemperatur vorzugsweise im Bereich zwischen 500 °C und 700°C.In the process, the treatment temperature is preferably in the range between 500 ° C and 700 ° C.
Bei dem Verfahren liegt die Reaktionstemperatur vorzugsweise im Bereich zwischen 800 und 1150 °C.In the process, the reaction temperature is preferably in the range between 800 and 1150 ° C.
Claims (13)
- A process for nitrocarburizing metallic workpieces, by treating the workpieces in a treatment atmosphere, which contains nitrogen, carbon monoxide and hydrogen, at a treatment temperature in a treatment chamber, in which carbon dioxide is used as carbon donor to produce the treatment atmosphere, wherein a carbon dioxide-containing gas stream (1; 21) is introduced into a reactor (4; 24) which is connected upstream of the treatment chamber (6; 27) and, in that reactor, is modified by reaction with a hydrogen donor (2; 22) at a reaction temperature which is higher than the treatment temperature to form a carburizing gas (5; 25) which at the treatment temperature has a carbon activity which is higher than the carbon dioxide-containing gas stream (1; 21).
- The process as claimed in claim 1, wherein a hydrocarbon-containing fluid (2) is used as hydrogen donor.
- The process as claimed in claim 1 or 2, wherein natural gas, propane or methane (2) is used as hydrogen donor.
- The process as claimed in claim 1, wherein ammonia (22) is used as hydrogen donor.
- The process as claimed in claim 4, wherein a cleaving unit (24) for ammonia is used as reactor.
- The process as claimed in claim 4 or 5, wherein moisture is extracted from the carburizing gas (5; 25) before it is introduced into the treatment chamber (6; 27 ) .
- The process as claimed in one of claims 1 to 6, wherein a means (9; 30) for controlling the carbon activity in the treatment chamber (6; 27) is provided, in which the feed rate of a partial stream containing the hydrogen donor is used as control variable.
- The process as claimed in claim 7, wherein the means (9; 30) for controlling the carbon activity comprises measuring the oxygen activity (8; 29) and/or the carbon monoxide concentration in the treatment chamber (6; 27).
- The process as claimed in one of claims 7 or 8, wherein a diluting gas (3; 23) is admixed with the carbon dioxide-containing gas stream (1; 21), the carburizing gas (5; 25) and/or the partial stream for the hydrogen donor (2; 22).
- The process as claimed in one of claims 1 to 9, wherein the carburizing gas (25), before being introduced into the treatment chamber (27), is cooled to a temperature which is in the region of the treatment temperature.
- The process as claimed in one of claims 1 to 9, wherein the carburizing gas (25), when it is introduced into the treatment chamber (6), is at a temperature which is in the region of the reaction temperature.
- The process as claimed in one of claims 1 to 11, wherein the treatment chamber is in the range between 500°C and 700°C.
- The process as claimed in one of claims 1 to 12, wherein the reaction temperature is in the range between 800 and 1150°C.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19940370A DE19940370C2 (en) | 1999-08-25 | 1999-08-25 | Process for nitrocarburizing metallic workpieces |
| DE19940370 | 1999-08-25 | ||
| PCT/EP2000/007576 WO2001014611A1 (en) | 1999-08-25 | 2000-08-04 | Method for nitro-carburization of metal workpieces |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP1230415A1 EP1230415A1 (en) | 2002-08-14 |
| EP1230415B1 true EP1230415B1 (en) | 2004-01-14 |
Family
ID=7919599
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP00962293A Expired - Lifetime EP1230415B1 (en) | 1999-08-25 | 2000-08-04 | Method for nitro-carburization of metal workpieces |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP1230415B1 (en) |
| AT (1) | ATE257865T1 (en) |
| CZ (1) | CZ298996B6 (en) |
| DE (2) | DE19940370C2 (en) |
| ES (1) | ES2214316T3 (en) |
| PL (1) | PL195105B1 (en) |
| WO (1) | WO2001014611A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6801111B2 (en) | 2002-08-21 | 2004-10-05 | Square D Company | Latch for an electrical device |
| US7621201B2 (en) * | 2008-03-05 | 2009-11-24 | Gm Global Technology Operations, Inc. | Hot forming tools for aluminum and magnesium sheets |
| DE102023133600A1 (en) * | 2022-12-01 | 2024-06-06 | Gottfried Pöckl | Process for nitriding components |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0024106B1 (en) * | 1979-07-09 | 1986-01-02 | Ford Motor Company Limited | Method of heat treating ferrous workpieces |
| JPH01129957A (en) * | 1987-11-13 | 1989-05-23 | Toyota Motor Corp | Surface treatment for maraging steel |
| DE3937699A1 (en) * | 1989-11-13 | 1991-05-16 | Thaelmann Schwermaschbau Veb | Producing epsilon carbonitride coatings on ferrous components - by controlling gas mixt. compsn. with respect to nitriding and carburising indices required to produce predetermined coating compsn. |
| DE4229803A1 (en) * | 1992-09-11 | 1994-03-17 | Iva Industrieoefen Verfahren A | Control of nitriding and nitro:carburising atmospheres - by oxygen probe using fully dissociated gas as reference gas |
| DE19514932A1 (en) * | 1995-04-22 | 1996-10-24 | Ipsen Ind Int Gmbh | Method and device for regulating the CO content of an oven atmosphere for carburizing and carbonitriding metallic workpieces |
| DE19652125C1 (en) * | 1996-12-14 | 1998-04-30 | Volker Dipl Ing Leverkus | Nitriding or carbonitriding atmosphere regulation |
| DE19719225C1 (en) * | 1997-05-07 | 1998-08-06 | Volker Dipl Ing Leverkus | Method and apparatus for controlling a nitriding or nitro-carburising atmosphere |
-
1999
- 1999-08-25 DE DE19940370A patent/DE19940370C2/en not_active Expired - Fee Related
-
2000
- 2000-08-04 PL PL00353217A patent/PL195105B1/en unknown
- 2000-08-04 EP EP00962293A patent/EP1230415B1/en not_active Expired - Lifetime
- 2000-08-04 CZ CZ20020645A patent/CZ298996B6/en not_active IP Right Cessation
- 2000-08-04 DE DE50005043T patent/DE50005043D1/en not_active Expired - Lifetime
- 2000-08-04 WO PCT/EP2000/007576 patent/WO2001014611A1/en not_active Ceased
- 2000-08-04 AT AT00962293T patent/ATE257865T1/en not_active IP Right Cessation
- 2000-08-04 ES ES00962293T patent/ES2214316T3/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CZ2002645A3 (en) | 2003-02-12 |
| ATE257865T1 (en) | 2004-01-15 |
| ES2214316T3 (en) | 2004-09-16 |
| WO2001014611A1 (en) | 2001-03-01 |
| DE50005043D1 (en) | 2004-02-19 |
| DE19940370A1 (en) | 2001-03-01 |
| CZ298996B6 (en) | 2008-04-02 |
| EP1230415A1 (en) | 2002-08-14 |
| PL353217A1 (en) | 2003-11-03 |
| PL195105B1 (en) | 2007-08-31 |
| DE19940370C2 (en) | 2001-07-12 |
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