EP0401482B1 - Wear resistant sintered alloy, especially for valve seats for internal combustion engines - Google Patents

Wear resistant sintered alloy, especially for valve seats for internal combustion engines Download PDF

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EP0401482B1
EP0401482B1 EP90105398A EP90105398A EP0401482B1 EP 0401482 B1 EP0401482 B1 EP 0401482B1 EP 90105398 A EP90105398 A EP 90105398A EP 90105398 A EP90105398 A EP 90105398A EP 0401482 B1 EP0401482 B1 EP 0401482B1
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weight
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sintered alloy
weight per
parts
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French (fr)
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EP0401482A3 (en
EP0401482A2 (en
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Kirit Dipl.-Ing. Dalal
Hans-Jochem Dr. Neuhäuser
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DALAL Kirit
Goetze GmbH
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0207—Using a mixture of prealloyed powders or a master alloy
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
    • F01L3/22—Valve-seats not provided for in preceding subgroups of this group; Fixing of valve-seats

Definitions

  • the invention relates to a wear-resistant sintered alloy based on iron as a matrix with embedded hard phases, its manufacture and its use for, in particular, valve seat rings for the lead-free and lead-containing fuel operation of internal combustion engines.
  • Valve seat rings of internal combustion engines are exposed to high mechanical loads, especially at the exhaust valve, under the simultaneous action of the very hot combustion gases and must accordingly consist of wear-resistant and heat-resistant materials.
  • Sintered materials best meet these conditions, so that today valve seat rings mostly consist of special sintered metal alloys with possibly additions to hard phases.
  • Organic lead compounds as additives to lead-containing fuels form lead combustion products during combustion in the engine, which are deposited in particular on the valve seat rings with the formation of coatings with a wear-protecting and corrosion-protecting effect.
  • sintered valve seat rings for lead-free operation are known, the matrix of which consists of a high-alloy steel alloy, in which 8 to 14 volume percent hard phases are finely distributed, consisting of a mixture of a chromium-tungsten-cobalt - Iron carbides are made with ferromolybdenum.
  • the free pores of the sintered material can additionally be filled with copper or copper alloys by impregnation or infiltration.
  • valve seat ring materials specially developed for lead-free fuels are not wear and corrosion resistant enough when operating with fuels containing lead. Deposits of lead combustion products lead to lead oxide corrosion phenomena with these sintered materials, and the vestile seat rings quickly become permeable during operation and show increased wear.
  • the sintered materials developed for lead-free operation are not yet ideally suited for mixed operation when used in lead-containing and lead-free fuels, as is common in practice.
  • the present invention is therefore based on the object of providing an inexpensive and therefore economical sintered material for valve seat rings for internal combustion engines in particular, which can be used in mixed operation with lead-free and lead-containing fuel with, above all, improved wear resistance, heat resistance, warm hardness and corrosion resistance.
  • the manufacture of the sintered material should be simple and inexpensive, above all due to its shape-specific processability.
  • this object is achieved by a sintered material, the matrix metal of which consists of a martensitic iron with 0.6 to 1.5 percent by weight of carbon and 0.2 to 2 percent by weight of manganese, as well as production-related impurities, and the finely divided hard phases of 5 to 20 percent by weight Intermetallic phases with iron, molybdenum, chromium and silicon exist.
  • the preferred intermetallic phase consists of an iron alloy with 20 to 40 weight percent molybdenum, 5 to 20 percent by weight of chromium, 0.5 to 4 percent by weight of silicon and iron as the remainder. To improve the heat resistance, the intermetallic phase can also contain 20 to 30 percent by weight of cobalt.
  • the embedded hard phase can also consist of a mixture of binary or ternary intermetallic phases from the metals iron-chromium-molybdenum-silicon, and a mixture of the intermetallic phases of ferro-molybdenum, molybdenum-silicon and is preferred as a mixture Chromium silicon is used, which is added to the matrix metal to 5 to 20 percent by weight.
  • the intermetallic phases are mixed together with the iron powder and pressed in the mold at a pressure between 600 and 800 MN / m2 to form valve seat rings, which are then sintered for 30 to 60 minutes at 1,100 to 1,300 ° C under protective gas or in a vacuum will.
  • the rings can be post-compacted at 800 to 900 MN / m2, and tempering treatment can be followed by one-hour austenitizing annealing at around 900 ° C, quenching in oil and tempering for one hour at around 250 ° C to form a martensitic structure that is as uniform as possible .
  • valve seat rings obtained were shown in Engine tests in mixed operation in lead-containing and lead-free fuels were tested, and after running times of over 500 hours, no significant signs of wear were found on the exhaust valve either.
  • the valve seat rings according to the invention show a uniformly improved corrosion behavior and thus improved wear behavior with good heat resistance at the same time.
  • the micrograph shows a predominantly martensitic basic structure of the matrix, in which the specified hard intermetallic phases are present undissolved and finely distributed.
  • the powder mixture as the starting material for sintering the valve seat rings has good flow properties and compressibility properties with low ejection resistance on the pressing tool. This increases the lifespan of the pressing tools and valve seat rings can be pressed to size. This enables economical mass production without significant mechanical reworking of the valve seat rings.
  • the iron powder used as the matrix metal is water-atomized iron powder, the content of dissolved 0.6 to 1.5 percent by weight of carbon ensures the formation of the martensitic structure. Less than 0.6 percent by weight of carbon in the basic structure would result in a ferritic structure, and contents of over 1.5 percent by weight would undesirably embrittle the matrix metal with the formation of cementite.
  • 1 to 5 percent by weight of nickel and / or 1 to 3 percent by weight of copper can be added to the sintered alloy. Smaller amounts than 1 percent by weight are not effective enough, and larger amounts than 3 to 5 percent by weight would deteriorate the dimensional accuracy and machinability of the sintered workpieces.
  • molybdenum disulfide and / or manganese sulfide can be added to the sintered powder mixture in amounts of 1 to 3 percent by weight.
  • the sulfides act as solid lubricants, with the manganese sulfide in particular facilitating the machining of the valve seat rings that may be required.
  • the finished sintered workpiece can also be impregnated or infiltrated with copper or copper alloys to improve the thermal conductivity. Corresponds to the free pores in the sintered material then the copper or copper alloy content between 10 and 20 percent by weight.
  • the invention thus creates a sintered material which is suitable for the production of valve seat rings for use with both lead-containing and lead-free fuels.
  • the corrosion resistance of the sintered material is equally good in both fuels, and at the same time the high wear resistance and heat resistance ensure a long service life of the sintered material when used as a valve seat ring.
  • the matrix metal used is only weakly alloyed and therefore inexpensive, and the intermetallic phases used are inexpensive commercially available.
  • the processability of the sintered powder mixture composed according to the invention is good and therefore economical.
  • the sintered powder mixture has good flow and compressibility properties, so that the powder mixture can also be used for the fully automated mass production of valve seat rings with low ejection resistance and therefore low tool wear.
  • the dimensional accuracy is so good that valve seat rings in particular can be pressed and sintered directly within the required dimensional tolerances. Expensive post-processing is eliminated or reduced to a minimum.
  • the sintered material according to the invention is preferred as a valve seat ring for exhaust valves in particular in mixed-mode internal combustion engines, it is also possible to use the sintered material according to the invention for the production of similarly loaded machine parts, especially in mixed-mode internal combustion engines. Particularly because of the good processability properties, the low price and the excellent technological properties, machine parts outside of the application for internal combustion engines can also advantageously be produced with the sintered material according to the invention.
  • the connected sintering takes place over 35 minutes at 1,190 ° C in a protective gas atmosphere made of 80% nitrogen and 20% hydrogen.
  • the sintered density of the sintered material is 6.9 g / cm3, and the subsequent pressing is carried out to a density of 7.25 g / cm3 at a pressure of 850 MN / m2.
  • the sintered bodies are austenitized for one hour at 900 ° C, quenched in oil and left in air for one hour at 250 ° C.
  • the micrograph shows the structure of the sintered alloy according to the invention in a magnification of 1,500 times.
  • the matrix metal 1 is martensitic and, in addition to the unfilled pores 2, contains the intermetallic hard phases 3 that are embedded.
  • the hot hardness of the sintered material is at room temperature 330 HB and at 600 ° C 200 HB
  • valve seat rings were over in the engine test Tested 500 hours corresponding to a mileage of 80,000 km in both unleaded and unleaded fuel.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Powder Metallurgy (AREA)

Description

Die Erfindung betrifft eine verschleißfeste Sinterlegierung auf der Basis von Eisen als Matrix mit eingelagerten harten Phasen, ihre Herstellung und ihre Verwendung für insbesondere Ventilsitzringe für den bleifreien und bleihaltigen Kraftstoffbetrieb von Verbrennugnskraftmaschinen.The invention relates to a wear-resistant sintered alloy based on iron as a matrix with embedded hard phases, its manufacture and its use for, in particular, valve seat rings for the lead-free and lead-containing fuel operation of internal combustion engines.

Ventilsitzringe von Verbrennungskraftmaschinen sind vor allem am Auslaßventil hohen mechanischen Belastungen unter gleichzeitiger Einwirkung der sehr heißen Verbrennungsgase ausgesetzt und müssen entsprechend aus vor allem verschleißfesten und warmfesten Werkstoffen bestehen. Sinterwerkstoffe erfüllen diese Bedingungen am besten, so daß heute Ventilsitzringe meistens aus speziellen Sintermetallegierungen mit gegebenenfalls Zusätzen an harten Phasen bestehen. Organische Bleiverbindungen als Zusätze an bleihaltigen Kraftstoffen bilden bei der Verbrennung im Motor Bleiverbrennungsprodukte, die sich insbesondere auch auf den Ventilsitzringen unter Bildung von Überzügen mit verschleißschützender und korrosionsschützender Wirkung abscheiden.Valve seat rings of internal combustion engines are exposed to high mechanical loads, especially at the exhaust valve, under the simultaneous action of the very hot combustion gases and must accordingly consist of wear-resistant and heat-resistant materials. Sintered materials best meet these conditions, so that today valve seat rings mostly consist of special sintered metal alloys with possibly additions to hard phases. Organic lead compounds as additives to lead-containing fuels form lead combustion products during combustion in the engine, which are deposited in particular on the valve seat rings with the formation of coatings with a wear-protecting and corrosion-protecting effect.

Bei Verwendung bleifreier Kraftstoffe entfällt diese Schutzwirkung, und man mußte daher bei der Umstellung von bleihaltigen auf bleifreie Kraftstoffe neue Sinterwerkstoffe mit vor allem verbesserter Verschleißfestigkeit entwickeln. Bewährt haben sich dabei Sinterwerkstoffe aus gesinterten Schnellstahllegierungen mit in dieser Matrix eingelagerten, fein verteilten Metallkarbiden.This is not applicable when using lead-free fuels Protective effect, and therefore one had to develop new sintered materials with above all improved wear resistance when switching from leaded to lead-free fuels. Sintered materials made of sintered high-speed steel alloys with finely distributed metal carbides embedded in this matrix have proven successful.

Nach beispielsweise der US-A-4.505.988 sind gesinterte Ventilsitzringe für den bleifreien Betrieb bekannt, deren Matrix aus einer hochlegierten Stahllegierung besteht, in die 8 bis 14 Volumenprozent harte Phasen fein verteilt eingelagert sind, die aus einem Gemisch eines Chrom-Wolfram-Kobalt-Eisen-Karbids mit Ferromolybdän bestehen. Die freien Poren des Sinterwerkstoffes können dabei zusätzlich durch Imprägnation beziehungsweise Infiltration mit Kupfer oder Kupferlegierungen gefüllt sein.According to US Pat. No. 4,505,988, for example, sintered valve seat rings for lead-free operation are known, the matrix of which consists of a high-alloy steel alloy, in which 8 to 14 volume percent hard phases are finely distributed, consisting of a mixture of a chromium-tungsten-cobalt - Iron carbides are made with ferromolybdenum. The free pores of the sintered material can additionally be filled with copper or copper alloys by impregnation or infiltration.

Diese Sinterlegierungen sind durch die hohen Anteile an Legierungsmetallen relativ teuer und aufwendig in der Herstellung. Vor allem aber sind diese speziell für bleifreie Kraftstoffe entwickelten Ventilsitzringwerkstoffe im Betrieb von bleihaltigen Kraftstoffen nicht verschleiß- und korrosionsbeständig genug. Ablagerungen von Bleiverbrennungsprodukten führen bei diesen Sinterwerkstoffen zu Bleioxidkorrosionserscheinungen, und die Vestilsitzringe werden im Betrieb schnell durchlässig und weisen erhöhten Verschleiß auf. Die für den bleifreien Betrieb entwickelten Sinterwerkstoffe sind für den Mischbetrieb bei Verwendung in bleihaltigen und bleifreien Kraftstoffen, wie er in der Praxis üblich ist, noch nicht ideal geeignet.Due to the high proportions of alloy metals, these sintered alloys are relatively expensive and complex to manufacture. Above all, however, these valve seat ring materials specially developed for lead-free fuels are not wear and corrosion resistant enough when operating with fuels containing lead. Deposits of lead combustion products lead to lead oxide corrosion phenomena with these sintered materials, and the vestile seat rings quickly become permeable during operation and show increased wear. The sintered materials developed for lead-free operation are not yet ideally suited for mixed operation when used in lead-containing and lead-free fuels, as is common in practice.

Der vorliegenden Erfindung liegt daher die Aufgabe zugrunde, einen kostengünstigen und dadurch wirtschaftlichen Sinterwerkstoff für insbesondere Ventilsitzringe für Verbrennungskraftmaschinen zu schaffen, der im Mischbetrieb mit Belastung durch bleifreien und durch bleihaltigen Kraftstoff mit vor allem verbesserter Verschleißfestigkeit, Warmfestigkeit, Warmhärte und Korrosionsbeständigkeit eingesetzt werden kann. Die Herstellung des Sinterwerkstoffes soll vor allem durch formgenaue Verarbeitbarkeit einfach und kostengünstig sein.The present invention is therefore based on the object of providing an inexpensive and therefore economical sintered material for valve seat rings for internal combustion engines in particular, which can be used in mixed operation with lead-free and lead-containing fuel with, above all, improved wear resistance, heat resistance, warm hardness and corrosion resistance. The manufacture of the sintered material should be simple and inexpensive, above all due to its shape-specific processability.

Erfindungsgemäß wird diese Aufgabe durch einen Sinterwerkstoff gelost, dessen Matrixmetall aus einem martensitischen Eisen mit 0,6 bis 1,5 Gewichtsprozent Kohlenstoff und 0,2 bis 2 Gewichtsprozent Mangan sowie herstellungsbedingten Verunreinigungen besteht, und dessen fein verteilt eingelagerte harte Phasen aus 5 bis 20 Gewichtsprozent intermetallischen Phasen mit Eisen, Molybdän, Chrom und Silizium bestehen. Die bevorzugt eingesetzte intermetallische Phase besteht dabei aus einer Eisenlegierung mit 20 bis 40 Gewichtsprozent Molybdän, 5 bis 20 Gewichtsprozent Chrom, 0,5 bis 4 Gewichtsprozent Silizium und Eisen als Rest. Zur Verbesserung der Warmfestigkeit kann die intermetallische Phase noch 20 bis 30 Gewichtsprozent Kobalt enthalten.According to the invention, this object is achieved by a sintered material, the matrix metal of which consists of a martensitic iron with 0.6 to 1.5 percent by weight of carbon and 0.2 to 2 percent by weight of manganese, as well as production-related impurities, and the finely divided hard phases of 5 to 20 percent by weight Intermetallic phases with iron, molybdenum, chromium and silicon exist. The preferred intermetallic phase consists of an iron alloy with 20 to 40 weight percent molybdenum, 5 to 20 percent by weight of chromium, 0.5 to 4 percent by weight of silicon and iron as the remainder. To improve the heat resistance, the intermetallic phase can also contain 20 to 30 percent by weight of cobalt.

Im Sinne der Erfindung kann aber auch die eingelagerte harte Phase aus einem Gemisch binärer oder ternärer intermetallischer Phasen aus den Metallen Eisen-Chrom-Molybdän-Silizium bestehen, und als bevorzugtes Gemisch wird ein Gemisch der intermetallischen Phasen von Ferro-Molybdän, Molybdän-Silizium und Chrom-Silizium verwendet, das zu 5 bis 20 Gewichtsprozent dem Matrixmetall zugegeben wird.In the sense of the invention, however, the embedded hard phase can also consist of a mixture of binary or ternary intermetallic phases from the metals iron-chromium-molybdenum-silicon, and a mixture of the intermetallic phases of ferro-molybdenum, molybdenum-silicon and is preferred as a mixture Chromium silicon is used, which is added to the matrix metal to 5 to 20 percent by weight.

Zur Herstellung des Sinterwerkstoffes werden die intermetallischen Phasen zusammen mit dem Eisenpulver gemischt und in der Form bei einer Preßkraft zwischen 600 und 800 MN/m² zu Ventilsitzringen verpreßt, die dann anschließend 30 bis 60 Minuten bei 1.100 bis 1.300°C unter Schutzgas oder im Vakuum fertiggesintert werden. Zusätzlich können die Ringe bei 800 bis 900 MN/m² nachverdichtet werden, und es kann sich eine Vergütungsbehandlung durch einstündiges Austenitisierungsglühen bei etwa 900°C, Abschrecken in Öl und Anlassen über eine Stunde bei etwa 250°C zur Ausbildung eines möglichst einheitlichen martensitischen Gefüges anschließen.To produce the sintered material, the intermetallic phases are mixed together with the iron powder and pressed in the mold at a pressure between 600 and 800 MN / m² to form valve seat rings, which are then sintered for 30 to 60 minutes at 1,100 to 1,300 ° C under protective gas or in a vacuum will. In addition, the rings can be post-compacted at 800 to 900 MN / m², and tempering treatment can be followed by one-hour austenitizing annealing at around 900 ° C, quenching in oil and tempering for one hour at around 250 ° C to form a martensitic structure that is as uniform as possible .

Die erhaltenen Ventilsitzringe wurden in Motorversuchen im Mischbetrieb in bleihaltigen und bleifreien Kraftstoffen getestet, und es wurden nach Laufzeiten von über 500 Stunden auch am Auslaßventil keine nennenswerten Verschleißerscheinungen festgestellt. Die erfindungsgemäßen Ventilsitzringe zeigen im Mischbetrieb ein einheitlich verbessertes Korrosionsverhalten und damit verbessertes Verschleißverhalten bei gleichzeitig guter Warmfestigkeit.The valve seat rings obtained were shown in Engine tests in mixed operation in lead-containing and lead-free fuels were tested, and after running times of over 500 hours, no significant signs of wear were found on the exhaust valve either. In mixed operation, the valve seat rings according to the invention show a uniformly improved corrosion behavior and thus improved wear behavior with good heat resistance at the same time.

Das Schliffbild zeigt ein überwiegend martensitisches Grundgefüge der Matrix, in der die angegebenen harten intermetallischen Phasen ungelöst fein verteilt eingelagert vorliegen. Dadurch wird das Aufreißen der Oberfläche des Sinterwerkstoffes durch wiederholte Schlagbeanspruchung vermieden und die mechanische Bearbeitbarkeit des Sinterwerkstoffes nicht beeinträchtigt.The micrograph shows a predominantly martensitic basic structure of the matrix, in which the specified hard intermetallic phases are present undissolved and finely distributed. As a result, the tearing of the surface of the sintered material by repeated impact stress is avoided and the mechanical workability of the sintered material is not impaired.

Das Pulvergemisch als Ausgangsmaterial zum Sintern der Ventilsitzringe besitzt gute Fließeigenschaften und Verpreßbarkeitseigenschaften bei geringem Ausstoßwiderstand am Preßwerkzeug. Dadurch wird die Lebensdauer der Preßwerkzeuge erhöht, und es können Ventilsitzringe maßgenau verpreßt werden. Dadurch ist eine wirtschaftliche Massenfertigung ohne wesentliche mechanische Nachbearbeitung der Ventilsitzringe möglich.The powder mixture as the starting material for sintering the valve seat rings has good flow properties and compressibility properties with low ejection resistance on the pressing tool. This increases the lifespan of the pressing tools and valve seat rings can be pressed to size. This enables economical mass production without significant mechanical reworking of the valve seat rings.

Das als Matrixmetall verwendete Eisenpulver ist wasserverdüstes Eisenpulver, dessen Gehalt an gelöstem 0,6 bis 1,5 Gewichtsprozent Kohlenstoff für die Ausbildung des martensitischen Gefüges sorgt. Weniger als 0,6 Gewichtsprozent Kohlenstoff im Grundgefüge würde ein ferritisches Gefüge ergeben, und Gehalte von über 1,5 Gewichtsprozent würden unter Zementitbildung das Matrixmetall unerwünscht verspröden.The iron powder used as the matrix metal is water-atomized iron powder, the content of dissolved 0.6 to 1.5 percent by weight of carbon ensures the formation of the martensitic structure. Less than 0.6 percent by weight of carbon in the basic structure would result in a ferritic structure, and contents of over 1.5 percent by weight would undesirably embrittle the matrix metal with the formation of cementite.

Zur weiteren Verbesserung der Härte, der Verschleißfestigkeit und der Maßhaltigkeit kann der Sinterlegierung 1 bis 5 Gewichtsprozent Nickel und/oder 1 bis 3 Gewichtsprozent Kupfer zugegeben werden. Kleinere Mengen als 1 Gewichtsprozent sind dabei nicht wirksam genug, und größere Mengen als 3 bis 5 Gewichtsprozent würden die Maßhaltigkeit und mechanische Bearbeitbarkeit der Sinterwerkstücke verschlechtern. Zusätzlich kann dem Sinterpulvergemisch Molybdändisulfid und/oder Mangansulfid in Mengen von 1 bis 3 Gewichtsprozent zugegeben werden. Die Sulfide wirken als Festschmierstoffe, wobei insbesondere das Mangansulfid die eventuell erforderliche spanabhebende Bearbeitung der Ventilsitzringe erleichtert.To further improve the hardness, wear resistance and dimensional stability, 1 to 5 percent by weight of nickel and / or 1 to 3 percent by weight of copper can be added to the sintered alloy. Smaller amounts than 1 percent by weight are not effective enough, and larger amounts than 3 to 5 percent by weight would deteriorate the dimensional accuracy and machinability of the sintered workpieces. In addition, molybdenum disulfide and / or manganese sulfide can be added to the sintered powder mixture in amounts of 1 to 3 percent by weight. The sulfides act as solid lubricants, with the manganese sulfide in particular facilitating the machining of the valve seat rings that may be required.

Das fertige Sinterwerkstück kann zusätzlich zur Verbesserung vor allem der Wärmeleitfähigkeit mit Kupfer oder Kupferlegierungen imprägniert beziehungsweise infiltriert werden. Entsprechend den im Sinterwerkstoff vorliegenden freien Poren liegt dann der Kupfer- oder Kupferlegierungsgehalt zwischen 10 und 20 Gewichtsprozent.The finished sintered workpiece can also be impregnated or infiltrated with copper or copper alloys to improve the thermal conductivity. Corresponds to the free pores in the sintered material then the copper or copper alloy content between 10 and 20 percent by weight.

Durch die Erfindung ist somit ein Sinterwerkstoff geschaffen, der sich zur Herstellung von Ventilsitzringen für den Einsatz mit sowohl bleihaltigen als auch bleifreien Kraftstoffen eignet. In beiden Kraftstoffen ist die Korrosionsbeständigkeit des Sinterwerkstoffes gleichermaßen gut, und gleichzeitig sorgt die hohe Verschleißfestigkeit und Warmfestigkeit für eine lange Lebensdauer des Sinterwerkstoffes beim Einsatz als Ventilsitzring. Das verwendete Matrixmetall ist nur schwach legiert und dadurch preiswert, und die verwendeten intermetallischen Phasen sind preiswert im Handel erhältlich. Die Verarbeitbarkeit des erfindungsgemäß zusammengesetzten Sinterpulvergemisches ist gut und dadurch wirtschaftlich. Einmal besitzt das Sinterpulvergemisch gute Fließ- und Verpreßbarkeitseigenschaften, so daß sich das Pulvergemisch bei geringem Ausstoßwiderstand und dadurch geringem Werkzeugverschleiß auch zur vollautomatischen Massenfertigung von Ventilsitzringen einsetzen läßt. Zum anderen ist auch die Maßhaltigkeit so gut, daß sich gerade Ventilsitzringe innerhalb der geforderten maßlichen Toleranzen direkt pressen und sintern lassen. Eine verteuernde Nachbearbeitung entfällt oder wird auf ein Minimum reduziert.The invention thus creates a sintered material which is suitable for the production of valve seat rings for use with both lead-containing and lead-free fuels. The corrosion resistance of the sintered material is equally good in both fuels, and at the same time the high wear resistance and heat resistance ensure a long service life of the sintered material when used as a valve seat ring. The matrix metal used is only weakly alloyed and therefore inexpensive, and the intermetallic phases used are inexpensive commercially available. The processability of the sintered powder mixture composed according to the invention is good and therefore economical. On the one hand, the sintered powder mixture has good flow and compressibility properties, so that the powder mixture can also be used for the fully automated mass production of valve seat rings with low ejection resistance and therefore low tool wear. On the other hand, the dimensional accuracy is so good that valve seat rings in particular can be pressed and sintered directly within the required dimensional tolerances. Expensive post-processing is eliminated or reduced to a minimum.

Während der erfindungsgemäße Sinterwerkstoff bevorzugt als Ventilsitzring für insbesondere Auslaßventile in im Mischbetrieb arbeitenden Verbrennungskraftmaschinen eingesetzt werden soll, ist es auch möglich, den erfindungsgemäßen Sinterwerkstoff für die Herstellung ähnlich belasteter Maschinenteile vor allem in im Mischbetrieb arbeitenden Verbrennungskraftmaschinen zu verwenden. Insbesondere wegen der guten Verarbeitbarkeitseigenschaften, des geringen Preises und der ausgezeichneten technologischen Eigenschaften können mit dem erfindungsgemäßen Sinterwerkstoff gegebenenfalls auch Maschinenteile außerhalb der Anwendung für Verbrennungskraftmaschinen vorteilhaft hergestellt werden.While the sintered material according to the invention is preferred as a valve seat ring for exhaust valves in particular in mixed-mode internal combustion engines, it is also possible to use the sintered material according to the invention for the production of similarly loaded machine parts, especially in mixed-mode internal combustion engines. Particularly because of the good processability properties, the low price and the excellent technological properties, machine parts outside of the application for internal combustion engines can also advantageously be produced with the sintered material according to the invention.

Die Erfindung wird durch ein Ausführungsbeispiel näher erläutert.The invention is explained in more detail by an embodiment.

Ausgegangen wird:

  • A) von einem wasserverdüstem Eisenpulver sowie zugemischtem 0,7 Gewichtsprozent Kohlenstoff und herstellungsbedingten Verunreinigungen
  • B) von einer wasserverdüsten intermetallischen Phase in Pulverform aus 30 Gewichtsprozent Molybdän, 3 Gewichtsprozent Silizium und 10 Gewichtsprozent Chrom sowie Eisen als Rest.
It is assumed:
  • A) from a water-atomized iron powder and admixed 0.7 percent by weight carbon and manufacturing-related impurities
  • B) a water-atomized intermetallic phase in powder form from 30 percent by weight molybdenum, 3 percent by weight silicon and 10 percent by weight chromium and iron as the rest.

90 Gewichtsteile des Pulvers A) und 10 Gewichtsteile des Pulvers B) sowie 1,5 Gewichtsteile Mangansulfidpulver und 1,5 Gewichtsteile Molybdändisulfidpulver werden miteinander gemischt und bei einem Preßdruck von 800 MN/m² in Formen zu Ventilsitzringen auf eine Preßdichte von 6,85 g/cm³ verpreßt.90 parts by weight of powder A) and 10 parts by weight of powder B) and 1.5 parts by weight of manganese sulfide powder and 1.5 parts by weight of molybdenum disulfide powder are mixed together and pressed at a pressure of 800 MN / m² in molds into valve seat rings to a compression density of 6.85 g / cm³.

Das angeschlossene Sintern erfolgt über 35 Minuten bei 1.190°C in einer Schutzgasatmosphäre aus 80 % Stickstoff und 20 % Wasserstoff. Die Sinterdichte des Sinterwerkstoffes beträgt 6,9 g/cm³, und anschließend erfolgt das Nachpressen auf eine Dichte von 7,25 g/cm³ bei einem Druck von 850 MN/m².The connected sintering takes place over 35 minutes at 1,190 ° C in a protective gas atmosphere made of 80% nitrogen and 20% hydrogen. The sintered density of the sintered material is 6.9 g / cm³, and the subsequent pressing is carried out to a density of 7.25 g / cm³ at a pressure of 850 MN / m².

Zur Wärmebehandlung werden die Sinterkörper eine Stunde bei 900°C austenitisiert, in Öl abgeschreckt und eine Stunde bei 250°C in Luft angelassen.For the heat treatment, the sintered bodies are austenitized for one hour at 900 ° C, quenched in oil and left in air for one hour at 250 ° C.

Das Schliffbild zeigt in 1.500-facher Vergrößerung das Gefüge der erfindungsgemäßen Sinterlegierung. Das Matrixmetall 1 ist martensitisch und enthält neben den ungefüllten Poren 2 die eingelagerten intermetallischen harten Phasen 3.The micrograph shows the structure of the sintered alloy according to the invention in a magnification of 1,500 times. The matrix metal 1 is martensitic and, in addition to the unfilled pores 2, contains the intermetallic hard phases 3 that are embedded.

Die Warmhärte des Sinterwerkstoffes beträgt bei Raumtemperatur 330 HB und bei 600°C 200 HB The hot hardness of the sintered material is at room temperature 330 HB and at 600 ° C 200 HB

Die Ventilsitzringe wurden im Motortest über 500 Stunden entsprechend einer Laufleistung von 80.000 km sowohl in bleihaltigem Kraftstoff als auch in bleifreiem Kraftstoff geprüft.The valve seat rings were over in the engine test Tested 500 hours corresponding to a mileage of 80,000 km in both unleaded and unleaded fuel.

In beiden Fällen wiesen die Auslaßventilsitzringe nur geringe, nicht störende Verschleißerscheinungen auf und waren nach dem Test voll funktionsfähig.In both cases, the exhaust valve seat rings showed only minor, non-disturbing signs of wear and were fully functional after the test.

Claims (9)

  1. Wear-resistant sintered alloy based on iron as matrix with intercalated hard phases for producing valve seat rings for operation with lead-containing and lead-free fuels for internal combustion engines, characterized in that the iron is martensitic and contains 0,6 to 1,5 weight per cent of carbon and 0,2 to 2 weight per cent of manganese, and in that the finely divided intercalated hard phases (3) are 5 to 20 weight per cent and consist of intermetallic phases with iron, molybdenum, chromium and silicon.
  2. Sintered alloy according to claim 1, characterized in that the intercalated intermetallic phase (3) consists of an iron alloy with 20 to 40 weight per cent of molybdenum, 5 to 20 weight per cent of chromium, 0,5 to 4 weight per cent of silicon and the remainder iron.
  3. Sintered alloy according to claim 2, characterised in that the intermetallic phase contains 20 to 30 weight per cent of cobalt.
  4. Wear resistant sintered alloy according to claim 1, characterised in that the intermetallic phase (3) consists of a mixture of ferro-molybdenum, molybdenum-silicon and chromium-silicon.
  5. Wear-resistant sintered alloy according to at least one of claims 1 to 4, characterised in that the sintered alloy contains 1 to 5 weight per cent of nickel and/or 1 to 3 weight per cent copper.
  6. Wear-resistant sintered alloy according to at least one of claims 1 to 5, characterised in that the sintered alloy contains 1 to 3 weight per cent of molybdenum disulphide (MoS₂) and/or 1 to 3 weight per cent of manganese sulphide (MnS).
  7. Process for producing the sintered alloy according to at least one of claims 1 to 6, characterised in that 5 to 20 parts by weight of intermetallic phase (3) are homogeneously mixed with 80 to 95 parts by weight of iron alloy (1) and optionally 1 to 5 parts by weight of nickel powder, 1 to 3 parts by weight of copper powder, 1 to 3 parts by weight of molybdenum disulphide (MoS₂), and/or 1 to 3 parts by weight of manganese sulphide (MnS), in that the powder mixture is pressed in moulds at 600 to 800 MN/m² to form moulded parts, in that the moulded parts are sintered in protective gas for 30 to 60 minutes at 1,100 to 1,300 °C, and in that the sintered moulded parts are repressed at 800 to 900 MN/m².
  8. Process according to claim 7, characterised in that the final pressed moulded parts are heat-treated by austenitising for one hour at 900 °C, by quenching in oil and age-hardening for one hour at 250 °C.
  9. Sintered alloy according to at least one of claims 1 to 6, characterised in that the free pores (2) of the sintered alloy are filled with copper or a copper alloy by infiltration.
EP90105398A 1989-06-09 1990-03-22 Wear resistant sintered alloy, especially for valve seats for internal combustion engines Revoked EP0401482B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3918875 1989-06-09
DE3918875 1989-06-09

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EP0401482A2 EP0401482A2 (en) 1990-12-12
EP0401482A3 EP0401482A3 (en) 1991-05-02
EP0401482B1 true EP0401482B1 (en) 1994-06-15

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EP90105398A Revoked EP0401482B1 (en) 1989-06-09 1990-03-22 Wear resistant sintered alloy, especially for valve seats for internal combustion engines

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EP (1) EP0401482B1 (en)
DE (1) DE59006107D1 (en)
ES (1) ES2055200T3 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2698808B1 (en) * 1992-12-07 1995-01-20 Renault Material for friction parts operating in a lubricated medium, and process for obtaining it.
JP3011076B2 (en) * 1995-10-31 2000-02-21 トヨタ自動車株式会社 Cylinder head of internal combustion engine
JP3346321B2 (en) 1999-02-04 2002-11-18 三菱マテリアル株式会社 High strength Fe-based sintered valve seat
GB0105721D0 (en) * 2001-03-08 2001-04-25 Federal Mogul Sintered Prod Sintered ferrous materials
CN103357863B (en) * 2013-06-21 2016-12-28 安徽吉思特智能装备有限公司 A kind of High abrasion resistant metallurgy valve seat and preparation method thereof

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4123265A (en) * 1974-02-21 1978-10-31 Nippon Piston Ring Co., Ltd. Method of producing ferrous sintered alloy of improved wear resistance
JPS56249A (en) * 1979-06-13 1981-01-06 Mazda Motor Corp Hard-grain-dispersed sintered alloy for valve seat
JPS5925959A (en) * 1982-07-28 1984-02-10 Nippon Piston Ring Co Ltd Valve seat made of sintered alloy
JPS5985847A (en) * 1982-11-08 1984-05-17 Mitsubishi Metal Corp Fe-base sintered material for sliding member of internal-combustion engine

Also Published As

Publication number Publication date
EP0401482A3 (en) 1991-05-02
DE59006107D1 (en) 1994-07-21
ES2055200T3 (en) 1994-08-16
EP0401482A2 (en) 1990-12-12

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