EP0554683A1 - Method to change the surface of castings by powder impregnating - Google Patents
Method to change the surface of castings by powder impregnating Download PDFInfo
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- EP0554683A1 EP0554683A1 EP93100455A EP93100455A EP0554683A1 EP 0554683 A1 EP0554683 A1 EP 0554683A1 EP 93100455 A EP93100455 A EP 93100455A EP 93100455 A EP93100455 A EP 93100455A EP 0554683 A1 EP0554683 A1 EP 0554683A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D19/00—Casting in, on, or around objects which form part of the product
- B22D19/08—Casting in, on, or around objects which form part of the product for building-up linings or coverings, e.g. of anti-frictional metal
Definitions
- the invention relates to a method for impregnating or embedding hard, wear-resistant phases in surface layers of metal products which are produced by pouring liquid metal.
- metal products for example made of iron
- the surfaces are coated, for example, by flame spray coating or plasma spray coating.
- flame spray coating or plasma spray coating a disadvantage of these processes is that the surface layers can flake off during the coating process and when the products are used. There are also high procedural costs.
- the mechanical properties of cast iron made by an EPC process are inferior to that of sand or core castings due to the presence of carbon defects. Furthermore, the EPC process requires special precautionary measures to keep small changes in shape during casting.
- the EPC process in a conventional foundry requires the installation of special devices.
- the cast products can have shape deviations which can be attributed to shape deviations of the foam models.
- the sand molding method for casting carbides known from the prior art requires carbide balls, which can make the process more expensive. Increased costs can also result from the requirement that the wear-resistant surface be formed flat. In this case, the cast product must be smoothed and a surface layer removed, which corresponds approximately to half the diameter of the spherical particles.
- the invention remedies this and proposes a method for embedding hard, wear-resistant phases in surface layers of metal products which are produced by pouring liquid metal into casting molds.
- a flowable mass which contains wear-resistant material, is shaped in such a way that a disc or layer is formed with preferably a series of pegs, projections, spikes or the like. This layer is sintered and adhered to a surface of the mold before the metal is cast.
- the projections result in a better bond between the wear-resistant material and the cast one Metal than is the case when using spherical sintered carbide particles.
- the present invention can basically be applied to the casting of any known metal through which a carbide surface can be wetted.
- Metals that can be used are, for example, iron, aluminum and the like.
- Cast iron, especially spheroidal graphite cast iron or gray cast iron is preferred for the most common wear-resistant carbide types, such as, for example, chromium carbide and the like.
- a first step involves forming a thin sheet or plate that contains wear-resistant material.
- the invention can be successfully applied with any hard phase known from the prior art, for example with carbides such as tungsten carbide and chromium carbide or with aluminum compounds and the like.
- the hard phases can be replaced by powder of any metal, an intermetallic compound or a ceramic material, which is determined by the matrix material (embedding material) used, such as. B. wetting iron or an alloy known from the prior art.
- aluminum can be used to improve the surface wear resistance of cast iron or nickel by forming intermetallic aluminum compounds. Suitable materials such as nickel or iron can also be used in aluminum casting.
- the wear-resistant material can be a metallic binder, e.g. B. from the iron group, preferably cobalt for the use of tungsten carbides or nickel for the use of chromium carbides, etc., included.
- a metallic binder e.g. B. from the iron group
- cobalt for the use of tungsten carbides or nickel for the use of chromium carbides, etc.
- particles containing tungsten carbide with a weight fraction of 14 to 17% cobalt are preferred for the casting of ductile iron.
- the size of the particles is not critical in the practice of the present invention, it becomes fine-grained Particles preferred which have a mesh size of 140/325 (approx. 110 to 50 microns) or finer.
- the thin plate is produced by mixing a powder of hard, wear-resistant material with a suitable organic binder, for example a 10% polyvinyl alcohol solution, and a suitable hardener, for example 2-ethylhexyl diphenyl phosphate, phosphate ester hardener (e.g. KRONITEX 3600 from FMC Corporation, USA) or a mixture of these hardeners.
- a suitable organic binder for example a 10% polyvinyl alcohol solution
- a suitable hardener for example 2-ethylhexyl diphenyl phosphate, phosphate ester hardener (e.g. KRONITEX 3600 from FMC Corporation, USA) or a mixture of these hardeners.
- the mixture forms a flowable mass with suitable rheological properties so that the mass can be brought into the form of a disk or plate.
- any hardener and / or organic binder that can be processed effectively with a certain hard, wear-resistant material is suitable for carrying out the invention.
- a pattern is formed on an outwardly facing surface of the thin plate, which has a structure that allows an improvement in the impregnation of the iron.
- Any pattern shape that has at least a peg, a peg, a protrusion, or the like that prevents lateral movement of the thin plate during casting is suitable.
- a hexagonal or waffle-shaped structure can be applied to the surface of the thin plate (FIG. 1).
- Other suitable patterns include circular, elliptical and similar structures.
- the pegs can take any conceivable shape that gives a desired contour to keep the distance of metal penetration small during casting.
- the pattern can be molded by suitable means, for example by using a stamp with the desired pattern is pressed onto the surface of the still flowable, plastic, thin plate.
- the thin plate is then dried, for example in an oven at 100 ° C., until it forms a dimensionally stable body.
- the thin plate is then sintered under suitable conditions so that on the one hand it achieves sufficient porosity and on the other hand it is stable enough to withstand further processing and / or the use of further process steps.
- suitable conditions include a 300 to 360 minute vacuum sintering process at about 1200 to 1250 ° C.
- the sintered thin plate described above consists of a porous sinter mixture with partial densifications (Fig. 2).
- This partially or sintered thin plate can now be fastened in a known manner on a suitable mold surface, for example on a cast core, so that the patterned surface comes into contact with the cast core.
- a suitable mold surface for example on a cast core
- a high-temperature carbon is used here according to an embodiment of the invention.
- the layer is then z. B. heated in an oven to 100 ° C so that the volatile constituents are expelled from the adhesive and the adhesive cures.
- the high temperature adhesive must have a flow temperature that is higher than the casting temperature of the metal.
- any adhesive in this regard is suitable, but an inorganic high-temperature adhesive is particularly preferred.
- a binder which contains a high-temperature ceramic adhesive, e.g. B. a high temperature binder, which is available from Aremco Products, Inc., USA under the trade name Ceramabond 569 is sold and contains, for example, oxides of aluminum, silicon and potassium in an aqueous colloidal suspension which has a maximum service temperature of approximately 1650 ° C.
- the liquid metal flows around the layer of hard, wear-resistant material, whereby any of the known casting methods, for example gravity casting, pressure die casting, vacuum casting or the like, can be used.
- gravity-based casting is preferred because of its ease of handling.
- the wear-resistant material partially dissolves in the casting metal and separates there as an integral part.
- chrome carbide partially dissolves in molten iron and solidifies again there.
- the microstructure of such a composite is shown in Fig. 3, which also shows that the composite is bonded to the iron substrate in such a way that it cannot be easily detached therefrom.
- Fig. 4 shows the ground surface of a composite in which the iron "network" surrounding the composite spigot is clearly visible.
- the method according to the invention can be used to produce metal products which cover a wide range of applications.
- the method can also be used with a large number of metals and their alloys.
- the surface conversion can already be carried out successfully during the casting process and requires neither subsequent soldering or welding, nor additional casting devices, such as may be associated with a dissolving foam core (EPC process) during casting.
- the process according to the invention can be used without difficulty in known sand molding processes.
- a fine chrome carbide powder (mesh size 140/325 or finer) is mixed with a 10% aqueous solution of polyvinyl alcohol and 2-ethylhexyl diphenyl phosphate or KRONITEX 3600 to form a flowable mass with adequate rheological properties, which form slices or thin Drain or roll out the plates.
- a pattern with a hexagonal structure is then embossed on the plate, as shown in FIG. 1.
- the thin plate is then dried in an oven in air at 100 ° C. and then sintered in a vacuum at 1200 to 1250 ° C. for 300 to 360 minutes.
- the carbide plate is attached to a sand core with the Ceramabond 569 adhesive from Aremco.
- the sand core and the carbide plate are tempered in an oven at 100 ° C. for 60 to 120 minutes in order to drive volatile constituents out of the binder and to set the adhesive. Now it will liquid iron is poured around the carbide plate by means of a conventional casting process, so that the metal plate solidifies the carbide plate with the metal surface.
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Abstract
Description
Die Erfindung betrifft ein Verfahren zum Imprägnieren oder Einbetten von harten, verschleißfesten Phasen in Oberflächenschichten von Metallerzeugnissen, die durch Abgießen von flüssigem Metall hergestellt werden.The invention relates to a method for impregnating or embedding hard, wear-resistant phases in surface layers of metal products which are produced by pouring liquid metal.
Es sind verschiedene Verfahren bekannt, durch die Metallerzeugnisse, beispielsweise aus Eisen, mit harten, verschleißfesten oder abriebsbeständigen Oberflächen versehen werden können. Die Beschichtung der Oberflächen erfolgt beispielsweise durch Flammspritzbeschichtung oder Plasmaspritzbeschichtung. Nachteilig bei diesen Verfahren ist jedoch, daß die Oberflächenschichten beim Beschichtungsverfahren und bei der Verwendung der Erzeugnisse abplatzen können. Ferner treten hohe Verfahrenskosten auf.Various methods are known by means of which metal products, for example made of iron, can be provided with hard, wear-resistant or abrasion-resistant surfaces. The surfaces are coated, for example, by flame spray coating or plasma spray coating. However, a disadvantage of these processes is that the surface layers can flake off during the coating process and when the products are used. There are also high procedural costs.
Aus der US-PS 4,119,459 ist es auch bekannt, Karbide in die Oberfläche einzuschmelzen, indem Karbidmakroteilchen auf ein Gießmodel aufgebracht werden und anschließend das Werkstück gegossen wird. Es ist jedoch hierbei schwierig, die Karbidmakroteilchen genau an den gewünschten Stellen und in dem gewünschten Verteilungsmuster zu plazieren.It is also known from US Pat. No. 4,119,459 to melt carbides into the surface by applying carbide macro particles to a casting model and then casting the workpiece. However, it is difficult to place the carbide macro particles precisely in the desired locations and in the desired distribution pattern.
Ferner sind für die Herstellung von Eisenprodukten einige Verfahren zum Angießen harter Oberflächen an die Eisenwerkstücke in Verbindung mit der Anwendung von Polystyrolmodellen bekannt. Ein solches Verfahren wurde beispielsweise von Hansen et al, "Application of Cast-On Ferrochrome-Based Hard Surfacings to Polystyrene Pattern Castings", Bureau of Mines Report of Investigations 8942, U.S. Department of the Interior, 1985, beschrieben. Bei diesem Verfahren wird zunächst eine Paste, die ein Haftmittel und das gewünschte harte Material, wie z. B. Wolframkarbidpulver, enthält, auf solche Oberflächen eines Polystyrolmodelles aufgetragen, die den zum Verschleiß neigenden Oberflächen des resultierenden Gusses entsprechen. Dann wird vor dem Abgießen des Metalls eine hitzebeständige Beschichtung auf das ganze Modell aufgetragen. Dieses Verfahren ist als "Evaporative Pattern Casting"-Verfahren oder EPC-Verfahren bekannt.Also known for the manufacture of iron products are some methods for casting hard surfaces onto the iron workpieces in connection with the use of polystyrene models. Such a method has been described, for example, by Hansen et al, "Application of Cast-On Ferrochrome-Based Hard Surfacings to Polystyrene Pattern Castings", Bureau of Mines Report of Investigations 8942, US Department of the Interior, 1985. In this method, a paste containing an adhesive and the desired hard material, such as. B. tungsten carbide powder, applied to those surfaces of a polystyrene model that correspond to the wear-prone surfaces of the resulting cast. Then a heat-resistant coating is applied to the entire model before the metal is poured off. This process is known as the "Evaporative Pattern Casting" process or EPC process.
Dieses Verfahren leidet jedoch an der mangelnden Haftfähigkeit zwischen der verschleißfesten Schicht, die beispielsweise aus Wolframkarbid besteht, und dem Schaummodell aus Polystyrol, die vor allem darauf zurückzuführen ist, daß die fast trockene Paste die Oberfläche des geschäumten Kunstharzes nicht ausreichend benetzt. Daher dringt das Eisen vor seinem Erstarren manchmal nicht in die Schicht ein, und anstatt das Eisen getränkt zu haben, platzt das Karbid von dem Erzeugnis ab. Ferner ist dieses Verfahren komplex und unwirtschaftlich und läßt sich nicht wirkungsvoll bei einer Produktion im großen Stil anwenden.However, this process suffers from the lack of adhesion between the wear-resistant layer, which consists for example of tungsten carbide, and the foam model made of polystyrene, which is mainly due to the fact that the almost dry paste does not adequately wet the surface of the foamed synthetic resin. Therefore, the iron sometimes does not penetrate the layer before it solidifies, and instead of having soaked the iron, the carbide flakes off the product. Furthermore, this process is complex and uneconomical and cannot be used effectively in large-scale production.
Die mechanischen Eigenschaften von Eisenguß, der durch ein EPC-Verfahren hergestellt wurde, sind wegen der Anwesenheit von Kohlenstoffdefekten minderwertiger als die von Sand- oder Kerngußerzeugnissen. Ferner erfordert das EPC-Verfahren besondere Vorsichtsmaßnahmen, um geringe Formänderungen beim Gießen einzuhalten.The mechanical properties of cast iron made by an EPC process are inferior to that of sand or core castings due to the presence of carbon defects. Furthermore, the EPC process requires special precautionary measures to keep small changes in shape during casting.
Aus der EP-A-0 421 374 und der EP-A-0 470 503 sind ferner unterschiedliche Verfahren bekannt, durch die das Imprägnieren von Metalloberflächen mit Karbiden während des Gießprozesses verbessert wird, indem Schichten aus Karbidteilchen auf einen Schaumstoffkern bzw. einen Sandkern übertragen werden, der dem Abgießen des herzustellenden, aus Eisen oder Aluminium bestehenden Werkstückes dient.Various processes are also known from EP-A-0 421 374 and EP-A-0 470 503, by means of which the impregnation of metal surfaces with carbides is improved during the casting process by transferring layers of carbide particles to a foam core or a sand core be the the casting of the workpiece to be manufactured, made of iron or aluminum.
Auch wenn diese letztgenannten Verfahren eine erhebliche Verbesserung mit sich brachten, sind sie immer noch nicht voll befriedigend. Beispielsweise erfordert das EPC-Verfahren in einer konventionellen Gießerei die Einrichtung spezieller Vorrichtungen. Ferner können die Gußerzeugnisse Formabweichungen aufweisen, die auf Formabweichungen der Schaumstoffmodelle zurückzuführen sind. Die aus dem Stand der Technik bekannte Sandformmethode zum Eingießen von Karbiden erfordert Karbidkugeln, durch die das Verfahren sich verteuern kann. Erhöhte Kosten können sich auch dadurch ergeben, daß gefordert wird, die verschleißfeste Oberfläche eben auszubilden. In diesem Fall muß das Gußerzeugnis geglättet und eine Oberflächenschicht abgetragen werden, die ungefähr dem halben Durchmesser der kugelförmigen Teilchen entspricht.Even though these latter methods have brought about a significant improvement, they are still not entirely satisfactory. For example, the EPC process in a conventional foundry requires the installation of special devices. Furthermore, the cast products can have shape deviations which can be attributed to shape deviations of the foam models. The sand molding method for casting carbides known from the prior art requires carbide balls, which can make the process more expensive. Increased costs can also result from the requirement that the wear-resistant surface be formed flat. In this case, the cast product must be smoothed and a surface layer removed, which corresponds approximately to half the diameter of the spherical particles.
Es besteht daher weiterhin das Bedürfnis nach einem Verfahren zur Imprägnierung von Metalloberflächen, insbesondere von Eisenerzeugnisoberflächen mit einem harten, verschleißfesten Material, durch welches sich die eingangs genannten Probleme der bekannten Verfahren überwinden lassen.There is therefore still a need for a method for impregnating metal surfaces, in particular iron product surfaces, with a hard, wear-resistant material, by means of which the problems of the known methods mentioned at the outset can be overcome.
Die Erfindung schafft hier Abhilfe und schlägt ein Verfahren zum Einbetten von harten, verschleißfesten Phasen in Oberflächenschichten von Metallerzeugnissen, welche durch Gießen von flüssigem Metall in Gießformen hergestellt werden, vor. Dabei wird eine fließfähige Masse, die verschleißfestes Material enthält, so geformt, daß sich eine Scheibe oder Lage mit vorzugsweise einer Reihe von Pflöcken, Vorsprüngen, Dornen oder dergleichen ausbildet. Diese Lage wird angesintert und vor dem Gießen des Metalls auf einer Oberfläche der Gießform angeheftet. Durch die Vorsprünge ergibt sich eine bessere Bindung zwischen dem verschleißfesten Material und dem gegossenen Metall, als dies bei der Verwendung von sphärischen gesinterten Karbidteilchen der Fall ist.The invention remedies this and proposes a method for embedding hard, wear-resistant phases in surface layers of metal products which are produced by pouring liquid metal into casting molds. A flowable mass, which contains wear-resistant material, is shaped in such a way that a disc or layer is formed with preferably a series of pegs, projections, spikes or the like. This layer is sintered and adhered to a surface of the mold before the metal is cast. The projections result in a better bond between the wear-resistant material and the cast one Metal than is the case when using spherical sintered carbide particles.
Die erfindungsgemäße Lehre wird durch den Patentanspruch 1 angegeben. Weitere vorteilhafte Ausgestaltungen und Weiterbildungen der Erfindung gehen aus den Unteransprüchen hervor.The teaching of the invention is given by claim 1. Further advantageous refinements and developments of the invention emerge from the subclaims.
Anhand der Zeichnung werden nachfolgend Ausführungsbeispiele sowie weitere Vorteile und vorteilhafte Weiterbildungen und Ausgestaltungen der Erfindung näher beschrieben und erläutert.Exemplary embodiments and further advantages and advantageous developments and refinements of the invention are described and explained in more detail below with reference to the drawing.
Es zeigt:
- Fig. 1
- zwei Photographien von Mustern eines Chromkarbidpulverschlamms, bevor dieser gesintert wird,
- Fig. 2
- die elektronenmikroskopische Aufnahme (SEM) der vorgesinterten Oberfläche eines Chromkarbidzapfens,
- Fig. 3
- zwei elektronenmikroskopische Aufnahmen der Mikrostruktur einer duktilen Eisen-Chromkarbid-Verbundoberfläche und
- Fig. 4
- die Photographie der geschliffenen und polierten Verbundoberfläche eines Erzeugnisses, das gemäß vorliegender Erfindung gefertigt wurde.
- Fig. 1
- two photographs of samples of a chrome carbide powder slurry before it is sintered,
- Fig. 2
- the electron micrograph (SEM) of the presintered surface of a chrome carbide pin,
- Fig. 3
- two electron micrographs of the microstructure of a ductile iron-chromium carbide composite surface and
- Fig. 4
- the photograph of the ground and polished composite surface of a product made in accordance with the present invention.
Die vorliegende Erfindung kann grundsätzlich beim Gießen jedes bekannten Metalls angewendet werden, durch das sich eine Karbidfläche benetzen läßt. Verwendbare Metalle sind beispielsweise Eisen, Aluminium und dergleichen. Jedoch wird Gußeisen, insbesondere Kugelgraphitguß oder Grauguß für die geläufigsten verschleißfesten Karbidarten, wie beispielsweise Chromkarbid und dergleichen bevorzugt.The present invention can basically be applied to the casting of any known metal through which a carbide surface can be wetted. Metals that can be used are, for example, iron, aluminum and the like. However Cast iron, especially spheroidal graphite cast iron or gray cast iron is preferred for the most common wear-resistant carbide types, such as, for example, chromium carbide and the like.
Gemäß der vorliegenden Erfindung beinhaltet ein erster Schritt die Ausbildung einer dünnen Lage oder Platte, die verschleißfestes Material enthält. Hinsichtlich der Wahl des harten, verschleißfesten Materials läßt sich die Erfindung mit jeder aus dem Stand der Technik bekannten harten Phase, beispielsweise mit Karbiden wie Wolframkarbid und Chromkarbid oder mit Aluminiumverbindungen und dergleichen erfolgreich anwenden. Ferner können die harten Phasen durch Pulver irgend eines Metalls, einer intermetallischen Verbindung oder eines Keramikwerkstoffes ersetzt werden, die sich durch das verwendete Matrixmaterial (Einbettungsmaterial), wie z. B. Eisen oder eine aus dem Stand der Technik bekannte Legierung benetzen lassen. Beispielsweise kann Aluminium verwendet werden, um die Oberflächenverschleißfestigkeit von Eisen- oder Nickelguß durch die Ausbildung von intermetallischen Aluminiumverbindungen zu verbessern. Ferner können beim Aluminiumguß geeignete Materialien, wie beispielsweise Nickel oder Eisen verwendet werden.According to the present invention, a first step involves forming a thin sheet or plate that contains wear-resistant material. With regard to the choice of the hard, wear-resistant material, the invention can be successfully applied with any hard phase known from the prior art, for example with carbides such as tungsten carbide and chromium carbide or with aluminum compounds and the like. Furthermore, the hard phases can be replaced by powder of any metal, an intermetallic compound or a ceramic material, which is determined by the matrix material (embedding material) used, such as. B. wetting iron or an alloy known from the prior art. For example, aluminum can be used to improve the surface wear resistance of cast iron or nickel by forming intermetallic aluminum compounds. Suitable materials such as nickel or iron can also be used in aluminum casting.
Gemäß einer bevorzugten Ausgestaltung der Erfindung, die den Eisenguß betrifft, kann das verschleißfeste Material ein metallisches Bindemittel, z. B. ein solches aus der Eisengruppe, vorzugsweise Kobalt für die Verwendung von Wolframkarbiden oder Nickel für die Verwendnung von Chromkarbiden usw., enthalten. Insbesondere werden für den Guß von duktilem Eisen Teilchen, die Wolframkarbid mit einem Gewichtsanteil von 14 bis 17 % Kobalt enthalten, bevorzugt.According to a preferred embodiment of the invention, which relates to iron casting, the wear-resistant material can be a metallic binder, e.g. B. from the iron group, preferably cobalt for the use of tungsten carbides or nickel for the use of chromium carbides, etc., included. In particular, particles containing tungsten carbide with a weight fraction of 14 to 17% cobalt are preferred for the casting of ductile iron.
Auch wenn die Größe der Teilchen bei der Anwendung der vorliegenden Erfindung nicht kritisch ist, werden feinkörnige Teilchen bevorzugt, die eine Maschenweite von 140/325 (ca. 110 bis 50 Mikrons) oder feiner haben.Although the size of the particles is not critical in the practice of the present invention, it becomes fine-grained Particles preferred which have a mesh size of 140/325 (approx. 110 to 50 microns) or finer.
Die Herstellung der dünnen Platte erfolgt durch Vermischen eines Pulvers aus hartem, verschleißfestem Material mit einem geeigneten organischen Bindemittel, beispielsweise einer 10 %-igen Polyvinylalkohollösung, und einem geeigneten Härter, beispielsweise 2-Äthylhexyl-Diphenyl-Phosphat, Phosphatesterhärter (z. B. KRONITEX 3600 der Fa. FMC Corporation, USA) oder einem Gemisch dieser Härter. Die Mischung bildet eine fließfähige Masse mit geeigneten rheologischen Eigenschaften, so daß sich die Masse in die Form einer Scheibe oder Platte bringen läßt. In diesem Sinne ist jeder Härter und/oder organische Binder zur Ausführung der Erfindung geeignet, der wirksam mit einem bestimmten harten verschleißfesten Material verarbeitet werden kann.The thin plate is produced by mixing a powder of hard, wear-resistant material with a suitable organic binder, for example a 10% polyvinyl alcohol solution, and a suitable hardener, for example 2-ethylhexyl diphenyl phosphate, phosphate ester hardener (e.g. KRONITEX 3600 from FMC Corporation, USA) or a mixture of these hardeners. The mixture forms a flowable mass with suitable rheological properties so that the mass can be brought into the form of a disk or plate. In this sense, any hardener and / or organic binder that can be processed effectively with a certain hard, wear-resistant material is suitable for carrying out the invention.
Auf einer nach außen weisenden Oberfläche der dünnen Platte wird ein Muster ausgebildet, welches eine Struktur aufweist, die eine Verbesserung der Imprägnierung des Eisens erlaubt. Jede Musterform, die wenigstens einen Pflock, einen Zapfen, einen Vorsprung oder dergleichen aufweist, durch die eine laterale Bewegung der dünnen Platte beim Gießen verhindert wird, ist geeignet. Beispielsweise kann eine hexagonale oder waffelförmige Struktur auf die Oberfläche der dünnen Platte aufgebracht werden (Fig. 1). Andere geeignete Muster enthalten kreisförmige, elliptische und ähnliche Strukturen.A pattern is formed on an outwardly facing surface of the thin plate, which has a structure that allows an improvement in the impregnation of the iron. Any pattern shape that has at least a peg, a peg, a protrusion, or the like that prevents lateral movement of the thin plate during casting is suitable. For example, a hexagonal or waffle-shaped structure can be applied to the surface of the thin plate (FIG. 1). Other suitable patterns include circular, elliptical and similar structures.
Tatsächlich können die Pflöcke jede vorstellbare Form einnehmen, durch die sich eine gewünschte Kontur ergibt, um die Strecke der Metallpenetration beim Gießen klein zu halten.In fact, the pegs can take any conceivable shape that gives a desired contour to keep the distance of metal penetration small during casting.
Ferner läßt sich das Muster durch geeignete Mittel abformen, beispielsweise, indem ein Stempel mit dem gewünschten Muster auf die Oberfläche der noch fließfähigen, plastischen, dünnen Platte aufgedrückt wird.Furthermore, the pattern can be molded by suitable means, for example by using a stamp with the desired pattern is pressed onto the surface of the still flowable, plastic, thin plate.
Anschließend wird die dünne Platte beispielsweise in einem Ofen bei 100°C so lange getrocknet, bis sie einen formbeständigen Körper bildet. Die dünne Platte wird dann unter geeigneten Bedingungen angesintert, so daß sie einerseits eine ausreichende Porösität erreicht, und andererseits stabil genug ist, um der Weiterverarbeitung und/oder der Anwendung weiterer Verfahrensschritte standzuhalten. Beispielsweisebeinhalten die geeigneten Bedingungen einen 300 bis 360 Minuten langen Sinterprozess im Vakuum bei ungefähr 1200 bis 1250°C.The thin plate is then dried, for example in an oven at 100 ° C., until it forms a dimensionally stable body. The thin plate is then sintered under suitable conditions so that on the one hand it achieves sufficient porosity and on the other hand it is stable enough to withstand further processing and / or the use of further process steps. For example, the appropriate conditions include a 300 to 360 minute vacuum sintering process at about 1200 to 1250 ° C.
Die oben beschriebene angesinterte dünne Platte besteht aus einem porösen Sintergemisch mit Teilverdichtungen (Fig. 2).The sintered thin plate described above consists of a porous sinter mixture with partial densifications (Fig. 2).
Diese teil- oder angesinterte dünne Platte kann nun in bekannter Weise auf einer geeigneten Gußformoberfläche, beispielsweise auf einem Gußkern befestigt werden, so daß die gemusterte Oberfläche mit dem Gußkern in Kontakt tritt. Beispielsweise wird hierbei gemäß einer erfindungsgemäßen Ausgestaltung ein Hochtemperaturkelbstoff angewendet. Die Schicht wird dann z. B. in einem Ofen auf 100°C erwärmt, so daß die flüchtigen Bestandteile aus dem Klebstoff ausgetrieben werden und der Klebstoff aushärtet.This partially or sintered thin plate can now be fastened in a known manner on a suitable mold surface, for example on a cast core, so that the patterned surface comes into contact with the cast core. For example, a high-temperature carbon is used here according to an embodiment of the invention. The layer is then z. B. heated in an oven to 100 ° C so that the volatile constituents are expelled from the adhesive and the adhesive cures.
Der Hochtemperaturklebstoff muß eine Fließtemperatur aufweisen, die höher ist als die Gießtemperatur des Metalls. Es ist grundsätzlich jeder diesbezügliche Klebstoff geeignet, jedoch wird ein anorganischer Hochtemperaturklebstoff besonders bevorzugt. Beispielsweise wird gemäß einer Ausgestaltung der Erfindung zur Verarbeitung duktilen Eisens ein Binder vorgeschlagen, der einen Hochtemperaturkeramikklebstoff enthält, z. B. ein Hochtemperaturbinder, der durch die Fa. Aremco Products, Inc., USA unter der Warenbezeichnung Ceramabond 569 vertrieben wird und beispielsweise Oxide von Aluminium, Silizium und Kalium in einer wässrigen kolloidalen Suspension enthält, die eine maximale Gebrauchstemperatur von ungefähr 1650°C aufweist.The high temperature adhesive must have a flow temperature that is higher than the casting temperature of the metal. In principle, any adhesive in this regard is suitable, but an inorganic high-temperature adhesive is particularly preferred. For example, according to an embodiment of the invention for processing ductile iron, a binder is proposed which contains a high-temperature ceramic adhesive, e.g. B. a high temperature binder, which is available from Aremco Products, Inc., USA under the trade name Ceramabond 569 is sold and contains, for example, oxides of aluminum, silicon and potassium in an aqueous colloidal suspension which has a maximum service temperature of approximately 1650 ° C.
Bei dieser Temperatur fließt das flüssige Metall rund um die Schicht aus hartem, verschleißfestem Material, wobei ein beliebiges der bekannten Gießverfahren, beispielsweise Gießen unter Ausnützung der Schwerkraft, Preßdruckgießen, Vakuumgießen oder dergleichen angewendet werden kann. Jedoch wird wegen dessen leichter Handhabbarkeit das Gießen unter Ausnützung der Schwerkraft bevorzugt.At this temperature, the liquid metal flows around the layer of hard, wear-resistant material, whereby any of the known casting methods, for example gravity casting, pressure die casting, vacuum casting or the like, can be used. However, gravity-based casting is preferred because of its ease of handling.
Wird ein geeignetes Gießverfahren angewendet, löst sich das verschleißfeste Material teilweise in dem Gießmetall und scheidet sich dort als fester Bestandteil ab. Beispielsweise löst sich Chromkarbid teilweise in geschmolzenem Eisen und verfestigt sich dort wieder. Die Mikrostruktur solch eines Verbunds ist in Fig. 3 dargestellt, die ebenfalls zeigt, daß der Verbund derart an das Eisensubstrat gebunden ist, daß er sich nicht leicht davon ablösen läßt.If a suitable casting process is used, the wear-resistant material partially dissolves in the casting metal and separates there as an integral part. For example, chrome carbide partially dissolves in molten iron and solidifies again there. The microstructure of such a composite is shown in Fig. 3, which also shows that the composite is bonded to the iron substrate in such a way that it cannot be easily detached therefrom.
Schließlich kann das Erzeugnis einer beliebigen, bekannten Nachbearbeitung unterzogen werden. Fig. 4 zeigt die geschliffene Oberfläche eines Verbunds, bei dem das Eisen-"Netzwerk", das die Verbundzapfen umgibt, deutlich erkennbar ist.Finally, the product can be subjected to any known post-processing. Fig. 4 shows the ground surface of a composite in which the iron "network" surrounding the composite spigot is clearly visible.
Das erfindungsgemäße Verfahren kann zur Erzeugung von Metallerzeugnissen angewendet werden, die einen weiten Anwendungsbereich abdecken. Ferner läßt sich das Verfahren bei einer Vielzahl von Metallen und deren Legierungen anwenden.The method according to the invention can be used to produce metal products which cover a wide range of applications. The method can also be used with a large number of metals and their alloys.
Im besonderen Fall von Eisen tritt zusätzlich eine metallurgische Reaktion auf, durch die die Eisen-Karbid-Bindung weiter verstärkt wird. Diese Reaktion kann durch Wahl geeigneter Muster der dünnen Platte unterstützt werden.In the special case of iron, a metallurgical reaction also occurs, through which the iron-carbide bond is further strengthened. This reaction can be supported by choosing suitable patterns of the thin plate.
Durch die Anwendung des erfindungsgemäßen Verfahrens können erhebliche Verfahrenskosten eingespart werden. Insbesondere kann die Oberflächenumwandlung schon während des Gießverfahrens erfolgreich durchgeführt werden und erfordert weder ein nachträgliches Löten oder Schweißen noch zusätzliche Gießeinrichtungen, wie sie beim Gießen mit einem sich auflösenden Schaumstoffkern (EPC-Verfahren) assoziiert sein können. Insbesondere läßt sich das erfindungsgemäße Verfahren ohne Schwierigkeiten bei bekannten Sandformgießverfahren anwenden.Considerable process costs can be saved by using the method according to the invention. In particular, the surface conversion can already be carried out successfully during the casting process and requires neither subsequent soldering or welding, nor additional casting devices, such as may be associated with a dissolving foam core (EPC process) during casting. In particular, the process according to the invention can be used without difficulty in known sand molding processes.
Zur näheren Beschreibung der vorliegenden Erfindung sowie weiterer Vorteile wird im folgenden ein Ausführungsbeispiel angegeben.An exemplary embodiment is given below for a more detailed description of the present invention and further advantages.
Ein feines Chromkarbidpulver (Maschenweite von 140/325 oder feiner) wird mit einer 10 %-igen wässrigen Polyvinylalkohollösung und 2-Äthylhexyl-Diphenyl-Phosphat oder KRONITEX 3600 gemischt, um eine fließfähige Masse mit angemessenen rheologischen Eigenschaften auszubilden, die sich zu Scheiben oder dünnen Platten abgießen oder ausrollen läßt. Auf die Platte wird dann ein Muster mit hexagonaler Struktur aufgeprägt, wie es Fig. 1 zeigt. Dann wird die dünne Platte in einem Ofen unter Luft bei 100°C getrocknet und anschließend 300 bis 360 Minuten lang im Vakuum bei 1200 bis 1250°C gesintert.A fine chrome carbide powder (mesh size 140/325 or finer) is mixed with a 10% aqueous solution of polyvinyl alcohol and 2-ethylhexyl diphenyl phosphate or KRONITEX 3600 to form a flowable mass with adequate rheological properties, which form slices or thin Drain or roll out the plates. A pattern with a hexagonal structure is then embossed on the plate, as shown in FIG. 1. The thin plate is then dried in an oven in air at 100 ° C. and then sintered in a vacuum at 1200 to 1250 ° C. for 300 to 360 minutes.
Die Karbidplatte wird mit dem Klebstoff Ceramabond 569 der Fa. Aremco auf einem Sandkern befestigt. Der Sandkern und die Karbidplatte werden 60 bis 120 Minuten lang in einem Ofen bei 100°C temperiert, um flüchtige Bestandteile aus dem Binder auszutreiben und den Klebstoff abzubinden. Nun wird das flüssige Eisen mittels eines üblichen Gießverfahrens um die Karbidplatte gegossen, so daß bei der Metallerstarrung die Karbidplatte fest mit der Metalloberfläche verbunden ist.The carbide plate is attached to a sand core with the Ceramabond 569 adhesive from Aremco. The sand core and the carbide plate are tempered in an oven at 100 ° C. for 60 to 120 minutes in order to drive volatile constituents out of the binder and to set the adhesive. Now it will liquid iron is poured around the carbide plate by means of a conventional casting process, so that the metal plate solidifies the carbide plate with the metal surface.
Claims (9)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/822,903 US5299620A (en) | 1992-01-21 | 1992-01-21 | Metal casting surface modification by powder impregnation |
| US822903 | 2001-03-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0554683A1 true EP0554683A1 (en) | 1993-08-11 |
Family
ID=25237294
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP93100455A Withdrawn EP0554683A1 (en) | 1992-01-21 | 1993-01-14 | Method to change the surface of castings by powder impregnating |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US5299620A (en) |
| EP (1) | EP0554683A1 (en) |
| JP (1) | JPH05318085A (en) |
| CA (1) | CA2086873A1 (en) |
| MX (1) | MX9300274A (en) |
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| WO1995001520A1 (en) * | 1993-07-02 | 1995-01-12 | Knorr-Bremse Ag | Brake disc for disc brakes |
| EP0687829A1 (en) * | 1994-06-17 | 1995-12-20 | Wagner Electric Corporation | Reinforced friction material |
| CN1053020C (en) * | 1994-12-30 | 2000-05-31 | 邵天敏 | Method for preparing aluminium and aluminium alloy surface coating |
| DE4418750C2 (en) * | 1994-05-28 | 2000-06-15 | Vaw Ver Aluminium Werke Ag | Process for the production of wear-resistant surfaces on molded parts |
| CN104707972A (en) * | 2015-02-15 | 2015-06-17 | 广东省工业技术研究院(广州有色金属研究院) | Composite wear-resistant part preparation method |
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| AR007698A1 (en) * | 1996-08-28 | 1999-11-10 | Deere & Co | METHOD TO CONTRIBUTE SURFACE HARDNESS TO A METALLIC SURFACE AND A MUD PREPARED BY SUCH METHOD |
| US5921333A (en) * | 1997-08-06 | 1999-07-13 | Naco, Inc. | Casting having in-situ cast inserts and method of manufacturing |
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| CN1318629C (en) * | 2005-09-05 | 2007-05-30 | 西安交通大学 | Complexing agent for preparing tungsten carbide granule reinforced steel matrix skin layer composite material |
| US9003681B2 (en) * | 2006-09-18 | 2015-04-14 | Deere & Company | Bucket teeth having a metallurgically bonded coating and methods of making bucket teeth |
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| DE102010014267A1 (en) * | 2010-04-08 | 2011-10-13 | H.C. Starck Gmbh | Dispersions, as well as processes for their preparation and their use |
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| CN105414532A (en) | 2012-01-31 | 2016-03-23 | 埃斯科公司 | Wear resistant material and system and method of forming wear resistant material |
| DE102012204614A1 (en) * | 2012-03-22 | 2013-09-26 | Man Diesel & Turbo Se | Manufacturing cast part used as cylinder heads for diesel engine, comprises introducing melted cast material into cavity of mold, solidifying cast material, and partially introducing additive into cast material to modify properties |
| US9283621B2 (en) | 2012-06-21 | 2016-03-15 | Deere & Company | Method for forming a composite article |
| CN102921924B (en) * | 2012-11-02 | 2015-03-04 | 北京电力设备总厂 | Compound wear-resistant part and preparation method thereof |
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| US10543985B2 (en) * | 2015-01-19 | 2020-01-28 | Flsmidth A/S | Interlocking wear-resistant panel system |
| CN109371333A (en) * | 2018-12-08 | 2019-02-22 | 河南工学院 | A kind of ceramics enhancing steel composite material and preparation method |
| US11103944B2 (en) | 2019-08-12 | 2021-08-31 | Deere & Company | Self-sharpening cutting tooth for a felling apparatus |
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| EP0687829A1 (en) * | 1994-06-17 | 1995-12-20 | Wagner Electric Corporation | Reinforced friction material |
| CN1053020C (en) * | 1994-12-30 | 2000-05-31 | 邵天敏 | Method for preparing aluminium and aluminium alloy surface coating |
| CN104707972A (en) * | 2015-02-15 | 2015-06-17 | 广东省工业技术研究院(广州有色金属研究院) | Composite wear-resistant part preparation method |
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Also Published As
| Publication number | Publication date |
|---|---|
| MX9300274A (en) | 1993-07-01 |
| US5299620A (en) | 1994-04-05 |
| CA2086873A1 (en) | 1993-07-22 |
| JPH05318085A (en) | 1993-12-03 |
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