WO2010058074A2 - Method for preparing a composite material and use of a composite material prepared by the method - Google Patents
Method for preparing a composite material and use of a composite material prepared by the method Download PDFInfo
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- WO2010058074A2 WO2010058074A2 PCT/FI2009/050927 FI2009050927W WO2010058074A2 WO 2010058074 A2 WO2010058074 A2 WO 2010058074A2 FI 2009050927 W FI2009050927 W FI 2009050927W WO 2010058074 A2 WO2010058074 A2 WO 2010058074A2
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- mold
- reinforcing
- composite material
- molten
- melt
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Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C47/00—Making alloys containing metallic or non-metallic fibres or filaments
- C22C47/02—Pretreatment of the fibres or filaments
- C22C47/06—Pretreatment of the fibres or filaments by forming the fibres or filaments into a preformed structure, e.g. using a temporary binder to form a mat-like element
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C3/00—Selection of compositions for coating the surfaces of moulds, cores, or patterns
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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
- B22D19/02—Casting in, on, or around objects which form part of the product for making reinforced articles
-
- 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
- B22D19/14—Casting in, on, or around objects which form part of the product the objects being filamentary or particulate in form
-
- 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
- B22D19/16—Casting in, on, or around objects which form part of the product for making compound objects cast of two or more different metals, e.g. for making rolls for rolling mills
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C47/00—Making alloys containing metallic or non-metallic fibres or filaments
- C22C47/08—Making alloys containing metallic or non-metallic fibres or filaments by contacting the fibres or filaments with molten metal, e.g. by infiltrating the fibres or filaments placed in a mould
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C49/00—Alloys containing metallic or non-metallic fibres or filaments
- C22C49/02—Alloys containing metallic or non-metallic fibres or filaments characterised by the matrix material
- C22C49/08—Iron group metals
Definitions
- the invention is related to a method for preparing a composite material and to the use of a composite material prepared by this method. More particularly, the method is related to composite materials prepared by casting, and particularly to metal matrix composites, without being limited to these.
- Multiphase materials such as metal matrix composites, or multimaterial structures consisting of two or more different materials which are obtained in this way have particularly many applications in wear parts of process devices.
- a composite material consists of at least two different phases, which are usually called a matrix and a reinforcement, and of which the volume fraction of the reinforcement is most typically 10 to 60 per cent of the total volume.
- the matrix is typically a uniform phase region extending through the entire material.
- the matrix is an alloy and the reinforcement is in most cases a metallic or ceramic material which is in particle, fiber or staple fiber form and has a composition and properties differing from those of the matrix.
- the properties of a composite material are determined not only by the properties of the starting materials but also for example by the manufacturing method and the processing parameters of the composite material which are actually used.
- Composite materials are multiphase materials, as are also such structures consisting of more than one distinguishable materials (phases) which structures do not satisfy the definition of a composite material but which often have at least partly corresponding physical or tribological properties.
- the term reinforcement means particles which can be classified as reinforcing material particles and which have a diameter of the order of 0.01 to 2 mm, or grains which have a diameter of the order of 2 to 5 mm, as well as material fragments larger than that, wherein the size of individual fragments at the largest is however less than 30 per cent of the total volume of the composite material or multiphase material to be manufactured.
- the reinforcement may be a ceramics (oxide, nitride, carbide, boride) and possibly a metallic binding agent mixed therein, which metallic binding agent can be an iron-, nickel-, chromium- or cobalt-based mixture containing mentioned other elements or other elements as mixing agents or as impurities.
- the reinforcement may also be a different alloy in solid form, which alloy differs by its composition from the matrix or the other composition regions of the multiphase material.
- the manufacturing of a solid precursor object suited for infiltration invariably requires relatively complicated process steps.
- the binding agent When a separate organic or inorganic binding agent is used, the binding agent must be mixed with the reinforcing particles for example in a mill or another corresponding device. The curing of the binding agent and the removal of volatile substances often require heating.
- the precursor object If a separate binding agent is not used, the precursor object is generally manufactured by sintering in a process which is rather lengthy and requires a special apparatus. Often the precursor object still must be coated for example by gas phase deposition to facilitate infiltration. Further, eventual impurities which remain in the casting from the applied binding agents may cause various manufacturing defects or quality deviations during use.
- the geometrical properties such as porosity and pore size, which control the filling of the precursor object to be infiltrated, so that the melt fills the free volume entirely and the phase distribution and the physical and functional properties, such as wear resistance, of the material to be manufactured correspond to the requirement profile of the application of the material
- the size distribution of the starting materials most usually the reinforcing particles, which are used for manufacturing the precursor object, must be controlled.
- the infiltration itself is carried out additionally as a pressure-assisted casting, which further complicates the process and requires the use of special equipment.
- the preservation of the reinforcement distribution during pouring, mold filling and solidification is often difficult to control. This problem is emphasized if the product to be prepared has a complex shape or if the distribution and volume fraction of the reinforcement are supposed to be different in different parts of the object. Also the use of factors external to the mold, such as for example an electromagnetic field, for controlling the structure is difficult and expensive particularly in the case of objects with a complex shape.
- the composite material and its manufacturing method according to the present invention are able to remove or at least to reduce the above presented disadvantages of the prior art.
- the manufacturing method according to the invention it is possible to prepare wear- resistant composite materials and products in which there are thicker reinforcement layers at determined regions than what is possible to prepare by known manufacturing methods, hi the manufacturing method the distribution of the reinforcement in the composite material to be cast can be well controlled, hi addition, the contact time of the melt and the reinforcements is shorter than in the case of mixing the reinforcement with the melt before pouring.
- the method according to the invention also enables the use of such reinforcements the density of which is clearly different from that of the melt.
- the invention enables the coating of objects with a complex geometry while reducing and simplifying the process steps needed in the manufacturing method.
- the composite material prepared according to the invention is particularly suitable for use in all kinds of wear materials, such as for example in different wear parts of excavation and mining industry and in applications of paper, process and metallurgical industry, such as rolls, guide rollers and impellers.
- the method according to the invention is characterized by what is disclosed in the characterizing part of claim 1, and the use of a composite material prepared by the method according to the invention is characterized by what is disclosed in claims 10 and 11.
- Figure 1 a shows an embodiment according to the invention before casting
- Figure Ib shows the embodiment according to Figure Ia during casting
- Figure 2a shows an embodiment according to the invention after casting
- Figure 2b shows a first alternative embodiment according to the invention after casting
- Figure 3 a shows a second alternative embodiment according to the invention after casting
- Figure 3b shows a third alternative embodiment according to the invention after casting
- Figure 4a shows a fourth alternative embodiment according to the invention after casting
- Figure 4b shows a fifth alternative embodiment according to the invention after casting
- Figure 5 shows a wear part prepared by the method according to the invention.
- Figure Ia shows a principal description of a preferred embodiment according to the invention at an initial casting stage 100, which comprises a casting mold 101, a support material inclosure 102, inside of which there are reinforcements 103, a reinforcement movement hindrance grid 104, and a melt front 105 rising in the mold.
- the reinforcements may be either microscopic particles, macroscopic objects, something in between, or combinations thereof.
- the reinforcements 103 packed in the support material 102 are secured to the mold 101 onto the movement hindrance, which in this example is a movement hindrance grid 104.
- the melt front 105 rising in the mold melts and preferably evaporates the support material 102 and mixes the reinforcements 103 on the movement hindrance grid 104.
- the melt 105 and the reinforcements 103 solidify to a composite material preferably before the movement hindrance grid 104 melts.
- Figure Ib shows an embodiment of the method according to the invention during casting.
- the manufacturing method according to the invention is based on the controlled dispersion and flow (rising and/or settling) of the layer consisting of the reinforcements 103 and the support material 102 within the molten material.
- This layer is preferably implemented so that a support material layer 102 with a thickness of circa 2 to 20 mm is placed below the reinforcements 103, and often also around them, which support material layer is preferably expanded polystyrene (EPS), polyurethane or other organic polymer material having a low specific weight.
- EPS expanded polystyrene
- a movement hindrance 104 is placed to limit the movement of the reinforcing material 103 during casting, which movement hindrance is preferably a thin metal grid which is secured or supported in a fixed way to the casting mold 101 or to a separate structure inside the mold.
- movement hindrance is preferably a thin metal grid which is secured or supported in a fixed way to the casting mold 101 or to a separate structure inside the mold.
- the opening of narrow passages limiting the infiltration as the melt flow mixes the reinforcements, particularly when particles are used as reinforcement, also enables the formation of relatively large composite regions, because the melt does not have to penetrate extremely small capillary pores, which are predominant in a bound solid reinforcing particle precursor.
- EPS or a corresponding packing or support material keeps the reinforcements in place in the casting mold until the melt melts and preferably evaporates it. At the same time a volume becomes free for movements of the reinforcements and the melt, which volume is limited by metal grids or corresponding flow hindrances to a desired fraction of the total volume of the mold.
- the cooling of the melt is in many cases accelerated owing to the heat-binding effect of the reinforcement, and a solid regular composite region consisting of the reinforcement and the solidifying melt is formed, the movement of which composite region in the surrounding melt can be controlled.
- a movement hindrance grid placed below the reinforcing material and the support material prevents an excessive sedimentation and dispersion of the solid composite zone and halts it at a desired location within the object.
- the flotation of the reinforcements that are lighter than the melt within the melt can be controlled and limited by placing the movement hindrances above them in the casting mold.
- the solution according to the invention also preferably enables the preparation of layer structures in the composite to be prepared so that the mixing of different-sized reinforcing particles and/or objects with the melt and thus to the different regions of the composite to be cast is controlled for example by the density of the movement hindrance grid.
- the movement hindrance grid may for example limit larger reinforcing particles and/or objects to a specific region, while small reinforcing particles and/or objects are able to be carried together with the melt through the movement hindrance over the whole product to the prepared, or they can be limited by another denser movement hindrance to a larger part of the composite to be prepared.
- the dispersion degree of a particulate reinforcement can be controlled by the thickness of the support material layer.
- Regular composite regions can be formed by a thin support material layer, and correspondingly larger uniform composite regions can be formed by a thicker support material layer as the volume left by the melting and evaporating support material is larger.
- a simple solid insert with a desired shape can be created from a suitable support material, such as EPS, which insert is packed with a desired reinforcing material, typically with metal carbide particles or other reinforcing particles.
- EPS polystyrene
- This insert can be shaped directly into a sand mold, whereby it will also function as a shape-giver to the cast object.
- the insert can be embedded to a ready sand mold for example by a metal grid, which additionally, at the same time, is able to function ⁇ s a fastening platform for the movement hindrances of the reinforcing material.
- the method according to the invention may also be used as such for sloped and vertical surfaces, as shown in Figures 3b, 4a and 4b.
- the lighter reinforcements 107 have been carried towards the upper movement hindrance 106 and correspondingly the heavier reinforcements 103 towards the lower movement hindrance 104.
- the movement of the reinforcements 103 and 107 within the melt is limited by the vertical movement hindrance 108 and the wall of the casting mold 101.
- Figure 5 illustrates a wear part 200 prepared by the method according to the invention.
- the molten material cast in the mold and used in the solution according to the invention is preferably an iron-based material or a mixture which has an iron concentration of over 50 wt-% (Fe > 50 wt-%).
- the material of the reinforcements used in the solution according to the invention is preferably a different solid-state iron-based mixture, which has an iron concentration of over 50 wt-% (Fe > 50 wt-%) and which has a composition different from that of the molten material to be cast in the mold.
- the chemical and physical compatibility e.g. controlled binding, reactivity, and thermal compatibility
- phase regions in the casting by means of the reinforcement, in which regions the hardness, wear-resistance, toughness or other desired properties are more advantageous than in the phase formed from the melt in view of the intended application.
- the wear-resistance of a low-alloy, relatively softer but tougher steel e.g. a low-alloy tempering steel or cast iron
- reinforcing phase regions can be for example prepared from a mixture, such as tool steel, which contains alloying elements forming hard carbides.
- the density of the material differs essentially from the density of the molten material to be cast in the mold.
- the term "essential difference” means a difference in specific weight which is larger than 5 %.
- the reinforcing material used in the solution according to the invention preferably comprises a ceramics, such as oxides, nitrides, carbides and borides, and a metallic binding agent mixed therein, which binding agent can be an iron-, nickel-, chromium- or cobalt-based mixture containing mentioned other elements or other elements as mixing agents or as impurities.
- the chemical and physical compatibility e.g. controlled binding, reactivity, and thermal compatibility
- the dimensioning and the material choice of the movement hindrances used in the method according to the invention are determined by the melt, the reinforcement and the process parameters to be used.
- the production material of the movement hindrances should at least partly withstand melting as long as the movement of the reinforcement is desired to be limited, preferably as long as the flow of the melt in the mold tends to move the reinforcements together with it.
- the dimensions of the movement hindrances must be chosen so that they are able to contribute to the movement of the reinforcement within the melt while not preventing or excessively slowing down complete filling of the mold.
- the movement hindrances can be prepared from a grid, plate, wire or band which is made from a suitable metallic material, often preferably a steel or a stainless steel, and they may melt partly or wholly or remain in the final structure of the cast object depending on their melting temperature, the temperature and composition of the melt used, the size of the casting mold, and generally the conditions in the casting mold.
- a suitable metallic material often preferably a steel or a stainless steel
- the embodiment according to the invention is suitable for preparing all kinds of wear surfaces, and the cast objects prepared by the method according to the invention alone or as attached to a larger assembly are preferably suitable for use in wear parts of demanding objects, such as for example in decreasing the size of stone materials, wooden materials, construction materials, waste materials and/or recycling materials.
- wear parts of demanding objects such as for example in decreasing the size of stone materials, wooden materials, construction materials, waste materials and/or recycling materials.
- Examples of such applications are i.a. jaw crusher jaws and cheek plates and other plate-like wear parts, such as refiner segments, and wear parts of impact crushers, such as distributor plates, anvils, ejector shoes, side liners, breaker plates and impact bars.
- the method according to the invention is also suitable for the products of paper industry and metallurgical industry, such as rolls, rollers, crusher and guide rolls, straight and conical tubular objects, such as crusher cones or separators, and wear protection surfaces, such as housings, impellers and inlet liners of pumps.
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Abstract
Method for preparing a composite material and use of a composite material prepared by the method, which composite material is prepared from a molten material cast in a mold and a reinforcing material, in which method at least part of the reinforcing material is placed inside at least one support material inclosure and/or onto at least one support material layer, which support material is melted and most preferably evaporated in connection with casting the molten material in the mold, and the distribution of the reinforcing material within the molten material cast in the mold is controlled in a controlled way.
Description
METHOD FOR PREPARING A COMPOSITE MATERIAL AND USE OF A COMPOSITE MATERIAL PREPARED BY THE METHOD
The invention is related to a method for preparing a composite material and to the use of a composite material prepared by this method. More particularly, the method is related to composite materials prepared by casting, and particularly to metal matrix composites, without being limited to these.
Background of the invention
Changing the physical, chemical or functional properties, such as the wear properties, of materials locally or throughout in certain parts of machinery, devices or structures helps to diversify the applicability of the parts or structures for varying applications. Multiphase materials, such as metal matrix composites, or multimaterial structures consisting of two or more different materials which are obtained in this way have particularly many applications in wear parts of process devices. A composite material consists of at least two different phases, which are usually called a matrix and a reinforcement, and of which the volume fraction of the reinforcement is most typically 10 to 60 per cent of the total volume. The matrix is typically a uniform phase region extending through the entire material. In metal matrix composites the matrix is an alloy and the reinforcement is in most cases a metallic or ceramic material which is in particle, fiber or staple fiber form and has a composition and properties differing from those of the matrix. The properties of a composite material are determined not only by the properties of the starting materials but also for example by the manufacturing method and the processing parameters of the composite material which are actually used. Composite materials are multiphase materials, as are also such structures consisting of more than one distinguishable materials (phases) which structures do not satisfy the definition of a composite material but which often have at least partly corresponding physical or tribological properties.
Known casting-based methods for manufacturing metal matrix composites or corresponding materials or objects containing another material phase are in most cases
based on either filling a solid precursor object with a melt (infiltration) or mixing a reinforcement with a melt before casting. In addition to process metallurgical manufacturing processes also other suitable methods for preparing composite materials and particularly metal matrix composites are known, such as powder metallurgical processes. With regard to cost-efficiency, methods based on casting are, however, the most inexpensive methods for manufacturing various materials and structures.
In the present context, the term reinforcement means particles which can be classified as reinforcing material particles and which have a diameter of the order of 0.01 to 2 mm, or grains which have a diameter of the order of 2 to 5 mm, as well as material fragments larger than that, wherein the size of individual fragments at the largest is however less than 30 per cent of the total volume of the composite material or multiphase material to be manufactured. The reinforcement may be a ceramics (oxide, nitride, carbide, boride) and possibly a metallic binding agent mixed therein, which metallic binding agent can be an iron-, nickel-, chromium- or cobalt-based mixture containing mentioned other elements or other elements as mixing agents or as impurities. The reinforcement may also be a different alloy in solid form, which alloy differs by its composition from the matrix or the other composition regions of the multiphase material.
The manufacturing of a solid precursor object suited for infiltration invariably requires relatively complicated process steps. When a separate organic or inorganic binding agent is used, the binding agent must be mixed with the reinforcing particles for example in a mill or another corresponding device. The curing of the binding agent and the removal of volatile substances often require heating. If a separate binding agent is not used, the precursor object is generally manufactured by sintering in a process which is rather lengthy and requires a special apparatus. Often the precursor object still must be coated for example by gas phase deposition to facilitate infiltration. Further, eventual impurities which remain in the casting from the applied binding agents may cause various manufacturing defects or quality deviations during use.
In order to be able to adjust the geometrical properties, such as porosity and pore size, which control the filling of the precursor object to be infiltrated, so that the melt fills the free volume entirely and the phase distribution and the physical and functional
properties, such as wear resistance, of the material to be manufactured correspond to the requirement profile of the application of the material, also the size distribution of the starting materials, most usually the reinforcing particles, which are used for manufacturing the precursor object, must be controlled. Often the infiltration itself is carried out additionally as a pressure-assisted casting, which further complicates the process and requires the use of special equipment. Often even in the best known cases the thickest possible reinforced regions of the castings are relatively thin, because infiltration cannot be made to proceed through precursor objects or reinforcement assemblies which are thicker than a certain maximum dimension. When for example a surface of a large wear part is desired to be protected by using a reinforcement across an area as wide as possible and extending as deep as possible, which would lead to a useful service life as long as possible, this restriction is a particularly significant restriction on the use of known methods.
If the reinforcement is mixed with the melt before casting, the preservation of the reinforcement distribution during pouring, mold filling and solidification is often difficult to control. This problem is emphasized if the product to be prepared has a complex shape or if the distribution and volume fraction of the reinforcement are supposed to be different in different parts of the object. Also the use of factors external to the mold, such as for example an electromagnetic field, for controlling the structure is difficult and expensive particularly in the case of objects with a complex shape.
Summary of the invention
The composite material and its manufacturing method according to the present invention are able to remove or at least to reduce the above presented disadvantages of the prior art.
By the manufacturing method according to the invention it is possible to prepare wear- resistant composite materials and products in which there are thicker reinforcement layers at determined regions than what is possible to prepare by known manufacturing methods, hi the manufacturing method the distribution of the reinforcement in the composite material to be cast can be well controlled, hi addition, the contact time of the melt and the reinforcements is shorter than in the case of mixing the reinforcement with
the melt before pouring. The method according to the invention also enables the use of such reinforcements the density of which is clearly different from that of the melt. In addition, the invention enables the coating of objects with a complex geometry while reducing and simplifying the process steps needed in the manufacturing method.
The composite material prepared according to the invention is particularly suitable for use in all kinds of wear materials, such as for example in different wear parts of excavation and mining industry and in applications of paper, process and metallurgical industry, such as rolls, guide rollers and impellers.
More particularly, the method according to the invention is characterized by what is disclosed in the characterizing part of claim 1, and the use of a composite material prepared by the method according to the invention is characterized by what is disclosed in claims 10 and 11.
Brief description of the drawings
The invention is described below in more detail by way of example by referring to the appended schematic Figures, in which
Figure 1 a shows an embodiment according to the invention before casting,
Figure Ib shows the embodiment according to Figure Ia during casting,
Figure 2a shows an embodiment according to the invention after casting,
Figure 2b shows a first alternative embodiment according to the invention after casting,
Figure 3 a shows a second alternative embodiment according to the invention after casting,
Figure 3b shows a third alternative embodiment according to the invention after casting,
Figure 4a shows a fourth alternative embodiment according to the invention after casting,
Figure 4b shows a fifth alternative embodiment according to the invention after casting, and
Figure 5 shows a wear part prepared by the method according to the invention.
Detailed description of the invention
Figure Ia shows a principal description of a preferred embodiment according to the invention at an initial casting stage 100, which comprises a casting mold 101, a support material inclosure 102, inside of which there are reinforcements 103, a reinforcement movement hindrance grid 104, and a melt front 105 rising in the mold.
In the solution according to the invention, the reinforcements may be either microscopic particles, macroscopic objects, something in between, or combinations thereof.
The reinforcements 103 packed in the support material 102 are secured to the mold 101 onto the movement hindrance, which in this example is a movement hindrance grid 104. The melt front 105 rising in the mold melts and preferably evaporates the support material 102 and mixes the reinforcements 103 on the movement hindrance grid 104. The melt 105 and the reinforcements 103 solidify to a composite material preferably before the movement hindrance grid 104 melts.
Figure Ib shows an embodiment of the method according to the invention during casting. The manufacturing method according to the invention is based on the controlled dispersion and flow (rising and/or settling) of the layer consisting of the reinforcements 103 and the support material 102 within the molten material. This layer is preferably implemented so that a support material layer 102 with a thickness of circa 2 to 20 mm is placed below the reinforcements 103, and often also around them, which support material layer is preferably expanded polystyrene (EPS), polyurethane or other organic polymer material having a low specific weight. To the direction of movement expected on the basis of the density difference between the reinforcements 103 and the melt 105, behind
the support material 102 when viewed from the reinforcements 103, a movement hindrance 104 is placed to limit the movement of the reinforcing material 103 during casting, which movement hindrance is preferably a thin metal grid which is secured or supported in a fixed way to the casting mold 101 or to a separate structure inside the mold. When the support material layer 102 melts and preferably evaporates due to the heat of the melt 105, the reinforcements 103 that are heavier than the melt will settle in a controlled way in the rising melt. Then the reinforcements 103 that are heavier than the melt will settle towards or onto the below-lying movement hindrance 104, as shown in Figure 2a. Correspondingly, the reinforcements 107 that are lighter than the melt 105, in accordance with Figure 2b, tend to rise together with the melt 105 towards or against the above-placed movement hindrance 106, as shown in Figures 2b and 3a.
When loose reinforcement particles and/or objects preferably suitable as reinforcements are used, they are able to move freely in the melt, and the molten metal is able to surround freely the reinforcements and to fill their interstices, because the reinforcements are not bound to each other.
The opening of narrow passages limiting the infiltration as the melt flow mixes the reinforcements, particularly when particles are used as reinforcement, also enables the formation of relatively large composite regions, because the melt does not have to penetrate extremely small capillary pores, which are predominant in a bound solid reinforcing particle precursor. EPS or a corresponding packing or support material keeps the reinforcements in place in the casting mold until the melt melts and preferably evaporates it. At the same time a volume becomes free for movements of the reinforcements and the melt, which volume is limited by metal grids or corresponding flow hindrances to a desired fraction of the total volume of the mold.
After the molten metal has come into contact with the surfaces of the reinforcement, the cooling of the melt is in many cases accelerated owing to the heat-binding effect of the reinforcement, and a solid regular composite region consisting of the reinforcement and the solidifying melt is formed, the movement of which composite region in the surrounding melt can be controlled. A movement hindrance grid placed below the reinforcing material and the support material prevents an excessive sedimentation and
dispersion of the solid composite zone and halts it at a desired location within the object. Correspondingly the flotation of the reinforcements that are lighter than the melt within the melt can be controlled and limited by placing the movement hindrances above them in the casting mold.
The solution according to the invention also preferably enables the preparation of layer structures in the composite to be prepared so that the mixing of different-sized reinforcing particles and/or objects with the melt and thus to the different regions of the composite to be cast is controlled for example by the density of the movement hindrance grid. In this case the movement hindrance grid may for example limit larger reinforcing particles and/or objects to a specific region, while small reinforcing particles and/or objects are able to be carried together with the melt through the movement hindrance over the whole product to the prepared, or they can be limited by another denser movement hindrance to a larger part of the composite to be prepared.
The dispersion degree of a particulate reinforcement can be controlled by the thickness of the support material layer. Regular composite regions can be formed by a thin support material layer, and correspondingly larger uniform composite regions can be formed by a thicker support material layer as the volume left by the melting and evaporating support material is larger.
Additionally, a simple solid insert with a desired shape can be created from a suitable support material, such as EPS, which insert is packed with a desired reinforcing material, typically with metal carbide particles or other reinforcing particles. This insert can be shaped directly into a sand mold, whereby it will also function as a shape-giver to the cast object. Alternatively, the insert can be embedded to a ready sand mold for example by a metal grid, which additionally, at the same time, is able to function ^s a fastening platform for the movement hindrances of the reinforcing material.
The method according to the invention may also be used as such for sloped and vertical surfaces, as shown in Figures 3b, 4a and 4b. In the embodiment according to Figure 3b the lighter reinforcements 107 have been carried towards the upper movement hindrance 106 and correspondingly the heavier reinforcements 103 towards the lower movement
hindrance 104. In addition, the movement of the reinforcements 103 and 107 within the melt is limited by the vertical movement hindrance 108 and the wall of the casting mold 101.
In the embodiment of Figure 4a the movement of the reinforcements 103 within the melt has been restricted to the area limited by the movement hindrances 104 and 108 and the casting mold.
By planting the insert carrying the reinforcements horizontally at the bottom of the mold, even horizontal composite surfaces can be formed, as shown in Figure 4b.
Figure 5 illustrates a wear part 200 prepared by the method according to the invention.
The molten material cast in the mold and used in the solution according to the invention is preferably an iron-based material or a mixture which has an iron concentration of over 50 wt-% (Fe > 50 wt-%). The material of the reinforcements used in the solution according to the invention is preferably a different solid-state iron-based mixture, which has an iron concentration of over 50 wt-% (Fe > 50 wt-%) and which has a composition different from that of the molten material to be cast in the mold. In the selection of the melt, the chemical and physical compatibility (e.g. controlled binding, reactivity, and thermal compatibility) with the reinforcement to be used must be taken into account. In this embodiment, it is desired to form phase regions in the casting by means of the reinforcement, in which regions the hardness, wear-resistance, toughness or other desired properties are more advantageous than in the phase formed from the melt in view of the intended application. Thus for example the wear-resistance of a low-alloy, relatively softer but tougher steel, e.g. a low-alloy tempering steel or cast iron, can be increased by means of reinforcing phase regions, which can be for example prepared from a mixture, such as tool steel, which contains alloying elements forming hard carbides.
In addition, in some preferred embodiments of the invention at least in a part of the reinforcing material the density of the material differs essentially from the density of the molten material to be cast in the mold. In the present context, the term "essential difference" means a difference in specific weight which is larger than 5 %.
The reinforcing material used in the solution according to the invention preferably comprises a ceramics, such as oxides, nitrides, carbides and borides, and a metallic binding agent mixed therein, which binding agent can be an iron-, nickel-, chromium- or cobalt-based mixture containing mentioned other elements or other elements as mixing agents or as impurities. In the selection of the melt, the chemical and physical compatibility (e.g. controlled binding, reactivity, and thermal compatibility) with the reinforcement to be used must be taken into account.
The dimensioning and the material choice of the movement hindrances used in the method according to the invention are determined by the melt, the reinforcement and the process parameters to be used. The production material of the movement hindrances should at least partly withstand melting as long as the movement of the reinforcement is desired to be limited, preferably as long as the flow of the melt in the mold tends to move the reinforcements together with it. The dimensions of the movement hindrances must be chosen so that they are able to contribute to the movement of the reinforcement within the melt while not preventing or excessively slowing down complete filling of the mold. The movement hindrances can be prepared from a grid, plate, wire or band which is made from a suitable metallic material, often preferably a steel or a stainless steel, and they may melt partly or wholly or remain in the final structure of the cast object depending on their melting temperature, the temperature and composition of the melt used, the size of the casting mold, and generally the conditions in the casting mold. By changing the arrangement and dimensioning of the movement hindrance or movement hindrances, such as the mesh size of a movement hindrance prepared from a grid, it is possible to affect the way in which the movement hindrance prevents or controls the movement of the reinforcement within the melt.
The embodiment according to the invention is suitable for preparing all kinds of wear surfaces, and the cast objects prepared by the method according to the invention alone or as attached to a larger assembly are preferably suitable for use in wear parts of demanding objects, such as for example in decreasing the size of stone materials, wooden materials, construction materials, waste materials and/or recycling materials. Examples of such applications are i.a. jaw crusher jaws and cheek plates and other plate-like wear
parts, such as refiner segments, and wear parts of impact crushers, such as distributor plates, anvils, ejector shoes, side liners, breaker plates and impact bars. The method according to the invention is also suitable for the products of paper industry and metallurgical industry, such as rolls, rollers, crusher and guide rolls, straight and conical tubular objects, such as crusher cones or separators, and wear protection surfaces, such as housings, impellers and inlet liners of pumps.
The invention is not intended to be limited to the embodiments described above but it can be applied widely within the scope determined by the claims defined in the following.
Claims
1. Method for preparing a composite material from a molten material cast in a mold and a reinforcing material, characterized in that the method comprises placing at least part of the reinforcing material inside at least one support material inclosure and/or onto at least one support material layer, which support material is melted and most preferably evaporated in connection with casting the molten material in the mold, and that the distribution of the reinforcing material within the molten material cast in the mold is controlled in a controlled way.
2. Method according to claim 1, characterized in that said support material is at least partly an organic material.
3. Method according to claim 2, characterized in that said organic material is expanded polystyrene (EPS), polyurethane, or a corresponding polymer having a low specific weight.
4. Method according to any of the claims 1 to 3, characterized in that the distribution of the reinforcing material in the cast molten material is controlled through at least one movement hindrance attached to or supported by the mold structure.
5. Method according to any of the claims 1 to 4, characterized in that said molten material is an iron-based mixture which has an iron concentration of over 50 wt-%.
6. Method according to any of the claims 1 to 5, characterized in that the reinforcing material is a different solid-state iron-based mixture which has an iron concentration of over 50 wt-% and which has a composition differing from that of said molten material.
7. Method according to any of the claims 1 to 6, characterized in that at least in a part of the reinforcing material the density of the material differs essentially from the density of said molten material.
8. Method according to any of the claims 1 to 7, characterized in that the reinforcing material comprises a ceramics and a metallic binding agent mixed with the ceramics, which binding agent can be an iron-, nickel, chromium- or cobalt-based mixture containing mentioned other elements or other elements as mixing agents or as impurities.
9. Method according to any of the claims 1 to 8, characterized in that the composite material to be prepared is a metal matrix composite material.
10. Use of a composite material prepared by a method according to any of the claims 1 to 9 in wear parts of mining and excavation machinery, such as wear parts of jaw, cone, gyratory and impact crushers and wear parts of grinding mills.
11. Use of a composite material prepared by a method according to any of the claims 1 to 9 in wear parts used in decreasing the size of stone material, wooden material, construction material, waste material or recycling material.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI20086088A FI20086088A (en) | 2008-11-18 | 2008-11-18 | Process for making a composite material and using a composite material made by the process |
FI20086088 | 2008-11-18 |
Publications (2)
Publication Number | Publication Date |
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WO2010058074A2 true WO2010058074A2 (en) | 2010-05-27 |
WO2010058074A3 WO2010058074A3 (en) | 2010-08-05 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/FI2009/050927 WO2010058074A2 (en) | 2008-11-18 | 2009-11-17 | Method for preparing a composite material and use of a composite material prepared by the method |
Country Status (2)
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FI (1) | FI20086088A (en) |
WO (1) | WO2010058074A2 (en) |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
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AU2530077A (en) * | 1976-05-26 | 1978-11-23 | Steel Castings Res | Forming moulds or cores using a vacuum |
EP0064411A1 (en) * | 1981-05-06 | 1982-11-10 | John Phin Oliver | A method of forming a one piece article comprising a body of base metal having one or more smaller bodies of another material anchored thereto |
DE4301743A1 (en) * | 1993-01-23 | 1994-07-28 | Karl Lange | Arrangement for positioning hard substances in castings |
JP2000317616A (en) * | 1999-05-17 | 2000-11-21 | Nippon Welding Rod Kk | Production of wear resistant clad plate |
WO2001046486A1 (en) * | 1999-12-21 | 2001-06-28 | Hitachi Metals, Ltd. | Method for producing metal-based composite material |
EP1502678A1 (en) * | 2003-07-28 | 2005-02-02 | Burcelik Bursali Celik Dokum Sanayi A.S. | A method of producing a composite component by using a preform |
DE10359784A1 (en) * | 2003-12-19 | 2005-07-21 | Daimlerchrysler Ag | Body or body part for a vehicle |
BE1018130A3 (en) * | 2008-09-19 | 2010-05-04 | Magotteaux Int | HIERARCHICAL COMPOSITE MATERIAL. |
-
2008
- 2008-11-18 FI FI20086088A patent/FI20086088A/en not_active Application Discontinuation
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2009
- 2009-11-17 WO PCT/FI2009/050927 patent/WO2010058074A2/en active Application Filing
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Also Published As
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WO2010058074A3 (en) | 2010-08-05 |
FI20086088A0 (en) | 2008-11-18 |
FI20086088A (en) | 2010-05-19 |
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