JP2023012613A - Method for manufacturing high metal powder containing aluminum composite, method for manufacturing preform, and high metal powder containing aluminum composite - Google Patents

Abstract

To provide a technique obtaining a high metal powder containing aluminum composite having less cracks or defects and having high metal content when establishing a manufacturing technique for obtaining a uniform preform capable of enhancing the filling factor of metal powder without having defects in the inside to high-pressure impregnate or non-pressure infiltrate aluminum alloy, etc., into the preform.SOLUTION: A method, etc., for manufacturing high metal powder containing aluminum composite comprises: the preform manufacturing step of calcinating a molding formed of a material obtained by adding and mixing an organic/inorganic binder to metal raw materials obtained by selecting two or more kinds of materials having different particle diameters from a metal powder material having an average particle size of 1-200 μm at a temperature of 300-800°C to obtain a preform having a metal raw material content of 55v% or more; and impregnating molten metal, such as aluminum alloy at a high pressure into the obtained preform.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a method for producing an aluminum composite containing high metal powder, a method for producing a preform, and an aluminum composite containing high metal powder. It relates to a new technology that can provide an aluminum composite containing a high metal powder, which is satisfactorily impregnated with, and that can dramatically improve the productivity and quality of the composite material.

In recent years, composite materials such as metals and Al alloys have been used as materials with light weight, high strength, high Young's modulus, high thermal conductivity, and low thermal expansion. , XY sliders, and vacuum chucks. These materials are a kind of so-called MMC (Metal Matrix Composite). Conventionally, MMC, in which a ceramic powder is compounded with a metal matrix, has been generally used, but in recent years, attention has been paid to a composite material composed of a metal powder and an Al alloy or the like. For example, composite materials such as silicon and Al alloys with high Young's modulus and low thermal expansion, and compounding Al alloys with high-strength titanium or iron powder have been proposed. In addition, as will be described below, composites of metal powders and Al alloys are attracting attention because of their excellent workability.

For example, silicon metal has a small coefficient of thermal expansion, so it is used for electronic parts and semiconductor parts. Therefore, a silicon-aluminum composite with an Al alloy or the like is being developed. For the above-mentioned reasons, firstly, a composite with aluminum containing as much silicon powder as possible is desired, and a composite with a small coefficient of thermal expansion and a large Young's modulus while maintaining workability is desired. ing. Specifically, for example, if a silicon-aluminum composite with a silicon content of 70 v% or more, preferably about 80 v%, can be produced, the application to heat sinks and electronic component packages for mounting electronic components with a small coefficient of thermal expansion will be dramatic. expected to spread to

Titanium metal has a small coefficient of thermal expansion and is used as a wide variety of machine parts as a lightweight and highly rigid metal. However, it has a high hardness and is a difficult-to-work material, which limits its applications. Therefore, if it is possible to improve workability by combining titanium metal with aluminum metal, the range of applications can be further expanded.

Here, as a method for producing a composite of metal powder and Al alloy, the following methods are generally used.
(Casting method for high silicon aluminum alloy)
In this method, silicon-containing aluminum alloy powder (also called silicon-aluminum alloy) commonly called silumin containing a silicon component is melted and cast into a sand mold or metal mold. However, in this method, if the silicon content is high, the flowability of the alloy is lowered and casting becomes impossible. Therefore, it is difficult to produce a high-silicon-aluminum composite with a desired high content of metal components by the casting method described above.

(Spray forming method)
In this method, silicon and aluminum are melted at a high temperature, the melt is sprayed to form a powder deposit, a bullet is produced, and a silicon-aluminum composite is produced by hot extrusion. called the law. In the spray forming method, metal is melted at a high temperature to produce a composite material powder in which the ratio of silicon and aluminum is freely changed. Therefore, it is theoretically possible to produce a silicon-rich aluminum composite with a high metal component content. However, in order to manufacture a composite material with a silicon content of 50 v % or more, it is necessary to melt the material at 1000° C. or more. In addition, in the spray cooling process, silicon precipitates first, and a uniform composite cannot be obtained. It has not been possible to obtain a silicon-aluminum composite with a higher content ratio of In addition, since voids are generated in the process of solidification and deposition in which the melted material is sprayed to produce a burette of the powder deposit, the resulting burette is semi-melted and high-pressure extruded or HIPed in order to produce a product. It needs to be treated to crush the voids. In this respect, the "spray forming method" has a serious industrial problem that the manufacturing cost is extremely high and the economy is inferior.

(Non-pressure impregnation method of aluminum into silicon powder packing)
In Patent Document 1, molten aluminum or aluminum alloy is added to a filled body or molded body having a silicon powder filling rate of 50 to 70% by volume at a temperature of 700 to 1000 ° C. in a nitrogen atmosphere containing magnesium vapor. Non-pressure infiltrated silicon-aluminum composite metals have been proposed. Patent Literature 1 discloses that the impregnation of the molten Al alloy into the filler can be accelerated by including magnesium vapor in the nitrogen atmosphere. Further, in the example, a filler obtained by filling a container with a mixture of 100 parts by mass of silicon powder having an average particle size of 5 μm and 2 parts by mass of magnesium powder is used, and the filling rate of silicon is 50% by volume. It is stated that It is described that silicon powder having an average particle size of 1 to 100 μm was used, if necessary, in contrast to the above examples.

As described above, what is disclosed in Patent Document 1 is that magnesium powder is added to one type of silicon powder, this is filled in a container, and the packed body is placed in a nitrogen atmosphere at normal pressure (non-pressurized ) to produce a composite metal by infiltrating a molten Al alloy. However, according to the study of the present inventors, a mere filling of silicon powder may be non-uniform or may leave pores inside. When such a filling body is impregnated with molten aluminum without pressure, cracks and defects occur, and a filling body in which the silicon powder is uniformly and sufficiently filled cannot be obtained. be. For this reason, the non-pressure infiltration method using the above-mentioned packing cannot produce a metal powder-aluminum composite with a high and uniform metal component content, which is required for products.

Further, in Patent Document 2, a metal powder such as silicon powder is added with PVA (polyvinyl alcohol) as a binder to form a metal powder compact or calcined body. It has been reported to penetrate in In the example, a material obtained by adding PVA as a binder to silicon powder having an average particle size of 20 μm was used, and a molded body obtained by press molding was placed in a nitrogen atmosphere furnace in which magnesium was present, and a molten Al alloy was added at normal pressure. It describes obtaining a composite metal by impregnation, using two types of metal powder, and mixing ceramic powder with metal powder. However, as can be seen from the fact that the technique described in Patent Document 2 mixes the ceramic powder with the metal powder, the molded body of the metal powder, which is the counterpart to be composited by infiltrating the molten metal without pressure, Also, it is not a technique aimed at increasing the metal content of the calcined body.

According to the studies of the present inventors, for example, when an aluminum alloy or the like is impregnated under high pressure or non-pressure impregnated into a filler filled with silicon powder at a high content, the filler and the Al alloy etc. When impregnated with a molten metal such as an Al alloy, stress is generated on the contact surface with the metal powder compact, and cracks or the like may occur in the metal powder molded body. On the other hand, all of the above-described prior arts are studies on how to obtain a high metal powder-aluminum composite with a high metal content and very few cracks and defects. nor does it provide For example, as in the above-described prior art, even when aluminum metal is impregnated into a silicon powder-filled body or a press-molded compact without pressure, the contact surface between the silicon powder-filled body and an Al alloy or the like stress is generated in the aluminum alloy, cracks or the like may occur during impregnation with a molten metal such as an Al alloy, or defects due to non-impregnation may occur.

Here, the advantage of impregnating a filled body or molded body with a molten metal such as an Al alloy without pressure infiltration, which is performed in the above-described conventional technology, is that a molded body obtained by press molding metal powder ( It is possible to produce a metal powder-aluminum composite having a shape close to that of a product after impregnation by gently impregnating a molded body with a molten metal such as an Al alloy while maintaining the shape of the preform by capillary action. That is, if it is possible to obtain a composite having a shape close to that of the product after impregnating the molded body with the molten metal, it is possible to reduce the machining required thereafter, which has the advantage of reducing the manufacturing cost.

This means that if a strong molded body (preform) that does not cause cracks or defects can be obtained when a molten metal such as an Al alloy is impregnated without pressure, the product value and cost benefits will increase dramatically. means Further, if the content of metal powder material such as silicon in the resulting metal powder-aluminum composite can be increased, a metal powder-aluminum composite having a lower thermal expansion and a higher Young's modulus can be obtained. For example, if a method for producing a silicon powder-aluminum composite containing more than 50 v% silicon can be established, its applications will be greatly increased.

In contrast to the above, it is widely practiced to manufacture a preform by sintering a molded body of metal powder having a fine particle size at a temperature slightly lower than the melting temperature of the metal, and by pre-sintering the powder. However, according to the study of the present inventors, in this method, a molded body (preform) is produced by sintering, but during sintering, the molded body shrinks and the preform is deformed, or the preform is deformed. There is a risk that the internal voids will become closed pores that are cut off from the outside, resulting in poor impregnation in the subsequent Al alloy impregnation step, resulting in a non-uniform metal powder aluminum composite.

Japanese Patent Application Laid-Open No. 2005-036253 Japanese Unexamined Patent Application Publication No. 2004-052011

Accordingly, an object of the present invention is to produce a strong molded body (preform) of metal powders represented by powders such as silicon, silicon aluminum alloy, iron, titanium, copper, nickel, ferrosilicon, etc., and achieve target performance. The filling rate of the metal powder can be increased according to the condition, and there are extremely few internal defects, and a technology for producing uniform preforms has been established. , a method for producing an aluminum composite containing a high metal powder, which has a high metal content, which has extremely low cracks and defects, both when impregnated under high pressure and when impregnated without pressure, and the high metal content obtained by the method An object of the present invention is to provide an aluminum composite containing metal powder.

The above objects are achieved by the following technique for producing high metal content, high metal powder content aluminum composites. That is, the present invention provides the following method for producing an aluminum composite containing high metal powder.
As a first invention, the following manufacturing method for obtaining an aluminum composite containing a high metal powder by impregnating an Al alloy or the like under high pressure is provided.
[1] A preform manufacturing process for obtaining a metal powder molded body (preform) having a high metal content, and an aluminum impregnation process for impregnating or permeating the obtained preform with molten aluminum or aluminum alloy. A method for producing a high metal powder-containing aluminum composite having
In the preform manufacturing process, two or more kinds of metal powder materials having different average particle sizes are selected from metal powder materials having an average particle size of 1 μm or more and 200 μm or less as metal raw materials for preforms, and the metal raw materials Then, the mixture obtained by adding and mixing an organic and inorganic binder is molded, and the obtained molded product is fired at a temperature of 300 ° C. or higher and 800 ° C. or lower, and the content (volume ratio) of the metal raw material is 55 v% or more to obtain a metal powder compact,
A high-metal-powder-containing aluminum composite characterized in that, in the step of impregnating aluminum or the like, the metal powder molded body obtained in the step of making the preform is impregnated with molten aluminum or aluminum alloy at a high pressure of 10 MPa to 200 MPa. body manufacturing method.

As a second invention, there is provided the following manufacturing method for obtaining an aluminum composite containing high metal powder by impregnating an Al alloy or the like without pressure.
[2] A preform manufacturing process for obtaining a metal powder compact (preform) with a high metal content, and an aluminum impregnation process for impregnating or permeating the obtained preform with molten aluminum or aluminum alloy. A method for producing a high metal powder-containing aluminum composite having
In the preform manufacturing process, a metal powder material having an average particle size of 1 μm or more and 200 μm or less (excluding each powder material of Mg powder, AlMg powder, ZnMg powder, ZnAl powder, and Mg ₂ Si powder), average particles Two or more kinds of metal powder materials having different diameters are selected as a metal raw material for a preform, and 100 parts by mass of the metal raw material is composed of Mg powder, AlMg powder, ZnMg powder, ZnAl powder and Mg ₂ Si powder. One or more powders selected from the group are added in an amount within the range of 0.2 to 5 parts by mass, and an organic and inorganic binder is added and mixed to form a mixture. sintering the molding at a temperature of 500° C. or less to obtain a metal powder molding having a content (volume ratio) of the metal raw material of 55 v % or more;
A method for producing a high-metal-powder-containing aluminum composite, characterized in that, in the step of impregnating aluminum or the like, aluminum or an aluminum alloy is impregnated into the metal powder molded body obtained in the step of making the preform without pressure. .

Preferred embodiments of the method for producing the high-metal-powder-containing aluminum composite of the present invention are as follows.
[3] The above [1], wherein the metal powder is selected from silicon powder or a silicon-based alloy powder containing silicon, titanium powder, iron powder or an iron-based alloy powder containing iron, and nickel powder or a nickel-based alloy powder containing nickel. Or the method for producing a high metal powder-containing aluminum composite according to [2].
[4] The high metal powder-containing aluminum composite according to any one of the above [1] to [3], wherein the volume content of the metal powder in the high metal powder-containing aluminum composite is 55 v% or more and 85 v% or less. Production method.
[5] The two or more types of metal powders having different average particle sizes include at least a metal powder A having an average particle size of 10 μm or less and a metal powder B having an average particle size of 40 μm or more. , Production of a high metal powder-containing aluminum composite according to any one of the above [1] to [4], which contains at least 3% in the total amount of the metal powder and contains 50% or more of the metal powder B on a mass basis. Method.
[6] The high metal powder-containing aluminum composite according to any one of [1] to [5] above, wherein the organic/inorganic binder is at least one selected from the group consisting of silicone resin, Si alkoxide and Al alkoxide. Production method.

Moreover, the present invention provides, as another embodiment, the following method for producing a preform, which is preferably used in the method for producing an aluminum composite containing high metal powder according to the first invention.
[7] A preform for obtaining a metal powder molded body (preform) with a high metal powder content, used for obtaining an aluminum composite metal containing a high metal powder content by impregnating molten aluminum or aluminum alloy at high pressure A method for producing the
A metal powder material having an average particle size of 1 μm or more and 200 μm or less includes at least a metal powder A having an average particle size of 10 μm or less and a metal powder B having an average particle size of 40 μm or more. , at least 3% of the total amount of the metal powder and containing 50% or more of the metal powder B, and selecting two or more kinds of metal powder materials having different average particle sizes as a metal raw material for a preform, A mixture obtained by adding and mixing an organic and inorganic binder to a metal raw material is molded, and the obtained molded product is fired at a temperature of 300 ° C. or higher and 800 ° C. or lower, and the content of the metal raw material (volume A method for producing a preform, characterized by obtaining a metal powder compact having a ratio) of 55 v% or more.

In addition, the present invention provides, as another embodiment, the following method for producing a preform that is preferably used in the method for producing an aluminum composite containing high metal powder of the second invention.
[8] For obtaining a metal powder molded body (preform) with a high metal powder content, which is used when obtaining an aluminum composite metal containing a high metal powder content by infiltrating molten aluminum or aluminum alloy without pressure A method of making a preform, comprising:
At least metal with an average particle size of 10 μm or less from metal powder materials with an average particle size of 1 μm or more and 200 μm or less (excluding each powder material of Mg powder, AlMg powder, ZnMg powder, ZnAl powder, and Mg ₂ Si powder) Powder A and metal powder B having an average particle size of 40 μm or more, containing at least 3% by mass of the metal powder A in the total amount of the metal powder, and containing 50% or more of the metal powder B, Two or more kinds of metal powder materials having different average particle sizes are selected as metal raw materials for preforms, and Mg powder, AlMg powder, ZnMg powder, ZnAl powder and Mg ₂ Si powder are added to 100 parts by mass of the metal raw materials. One or more powders selected from the group consisting of are added in an amount within the range of 0.2 to 5 parts by mass, and an organic and inorganic binder is added and mixed. A method for producing a preform, characterized in that the molded product thus obtained is fired at a temperature of 500° C. or less to obtain a metal powder molded product having a content (volume ratio) of the metal raw material of 55 v % or more.

Moreover, the present invention provides, as another embodiment, the following high metal powder-containing aluminum composite.
[9] A high metal powder-containing aluminum composite with extremely few internal defects such as blowholes, the high metal powder using high pressure impregnation according to any one of the above [1], [3] to [6]. An aluminum composite containing a high metal powder obtained by a method for producing an aluminum containing composite.
[10] A near-net high-metal-powder-containing aluminum composite close to the shape of the product, the high-metal-powder-containing aluminum composite utilizing non-pressure infiltration according to any one of [2] to [6] above. A high metal powder-containing aluminum composite obtained by the manufacturing method of.

According to the present invention, for example, in the production of molded bodies (preforms) of metal powders typified by powders of silicon, silicon aluminum alloys, iron, titanium, copper, nickel, ferrosilicon, etc., metals are used according to the target performance. The volume filling rate of the powder can be increased to 55 v% or more, and the preform obtained can be made uniform with extremely few internal defects. High-quality metal powder-containing aluminum composites with high metal volume content and reduced occurrence of cracks and defects in both cases of high-pressure impregnation and non-pressure infiltration of alloys, etc. Provided is a method for producing an excellent high-metal-powder-containing aluminum composite. Further, according to the present invention, there is provided a high-quality aluminum composite containing high metal powder, which has extremely few internal defects such as blowholes. These composites can be used, for example, as vacuum components in semiconductors, liquid crystal manufacturing equipment, electron microscopes, optical communication packages, and the like. In addition, according to the present invention, it is possible to produce a near-net high metal powder-containing aluminum composite that is close to the shape of the product. can be increased in size, it is expected to be used as a large-sized structural part such as a robot arm, a shape measuring device stand, and an XY table.

FIG. 3 is a schematic diagram for explaining a pressurized infiltration method of pressurizing and infiltrating a molten metal such as an Al alloy into a preform, which is used in the method for producing an aluminum composite containing high metal powder according to the present invention. FIG. 2 is a schematic diagram for explaining how molten metal such as an Al alloy permeates and impregnates a preform by a capillary phenomenon by a non-pressure infiltration method performed in the method for producing an aluminum composite containing a high metal powder content of the present invention.

The present invention will be described below with reference to preferred embodiments, but the present invention is not limited to these embodiments.

[Preparation of metal powder compact (preform)]
In view of the above-mentioned prior art, the present inventors are earnestly developing a method for producing an aluminum composite containing a high metal powder content, which has a high metal volume content, is uniform with few internal defects, and can be expected to be used in a variety of applications. As a result of the investigation, we came to the conclusion that it is important to establish a method for easily producing a metal powder compact (preform) with a high metal volume content and few internal voids. . First, the inventors of the present invention have found that in order to obtain a metal preform with few voids that cause defects in the finally obtained composite material, metal powders having the same particle size are used as materials. Instead, it has been found that it is effective to use a material in which two or more kinds of metal powders having different average particle sizes are mixed together. In other words, it was found that with such a configuration, fine particles with a small average particle size enter between particles with a large average particle size, and as a result, the effects of the present invention can be obtained. In the present invention, two or more types of metal powders having different average particle sizes are selected, and a mixture obtained by mixing these powders is used as the metal raw material for the preform.

(Metal powder material)
In the present invention, a material having an average particle size of 1 μm or more and 200 μm or less is used as a metal powder material for producing a preform. A metal powder having a particle diameter of preferably 3 μm or more and 180 μm or less, more preferably 3 μm or more and 100 μm or less is used. The preform constituting the present invention is produced from a mixture obtained by selecting and mixing two or more kinds of metal powders having different average particle sizes from among the metal powders having an average particle size within this range. It requires If only a material having an average particle size of less than 1 μm is used, the particles are too fine, the surface oxidation phase of the metal powder increases, and there is a possibility that the performance as the metal powder may deteriorate. On the other hand, if the metal powder to be used is only over 200 μm, the particle diameter is too large, and the particle filling property for performing press molding, CIP molding, sedimentation molding, etc. deteriorates, which is not preferable.

In the present invention, when selecting two or more kinds of metal powder materials having different average particle sizes for producing a preform, a mixture of a metal powder having a large particle size and a metal powder having a small particle size is used. It is preferable to use For example, at least a metal powder A having an average particle size of 10 μm or less and a metal powder B having an average particle size of 40 μm or more are included, and the metal powder A is contained at least 3% in the total amount of the metal powder on a mass basis, Moreover, it is preferable that the metal powder B is contained in an amount of 50% or more.

For example, when silicon powders having different average particle sizes of 45 μm and 5 μm are separately press-molded, the volume filling rates (v%: Vf) are 47% and 52%, respectively. According to the studies of the present inventors, by mixing silicon powders of 45 μm and 5 μm in a mass ratio of 70:30 and using the mixture for press molding, etc., finally Vf = 73 v% molded body can be obtained. Similarly, silicon powders of 70 µm, 25 µm, and 5 µm are mixed at a ratio of 70:25:5 on a mass basis, and the mixture is press-molded or the like to obtain Vf = 78 v% (% by volume). can be obtained.

Metal powder such as silicon powder has a filling rate that varies depending on its average particle size, particle shape, particle size distribution, etc. Therefore, as a method of obtaining a desired high volume filling rate (v%), for example, it is placed in a carbon vessel or the like, and In order to achieve a high filling rate, there is also a method of carefully applying vibrations to obtain a filling that is filled with as few voids as possible. However, according to the studies of the present inventors, it is not easy to obtain a filling with a metal powder raw material content of 55 v% or more by this method using vibration, and even if it is obtained, When the filler is impregnated with a molten metal such as an Al alloy at high pressure, cracks or streak-like defects occur, and it is not possible to obtain a high-quality aluminum composite containing metal powder. rice field.

As a result of intensive studies based on the above findings, the present inventors have found that two or more kinds of metal powder materials having different average particle sizes are used, and the mixed powder is subjected to molding methods such as press molding, CIP molding, and sedimentation. By adopting and molding so that the metal powder is packed as tightly as possible, the content of the metal raw material is 55 v% or more, and the filling rate is higher, and it can withstand even when impregnated with a molten metal such as an Al alloy at high pressure. We have found that it is possible to produce a strong preform. Furthermore, in order to further increase the strength of the preform, an organic/inorganic binder is added to and mixed with the mixture of metal powders composed as described above, and the molded article made of the obtained mixture is fired at a temperature of 300 ° C. or more and 800 ° C. or less. It was found that it is effective to These points will be described later.

In addition, the present inventors diligently studied the production of a preform having a metal powder raw material content of 55 v% or more, which is capable of infiltrating a molten metal such as an Al alloy without pressurization. As a result, on a mass basis, for 100 parts by mass of the metal powder material, metal Mg powder, Al--Mg alloy powder, Zn--Mg alloy powder, magnesium-based alloy such as Zn--Al alloy powder, magnesium One or more powders selected from compounds such as Mg ₂ Si powder having a high content of Using a mixture to which parts by mass are added, adding an organic and inorganic binder specific to the mixture, and using a preform obtained by firing a molded product made of the mixture at a temperature of 500 ° C. or less, Al alloy etc. can be infiltrated in a good state without pressure, and a high-quality, high-metal-powder-containing aluminum composite can be obtained. That is, for example, the Mg component present in the preform generates Mg ₃ N ₂ in a nitrogen atmosphere during non-pressure infiltration, which will be described later, and also converts the metal oxide on the metal powder surface to Mg. It is reduced and metallized by a thermite reaction to improve the wettability between the metal powder and the molten metal such as an Al alloy. According to the present invention, it is believed that the function of these Mg components enabled the molten metal such as an Al alloy to permeate the manufactured preform in a good state without pressure.

It is preferable to use a powder having an average particle size of 0.5 μm or more and 150 μm or less as the above-mentioned Mg component-containing metal powder or the like. A powder of more than 150 μm is not preferred because it is too coarse and may not be uniformly mixed with the metal powder material described above. Furthermore, when the particle size is coarse, the surface area of the Mg component becomes small, and the amount of Mg ₃ N ₂ produced after the Mg contained in the preform reacts with nitrogen in the atmosphere and is nitrided becomes small. Here, if the amount of Mg ₃ N ₂ produced is small, the permeation rate of the Al alloy or the like into the preform becomes slow, which is not preferable. On the other hand, the finer the Mg component, the larger the surface area, and the more easily it is oxidized by oxygen in the air to form MgO, which is not preferable because the amount of Mg decreases. Therefore, it is desirable to use Mg component-containing metal powder or the like having an average particle size of 0.5 μm or more. On the other hand, if the average particle size exceeds 150 μm, the surface area of the whole becomes small, and as described above, the production amount of Mg ₃ N ₂ becomes small, which is not preferable.

The amount of the Mg component-containing metal powder or the like to be added and mixed is in the range of 0.2 to 5 parts by mass in terms of Mg per 100 parts by mass of the metal powder. More preferably, it is used within the range of 0.5 to 5 parts by mass. If the amount of the Mg component-containing metal powder is less than 0.2 parts by mass, the amount of Mg ₃ N ₂ produced will be small, and the permeation rate of molten metal such as Al alloy will not be sufficiently accelerated, which is not preferable. On the other hand, if the amount of the Mg component-containing metal powder or the like is more than 5 parts by mass, the distribution state of the Mg component in the preform produced from these raw materials is locally increased, and this causes Al to permeate. This is not preferable because the amount of the alloy, etc. may become non-uniform. When using the Mg-based alloy or the Mg-containing compound as described above, the amount to be mixed may be determined by converting to the Mg contained therein.

The metal powder used in the present invention is not particularly limited, and examples thereof include metals such as silicon powder, silicon aluminum alloy powder, ferrosilicon alloy powder, iron or iron-based powder, titanium powder, nickel or nickel-based powder, and the like. powder. As described above, in order to impregnate the preform with the molten metal such as an Al alloy in a good state without applying pressure, it is preferable to allow the Mg component to exist in the preform. . Therefore, in addition to the above-mentioned metal powders, the mixture for producing the preform used for non-pressure infiltration contains one or more Mg component-containing metal powders, etc. in an amount of 0.2 to 5 parts by mass. In addition, the molding is fired at a temperature of 500° C. or less. Therefore, when producing a preform used for non-pressure infiltration, it is necessary not to use any of two or more metal powder materials having different average particle sizes, such as a metal powder containing a Mg component. .

On the other hand, when the preform is used for high-pressure impregnation, two or more kinds of metal powder materials having different average particle sizes are used in the preparation of the preform, such as Mg component-containing metal powder. You can use it without any problem. In this case, the molded product obtained by molding the mixture is fired at a temperature of 300° C. or higher and 800° C. or lower to prepare the preform. The Mg in it, for example, is oxidized to MgO, leaving the preform free of the Mg component, which is important during non-pressure infiltration. Moreover, at a temperature exceeding 800° C., the metal powder is oxidized and the original properties of the metal are damaged.

(organic/inorganic binder)
Molten metal such as Al alloy is impregnated into the preform under high pressure or permeates without pressure, so the preform used must be strong enough to withstand the stress generated by the impregnation and permeation of molten metal such as Al alloy. is. In the first aspect of the present invention, it is necessary to impregnate a molten Al alloy or the like under high pressure. requires higher strength to withstand high pressures. Moreover, even when the molten Al alloy or the like is impregnated into the preform of the second aspect of the present invention without pressure, stress is generated on the surface where the molten Al alloy or the like contacts the preform. According to the studies of the present inventors, cracks and defects occur when a molten metal such as an Al alloy is infiltrated under high pressure or without pressure into the packed phase of the metal powder filled by a method such as vibration. Sometimes. For this reason, it is desirable to fabricate a stronger preform and to impregnate the preform with the Al alloy or the like, regardless of which method is used to impregnate or infiltrate the molten metal such as the Al alloy.

Normally, in order to produce a high-strength preform from ceramics powder or the like and obtain a composite such as a ceramics-Al alloy, an inorganic binder such as colloidal silica is added to the ceramics and mixed and molded, and the obtained molding is The body must be fired at temperatures above about 1000° C. to make the preform. However, the composite of the present invention is a composite of metal powder and an Al alloy or the like, and the above-described prior art cannot be used. That is, if a compact obtained by adding and mixing an inorganic binder to metal powder is fired at a temperature of 1000° C. for the purpose of obtaining a high-strength preform, the metal powder is oxidized and its performance as a metal is impaired. The conventional method could not be adopted. On the other hand, in the present invention, as defined in the present invention, by adding and mixing an organic/inorganic binder to metal powder to obtain a molded body, it is possible to obtain a solid body by firing in a low temperature range of 300 to 800 ° C. , it has become possible to produce a preform containing metal powder at a high content rate, and as a result, a remarkable effect of the present invention is obtained.

As a result of intensive development by the present inventors in response to the above demand, it is more advantageous to use a mixture obtained by adding and mixing an organic-inorganic binder to two or more kinds of metal powder materials having different average particle sizes as described above. It was found to be effective as a means for obtaining a strong preform. I will explain the background to this.

In order to strengthen the preform, it is possible to pack the metal powder as densely as possible and pressurize it by the above-described press, CIP, sedimentation method, etc., and add a binder to the raw metal mixed powder. desired. Generally, organic substances such as polyvinyl alcohol (PVA) and polyvinyl butyral (PVB) are used as binders for molding ceramics. However, if a preform prepared using these organic binders is impregnated with a molten Al alloy or the like under high pressure or impregnated with no pressure, gas is generated, which may hinder the impregnation of the Al alloy or the like. In order to prevent this problem, the preform must be baked in advance to remove the organic matter that is the source of gas generation. This means that organic binders such as PVA and PVB cannot be used because they cannot function as binders for strengthening preforms after firing. On the other hand, it is conceivable to add an inorganic binder such as colloidal silica or colloidal alumina to the metal powder material, press, CIP, or the like, and then bake to strengthen the preform. In order to obtain a preform exhibiting strength with these inorganic binders, it is necessary to bake the preform at 1000° C. or higher. However, when fired at this temperature, the metal powder, which is the main raw material, is oxidized and its function as a metal is impaired. Therefore, general inorganic binders such as colloidal silica and colloidal alumina cannot be used.

In response to the above, the present inventors have made intensive studies, and have found that a mixture obtained by adding and mixing two or more kinds of metal powder materials with an organic and inorganic binder is used for molding, and the obtained molded product is a molten Al alloy or the like. Depending on the impregnation method, by baking at a specific temperature to produce a preform, impregnation of molten metal such as Al alloy under pressure or without pressure can be realized in a good state. It has been found that a good preform can be obtained.

Examples of the organic/inorganic binder used in the present invention include silicone resins, silicon organic derivatives such as Si alkoxides having a chemical structure of Si—O—R (R: organic matter), and Al—O—R (R: organic matter). Aluminum organic derivatives such as aluminum alkoxides having the chemical structure of can be used. According to the studies of the present inventors, first, by using a mixture of metal powders to which the above-mentioned organic and inorganic compounds are added as a binder, it is possible to produce a strong molding at room temperature. Then, according to the studies of the present inventors, after that, the obtained molding is fired at a temperature of 300° C. or more and 800° C. or less, which is 800° C. or less at which the metal powder is not oxidized, to produce a preform. It has been found that a strong metal powder compact (preform) can be obtained after sintering, although the organic matter in the compact is removed by sintering. The inventors consider the reason why such an effect was obtained as follows. First, when the organic/inorganic compounds listed above are added to metal powder and molded, they exhibit strength as a so-called glue at room temperature, like a general organic binder. Furthermore, when heated at 300° C. or higher, the organic matter of the organic-inorganic compound is burned off, but the inorganic matter in the structure of the organic-inorganic compound acts as an inorganic binder to strengthen the preform obtained after firing. The effect obtained by using the organic/inorganic binder will be described in more detail below.

As described above, common inorganic binders such as colloidal silica and colloidal alumina cannot contribute to development of preform strength unless they are fired at a temperature of 1000° C. or higher. On the other hand, when the organic inorganic binder used in the present invention is fired, the organic matter is removed by firing at a firing temperature of 300° C. or higher, and the SiO ₂ component, Al ₂ O ₃ component, etc. remaining after firing are amorphous (amorphous). ) remains, and is combined with the metal powder. Therefore, even at a low temperature of about 300° C., for example, the preform after sintering exhibits strength. Further, according to the studies of the present inventors, the metal powder is not oxidized even when fired at a high temperature of 800° C. or less, so that a sufficiently strong preform can be manufactured. In addition, the above-mentioned organic/inorganic binders have the advantage that the organic matter is decomposed and removed at a temperature of 300° C., so that the organic matter does not generate organic gas when impregnated with a molten Al alloy or the like. . The reason why the above effect was obtained is that the organic/inorganic binder used in the present invention, such as Si aloxide, has a molecular structure of Si—O—R (R: organic substance), and therefore, a general organic binder Compared to , even at a temperature of 300 to 800 ° C., the organic matter is less likely to remain carbonized and is easily removed by burning, so it functions as an inorganic binder for SiO ₂ in the molded body after firing. It seems that the strength has been demonstrated. Moreover, the inorganic-organic binder required to be used in the present invention can be used in organic solvents such as ethanol, IPA, toluene, etc., and thus has the advantage of suppressing deterioration due to reaction between metal powder and water.

As described above, in both the first invention and the second invention of the present invention, the organic matter is decomposed and removed at a relatively low temperature to obtain a strong preform. As will be described below, this is an important factor for the obtained preform to be impregnated with molten metal such as Al alloy under high pressure or without pressure in good condition. That is, in the case of high pressure impregnation performed in the first aspect of the present invention, specifically, after preheating the preform at a temperature of 800 ° C. or less, the preform is coated with an Al alloy or the like at a temperature of 700 ° C. to 800 ° C. The molten metal is impregnated under high pressure, and at that time, the preform can exhibit sufficient strength against such a high-temperature molten metal. Furthermore, since there is no gas generated from the inside of the preform, which is difficult to remove, molten metal such as Al alloy can be impregnated to the inside.

On the other hand, in the case of non-pressure infiltration performed in the second aspect of the present invention, as described above, a predetermined amount of Mg component-containing metal powder or the like is mixed in the preform. If the component-containing metal powder or the like is, for example, metal Mg powder or Mg-containing alloy powder, it will be oxidized to MgO at a temperature exceeding 500°C, so the preform must be fired at a temperature of 500°C or less. According to the studies of the present inventors, in addition to firing the preform at a low temperature of 500° C. or less, the desired organic/inorganic binder is used when the metal powder material is mixed to obtain the molding. By adding a large amount, the Mg component-containing metal powder is not oxidized when the molded product is fired, and a strong preform that does not collapse when a molten metal such as an Al alloy is impregnated without pressure can be manufactured. be able to.

If the organic/inorganic binder used in the present invention is in a solid state, it may be added after being dissolved in an organic solvent such as ethanol or IPA. Moreover, in the case of a liquid one, it can be added as it is or after being diluted with an organic solvent such as ethanol or IPA. An appropriate amount of an organic solvent such as ethanol or IPA may be added and mixed so that the metal powder raw material and the organic/inorganic binder can be easily mixed. The amount of the organic/inorganic binder used in the present invention is, for example, about 0.3 to 5.0 parts by mass in terms of SiO ₂ or Al ₂ O ₃ with respect to 100 parts by mass of the metal powder raw material. It is preferable to add and mix in the range. If the addition amount is less than the above range, it may be too small to obtain the desired strength of the preform. If the addition amount is larger than the above range, the finally obtained aluminum composite will have a large amount of inorganic substances such as SiO ₂ and Al ₂ O ₃ , and the metal content that is the object of the present invention will be high. It is not preferable because there is concern that an aluminum composite containing a high metal powder content with a high modulus cannot be obtained, and the performance of the product is lowered.

(Method for preparing molding)
In the present invention, a mixture obtained by selecting two or more kinds of metal powder materials having mutually different average particle sizes as a metal raw material for a preform, and adding and mixing an organic/inorganic binder such as those listed above to the metal raw material. is molded to obtain a molded product, and the obtained molded product is fired at a specific temperature to produce a preform with high strength. Specifically, a molded product is obtained by molding a metal powder mixture in which two or more kinds of metal powder materials having different average particle sizes are mixed with an organic-inorganic binder as described above.

The molding method of the molded product is not particularly limited, and examples thereof include the following methods. The metal powder mixture is dried and then dry-molded by press molding or CIP to obtain a compact, or the metal powder mixture is slurried using an organic solvent and vibration sedimentation molding is performed. and a method of obtaining a molded product. When the metal powder mixture is slurried, it is preferable to reduce the amount of water used and prepare the slurry with an organic solvent. This is because if there is a large amount of water, the metal powder and water may react with each other, and the metal powder may change into hydroxide or the like, resulting in deterioration. For example, if the metal powder is silicon powder, the following reaction may progress and silicon may deteriorate.
Si ₊ 4H2O⇒Si(OH) ₄ + _2H2

Also, when the metal powder is titanium powder, the following reaction may progress and titanium may deteriorate. That is, the reaction of Ti+2H ₂ O→TiO ₂ +2H ₂ turns titanium into an oxide. Other metal powders also react with water to form oxides, so it is basically not preferable to use water. To suppress this problem, an organic solvent such as alcohol is used, or a mixed solvent of water and a hydrophilic organic solvent such as alcohol is used. Also in this case, in order to suppress the above reaction, it is preferable to reduce the water content in the mixed solvent. According to the studies of the present inventors, the above reaction does not occur if the water content is 30 parts by weight or less with respect to 100 parts by weight of the organic solvent.

When the metal powder mixture is dried and dry-molded such as press molding or CIP to obtain a molded product, the above problems do not occur. By using press molding, which is widely used as a method for obtaining molded articles of powder materials, the desired molded article can be easily obtained in the present invention. In addition, it is also preferable to obtain a molded product by using CIP molding, because the density of the obtained molded product can be homogenized by using CIP molding. For example, it is also a preferable method to perform temporary molding by press molding and then perform CIP molding.

(Firing of molding)
In the present invention, the molded product obtained as described above is fired (calcined) to obtain a metal powder molded body (preform) having a high metal content. In that case, when the preform is impregnated with a molten metal such as an Al alloy at a high pressure of 10 MPa to 200 MPa, the preform is fired at a temperature of 300° C. or higher and 800° C. or lower. Further, when a molten metal such as an Al alloy is impregnated into the preform without pressure, the preform is fired at a temperature of 500° C. or less, for example, 300° C. or more and 500° C. or less. First, by firing the molded article at the temperature described above, the organic substances derived from the organic/inorganic binders and the like contained in the molded article are removed. If organic matter remains in the molding, when the Al alloy or the like is permeated into the molding, the high-temperature hot water of the Al alloy or the like and the organic matter come into contact with each other to generate gas, which hinders the permeation of the Al alloy or the like. Therefore, it is necessary to remove the organic matter by firing.

Furthermore, by baking the molded product at the above-described temperature to produce a preform, the preform, which is the original object of the present invention, can be impregnated with a molten Al alloy or the like under either high pressure or non-pressure conditions. It is possible to provide sufficient strength even in the case of Moreover, as described above, if the present invention can produce a near-net high-metal-powder-containing aluminum composite having a shape close to that of the product, the processing cost can be greatly reduced, which is very useful. In order to achieve this purpose, it is necessary to make the preform strong enough to be machined before being impregnated with the molten Al alloy or the like. Firing to produce a preform is important.

The temperature conditions for obtaining a metal powder molded body (preform) with a high metal content are as follows. It depends on whether pressurized infiltration is performed. When obtaining a preform for high-pressure impregnation, molten metal such as an Al alloy is impregnated at a relatively high pressure of about 10 MPa to 100 MPa, so the preform to be used must have strength to withstand this pressure. However, according to the studies of the present inventors, if the firing temperature is too high, the metal powder, which is the raw material of the preform, is oxidized. Further, in order to sufficiently remove the organic matter derived from the organic/inorganic binder added to the metal powder, it is necessary to bake at a temperature of 300° C. or higher. According to studies by the present inventors, when obtaining a preform to be subjected to high-pressure impregnation, it is preferable to bake at a temperature higher than 500° C. and 800° C. or lower. More preferably, it is fired at a temperature of 700° C. or higher and 800° C. or lower.

According to the studies of the present inventors, when obtaining a preform subjected to non-pressurized infiltration, stress is generated in the part of the preform that is in contact with molten metal such as an Al alloy. A durable preform strength is required. Therefore, similar to preforms subjected to high-pressure impregnation, sintering removes the organic matter from the molding and improves the strength of the resulting preform. However, in the case of non-pressurized infiltration, as described above, in order to infiltrate molten metal such as an Al alloy in a good state without pressure, the preform to be subjected to infiltration must be the Mg metal described above. It is required to be in a state in which Mg component-containing metal powder such as powder is added. On the other hand, for example, when the temperature exceeds 500° C., Mg metal powder reacts with oxygen in the air to become MgO, resulting in a shortage of the Mg component necessary for non-pressure penetration. Therefore, the firing temperature must be 500° C. or lower. According to the studies of the present inventors, when subjected to non-pressure infiltration, a preform having a high metal content can be obtained by firing at a temperature of 300° C. or more and 450° C. or less, and the organic matter can be sufficiently removed by firing. It becomes possible to make it strong enough to withstand non-pressurized penetration.

[Preparation of aluminum composite containing high metal powder]
Next, the step of impregnating aluminum or the like, which is performed when obtaining the high-metal-powder-containing aluminum composite of the present invention, will be described. In this step, a preform having a high metal content and excellent strength obtained by the structure described above is impregnated or permeated with molten aluminum or an aluminum alloy (such as an Al alloy). A method by high-pressure impregnation and a method by non-pressure impregnation will be described below.

(Method for high-pressure impregnation of Al alloy or the like into preform)
FIG. 1 schematically shows a conceptual diagram of high-pressure impregnation. As shown in FIG. 1(A), a preform having a high metal content is heated to 300° C. to 800° C. and loaded into a preheated press frame. The reason for loading the preform in a preheated state is that when the preform is impregnated with a molten metal such as an Al alloy under high pressure, if the temperature of the preform is low, the Al alloy or the like cools and solidifies during the high pressure impregnation, and the preform is damaged. This is to prevent impregnation to the inside, which may occur. Similarly, the frame mold should be heated (preheated) to 200 to 400° C. with a burner or the like so that the Al alloy or the like does not cool and solidify during the impregnation.

An Al alloy or the like melted at 600° C. to 800° C. is poured into the container loaded with the preform as described above, and as shown in FIG. The preform is impregnated with molten metal such as Al alloy. The pressing pressure is 10Mpa to 200Mpa. If the pressure is less than 10 MPa, the pressure is too low and the preform may not be impregnated with molten metal such as Al alloy, which is not preferable. Although the impregnation may be carried out at a higher pressure of over 200 MPa, the pressing pressure within the range described above is sufficient for the ability of the apparatus to obtain the composite of the present invention. The press-impregnated body thus obtained is cooled and the aluminum around the preform is removed to obtain the high-metal-powder-containing aluminum composite which is the object of the present invention.

(Non-pressure infiltration method of Al alloy etc. into preform)
FIG. 2 schematically shows a step-by-step conceptual diagram of non-pressure infiltration. First, a preform containing Mg component-containing metal powder such as Mg metal powder and having a high metal content is loaded into an electric furnace in which a nitrogen atmosphere can be secured as described below. A small piece of the same material as the preform is preferably placed in the lower part of the preform as an infiltration channel. A solid Al alloy or the like to be permeated is placed near the preform so as not to come into contact with the preform. The preform, Al alloy, etc. are placed in a carbon vessel or the like as shown in FIG. 2 so as not to react with the members inside the electric furnace.

After arranging the preform and the solid Al alloy, etc. as described above, the temperature is gradually raised while maintaining the nitrogen atmosphere inside the electric furnace, and the temperature is maintained at 700 to 900° C. for 2 to 5 hours. During this time, as shown step by step in FIG. 2, the molten Al alloy or the like permeates the preform through the permeation channel without pressure, thereby obtaining an aluminum composite containing a high amount of metal powder.

A case where the Mg component-containing metal powder or the like is Mg powder will be described below as an example. The principle of non-pressure infiltration described above is that Mg reacts with nitrogen to form Mg ₃ N ₂ and precipitate in the preform to improve wettability with Al alloys or the like, or Mg forms thermite It is believed that this is because a reaction occurs to reduce the surface oxide of the metal powder constituting the preform, thereby improving the wettability between the metal powder and the Al alloy or the like. As described above, in the prior art, a molded product obtained by press molding or the like is used for non-pressure infiltration without firing, and when Al alloy or the like is non-pressure infiltration, Mg powder is used. A method of using a molding that does not contain magnesium and placing it in a nitrogen atmosphere containing magnesium vapor to allow Al metal to permeate is performed. However, according to the studies of the present inventors, with this method, Mg vapor and nitrogen in the atmosphere react to form Mg ₃ N ₂ on the surface of the preform, and in this state, Al alloys and the like are formed. Since it will permeate, it takes a long time to impregnate the entire preform with aluminum. In addition, since Mg ₃ N ₂ is not generated uniformly on the surface of the preform, there have been cases where the Al alloy or the like permeates unevenly and the entire preform is not uniformly impregnated.

According to the technique of the present invention, unlike the above-described conventional technique, Mg powder can be uniformly mixed in the preform, so that Mg ₃ N ₂ is generated throughout the preform. The speed is dramatically increased, and the entire preform can be uniformly impregnated. In addition, when non-pressurized infiltration is used, it is possible to infiltrate an Al alloy or the like while maintaining the shape of the preform. There is a big merit that processing can be reduced.

Examples and comparative examples are given below to describe further specific examples of the above-described embodiment, but the present invention is not limited to the following examples. In the text, w% is based on mass, and v% is based on volume. The average particle size in this specification is a value measured with a laser diffraction particle size distribution analyzer.

[Example 1] (using high-pressure impregnation method)
First, a metal powder compact (preform) having a high metal content was produced by the following procedure. In this example, three types of silicon (silicon) powders having different average particle sizes were combined according to the following formulations and mixed by stirring to produce a preform. Specifically, 1820 g of silicon powder with an average particle size of 45 μm, 780 g of silicon powder with an average particle size of 25 μm, and 100 g of silicon powder with an average particle size of 5 μm are blended, and a total of 2700 g of the average particle size is mixed with each other. A mixture of three different silicon powders was used. To this mixture, 130 g of ethyl silicate, which is an organic/inorganic binder containing 40 wt% of silicon in terms of SiO ₂ , is added, and further stirred and mixed with a stirrer for 15 minutes to obtain the mixed powder used in this example. got a body

The entire mixed powder obtained above was placed in a press mold having internal dimensions of 200 mm×200 mm×150 mm (depth), and press molding was performed at a total pressure of 120 tons of 300 kg/cm ² . Then, the obtained press-molded product was placed in an electric furnace, heated to 700° C. at a temperature increase rate of 50° C./hr, held at this temperature for 3 hours, and then cooled to room temperature to form a silicon metal. A preform was produced. The weight and outer dimensions of this preform were measured, and the bulk density was calculated.

The preform obtained above is preheated to 500°C in an electric furnace, and the preheated preform is heated to 250°C by a burner of a high pressure impregnation press for high pressure impregnation. , loaded. An aluminum alloy (AC4C) melted at 750 ° C. is put into this mold up to about 20 mm above the mold, a press punch is pushed into the mold from above, and a pressure of 100 Mpa is held for 10 minutes to obtain it first. A silicon preform was high pressure impregnated with molten aluminum (see FIG. 1).

After cooling, the aluminum around the preform was removed by machining, and the product portion of the silicon-aluminum composite was taken out. The product part was a silicon-aluminum composite (hereinafter also referred to as a silicon-aluminum composite) uniformly impregnated with aluminum without small pores (blowholes) or cracks. When the bulk specific gravity was calculated from weight measurement and external dimension measurement, it was found to be a silicon-aluminum composite containing 78 v% silicon and 22 v% aluminum alloy.

[Example 2] (Using a non-pressure permeation method)
A metal powder compact (preform) having a high metal content used in this example was produced by the following procedure. 50 g of Mg powder with an average particle size of 80 μm was added to a total of 2700 g of three kinds of silicon powders with different average particle sizes weighed so as to have the same formulation as used in Example 1. Furthermore, 130 g of ethyl silicate was added to this mixture in the same manner as in Example 1, and mixed with a stirrer for 10 minutes.

The entire mixed powder obtained above was placed in a press mold having internal dimensions of 200 mm×200 mm×150 mm (depth), and press molding was performed at a total pressure of 60 tons of 150 kg/cm ² . This was removed from the mold, and the obtained pressed product was placed in a normal air atmosphere electric furnace, heated to 450°C at a heating rate of 50°C/hr, held at this temperature for 3 hours, and then cooled. A preform was produced by When the bulk density was calculated in the same manner as in Example 1, the volume filling factor (Vf) was 73%.

The preform obtained above was placed in a vessel made of carbon so as to form a "non-pressurized permeation principle diagram" schematically shown in FIG. Specifically, four infiltration channels each having a size of 30 mm x 30 mm x 30 mm, which are prepared from the same material as the preform obtained above, are placed under the preform in a state of being grounded, and further, 2500 g of solid aluminum alloy (AC4A) was placed next to the preform. Then, the entire carbon vessel in which the preform and the like were arranged as described above was placed in a nitrogen atmosphere furnace, heated at a rate of 50° C./hr, held at 800° C. for 5 hours, and then cooled.

After cooling, the infiltration path was removed and the surface and interior of the preform were processed and observed. From the weight of the obtained silicon-aluminum composite and the bulk specific gravity calculated from the measured value of the outer shape, the composite was 73 v% silicon, 26 v% aluminum alloy, and had no pores or cracks. rice field.

[Example 3] (using high-pressure impregnation method)
A metal powder compact (preform) having a high metal content used in this example was produced by the following procedure. 1,820 g of silicon powder with an average particle size of 80 μm, 780 g of silicon powder with an average particle size of 25 μm, and 100 g of silicon powder with an average particle size of 3 μm, totaling 2,700 g. A mixture of silicon powders was used. To this mixture, 180 g of an isopropyl alcohol solution in which a silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KR-220L) was dissolved so as to be 30 w% was added, and after stirring with a stirrer for 15 minutes, the same procedure as in Example 1 was performed. The entire amount was charged into a press mold and press-molded under the same conditions as in Example 1. Then, the obtained press-molded product was placed in an electric furnace, heated to 750° C. at a heating rate of 70° C./hr, and fired at this temperature to obtain a preform having a volumetric filling rate of 78 v %. The volume filling factor was obtained in the same manner as in Example 1.

The preform obtained above was impregnated with a molten aluminum alloy using a high-pressure impregnation press under the same conditions and procedures as in Example 1. After cooling, the surrounding aluminum was removed by machining, the product part was taken out, its weight and outer shape were measured, and the bulk specific gravity was calculated. As a result, it was confirmed that the obtained composite was a silicon-aluminum composite containing 78 v% silicon and 22 v% aluminum alloy, and free of pores (blowholes) and cracks.

[Example 4] (Using a non-pressure permeation method)
A metal powder compact (preform) having a high metal content used in this example was produced by the following procedure. A preform containing Mg powder and having a shape of 200 mm × 200 mm × 40 mm and having a shape of 200 mm × 200 mm × 40 mm was produced by the same procedure as in Example 2. A preform having a rib structure in which four cavities of 25 mm (depth) were evenly arranged was obtained. The resulting preform was a strong preform with machinable strength.

Using the preform obtained above, in the same manner as in Example 2, non-pressure infiltration of the aluminum alloy (AC4A) was performed from the infiltration path under the preform placed in the carbon vessel. Then, in the same manner as in Example 2, the permeation channel was removed and the bulk specific gravity was measured. Confirmed that it was obtained. In addition, there was no exudation of the aluminum alloy inside the cavity, and the silicon-aluminum composite could be manufactured in a near-net state in the shape of the preform.

[Example 5] (using high-pressure impregnation method)
A metal powder compact (preform) having a high metal content used in this example was produced by the following procedure. To 1400 g of iron powder having an average particle size of 80 μm and 600 g of iron powder having an average particle size of 10 μm, 80 g of ethyl silicate containing 40 wt % of silicon (calculated as SiO ₂ ) was added and mixed with stirring for 15 minutes. This mixed powder was placed in a press mold having internal dimensions of 200 mm×200 mm×150 mm (depth), and press molding was performed at a total pressure of 60 tons of 150 kg/cm ² . Then, the press-formed product is placed in an electric furnace, heated to 700° C. at a temperature increase rate of 50° C./hr, held at this temperature for 3 hours, and then cooled to room temperature to obtain a preform made of iron metal. made. The weight and outer dimensions of the obtained preform were measured, and the bulk density was calculated.

The preform obtained above was preheated to 500° C. in an electric furnace and charged into a mold of 300 mmΦ×250 mm depth heated to 250° C. by a burner of a high pressure impregnation press for high pressure impregnation. An aluminum alloy (AC4C) melted at 750° C. was put into the mold up to about 20 mm above the mold, a press punch was pushed into the mold from above, and the pressure was maintained at 100 MPa for 10 minutes to perform high-pressure impregnation.

After cooling, the surrounding aluminum was removed by processing, and the product part of the iron-aluminum alloy composite (hereinafter also referred to as the iron-aluminum composite) was taken out. The product part was an iron-aluminum composite with no small pores (blowholes) or cracks, in which a preform made of iron powder was uniformly impregnated with aluminum. When the bulk specific gravity was calculated from weight measurement and external dimension measurement, it was found to be an iron-aluminum composite containing 73 v% iron and 27 v% aluminum alloy.

[Comparative Example 1] (Binder not used, high pressure impregnation method used)
The silicon mixed powder having the same composition and weight as in Example 1 was put into a 200 mm × 200 mm × 100 mm iron box as it was without adding a binder such as silicone resin or ethyl silicate. The filling was performed by vibrating for a minute. Then, the entire box was impregnated with aluminum at high pressure in the same manner as in Example 1, and after cooling, the composite was cut out.

Observation of the machined surface of the cut out composite revealed many streak-like aluminum defects. This is presumably because cracks were generated in the metal powder packing during high-pressure impregnation, and the aluminum alloy penetrated into the cracks. A crack-free portion was cut out and the bulk specific gravity was calculated. The above results show that if silicon powder particles are simply filled as they are, the silicon filling rate is low, and the strength of the silicon filling phase is not sufficient, and the filling phase cracks during high-pressure impregnation with molten aluminum. , indicating that aluminum has penetrated into the defect.

[Comparative Example 2] (Binder not used, preform produced by press molding)
Press molding was performed using the mixed powder of silicon having the same composition and weight as in Example 1 without adding ethyl silicate, and using the same procedure. However, the resulting molded article lacked strength and collapsed when removed from the mold, making it impossible to produce a preform that could be used for manufacturing a composite. From the above results, it was found that it is essential to add a binder to the powder material when the silicon mixed powder material is used for press molding.

[Comparative Example 3] (Binder not used, preform produced by sedimentation molding)
A slurry was prepared using the mixed powder of silicon having the same composition and weight as in Example 3 without adding a binder such as a silicone resin or ethyl silicate, and the slurry was subjected to sedimentation molding. When this was dried, the resulting molded body was found to be weak and brittle, such that it would crumble when touched by hand. In addition, when a part of the molded body was heated to 700 ° C. in the same manner as in Example 1, it had almost no strength and was so fragile that it collapsed immediately. It wasn't something you could use.

[Comparative Example 4] (Use of organic binder, preform production by press molding and calcination)
An ethanol solution of polyvinyl butyral (hereinafter abbreviated as PVB) with a solid content of 20 wt% is used for the silicon mixed powder having the composition and weight of Example 1, and PVB is added to the silicon mixed powder at a ratio of 2 wt%. After the addition, the same operation as in Example 1 was performed to produce a compact by press molding. When the obtained compact was calcined at 750° C., it became so brittle that it collapsed when touched. The reason for this is thought to be that although PVB functions as a binder for the mixed powder of silicon at room temperature, it was destroyed by calcination. From the above results, it was confirmed that although the organic binder can be used to retain the shape of the press-molded product, the strength of the preform cannot be maintained in subsequent firing steps.

[Comparative Example 5] (Using an organic/inorganic binder, calcining at 850°C to prepare a preform, and using a non-pressure permeation method)
The same amount of mixed silicon powder prepared by adding the same amount of ethyl silicate as an organic/inorganic binder to the mixture of three kinds of silicon powders having different average particle sizes and mixing them with stirring was used in Example 1. Press molding was performed in the same manner as in Example 1. The obtained press-molded product is placed in an electric furnace, heated to 850° C. at a heating rate of 50° C./hr, held at this temperature for 3 hours to be fired, and then cooled to room temperature to obtain a silicon preform. made.

When the surface of the fired body obtained above was observed, it was found that the silicon had been oxidized to SiO ₂ and discolored whitish. In addition, since the silicon becomes SiO ₂ and the volume increases, stress is generated on the surface and microcracks are generated, making it impossible to obtain a defect-free preform.

[Comparative Example 6] (Using Mg powder and an organic/inorganic binder, calcining at 570°C to produce a preform)
Mg powder with an average particle size of 80 μm was added to the same three types of silicon powders with different average particle sizes as used in Example 2, ethyl silicate was added to this mixture, and the mixture was mixed with a stirrer. was used, and press molding was performed in the same manner as in Example 2 to obtain a pressed product. Then, the press-molded product obtained above was baked and degreased at 570° C. for 3 hours to prepare a preform (baked body).

In the same manner as in Example 2, the preform (fired body) obtained above was tried to be impregnated with molten aluminum alloy without pressure. However, the aluminum alloy did not permeate the preform (fired body) without pressure. The reason for this is thought to be that the Mg added to the pressed product was oxidized to MgO by firing at 570° C., and could not contribute to non-pressure penetration.

[Comparative Examples 7 to 9] (preform preparation using silicon powder with each average particle size alone)
Press-molded and pressed in the same procedure as in Example 1 except that 2700 g of each of the silicon powders having an average particle size of 45 μm, 25 μm, and 5 μm used in the mixture of silicon powders in Example 1 was used alone. A preform was produced by firing the molded article. Then, the volume filling factor (Vf) was calculated in the same manner as in Example 1 for the preforms obtained by using the obtained silicon powders having average particle sizes of 45 μm, 25 μm, and 5 μm alone. . As a result, the preform using 45 µm silicon powder had a filling rate of 50 v%, the preform using 25 µm silicon powder had a filling rate of 52 v%, and the preform using 5 µm silicon powder had a filling rate of 52 v%. The filling rate was 53 v%. As described above, it was confirmed that the filling rate of each preform obtained by using the silicon powder of each average particle size alone was lower than that of the preforms of the examples, and the content rate was high. It has been found that it is necessary to mix and use metal powders such as silicon having different average particle sizes in order to produce a preform of the above.

Table 1 summarizes the preform manufacturing conditions, the method of impregnating the Al alloy, etc., and the properties of the obtained high-metal powder-containing aluminum composites, which were carried out in Examples and Comparative Examples.

Claims (10)

High metals having a preform manufacturing process for obtaining a metal powder molded body (preform) with a high metal content, and an aluminum impregnation process for impregnating or permeating the obtained preform with molten aluminum or aluminum alloy. A method for producing a powder-containing aluminum composite, comprising:
In the preform manufacturing process, two or more kinds of metal powder materials having different average particle sizes are selected from metal powder materials having an average particle size of 1 μm or more and 200 μm or less as metal raw materials for preforms, and the metal raw materials Then, the mixture obtained by adding and mixing an organic and inorganic binder is molded, and the obtained molded product is fired at a temperature of 300 ° C. or higher and 800 ° C. or lower, and the content (volume ratio) of the metal raw material is 55 v% or more to obtain a metal powder compact,
A high-metal-powder-containing aluminum composite characterized in that, in the step of impregnating aluminum or the like, the metal powder molded body obtained in the step of making the preform is impregnated with molten aluminum or aluminum alloy at a high pressure of 10 MPa to 200 MPa. body manufacturing method. High metals having a preform manufacturing process for obtaining a metal powder molded body (preform) with a high metal content, and an aluminum impregnation process for impregnating or permeating the obtained preform with molten aluminum or aluminum alloy. A method for producing a powder-containing aluminum composite, comprising:
In the preform manufacturing process, a metal powder material having an average particle size of 1 μm or more and 200 μm or less (excluding each powder material of Mg powder, AlMg powder, ZnMg powder, ZnAl powder, and Mg ₂ Si powder), average particles Two or more kinds of metal powder materials having different diameters are selected as a metal raw material for a preform, and 100 parts by mass of the metal raw material is composed of Mg powder, AlMg powder, ZnMg powder, ZnAl powder and Mg ₂ Si powder. One or more powders selected from the group are added in an amount within the range of 0.2 to 5 parts by mass, and an organic and inorganic binder is added and mixed to form a mixture. sintering the molding at a temperature of 500° C. or less to obtain a metal powder molding having a content (volume ratio) of the metal raw material of 55 v % or more;
A method for producing a high-metal-powder-containing aluminum composite, characterized in that, in the step of impregnating aluminum or the like, aluminum or an aluminum alloy is impregnated into the metal powder molded body obtained in the step of making the preform without pressure. . The metal powder is one or more selected from silicon powder or silicon-containing silicon-based alloy powder, titanium powder, iron powder or iron-containing iron-based alloy powder, and nickel powder or nickel-containing nickel-based alloy powder. 3. A method for producing a high metal powder-containing aluminum composite according to claim 1 or 2. The method for producing a high metal powder-containing aluminum composite according to any one of claims 1 to 3, wherein the volume content of the metal powder in the high metal powder-containing aluminum composite is 55 v% or more and 85 v% or less. The two or more types of metal powders having different average particle sizes include at least a metal powder A having an average particle size of 10 μm or less and a metal powder B having an average particle size of 40 μm or more. The method for producing a high metal powder-containing aluminum composite according to any one of claims 1 to 4, wherein the total amount of the metal powder is at least 3%, and the metal powder B is contained at 50% or more. The method for producing a high metal powder-containing aluminum composite according to any one of claims 1 to 5, wherein the organic/inorganic binder is at least one selected from the group consisting of silicone resin, Si alkoxide and Al alkoxide.
A method for producing a preform for obtaining a metal powder molded body (preform) with a high metal powder content, which is used when obtaining an aluminum composite metal containing a high metal powder content by impregnating molten aluminum or aluminum alloy at high pressure and
A metal powder material having an average particle size of 1 μm or more and 200 μm or less includes at least a metal powder A having an average particle size of 10 μm or less and a metal powder B having an average particle size of 40 μm or more. , at least 3% of the total amount of the metal powder and containing 50% or more of the metal powder B, and selecting two or more kinds of metal powder materials having different average particle sizes as a metal raw material for a preform, A mixture obtained by adding and mixing an organic and inorganic binder to a metal raw material is molded, and the obtained molded product is fired at a temperature of 300 ° C. or higher and 800 ° C. or lower, and the content of the metal raw material (volume A method for producing a preform, characterized by obtaining a metal powder compact having a ratio) of 55 v% or more. A preform for obtaining a metal powder compact (preform) with a high metal powder content, which is used when obtaining an aluminum composite metal containing a high metal powder content by infiltrating molten aluminum or aluminum alloy without pressure. A method of making,
At least metal with an average particle size of 10 μm or less from metal powder materials with an average particle size of 1 μm or more and 200 μm or less (excluding each powder material of Mg powder, AlMg powder, ZnMg powder, ZnAl powder, and Mg ₂ Si powder) Powder A and metal powder B having an average particle size of 40 μm or more, containing at least 3% by mass of the metal powder A in the total amount of the metal powder, and containing 50% or more of the metal powder B, Two or more kinds of metal powder materials having different average particle sizes are selected as metal raw materials for preforms, and Mg powder, AlMg powder, ZnMg powder, ZnAl powder and Mg ₂ Si powder are added to 100 parts by mass of the metal raw materials. One or more powders selected from the group consisting of are added in an amount within the range of 0.2 to 5 parts by mass, and an organic and inorganic binder is added and mixed. A method for producing a preform, characterized in that the molded product thus obtained is fired at a temperature of 500° C. or less to obtain a metal powder molded product having a content (volume ratio) of the metal raw material of 55 v % or more. A high-metal-powder-containing aluminum composite having extremely few internal defects such as blowholes, and manufacturing the high-metal-powder-containing aluminum composite using high-pressure impregnation according to any one of claims 1 and 3 to 6 A high metal powder-containing aluminum composite obtained by a method. A near-net high-metal-powder-containing aluminum composite close to the product shape, wherein the method for producing a high-metal-powder-containing aluminum composite using non-pressure infiltration according to any one of claims 2 to 6 A high metal powder-containing aluminum composite, characterized in that it is obtained.

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