CN115812011A

CN115812011A - Method for manufacturing aluminum composite containing high metal powder, method for manufacturing preform, and aluminum composite containing high metal powder

Info

Publication number: CN115812011A
Application number: CN202280004772.5A
Authority: CN
Inventors: 林睦夫; 胜亦修平; 落合翔梧
Original assignee: Advanced Composite Materials Co ltd
Current assignee: Advanced Composite Materials Co ltd
Priority date: 2021-07-14
Filing date: 2022-04-13
Publication date: 2023-03-17
Also published as: EP4144461A1; JP7037848B1; WO2023286407A1; JP2023012613A

Abstract

A technique for producing a preform capable of improving the filling rate of metal powder and providing a uniform metal powder without defects inside is established, and a technique for obtaining a high-metal-powder-containing aluminum composite with few cracks and defects and a high metal content by infiltrating an Al alloy or the like into the preform under high pressure or non-high pressure is provided. A method for producing a high-metal-powder-content aluminum composite, which comprises selecting 2 or more materials having different particle diameters from 1 to 200 [ mu ] m metal powder materials in a preform production step, adding an organic-inorganic binder to the metal materials to obtain a material, obtaining a molded article from the material, firing the obtained molded article at a temperature of 300 ℃ or higher to obtain a preform having a metal material content of 55v% or more, and impregnating or infiltrating a molten metal such as an aluminum alloy into the obtained preform under high or non-pressurized conditions, a composite obtained by the production methods, and a method for producing a preform.

Description

Method for manufacturing aluminum composite containing high metal powder, method for manufacturing preform, and aluminum composite containing high metal powder

Technical Field

The present invention relates to a method for producing an aluminum composite body containing high-metal powder, a method for producing a preform, and an aluminum composite body containing high-metal powder. More specifically, the present invention relates to a novel technique for providing an aluminum composite containing a high metal powder, in which a preform containing a metal powder having a high volume filling ratio is well impregnated with a metal aluminum or an aluminum alloy (hereinafter, also referred to as an Al alloy or the like), and which can dramatically improve the productivity and quality of the composite material.

Background

In recent years, materials obtained by compounding a metal with an Al alloy and the like have attracted attention as materials having light weight, high strength, high young's modulus, high thermal conductivity, and low thermal expansion, for example, electronic materials such as heat sinks, heat dissipation diffusers, and electronic component packaging products, and semiconductor device members such as XY sliders and vacuum chucks. These materials are one of the so-called Metal Matrix Composites (MMC). Conventionally, a ceramic powder is generally combined with a metal matrix to form an MMC, but recently, a composite material including a metal powder and an Al alloy or the like has been attracting attention. For example, a composite material of silicon and an Al alloy having a high young's modulus and low thermal expansion, an Al alloy obtained by combining titanium and iron powder having high strength, and the like have been proposed. As described below, a composite of metal powder and an Al alloy or the like is also attracting attention because of its excellent workability.

For example, silicon metal has a small thermal expansion coefficient and is used as an electronic component or a semiconductor component, but has a disadvantage that it is very brittle and cannot be manufactured into a complicated and large-sized component. Therefore, a silicon-aluminum composite with Al alloy or the like is being developed. For the above reasons, a composite body with aluminum containing as much silicon powder as possible is desired, and development of a composite body having a small thermal expansion coefficient and a large young's modulus while maintaining workability is sought. Specifically, for example, if a silicon-aluminum composite having a silicon content of 70v% or more, preferably about 80v% can be produced, the application to a heat sink or an electronic component package on which an electronic component having a small thermal expansion coefficient is mounted is expected to be dramatically expanded.

Titanium metal is used as a metal having a small thermal expansion coefficient, a light weight, and high rigidity, and is used as various machine components. However, the material is hard and difficult to process, and has limited usefulness in this point. Therefore, if aluminum metal can be composited with titanium metal to improve workability, the application range can be further expanded, and development of a titanium-aluminum composite is desired and advanced.

Here, the following methods are generally exemplified as a method for producing a composite of metal powder and Al alloy.

(casting method of high silicon aluminum alloy)

This method is a method of melting a powder of a silicon-containing aluminum alloy (also referred to as a silicon aluminum alloy) called a sialon alloy, which contains a silicon component, and casting the melt in a sand mold or a die. However, in this method, since the fluidity of the alloy is lowered and the alloy cannot be cast when the silicon component is increased, the content of the silicon component is usually about 20v% at the maximum. Therefore, it is difficult to produce a high-silicon aluminum composite having a high content of metal components, which is desired in the casting method.

(injection Molding method)

This method is called "spray forming method" and is a method of manufacturing a silicon-aluminum composite by thermal extrusion by making a dropper (burette) of a powder deposit obtained by melting silicon and aluminum at a high temperature and spraying the melt. In the spray forming method, a composite raw material powder in which the ratio of silicon to aluminum is freely changed can be produced by melting a metal at a high temperature. Therefore, it is theoretically possible to produce a high-silicon containing aluminum composite body having a high content ratio of the metal component. However, in order to produce a composite material having a silicon content of 50v% or more, it is necessary to melt the material at 1000 ℃ or more. In addition, during the spray cooling, silicon precipitates first, and a uniform composite cannot be obtained, and when the composite is produced, a product having a silicon component of only about 50v% cannot be obtained, and a silicon-aluminum composite having a higher content of the silicon component cannot be obtained. Further, since voids are generated in the solidification process of a dropper for manufacturing a powder deposit by spraying a melt, the obtained dropper needs to be half-melted and extruded under high pressure or to be subjected to HIP treatment to crush the voids in order to form a product. In this regard, the "injection molding method" also has a significant industrial problem that the manufacturing cost is very high and the economical efficiency is deteriorated.

(non-pressure infiltration method of aluminum into silicon powder packing)

Patent document 1 proposes a silicon-aluminum composite metal obtained by infiltrating a molten Al alloy or the like into a filler or a compact having a silicon powder filling rate of 50 to 70 vol% at a temperature of 700 to 1000 ℃ in a nitrogen atmosphere containing magnesium vapor. Patent document 1 discloses that the penetration of a molten Al alloy or the like into a filler can be accelerated by containing magnesium vapor in a nitrogen atmosphere. In the examples, it is described that a filler is obtained by adding and mixing 2 parts by mass of magnesium powder to 100 parts by mass of silicon powder having an average particle size of 5 μm and filling the mixture into a container, and the filling rate of silicon is 50% by volume using the filler. In the above examples, it is described that silicon powder having an average particle diameter of 1 to 100 μm is used, if necessary.

As described above, patent document 1 discloses that a magnesium powder is added to 1 kind of silicon powder, the mixture is filled into a container, and a molten Al alloy or the like is infiltrated into the filled body in a nitrogen atmosphere at normal pressure (without pressurization) to produce a composite metal. However, according to the study by the present inventors, there are cases where a simple filler of the silicon powder is not uniform or holes remain inside. On the other hand, when such a filler is impregnated with a molten aluminum without pressure, there are problems that cracks or defects are generated or a filler sufficiently filled with silicon powder in a uniform state cannot be obtained. Therefore, when the non-pressure infiltration method using the filler described above is used, it is not possible to produce a uniform metal powder-aluminum composite having a high content of metal components as required for a product.

Patent document 2 describes that PVA (polyvinyl alcohol) as a binder is added to a metal powder such as silicon powder to obtain a molded body or a calcined body of the metal powder, and a metal such as molten aluminum is infiltrated into the obtained molded body or calcined body of the metal powder in a non-pressurized manner. In the examples, it is described that a compact is obtained by press-molding silicon powder having an average particle size of 20 μm using a material containing PVA as a binder, the compact is impregnated with a molten Al alloy at normal pressure in a nitrogen atmosphere furnace containing magnesium to obtain a composite metal, and 2 kinds of metal powder are used, and ceramic powder is mixed with the metal powder. However, the technique described in patent document 2 is not intended to set the metal content of a molded or calcined metal powder to be combined by non-pressure infiltration of a molten metal to a high level, as is known from the mixing of a ceramic powder with a metal powder.

According to the studies of the present inventors, for example, when a filler filled with a silicon powder at a high content is impregnated with an Al alloy or the like under high pressure or under non-high pressure, stress may be generated at a contact surface between the filler and the Al alloy or the like during the impregnation, cracks may be generated in the metal powder compact during the impregnation of a melt of the Al alloy or the like, or capillary phenomenon may be damaged by the cracks, or defects may be generated that are not impregnated. In contrast, even when the above-mentioned conventional techniques have been studied on how to obtain a high metal powder-aluminum composite with few defects and a high metal content, such a composite has not been provided. For example, even in the case of a compact which is merely press-formed by infiltrating aluminum metal into a silicon powder filler under non-pressure as in the above-described conventional technique, stress may be generated on the contact surface between the silicon powder filler and an Al alloy or the like, cracks may be generated at the time of infiltration of a molten metal such as an Al alloy, or defects may be generated which are not infiltrated.

Here, the advantage achieved by impregnating the filler or the molded body with the molten metal such as Al alloy by the non-pressure infiltration method as in the above-described conventional technique is that the molten metal such as Al alloy is quietly impregnated into the molded body by capillary action in the shape of the molded body (preform) obtained by press molding or the like of the metal powder, and the metal powder-aluminum composite body close to the product shape can be produced after the impregnation. That is, when a composite body having a shape close to that of a product can be obtained by impregnating a molded body with a molten metal, the subsequent machining which is necessary can be reduced, and therefore, there is an advantage of reducing the production cost.

This means that, when a melt of an Al alloy or the like is infiltrated without pressurization, if a strong molded body (preform) in which cracks and defects are not generated is obtained, the product value and cost advantage are dramatically increased. Further, if the content of the metal powder material such as silicon in the obtained metal powder-aluminum composite can be increased, a metal powder-aluminum composite having further low thermal expansion and high young's modulus can be obtained. For example, if a method for producing a silicon powder-aluminum composite having silicon in an amount of more than 50v% can be established, the use thereof is remarkably increased.

In contrast, the production of preforms by the powder presintering method has been widely carried out by sintering a compact of a metal powder having a fine particle size at a temperature slightly lower than the melting temperature of the metal. However, according to the study of the present inventors, in this method, since a molded body (preform) is manufactured by sintering, there are cases where: during sintering, the compact shrinks and the preform deforms, or voids in the preform form closed pores that block the outside, and in the subsequent infiltration step of Al alloy or the like, good infiltration is not performed, and an uneven metal powder aluminum composite is formed.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2005-036253

Patent document 2: japanese patent laid-open No. 2004-052011

Disclosure of Invention

Problems to be solved by the invention

Accordingly, an object of the present invention is to establish a technique for producing a strong molded body (preform) of metal powder represented by powder of silicon, silicon-aluminum alloy, iron, titanium, copper, nickel, silicon-iron alloy, or the like, for example, and producing a uniform preform that can improve the filling rate of the metal powder according to the target performance and has few internal defects, and to provide a technique for obtaining an aluminum composite body containing high-metal powder with few cracks and defects and high metal content, in any of the obtained preforms, by high-pressure infiltration or non-high-pressure infiltration of Al alloy or the like.

Means for solving the problems

The above object is achieved by the following technique for producing an aluminum composite containing a high metal content and a high metal powder. That is, the present invention provides the following method for producing an aluminum composite containing high-metal powder.

The following method for producing an aluminum composite containing high-metal powder is provided as the invention 1, in which an Al alloy or the like is impregnated under high pressure to obtain the aluminum composite.

[1] A method for producing an aluminum composite containing a high-metal powder, comprising: a preform manufacturing step of obtaining a metal powder compact (preform) having a high metal content; and an infiltration step of aluminum or the like, in which the obtained preform is infiltrated or infiltrated with molten aluminum or aluminum alloy,

in the preform producing step, 2 or more kinds of metal powder materials having different average particle diameters from each other are selected as metal raw materials for a preform from metal powder materials having an average particle diameter of 1 to 200 μm, an organic-inorganic binder is added and mixed to the metal raw materials to obtain a mixture, the mixture is molded, and the molded article obtained is fired at a temperature of 300 to 800 ℃ to obtain a metal powder molded article having a content (volume fraction) of the metal raw materials of 55% by volume or more,

in the step of impregnating aluminum or the like, the metal powder compact obtained in the step of producing a preform is impregnated with a molten aluminum or aluminum alloy under a high pressure of 10 to 200 MPa.

In particular, the organic-inorganic binder may be in a liquid state or a liquid state, and may be at least one selected from the group consisting of silicone resins, si alkoxides, and Al alkoxides.

The invention of claim 2 provides the following method for producing an aluminum composite containing high-metal powder by non-pressure infiltration of an Al alloy or the like.

[2] A method for producing an aluminum composite containing a high-metal powder, comprising: a preform manufacturing step of obtaining a metal powder compact (preform) having a high metal content; and an infiltration step of aluminum or the like, in which the obtained preform is infiltrated or infiltrated with molten aluminum or aluminum alloy,

in the preform manufacturing step, the metal powder material (excluding Mg powder, alMg powder, znMg powder, znAl powder and Mg powder) having an average particle diameter of 1 μm or more and 200 μm or less is selected ₂ Other than the respective powder materials of the Si powder) 2 or more metal powder materials having mutually different average particle diameters are selected as the metal raw material for the preform, and a metal powder selected from the group consisting of Mg powder, alMg powder, znMg powder, znAl powder and Mg powder is added in an amount within a range of 0.2 to 5 parts by mass relative to 100 parts by mass of the metal raw material ₂ 1 or more kinds of powders selected from the group consisting of Si powders, an organic-inorganic binder, a molding compound obtained by molding the obtained mixture, and a metal powder molded body having a content (volume ratio) of the metal raw material of 55v% or more obtained by baking the obtained molded body at a temperature of 500 ℃ or lower,

in the step of impregnating aluminum or the like, aluminum or an aluminum alloy is infiltrated into the metal powder compact obtained in the step of producing a preform without applying pressure.

As a preferred embodiment of the above-described method for producing a high metal powder-containing aluminum composite of the present invention, the following can be mentioned.

[3] The method for producing a high-metal powder-containing aluminum composite according to the above item [1] or [2], wherein the metal powder is selected from a silicon powder or a silicon-containing silicon-based alloy powder, a titanium powder, an iron powder or an iron-containing iron-based alloy powder, and a nickel powder or a nickel-containing nickel-based alloy powder.

[4] The method for producing a high-metal-powder-containing aluminum composite body according to any one of the above [1] to [3], wherein a volume content of the metal powder of the high-metal-powder-containing aluminum composite body is 55v% or more and 85v% or less.

[5] The method for producing a high-metal powder-containing aluminum composite according to any one of the above [1] to [4], wherein the 2 or more kinds of metal powders having different average particle diameters each contain at least a metal powder A having an average particle diameter of 10 μm or less and a metal powder B having an average particle diameter of 40 μm or more, and the metal powder A is contained in an amount of at least 3% by mass and the metal powder B is contained in an amount of 50% by mass or more of the total amount of the metal powders.

[6] The method for producing a high-metal powder-containing aluminum composite according to any one of the above [1] to [5], wherein the organic-inorganic binder is at least one selected from the group consisting of Si alkoxides and Al alkoxides.

In another embodiment, the present invention provides a method for producing a preform, which is suitably used in the method for producing a high-metal-powder-containing aluminum composite according to claim 1, as described below.

[7] A method for producing a preform, characterized by obtaining a metal powder compact (preform) having a high content of metal powder, which is used when an aluminum composite metal containing high metal powder is obtained by impregnating molten aluminum or aluminum alloy under high pressure,

selecting, as a metal material for a preform, 2 or more metal powder materials having mutually different average particle diameters, from metal powder materials having an average particle diameter of 1 to 200 μm, the 2 or more metal powder materials having mutually different average particle diameters, containing at least a metal powder A having an average particle diameter of 10 μm or less and a metal powder B having an average particle diameter of 40 μm or more, the metal powder A being contained in an amount of at least 3% by mass and the metal powder B being contained in an amount of 50% by mass or more, adding a mixed organic-inorganic binder to the metal material to obtain a mixture, molding the mixture, and firing the molded article at a temperature of 300 to 800 ℃ to obtain a metal powder molded article having a content (volume fraction) of the metal material of 55v% or more.

In another embodiment, the present invention provides a method for producing a preform described below, which is suitably used in the method for producing a high metal powder-containing aluminum composite according to claim 2.

[8] A method for producing a preform, characterized by obtaining a metal powder compact (preform) having a high content of metal powder, which is used when molten aluminum or aluminum alloy is infiltrated in a non-pressurized manner to obtain an aluminum composite metal containing high metal powder,

from a metal powder material having an average particle diameter of 1 μm or more and 200 μm or less (except for Mg powder, alMg powder, znMg powder, znAl powder and Mg) ₂ Other than the respective powder materials of Si powder) 2 or more metal powder materials having mutually different average particle diameters are selected as the metal raw material for the preform, the 2 or more metal powder materials having mutually different average particle diameters contain at least metal powder a having an average particle diameter of 10 μm or less and metal powder B having an average particle diameter of 40 μm or more, the metal powder a is contained in an amount of at least 3% by mass and the metal powder B is contained in an amount of 50% by mass or more in the total amount of the metal powders, and the metal powder materials selected from the group consisting of Mg powder, alMg powder, znMg powder, znAl powder and Mg powder are added in an amount within a range of 0.2 to 5 parts by mass with respect to 100 parts by mass of the metal raw material ₂ 1 or more kinds of powders selected from the group consisting of Si powders, an organic-inorganic binder, a molding compound, and a firing at 500 ℃ or lower to obtain a molded article having a content (volume fraction) of the metal raw material of 55v% or moreA metal powder compact.

In particular, the organic-inorganic binder may be in a liquid state or a liquid state, and may be at least one selected from the group consisting of a silicone resin, a Si alkoxide, and an Al alkoxide.

In addition, the present invention provides, as another embodiment, the following high-metal powder-containing aluminum composite.

[9] A high-metal-powder-containing aluminum composite body which is characterized by having extremely few internal defects such as pores and is obtained by the method for producing a high-metal-powder-containing aluminum composite body by high-pressure infiltration according to any one of [1] and [3] to [6 ].

[10] A high-metal-powder-containing aluminum composite body which is a near-net-shape high-metal-powder-containing aluminum composite body having a shape close to a product shape, and which is obtained by the method for producing a high-metal-powder-containing aluminum composite body by non-pressure infiltration according to any one of the above [2] to [6 ].

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, in the production of a compact (preform) of metal powder represented by powder of silicon, silicon-aluminum alloy, iron, titanium, copper, nickel, silicon-iron alloy, or the like, for example, the volume filling rate of the metal powder can be increased to 55v% or more in accordance with the target performance, and the obtained preform can be made uniform with extremely few internal defects. As a result, the present invention provides a method for producing an excellent high-metal-powder-containing aluminum composite body, which can produce a high-quality high-metal-powder-containing aluminum composite body with reduced occurrence of cracks and defects, and a high metal volume content, even when the preform is impregnated with an Al alloy or the like under high pressure or is not impregnated with an Al alloy or the like under high pressure. Further, according to the present invention, it is possible to provide a high-quality aluminum composite containing high-metal powder with few internal defects such as blowholes. These composites can be used as vacuum parts in, for example, semiconductors, liquid crystal manufacturing apparatuses, electron microscopes, packages for optical communications, and the like. Further, according to the present invention, since the aluminum composite containing the high metal powder can be manufactured in a near-net form close to the product shape, the machining process which is necessary thereafter and the cost for the process can be reduced, and the composite can be made larger, and therefore, the present invention is expected to be used as a large-sized component such as a robot arm, a shape measuring apparatus base, and an XY table.

Drawings

Fig. 1 (a) is a schematic view for explaining a step of a pressure infiltration method for pressure infiltrating a molten metal such as an Al alloy into a preform, which is used in the method for producing a high-metal powder-containing aluminum composite body according to the 1 st aspect of the present invention. A schematic view of pouring a melt of Al alloy or the like 2 into a frame mold 3 of a press for high-pressure infiltration filled with a preform 1 is shown.

Fig. 1 (B) is a schematic view illustrating a state where a press punch is provided in an opening of a frame-shaped mold 3 in a state where a preform 1 and a molten metal such as Al alloy 2 are filled, which are obtained by the operation of fig. 1 (a).

Fig. 1C is a schematic view showing a state in which a load (high pressure) is applied to the melt in the frame-shaped mold 3 in the state of fig. 1B, and the preform 1 is impregnated with the melt of Al alloy or the like 2.

Fig. 2 (a) is a schematic view for explaining a state in which a molten metal such as an Al alloy is infiltrated into a preform by capillarity by a non-pressure infiltration method in the method for producing a high metal powder-containing aluminum composite body according to the 2 nd aspect of the present invention. A schematic view showing the arrangement of a preform 1 and an Al alloy or the like 2 filled in a carbon container 5 is shown.

Fig. 2 (B) is a schematic view showing a state in which a molten metal such as an Al alloy 2 in a carbon container 5 is formed and the molten metal penetrates into a penetration path 4 for supporting the preform 1 without being pressurized.

Fig. 2 (C) is a schematic view showing the state of the preform 1 in which the molten metal of Al alloy or the like 2 is non-pressurized and infiltrated into the carbon container 5 through the infiltration passage 4 supporting the preform 1.

Fig. 2 (D) is a schematic view showing the state after the molten metal of Al alloy or the like 2 has infiltrated the entire preform 1 in the carbon container 5 in a non-pressurized manner.

Detailed Description

The present invention will be described below by referring to preferred embodiments. The present invention is not limited to these embodiments.

[ production of Metal powder molded body (preform) ]

In view of the above-described conventional techniques, the present inventors have made intensive studies on a method for producing a uniform aluminum composite containing a high metal powder, which has a high volume content of metal and few internal defects and is expected to be used in various applications. As a result, it is important to establish a method for easily producing a metal powder compact (preform) having a high volume content of metal and a small number of internal voids. The present inventors have also found that, in order to obtain a metallic preform having few voids, which causes defects in a composite material to be finally obtained, it is effective to use a mixture of 2 or 3 or more kinds of metal powders having different average particle diameters, but not to use metal powders having the same particle diameter as the material. That is, with such a configuration, fine particles having a small average particle diameter are introduced between particles having a large average particle diameter, and as a result, the effects of the present invention are obtained. In the present invention, 2 or more kinds of metal powders having different average particle diameters are selected and a mixture of these metal powders is used as a metal material for a preform.

(Metal powder Material)

In the present invention, as the metal powder material for producing the preform, a material having an average particle diameter in a range of 1 μm or more and 200 μm or less is used. The metal powder is preferably used in a range of 3 μm or more and 180 μm or less, more preferably 3 μm or more and 100 μm or less. The preform constituting the present invention is prepared by selecting 2 or more kinds of metal powders having different average particle diameters from among the metal powders having the average particle diameters within the above range and mixing them. When only the material having an average particle diameter of less than 1 μm is used, the particles become too fine, the surface oxidation phase of the metal powder increases, and the performance as the metal powder may be deteriorated. On the other hand, if the metal powder used exceeds 200 μm, the particle diameter becomes too large and the particle-filling property for press forming, CIP forming, sedimentation forming, etc. is not preferable.

In the present invention, when 2 or more kinds of metal powder materials having different average particle diameters are selected for producing the preform, it is preferable to use a mixture of a metal powder having a large particle diameter and a metal powder having a small particle diameter. For example, it is preferable that at least a metal powder A having an average particle diameter of 10 μm or less and a metal powder B having an average particle diameter of 40 μm or more are contained, and that at least 3% of the metal powder A and at least 50% of the metal powder B are contained in the total amount of the metal powder by mass.

For example, when silicon powders having an average particle diameter of 45 μm and an average particle diameter of 5 μm which are different from each other are individually press-molded, the volume filling ratios (v%: vf) thereof are 47% and 52%, respectively. According to the study of the present inventors, a compact having Vf =73v% can be obtained by mixing 45 μm and 5 μm silicon powders at a ratio of 70. Similarly, when 70 μm, 25 μm, and 5 μm silicon powders were mixed at a ratio of 70.

Since the filling rate of metal powder such as silicon powder varies depending on the average particle diameter, particle shape, particle size distribution, etc., there is also a method of forming a filled filler so as to have as few voids as possible by applying vibration carefully so as to form a high filling rate (v%) as possible by adding the powder to a carbon container, etc., for example. However, according to the studies of the present inventors, it has been found that when such a method using vibration is used, it is difficult to obtain a filler having a content of a metal powder raw material of 55v% or more, and even if the filler is obtained, cracks or streak-like defects are generated when the filler is impregnated with a molten solution of an Al alloy or the like at a high pressure, and a high-quality aluminum composite containing a high-metal powder cannot be obtained.

The present inventors have intensively studied from the above findings and, as a result, have found the following. By mixing 2 or more kinds of metal powder materials having different average particle diameters to obtain a mixed powder and molding the obtained mixed powder by a molding method such as press molding, CIP molding or sedimentation to incorporate the metal powder as free as possible, a preform having a higher filling ratio of 55v% or more of the metal raw material content and being strong enough to withstand high-pressure infiltration of a melt of an Al alloy or the like can be produced. Further, it has been found that, since the strength of the preform is further improved, it is effective to add an organic-inorganic binder to the mixture of the metal powders constituted as described above to obtain a mixture, and to bake a molded article formed of the obtained mixture at a temperature of 300 ℃ to 800 ℃. Details of these points are described later.

The present inventors have made intensive studies on the production of a preform having a content of a metal powder raw material of 55v% or more, which can be infiltrated with a melt of an Al alloy or the like under non-pressure. As a result, it was found that a magnesium alloy selected from the group consisting of metallic Mg powder, al-Mg alloy powder, zn-Mg alloy powder and Zn-Al alloy powder, and a Mg alloy having a high magnesium content was used in an amount of 100 parts by mass based on the metal powder material ₂ A mixture of 0.2 to 5 parts by mass of 1 or more kinds of powders (these are also referred to as Mg-containing metal powders and the like, and may be described as Mg components) in the compounds such as Si powder is effective. It has been found that a high-quality aluminum composite containing high-metal powder can be obtained by adding a specific organic-inorganic binder to the mixture, firing the molded article formed from the mixture at a temperature of 500 ℃ or lower to obtain a preform, and using the preform to allow a molten metal such as an Al alloy to infiltrate in a good state without pressurization. That is, for example, the Mg component present in the preform generates Mg in a nitrogen atmosphere at the time of non-pressure infiltration described later ₃ N ₂ In addition, the metal oxide on the surface of the metal powder is reduced and metallized by the thermite reaction of Mg, and the wettability of the metal powder with a molten metal such as Al alloy is improved. It is considered that the function of the Mg component constituting the present invention allows penetration of a molten metal such as an Al alloy into a preform to be produced in a favorable state without pressurization.

The above-listed Mg-containing metal powders and the like are preferably used in such a manner that the average particle diameter is 0.5. Mu.mA powder of the above-mentioned size and 150 μm or less. Powders exceeding 150 μm are not preferable because they are too coarse to be uniformly mixed with the metal powder material described above. Further, if the particle diameter is coarse, the surface area of the Mg component decreases, and Mg contained in the preform reacts with nitrogen in the atmosphere to be nitrided ₃ N ₂ The amount of production of (2) is reduced. If Mg here ₃ N ₂ The amount of (3) is not preferable because the infiltration rate of the Al alloy or the like into the preform is reduced when the amount of the produced (B) is small. On the other hand, the smaller the Mg component, the larger the surface area, and the more likely it is oxidized by oxygen in the air to form MgO, and the Mg content is decreased, which is not preferable. Therefore, it is preferable to use a metal powder containing a Mg component having an average particle diameter of 0.5 μm or more. When the average particle diameter exceeds 150 μm, the surface area of the whole decreases, and Mg is as described above ₃ N ₂ The amount of (2) produced is reduced, which is not preferable.

The amount of the metal powder containing Mg or the like to be added 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 in the range of 0.5 to 5 parts by mass. If the amount of the metal powder containing Mg component is small and less than 0.2 part by mass, mg is contained ₃ N ₂ The amount of (2) is reduced, and the penetration rate of the molten metal such as Al alloy cannot be sufficiently accelerated, which is not preferable. On the other hand, if the amount of the metal powder containing Mg component or the like exceeds 5 parts by mass, the distribution state of Mg component in the preform produced from these raw materials is locally increased, and the amount of the Al alloy or the like infiltrated due to this may become uneven, which is not preferable. When the Mg-based alloy or the Mg-containing compound as described above is used, the amount to be mixed may be determined in terms of Mg contained therein.

The metal powder used in the present invention is not particularly limited, and examples thereof include silicon powder, silicon-aluminum alloy powder, silicon-iron alloy powder, iron or iron-based powder, titanium powder, nickel or nickel-based powder, and the like. As described above, in order to infiltrate a melt of Al alloy or the like into a preform in a good state without pressurization, it is preferable that a Mg component is present in the preform. Therefore, in the case of producing a preform used for non-pressure infiltration, it is necessary to add 1 or more kinds of metal powder containing Mg component in an amount within the range of 0.2 to 5 parts by mass in addition to the above-mentioned metal powder, and to bake a molded product at a temperature of 500 ℃. Therefore, when a preform used for non-pressure infiltration is produced, it is necessary to use no metal powder containing Mg component as the metal powder material of 2 or more types having different average particle diameters.

In contrast to the above, when the preform is used for high-pressure infiltration, as the 2 or more kinds of metal powder materials having different average particle diameters from each other in the production of the preform, metal powder containing a Mg component or the like can be used. In this case, since the preform is produced by firing the molded article obtained by molding the mixture at a temperature of 300 ℃ to 800 ℃, for example, mg in the metal powder containing Mg component is oxidized to form MgO when firing at a temperature exceeding 500 ℃, and the Mg component important in the non-pressure infiltration does not exist in the preform. In addition, at temperatures exceeding 800 ℃, the metal powder is oxidized, and the properties inherent in the metal are impaired.

(organic and inorganic Binders)

Since a molten metal of Al alloy or the like is infiltrated under high pressure or infiltrated into a preform in a non-pressurized manner, the preform used needs to have strength to withstand the stress generated by infiltration/infiltration of the molten metal of Al alloy or the like. In the invention 1, since a molten metal such as an Al alloy needs to be impregnated at high pressure, specifically, a molten Al alloy needs to be impregnated at several tens MPa, a preform used in this case needs to have higher strength capable of withstanding high pressure. In addition, even when the preform of invention 2 of the present invention is infiltrated with molten Al alloy or the like by the non-pressure infiltration method, stress is generated in the surface of the molten Al alloy or the like in contact with the preform. According to the studies of the present inventors, when a molten metal such as an Al alloy penetrates under high pressure or in a non-pressurized manner into a filler phase of a metal powder filled by a method such as vibration alone, cracks or defects are generated. Therefore, in the case where a melt of Al alloy or the like is infiltrated/infiltrated by any method, it is desirable to form a stronger preform and to form a structure in which the preform is infiltrated with Al alloy or the like.

In general, in order to produce a preform having high strength from ceramic powder or the like to obtain a composite of a ceramic-Al alloy or the like, it is necessary to add an inorganic binder such as colloidal silica to a ceramic, mix the mixture with the ceramic, mold the mixture, and bake the resulting molded body at a temperature of about 1000 ℃. However, the composite of the present invention is a composite of metal powder and Al alloy, and the above-described conventional techniques cannot be used. That is, in order to obtain a preform having high strength, if a compact obtained by adding and mixing an inorganic binder to a metal powder is fired at a temperature of 1000 ℃, the metal powder is oxidized and the performance as a metal is impaired, and therefore, the conventional method cannot be adopted. In contrast, in the present invention, by adding and mixing an organic-inorganic binder to a metal powder to obtain a compact as defined in the present invention, a preform containing a metal powder with a high content can be firmly produced by firing at a low temperature range of 300 to 800 ℃.

As a result of extensive development of the above-described desire, the present inventors have found that the use of a mixture obtained by adding an organic-inorganic binder to 2 or more metal powder materials having different average particle diameters as described above is effective as a means for obtaining a stronger preform. The original commission will be explained.

In order to make the preform strong, it is desirable to pack metal powder as closely as possible and apply pressure for forming by the previously described pressing, CIP, sedimentation, or the like, and to add a binder to the metal mixed powder of the raw material. In general, as a binder used for molding ceramics and the like, organic materials typified by polyvinyl alcohol (PVA) and polyvinyl butyral (PVB) are used. However, when a preform made of such an organic binder is infiltrated with a molten Al alloy under a high pressure or in a non-pressurized manner, gas is generated, which may inhibit infiltration of the Al alloy or the like. In order to prevent this problem, the preform must be baked in advance to remove the organic material that is the gas generating source. This means that organic binders such as PVA and PVB cannot function as binders for making the fired preform strong, and therefore cannot be used. On the other hand, it is considered that an inorganic binder such as colloidal silica or colloidal alumina is added to a metal powder material, and after molding by pressing, CIP or the like, the preform is baked to be strong. And in order to obtain a preform exhibiting strength using these inorganic binders, the preform needs to be fired at 1000 ℃ or higher. However, when the powder is fired at this temperature, the metal powder as a main raw material is oxidized to deteriorate the function as a metal. Therefore, a usual inorganic binder such as colloidal silica or colloidal alumina cannot be used.

As a result of intensive studies by the present inventors, it has been found that a strong preform can be obtained in which both pressure and non-pressure infiltration of a molten metal such as an Al alloy can be achieved in a good state by molding a mixture obtained by adding and mixing an organic-inorganic binder to 2 or more kinds of metal powder materials and baking the obtained molded product at a specific temperature according to an infiltration method of a molten Al alloy or the like to produce a preform.

As the organic-inorganic binder used in the present invention, silicone resins, silicon organic derivatives such as Si alkoxides having a chemical structure of Si-O-R (R: organic substance), or aluminum organic derivatives such as aluminum alkoxides having a chemical structure of Al-O-R (R: organic substance) can be used. According to the studies of the present inventors, a strong molded article can be produced at room temperature by using a mixture of metal powders to which the above-listed organic-inorganic compounds are added as a binder. Then, according to the study of the present inventors, it has been found that a strong metal powder compact (preform) can be obtained after firing, even though the organic components in the molded article are removed by firing, by firing the molded article obtained by firing at a temperature of 800 ℃ or lower and 300 ℃ or higher and 800 ℃ or lower at which the metal powder is not oxidized. The present inventors considered the following reasons for obtaining such an effect. First, when the organic-inorganic compound as exemplified above is added to a metal powder to be molded, it exerts strength as a so-called paste at normal temperature in the same manner as a general organic binder. Furthermore, when the preform is heated at 300 ℃ or higher, the organic component of the organic-inorganic compound is burned and removed, and the inorganic component in the structure of the organic-inorganic compound functions as an inorganic binder, so that the preform obtained after firing is strengthened. That is, the organic component in the molded article is removed by firing at a temperature of 300 ℃ or higher, and the inorganic component functions as an inorganic binder, so that a metal powder molded article having a content (volume fraction) of the metal raw material of 55v% or more can be obtained. The effects obtained by using the organic-inorganic binder will be described in more detail below.

As described above, an inorganic binder such as general colloidal silica or colloidal alumina does not contribute to the expression of the strength of the preform unless it is calcined at a temperature of 1000 ℃. On the other hand, in the case where the organic-inorganic binder used in the present invention is calcined, the organic component is calcined and removed at a calcination temperature of 300 ℃ or higher, and SiO remaining after calcination ₂ Component (C) and Al ₂ O ₃ The components, etc. are still combined with the metal powder in an amorphous (amophorus) state. Thus, for example, the fired preform exhibits strength even at a low temperature of about 300 ℃. Further, according to the study of the present inventors, even when the metal powder is fired at a high temperature of 800 ℃ or lower, the metal powder is not oxidized, and therefore a sufficiently strong preform can be produced. In addition, since the organic-inorganic binder as exemplified above decomposes and removes organic components at a temperature of 300 ℃, there is an advantage that no organic gas is generated due to organic substances when a molten metal such as an Al alloy is infiltrated. The reason why the above-described effects are obtained is considered as follows. That is, it is considered that, since the molecular structure of the organic-inorganic binder used in the present invention, for example, si alkoxide or the like is Si — O — R (R: organic substance), the organic component is less likely to be carbonized and remain even at a temperature of 300 to 800 ℃ and the organic component is easily burned and removed as SiO in the formed body after firing, as compared with the ordinary organic binder ₂ The inorganic binder of (3) functions, and as a result, the obtained preform exerts strength. The inorganic-organic binder used in the present invention is also required to be usable in an organic solvent such as ethanol, IPA, or toluene, and therefore has an advantage that deterioration due to a reaction between the metal powder and water is suppressed.

As described above, in both the invention 1 and the invention 2, the organic component is decomposed and removed at a relatively low temperature to obtain a strong preform. As described below, this is an important element for impregnating the obtained preform with a molten metal such as an Al alloy in a good state under high pressure or non-pressure. In the case of the high-pressure infiltration according to the invention 1, specifically, the preform is preheated at a temperature of 800 ℃ or lower, and then the preform is infiltrated with a melt of an Al alloy or the like at a temperature of 700 to 800 ℃ under high pressure. The preform constituting the present invention can exhibit sufficient strength even for such a high-temperature melt. Further, in the present invention using a special preform, since there is no generated gas which is not easily removed from the inside of the preform, the melt of Al alloy or the like can be infiltrated into the inside.

On the other hand, in the case of the non-pressurized infiltration according to invention 2 of the present invention, a preform manufactured as described below is used. As described above, in the invention 2, the metal powder containing Mg is mixed into the preform in a predetermined amount. In the case of metal Mg powder or Mg-containing alloy powder, for example, the preform needs to be baked at a temperature of 500 ℃ or lower because the metal powder or Mg-containing alloy powder is oxidized to MgO at a temperature exceeding 500 ℃. Further, according to the studies of the present inventors, in addition to firing the preform at a low temperature of 500 ℃ or lower, a desired amount of the organic-inorganic binder described above is added when the metal powder material is mixed to obtain a molded article, whereby a strong preform can be produced which is free from oxidation of the metal powder containing Mg component or the like when the molded article is fired and from deformation when the melt of the Al alloy or the like is not infiltrated under pressure.

In the inventionWhen the organic-inorganic binder used is solid, it may be added by dissolving in an organic solvent such as ethanol or IPA. In the case of a liquid, the solvent may be added as it is or 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 to the metal powder material and the organic-inorganic binder to facilitate mixing. The organic-inorganic binder used in the present invention is preferably added in an amount of SiO ₂ 、Al ₂ O ₃ The metal powder is added and mixed in a range of, for example, about 0.3 to 5.0 parts by mass with respect to 100 parts by mass of the metal powder raw material. If the amount of addition is less than the above range, the amount may be too small to obtain sufficient strength of the preform. When the amount is more than the above range, siO in the aluminum composite to be finally obtained ₂ 、Al ₂ O ₃ The amount of inorganic material is large, and the high metal powder-containing aluminum composite having a high metal content, which is the object of the present invention, may not be obtained, and the performance of the product may be lowered, which is not preferable.

(method of producing molded article)

In the present invention, 2 or more kinds of metal powder materials having different average particle diameters are selected as metal raw materials for preforms, a mixture is obtained by adding and mixing the above-mentioned organic-inorganic binder to the metal raw materials, a molded article is obtained by molding the obtained mixture, and the obtained molded article is fired at a specific temperature, thereby producing a preform having high strength. Specifically, a metal powder mixture obtained by mixing 2 or more kinds of metal powder materials having different average particle diameters with the organic-inorganic binder as described above is molded to obtain a molded article.

The method of molding the molded article is not particularly limited, and the following methods may be mentioned. Examples of the method include a method in which a metal powder mixture is dried, press-molded, or dry-molded by CIP or the like to obtain a molded body; a method of forming a metal powder mixture into a slurry using an organic solvent, and performing vibration settling molding or cast molding using a plaster mold to obtain a molded body. When the metal powder mixture is formed into a slurry, it is preferable to reduce the amount of water used and prepare the slurry using an organic solvent. This is because, if the moisture content is large, the metal powder may react with water, and the metal powder may be changed into a hydroxide or the like, and may be deteriorated. For example, when the metal powder is silicon powder, the following reaction proceeds, and there is a possibility that silicon is deteriorated.

In addition, when the metal powder is a titanium powder, the following reaction proceeds, and the titanium may be deteriorated. That is, due to Ti +2H ₂ O→TiO ₂ +2H ₂ To form an oxide. In the case of other metal powders, water is also reacted with water to form an oxide, and therefore, it is not preferable to use water basically. In order to suppress such a problem, an organic solvent such as alcohol or a mixed solvent of water and a hydrophilic organic solvent such as alcohol is used. In this case, it is also preferable to reduce the amount of water in the mixed solvent in order to suppress the above reaction. According to the study of the present inventors, if the water content is 30 parts by mass or less based on 100 parts by mass of the organic solvent, the above-described reaction does not occur.

When a molded article is obtained by drying the metal powder mixture and then performing press molding, CIP or other dry molding, the above-described problems do not occur. The molded article desired in the present invention can be easily obtained by press molding commonly used as a method for obtaining a molded article of a powder material. In addition, CIP molding is also preferable because the density of the molded article obtained can be made uniform. Preforming by press forming, for example, followed by CIP forming is also a preferred method.

(calcination of the molded article)

In the present invention, the molded article obtained as described above is fired to obtain a metal powder molded article (preform) having a high metal content. In this case, when a preform is impregnated with a molten metal such as an Al alloy under a high pressure of 10MPa to 200MPa, the preform is fired at a temperature of 300 ℃ to 800 ℃. When the molten metal such as Al alloy is infiltrated into the preform without pressurization, the preform is fired at a temperature of 500 ℃ or lower, for example, 300 ℃ or higher and 500 ℃ or lower. First, the molded product is fired at the above temperature to remove organic components derived from the organic-inorganic binder and the like contained in the molded product. When the organic component remains in the molded article and the Al alloy or the like is infiltrated into the molded article, the molten metal of the high-temperature Al alloy or the like comes into contact with the organic component to generate gas, and infiltration of the Al alloy or the like may be inhibited.

Further, by firing the molded article at the above temperature to produce a preform, sufficient strength can be provided in the case where the preform is impregnated with the molten Al alloy or the like which is the primary object of the present invention under any of high pressure and non-high pressure. As described above, the present invention is very useful for manufacturing a near-net-shape aluminum composite containing high-metal powder, which can significantly reduce the processing cost. In order to achieve such an object, it is necessary to impart a strength to the preform that enables machining before infiltration of the melted Al alloy or the like, and for achieving such an object, it is also important to produce the preform by firing the molded article.

The temperature conditions for obtaining a metal powder compact (preform) having a high metal content vary depending on the method of impregnating the preform with the molten Al alloy or the like in the subsequent step, the high-pressure impregnation, or the non-pressure infiltration. In the case of obtaining a preform for high-pressure infiltration, a molten metal such as Al alloy is infiltrated under a relatively large pressure of about 10 to 100MPa, and therefore the preform used needs to have strength to withstand this pressure. However, according to the study of the present inventors, if the firing temperature is too high, the metal powder as the raw material of the preform is oxidized, and therefore, in order to suppress the oxidation, firing at a temperature of 800 ℃. In addition, in order to sufficiently remove organic components derived from an organic-inorganic binder or the like added to the metal powder, it is necessary to perform firing at a temperature of 300 ℃ or higher. According to the study of the present inventors, when obtaining a preform for high-pressure infiltration, it is preferable to bake at a temperature exceeding 500 ℃ and 800 ℃ or less. More preferably, the firing may be carried out at a temperature of 700 ℃ or higher and 800 ℃ or lower.

According to the study of the present inventors, when a preform subjected to non-pressure infiltration is obtained, stress is generated in a portion where the preform contacts a melt of an Al alloy or the like due to the non-pressure infiltration, and therefore, a preform strength capable of withstanding the stress is required. Therefore, by firing in the same manner as in the case of the preform subjected to high-pressure infiltration, the organic component in the molded article is removed, and the strength of the obtained preform is improved. However, in the case of non-pressure infiltration, as described above, in order to infiltrate a molten metal such as an Al alloy in a good state under non-pressure, it is necessary that the preform to be infiltrated be in a state to which a metal powder containing a Mg component such as the Mg metal powder described above is added. On the other hand, for example, if the temperature exceeds 500 ℃, the Mg metal powder reacts with oxygen in the air to form MgO, and the Mg component required for the non-pressure infiltration is insufficient. Therefore, it is necessary to carry out the calcination at a temperature of 500 ℃ or lower. According to the study of the present inventors, when non-pressure infiltration is used, organic components can be sufficiently removed by baking at a temperature of 300 ℃ to 450 ℃ and the preform having a high metal content can be made strong enough to withstand the non-pressure infiltration.

[ production of aluminum composite containing high Metal powder ]

Next, the step of impregnating aluminum or the like to obtain 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 above-described configuration is impregnated or infiltrated with a molten Al alloy or the like. The method of impregnation by high pressure and the method of non-pressure infiltration are described below.

(method of high-pressure infiltration of Al alloy isotropic preform)

Fig. 1 (a) to 1 (C) schematically show conceptual views of high-pressure infiltration. As shown in fig. 1 (a), a preform 1 having a high metal content is heated to 300 to 800 ℃ and loaded into a frame mold 3 of a preheated press machine. The reason why the preform 1 is loaded in a preheated state is that when the preform 1 is high-pressure infiltrated with a melt of Al alloy or the like 2, if the temperature of the preform 1 is low, the Al alloy or the like 2 may be cooled and solidified in the middle of the high-pressure infiltration, and cannot infiltrate into the inside of the preform 1, thereby preventing this problem. Similarly, the frame mold and the die 3 may be heated (preheated) to 200 to 400 ℃ by a burner or the like so that the Al alloy 2 does not cool and solidify during the infiltration.

The frame mold 3 filled with the preform 1 as described above is poured with Al alloy or the like 2 melted at 600 to 800 ℃, and as shown in fig. 1 (B) and 1 (C), pressing is performed by applying a load by a punch, and the preform 1 is isotropically impregnated with a melt of the Al alloy or the like 2. The process is carried out under the stamping pressure of 10MPa to 200 MPa. If the pressure is less than 10MPa, the pressure is too low, and the preform 1 may not be impregnated with the molten Al alloy 2. The impregnation can be carried out at a higher pressure of more than 200MPa, but as the capability of the apparatus for obtaining the composite of the present invention, it is sufficient to obtain a pressing pressure in the above range. The press-infiltrated body thus obtained is cooled to remove aluminum around the preform, thereby forming the high-metal-powder-containing aluminum composite body targeted by the present invention.

(non-pressure infiltration method of Al alloy isotropic preform)

Fig. 2 (a) to 2 (D) schematically show conceptual views of the stages of non-pressure infiltration. First, as described below, a preform 1 having a high metal content such as a metal powder containing a Mg component such as a Mg metal powder is arranged and charged in an electric furnace (not shown) capable of ensuring a nitrogen atmosphere. In the lower part of the preform 1, a small piece of the same material as the preform 1 is preferably arranged as a penetration channel 4. Further, a solid Al alloy or the like 2 for infiltration is provided in the vicinity without contacting the preform 1. The preform 1 and the Al alloy or the like 2 are charged into the electric furnace in a state of being charged into a carbon container 5 as shown in fig. 2 (a) so as not to react with members inside the electric furnace.

After the preform 1 and the solid Al alloy or the like 2 are arranged and charged in the electric furnace as described above, the temperature is slowly raised while maintaining the nitrogen atmosphere in the electric furnace, and the temperature is maintained at 700 to 900 ℃ for 2 to 5 hours. Meanwhile, as schematically shown in fig. 2 (B) to 2 (D), the molten Al alloy or the like 2 is infiltrated into the preform 1 through the infiltration passage 4 in a non-pressurized manner, and an aluminum composite containing high metal powder is obtained.

Hereinafter, a case where the metal powder containing Mg component or the like is Mg powder will be described as an example. The principle of obtaining an excellent high-metal-powder-containing aluminum composite by non-pressure infiltration in the above-described configuration is considered as follows. It is considered that the reaction of Mg with nitrogen gas to form Mg ₃ N ₂ And the metal powder precipitates in the preform to improve wettability with Al alloy or the like, or Mg reacts with thermite to reduce the surface oxide of the metal powder constituting the preform, thereby improving wettability of the metal powder with Al alloy or the like. As described above, the following method is performed in the prior art: when a molded article obtained by press molding or the like is used for non-pressure infiltration without firing, and when an Al alloy or the like is infiltrated without pressure, a molded article containing no Mg powder is used, and is placed in a nitrogen atmosphere containing magnesium vapor to infiltrate the Al metal. However, according to the study of the present inventors, in this method, mg vapor in the atmosphere reacts with nitrogen gas to generate Mg on the surface of the preform ₃ N ₂ In this state, al alloy or the like penetrates, and therefore, it takes a long time to infiltrate aluminum into the entire preform. In addition, since Mg is not uniformly generated on the surface of the preform ₃ N ₂ Therefore, the Al alloy or the like does not uniformly penetrate, and the entire preform may not be uniformly infiltrated.

According to the technique of the present invention, unlike the case of the prior art described above, it is possible to mix the Mg powder homogeneously within the preform, so that Mg is therefore present ₃ N ₂ Generated in the whole of the prefabricated member. Therefore, the Al alloy or the like can be infiltrated uniformly into the entire preform while the infiltration rate is dramatically increased. In addition, in the case of non-pressure infiltration, since Al alloy or the like can be infiltrated directly in the shape of a preform, there is a great advantage that secondary processing can be reduced in such a manner that an aluminum composite containing high metal powder can be produced in a near-net shape close to the shape of a product.

[ examples ]

Further specific examples of the above-described embodiment will be described below by referring to examples and comparative examples, but the present invention is not limited to the following examples. Herein, w% refers to mass basis and v% refers to volume basis. The average particle diameter in the present specification is a value measured by a laser diffraction particle size distribution measuring instrument.

[ example 1] (Using high pressure infiltration method)

First, a metal powder compact (preform) having a high metal content is produced by the following steps. In this example, 3 kinds of silicon (silicon) powders having different average particle diameters were combined and mixed with stirring to prepare a preform. Specifically, a mixture of 3 kinds of silicon powders different from each other in average particle diameter, which was composed of 1820g of silicon powder having an average particle diameter of 45 μm, 780g of silicon powder having an average particle diameter of 25 μm, and 100g of silicon powder having an average particle diameter of 5 μm, and which was 2700g in total, was used. Adding SiO to the mixture ₂ The resultant mixture was stirred and mixed with a stirrer for 15 minutes in 130g of ethyl silicate as an organic-inorganic binder containing 40w% of a silicon component (silicon) to obtain a mixed powder used in the present example.

Adding the total amount of the mixed powder obtained above into a press metal mold with inner dimensions of 200mm × 200mm × 150mm (depth) at a rate of 300kg/cm ² The press forming was performed with a total pressure of 120 t. The obtained press-molded article was then charged into an electric furnace, heated to 700 ℃ at a heating rate of 50 ℃/hr, held at that temperature for 3 hours, and then cooled to room temperature to produce a preform made of silicon metal. The weight and the outer dimensions of the preform were measured, and the bulk density was calculated to obtain a silicon preform having a volume filling rate (Vf) of 77%.

The preform obtained as described above was preheated to 500 ℃ by an electric furnace, and the preheated preform was loaded into a 300mm Φ × 250mm deep frame mold and mold heated to 250 ℃ by a burner of a press for high-pressure infiltration. An aluminum alloy (AC 4C) melted at 750 ℃ was charged into the frame mold and the die approximately 20mm above the die, a press punch was pushed into the frame mold and the die from the upper side, and the die was held at a pressure of 100MPa for 10 minutes, so that the melted aluminum was high-pressure impregnated into the previously obtained silicon preform (see fig. 1 a to 1C).

After cooling, the aluminum around the preform is machined off, and the product portion of the silicon-aluminum composite is taken out. This product portion is a silicon-aluminum composite (hereinafter also referred to as a silicon-aluminum composite) which is uniformly impregnated with aluminum without small pores (pores) or cracks. The bulk density was calculated from the weight measurement and the external dimension measurement, and the result was a silicon-aluminum composite containing 78v% silicon and 22v% aluminum alloy.

[ example 2] (Using non-pressure infiltration method)

A metal powder compact (preform) having a high metal content used in the present example was produced by the following procedure. To a total of 2700g of 3 kinds of silicon powders different from each other in average particle diameter, which were weighed in such a manner as to become the same compounding as that used in example 1, 50g of Mg powder having an average particle diameter of 80 μm was added. Further, 130g of ethyl silicate was added to the mixture in the same manner as in example 1, and the mixture was mixed with a stirrer for 10 minutes.

Adding the total amount of the mixed powder obtained above into a press metal mold with inner dimensions of 200mm × 200mm × 150mm (depth) at a rate of 150kg/cm ² The press forming was carried out at a total pressure of 60 t. The resultant was removed from the mold, and the obtained compact was charged into a normal air atmosphere electric furnace, heated at a heating rate of 50 ℃/hr to 450 ℃, held at that temperature for 3 hours, and then cooled to produce a preform. The bulk density was calculated in the same manner as in example 1, and the resulting bulk filling ratio (Vf) was 73%.

The preform obtained as described above is arranged in a carbon container 5 so as to be a "non-pressurized infiltration schematic diagram" schematically shown in fig. 2 (a) to 2 (D). Specifically, 4 penetration channels 4 having a size of 30mm × 30mm × 30mm, which are made of the same material as the preform 1 obtained above, were placed under the preform 1 in a grounded state, and 2500g of a solid aluminum alloy (AC 4A) 2 was disposed beside the preform 1. Subsequently, the entire carbon container 5 in which the preform 1 and the like are arranged as described above is charged into a nitrogen atmosphere furnace, heated at 50 ℃/hr, held at 800 ℃ for 5 hours, and then cooled.

After cooling, the infiltration path 4 was removed, and the surface and the inside of the preform 6 after infiltration were processed and observed, and as a result, it was confirmed that the aluminum was completely infiltrated into the preform. The bulk density calculated from the measured values of the weight and the external shape of the resulting silicon-aluminum composite showed that the composite was a silicon-aluminum composite containing 73v% of silicon and 26v% of aluminum alloy and having no pores or cracks.

[ example 3] (Using high pressure infiltration method)

A metal powder compact (preform) having a high metal content used in the present example was produced by the following procedure. A mixture of 3 kinds of silicon powders different from each other in average particle diameter, which was composed of 1820g of silicon powder having an average particle diameter of 80 μm, 780g of silicon powder having an average particle diameter of 25 μm, and 100g of silicon powder having an average particle diameter of 3 μm, and which was 2700g in total, was used. 180g of an isopropyl alcohol solution in which a silicone resin (KR-220L, trade name, manufactured by shin-Etsu chemical Co., ltd.) was dissolved so as to be 30w% was added to the mixture, and the mixture was stirred with a stirrer for 15 minutes, and then the total amount was charged into a press mold in the same manner as in example 1, and press-molded under the same conditions as in example 1. The obtained press-molded article was then charged into an electric furnace, heated to 750 ℃ at a heating rate of 70 ℃/hr, and fired at that temperature to obtain a preform having a volume filling rate of 78 v%. The volume filling ratio was obtained in the same manner as in example 1.

The obtained preform was impregnated with the molten aluminum alloy by using a high-pressure impregnation press under the same conditions and under the same steps as those in example 1. After cooling, the surrounding aluminum was removed by machining, and the product portion was taken out and subjected to weight and shape measurement to calculate the bulk density. As a result, it was confirmed that the obtained composite was a silicon-aluminum composite containing 78v% silicon and 22v% aluminum alloy, and had no pores (air holes) or cracks.

[ example 4] (Using non-pressure infiltration method)

A metal powder compact (preform) having a high metal content used in the present example was produced by the following procedure. A preform having a shape of 200mm × 200mm × 40mm containing Mg powder, which was produced by the same procedure as that performed in example 2, was machined by a milling cutter. Specifically, a preform having a rib-like structure in which 4 cavities of 75mm × 75mm × 25mm (depth) were uniformly arranged in the preform obtained above was obtained. The resulting preform is a strong preform with strength to enable machining.

Using the preform obtained above, non-pressure infiltration of the aluminum alloy (AC 4A) was performed from the infiltration path disposed under the preform in the carbon container in the same manner as in example 2. Subsequently, the same procedure as in example 2 was carried out, and the permeation channels were removed to measure the bulk density, whereby it was confirmed that a silicon-aluminum composite was obtained which contained 73v% of silicon and 27v% of aluminum alloy and which was free from pores and cracks. In addition, no aluminum alloy bleeds out inside the cavity, and a silicon-aluminum composite can be produced in a near-net manner still in the shape of the preform.

[ example 5] (Using high pressure infiltration method)

A metal powder compact (preform) having a high metal content used in the present example was produced by the following procedure. 1400g of iron powder having an average particle size of 80 μm and 600g of iron powder having an average particle size of 10 μm were added as SiO ₂ 80g of ethyl silicate (40 w% in terms of silicon content) (silicon) was stirred and mixed for 15 minutes. The mixed powder was charged into a press metal mold having an inner size of 200mm X150 mm (depth) at 150kg/cm ² The press forming was carried out at a total pressure of 60 t. Then, the press-formed product was charged into an electric furnace, heated to 700 ℃ at a heating rate of 50 ℃/hr, held at that temperature for 3 hours, and then cooled to room temperature to produce a ferrous metal preform. The weight and the outer dimensions of the obtained preform were measured, and the bulk density was calculated to obtain an iron powder preform having a volume filling rate (Vf) of 73%.

The preform obtained above was preheated to 500 ℃ by an electric furnace, and loaded into a frame-shaped mold having a depth of 300 mm. Phi. Times.250 mm, which was heated to 250 ℃ by a burner, of a press for high-pressure infiltration. An aluminum alloy (AC 4C) melted at 750 ℃ was charged into the frame mold and the die about 20mm above the frame mold and the die, and a press punch was pushed into the frame mold and the die from the upper side, and the die was held under a pressure of 100MPa for 10 minutes to perform high-pressure impregnation.

After cooling, the surrounding aluminum is machined and removed, and a product portion of an iron-aluminum alloy composite (hereinafter also referred to as an iron-aluminum composite) is taken out. The product portion is an iron-aluminum composite in which an iron powder preform is uniformly impregnated with aluminum without small holes (pores) or cracks. The bulk density was calculated from the weight measurement and the external dimension measurement, and the result was an iron-aluminum composite containing 73v% iron and 27v% aluminum alloy.

Comparative example 1 (high pressure impregnation method without using a binder)

The same compounding and weight of silicon mixed powder as in example 1 was added to a 200mm × 200mm × 100mm iron box as powder without adding a binder such as silicone resin and ethyl silicate, and the whole box was placed on a shaker and filled by applying shaking for 20 minutes. Subsequently, high-pressure impregnation of aluminum was performed in the same manner as in example 1 with the tank, and the composite was cut after cooling.

The machined surface of the cut composite was observed, and as a result, many streak-like aluminum defects were found. This is considered to be because cracks are generated in the metal powder filler during the high-pressure impregnation, and the aluminum alloy enters the cracks. The portion having no cracks was cut out, and the volume density was calculated, and as a result, the filling rate of silicon was 62v%, which was lower than that in the case of producing the preform of example 1. The above results show that when only the particles of the silicon powder are directly filled, the filling rate of silicon is low, the strength of the silicon filling phase is insufficient, and the filling phase is broken in the middle of high-pressure infiltration of the aluminum melt, resulting in defects of aluminum intrusion.

Comparative example 2 (production of preform by press molding without using a binder)

The same compounding and weight of the silicon mixed powder as in example 1 was not added with ethyl silicate, and press-forming was performed by the same procedure using the mixed powder. However, the strength of the obtained molded article was insufficient, and the molded article became deformed when removed from the mold, and a preform usable for producing a composite could not be produced. From the above results, it is found that when the press molding is performed using the silicon mixed powder material, a binder must be added to the powder material.

Comparative example 3 (fabrication of preform by Settlement Molding without Binder)

A slurry was prepared by using the same compounding and weight of silicon mixed powder as in example 3 without adding a binder such as a silicone resin or ethyl silicate, and this slurry was used for sedimentation molding. As a result of drying, the strength of the resulting molded article was insufficient, and the molded article was brittle and could be easily deformed by touching with a hand. In addition, a part of the molded article was heated to 700 ℃ at elevated temperature in the same manner as in example 1, and as a result, the molded article had almost no strength and was brittle to such an extent that the molded article could not be used for high-pressure impregnation or non-pressure impregnation.

Comparative example 4 production of a preform by Press Molding and calcination Using an organic Binder

The silicon mixed powder compounded and weighed in example 1 was added to the silicon mixed powder in a ratio of 2w% to PVB using an ethanol solution of polyvinyl butyral (hereinafter abbreviated as PVB) having a solid content of 20w%, and then a compact was prepared by press molding in the same operation as that performed in example 1. The obtained molded article was fired at 750 ℃ and was so brittle that it became deformed by touch. The reason for this is considered to be that PVB functions as a binder for the silicon mixed powder at room temperature, but burns off due to firing. From the above results, it was confirmed that the organic binder can be used for shape retention of the press-formed article, but the strength of the preform cannot be retained by the firing in the subsequent step.

Comparative example 5 (preparation of preform by calcination at 850 ℃ C. Using organic-inorganic Binder)

To a mixture of 3 types of silicon powders having different average particle diameters used in example 1, ethyl silicate as an organic-inorganic binder was added in the same amount, and the mixture was stirred and mixed to produce a silicon mixed powder, and the same amount of the silicon mixed powder was used to perform press molding in the same manner as in example 1. The obtained press-formed article was charged into an electric furnace, heated up to 850 ℃ at a heating rate of 50 ℃/hr, held at that temperature for 3 hours for calcination, and then cooled to room temperature to produce a silicon preform.

The surface of the obtained calcined body was observed, and as a result, silicon was oxidized to form SiO ₂ The color changed to be whitish. In addition, silicon forms SiO ₂ Since the volume increases, a stress is generated on the surface to generate a fine crack, and a preform having no defects cannot be obtained.

Comparative example 6 (preparation of preform by calcination at 570 ℃ C. Using Mg powder and organic-inorganic Binder, non-pressure infiltration method)

To 3 kinds of silicon powders having the same average particle size as that used in example 2, mg powder having an average particle size of 80 μm was added, ethyl silicate was added to the mixture, and the mixture was mixed by a stirrer to obtain a mixture, and the obtained mixture was subjected to press molding in the same manner as in example 2 to obtain a compact. Subsequently, the press-molded article obtained above was calcined and degreased at 570 ℃ for 3 hours to prepare a preform (calcined body).

The preform (fired body) obtained as described above was subjected to non-pressure infiltration with a molten aluminum alloy by the same method as in example 2. However, the aluminum alloy does not penetrate into the preform (fired body) in a non-pressurized manner. The reason for this is considered to be that Mg added to the compact by firing at 570 ℃ oxidizes to form MgO, and does not contribute to non-pressure infiltration.

[ comparative examples 7 to 9] (preparation of preforms from silicon powders having respective average particle diameters alone)

Preforms were produced by firing the press-formed articles by the same procedure as in example 1 except that 2700g of each silicon powder having an average particle diameter of 45 μm, 25 μm, or 5 μm used in the mixture of silicon powders in example 1 was used alone. Subsequently, the volume filling factor (Vf) was calculated in the same manner as in example 1 for the obtained preforms using the silicon powders having the average particle diameters of 45 μm, 25 μm and 5 μm. As a result, the filling rate was 50v% for the preform using 45 μm silicon powder, 52v% for the preform using 25 μm silicon powder, and 53v% for the preform using 5 μm silicon powder. In the case of any of the preforms obtained by using the silicon powders having the respective average particle diameters alone, it was confirmed that the filling ratio was decreased as compared with the case of the preforms of examples, and it was found that in order to produce a preform having a high content, it was necessary to mix and use metal powders of silicon or the like having different average particle diameters.

Table 1 summarizes the conditions for producing preforms, the method for impregnating Al alloy and the like, and the properties of the high-metal-powder-content aluminum composite obtained in examples and comparative examples.

Table 1: production conditions of examples and comparative examples and properties of the obtained composite materials

Description of the reference numerals

1: prefabricated part

2: al alloy and the like

3: frame-shaped metal mold

4: permeation channel

5: carbon container

6: infiltrated preform

Claims

1. A method for producing an aluminum composite containing a high-metal powder, comprising: a preform manufacturing step for obtaining a preform that is a metal powder compact having a high metal content; and an infiltration step of aluminum or the like, in which the obtained preform is infiltrated or infiltrated with molten aluminum or aluminum alloy,

in the preform production step, 2 or more metal powder materials having different average particle diameters from each other are selected as a metal raw material for a preform from metal powder materials having an average particle diameter of 1 to 200 μm, at least one organic-inorganic binder selected from the group consisting of silicone resins, si alkoxides and Al alkoxides is added to the metal raw material in a mixed liquid state or a liquid state to obtain a mixture, the mixture is molded using the obtained mixture, and the molded product obtained is fired at a temperature of 300 to 800 ℃, whereby an organic component in the molded product is removed and an inorganic component functions as an inorganic binder to obtain a metal powder molded product having a content (volume fraction) of the metal raw material of 55v% or more,

in the step of impregnating the aluminum or the like, the metal powder compact obtained in the step of producing the preform is impregnated with a molten aluminum or aluminum alloy under a high pressure of 10 to 200 MPa.

2. A method for producing an aluminum composite containing a high-metal powder, comprising: a preform manufacturing step for obtaining a preform that is a metal powder compact having a high metal content; and an infiltration step of aluminum or the like, in which the obtained preform is infiltrated or infiltrated with molten aluminum or aluminum alloy,

in the preform manufacturing step, 2 or more kinds of metal powder materials having different average particle diameters from each other are selected as the metal raw material for the preform from the metal powder materials having an average particle diameter of 1 to 200 [ mu ] m excluding Mg powder, alMg powder, znMg powder, znAl powder and Mg powder ₂ In addition to the respective powder materials of the Si powder, an amount selected from the group consisting of Mg powder, alMg powder, znMg powder, znAl powder and Mg is added in a range of 0.2 to 5 parts by mass per 100 parts by mass of the metal raw material ₂ 1 or more kinds of powders selected from the group consisting of Si powders, further adding at least one organic-inorganic binder selected from the group consisting of silicone resins, si alkoxides and Al alkoxides which is mixed in a liquid state or is formed into a liquid state to obtain a mixture, molding the mixture using the obtained molded article, and baking the molded article at a temperature of 300 ℃ or higher and 500 ℃ or lower, whereby organic matter components in the molded article are removed and inorganic matter components function as an inorganic binder to obtain a metal powder molded article having a content (volume fraction) of the metal raw material of 55v% or higher,

in the step of impregnating the aluminum or the like, aluminum or an aluminum alloy is infiltrated into the metal powder compact obtained in the step of producing the preform in a nitrogen atmosphere without pressurization.

3. The method for producing a high-metal powder-containing aluminum composite according to claim 1 or 2, wherein the metal powder is 1 or 2 or more selected from the group consisting of a silicon powder or a silicon-containing silicon-based alloy powder, a titanium powder, an iron powder or an iron-containing iron-based alloy powder, and a nickel powder or a nickel-containing nickel-based alloy powder.

4. The method for producing a high-metal-powder-containing aluminum composite body according to any one of claims 1 to 3, wherein the content (volume ratio) is 55v% or more and 85v% or less.

5. The method for producing a high-metal-powder-content aluminum composite according to any one of claims 1 to 4, wherein the 2 or more types of metal powders having different average particle diameters each contain at least a metal powder A having an average particle diameter of 10 μm or less and a metal powder B having an average particle diameter of 40 μm or more, and the metal powder A is contained in an amount of at least 3% by mass and the metal powder B is contained in an amount of 50% by mass or more of the total amount of the metal powders.

6. The method for producing a high-metal powder-containing aluminum composite body according to any one of claims 1 to 5, wherein the organic-inorganic binder is at least any one selected from the group consisting of Si alkoxides and Al alkoxides.

7. A method for producing a preform, which is characterized by obtaining a preform that is a metal powder compact having a high content of metal powder and used when an aluminum composite metal containing high metal powder is obtained by impregnating molten aluminum or an aluminum alloy under high pressure,

a metal material for a preform is selected from metal powder materials having an average particle diameter of 1 to 200 [ mu ] m, wherein 2 or more metal powder materials having an average particle diameter of 10 [ mu ] m or less and 2 or more metal powder materials having an average particle diameter of 40 [ mu ] m or more are selected as metal raw materials for the preform, wherein the 2 or more metal powder materials having an average particle diameter of 10 [ mu ] m or less contain at least 3% by mass of the metal powder A and 50% by mass of the metal powder B, and at least one organic-inorganic binder selected from the group consisting of silicone resins, si alkoxides and Al alkoxides is added to the metal raw materials in a mixed liquid state or in a liquid state to obtain a mixture, the mixture is molded, and the molded product obtained is fired at a temperature of 300 to 800 ℃, whereby a metal powder having a content (volume fraction) of the metal raw materials of 55v% or more is obtained.

8. A method for producing a preform, characterized by obtaining a preform that is a metal powder compact having a high content of metal powder and used for obtaining an aluminum composite metal containing high metal powder by non-pressure infiltration of molten aluminum or aluminum alloy in a nitrogen atmosphere,

selecting, as a metal material for a preform, 2 or more metal powder materials having different average particle diameters from each other from among metal powder materials having an average particle diameter of 1 μm or more and 200 μm or less, excluding Mg powder, alMg powder, znMg powder, znAl powder and Mg powder ₂ In addition to the respective powder materials of Si powder, the metal powder materials of 2 or more kinds having different average particle diameters from each other contain at least metal powder A having an average particle diameter of 10 μm or less and metal powder B having an average particle diameter of 40 μm or more, the metal powder A is contained in an amount of at least 3% by mass and the metal powder B is contained in an amount of 50% by mass or more in the total amount of the metal powder, and the metal powder materials are added in an amount selected from the group consisting of Mg powder, alMg powder, znMg powder, znAl powder and Mg powder in an amount within a range of 0.2 to 5 parts by mass based on 100 parts by mass of the metal raw material ₂ 1 or more kinds of powders selected from the group consisting of Si powders, further adding at least one organic-inorganic binder selected from the group consisting of silicone resins, si alkoxides, and Al alkoxides, which is mixed in a liquid state or brought into a liquid state, to obtain a mixture, molding the mixture using the obtained molded article, and subjecting the molded article obtained to a temperature of 300 ℃ or more and 500 ℃ or lessAnd calcining the mixture to obtain a metal powder compact having a content (volume fraction) of the metal raw material of 55v% or more.

9. A high-metal-powder-containing aluminum composite body which has few internal defects such as pores and is obtained by the method for producing a high-metal-powder-containing aluminum composite body by high-pressure infiltration according to any one of claims 1 and 3 to 6.

10. A high-metal-powder-containing aluminum composite body which is a near-net-shape high-metal-powder-containing aluminum composite body close to a product shape, obtained by the method for producing a high-metal-powder-containing aluminum composite body by non-pressure infiltration in a nitrogen atmosphere according to any one of claims 2 to 6.