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

Abstract

By establishing a production technique of a preform which can improve the filling rate of metal powder and which is uniform and has no internal defects, a technique is provided for infiltrating or non-pressurized infiltration of Al alloy or the like into the preform to obtain an aluminum composite with high metal powder having few cracks and defects and high metal content. A production method of an aluminum composite with high metal powder is provided, in which, in a preform production step, two or more materials having different particle diameters are selected from metal powder materials of 1 to 200 μm, an organic and inorganic binder is added to the metal raw materials to obtain a material, a shaped product is obtained from the material, the obtained shaped product is fired at a temperature of 300°C or higher to obtain a preform having a metal raw material content of 55 vol% or more, and a molten liquid of Al alloy or the like is infiltrated or non-pressurized infiltrated into the obtained preform.

Description

Technical Field

[0001] This invention relates to a method for manufacturing an aluminum composite containing high levels of metal powder, a method for fabricating a preform, and the aluminum composite containing high levels of metal powder. Specifically, it relates to a new technology that provides an aluminum composite containing high levels of metal powder by well infiltrating metallic aluminum or aluminum alloys (hereinafter also referred to as Al alloys, etc.) into a preform containing metal powder with a high volumetric filling rate, and that can achieve a leap in the productivity and quality of the composite material. Background Technology

[0002] In recent years, materials composed of metals and Al alloys have attracted attention as lightweight, high-strength, high Young's modulus, high thermal conductivity, and low thermal expansion materials. These materials are used in electronic applications such as heat sinks, heat diffusers, and electronic component packaging, as well as in semiconductor device components such as XY sliders and vacuum chucks. These materials are a type of so-called metal matrix composite (MMC). Previously, MMCs were typically made by composite ceramic powders with a metal matrix, but in recent years, composite materials containing metal powders and Al alloys have gained attention. For example, composite raw materials with high Young's modulus and low thermal expansion, such as silicon and Al alloys, have been proposed, as well as Al alloys composited with high-strength titanium and iron powders. Furthermore, as described below, composites of metal powders and Al alloys have also attracted attention due to their excellent processability.

[0003] For example, silicon metal, due to its low coefficient of thermal expansion, is used as an electronic component and semiconductor component. However, it has weaknesses such as being very brittle and being unable to manufacture complex, large components. Therefore, silicon-aluminum composites with alloys such as Al are being developed. For the reasons mentioned above, composites with aluminum containing as much silicon powder as possible are expected, and the development of composites that maintain processability, have a low coefficient of thermal expansion, and a high Young's modulus is sought. Specifically, if silicon-aluminum composites with a silicon content of 70% or more, preferably around 80% vol%, can be manufactured, a leap in applications for heat sinks and electronic component packaging that house electronic components with low coefficients of thermal expansion is anticipated.

[0004] Titanium, a metal with a low coefficient of thermal expansion, is lightweight and highly rigid, and is used in a wide variety of mechanical components. However, its high hardness and difficulty in machining limit its applications. Therefore, if aluminum can be combined with titanium to improve machinability, its applications could be greatly expanded, thus the development of titanium-aluminum composites is anticipated and promoted.

[0005] Here, the method for manufacturing a composite of metal powder and Al alloy, etc., is generally exemplified by the following method.

[0006] (Casting methods for high-silicon aluminum alloys)

[0007] This method involves melting silicon-containing aluminum alloy powder (also known as silicon-aluminum alloy), commonly referred to as silicon-aluminum alloy, and then casting it in a sand mold or metal mold. However, in this method, if the silicon content increases, the alloy's fluidity decreases, making casting impossible. Therefore, the silicon content is typically limited to a maximum of around 20% vol%. Consequently, it is difficult to manufacture high-silicon-aluminum composites with the high metal composition content desired in the aforementioned casting method.

[0008] (Spray forming method)

[0009] This method, known as "spray forming," involves creating a burette from powder material and manufacturing a silicon-aluminum composite through thermal extrusion. The burette is obtained by melting silicon and aluminum at high temperatures and then spraying the molten material. In spray forming, melting the metal at high temperatures allows for the production of composite raw material powders with freely adjustable silicon-to-aluminum ratios. Therefore, it is theoretically possible to manufacture high-silicon aluminum composites with a high metal content. However, to manufacture composites with a silicon content of 50% or more, the material needs to be melted at temperatures above 1000°C. Furthermore, during the spray cooling process, silicon precipitates first, resulting in an uneven composite. When commercialized, the product only contains approximately 50% silicon, not a silicon-aluminum composite with a higher silicon content. Additionally, during the solidification and deposition of the burette from the sprayed molten material, voids are generated. Therefore, to form a finished product, the resulting burette needs to be semi-melted, extruded under high pressure, or subjected to HIP treatment to break up these voids. In this respect, "jet forming" also has major industrial problems such as very high manufacturing costs and reduced economic efficiency.

[0010] (Non-pressurized infiltration method of aluminum into silicon powder filler)

[0011] Patent Document 1 discloses a silicon-aluminum composite metal formed by non-pressurized infiltration of molten Al alloys or the like into silicon powder at a temperature of 700°C to 1000°C in a nitrogen atmosphere containing magnesium vapor, resulting in a filler or molded body with a filling rate of 50 to 70% by volume. Patent Document 1 discloses that by containing magnesium vapor in a nitrogen atmosphere, the infiltration of molten Al alloys or the like into the filler can be accelerated. Furthermore, its embodiments describe adding 2 parts by mass of magnesium powder to 100 parts by mass of silicon powder with an average particle size of 5 μm to obtain a mixture, filling this mixture into a container to obtain a filler body, using which the silicon filling rate is 50% by volume. The above embodiments describe using silicon powder with an average particle size of 1 to 100 μm, if desired.

[0012] As described above, Patent Document 1 discloses a method for producing a composite metal by adding magnesium powder to a silicon powder, filling the container with the mixture, and then permeating molten Al alloy or the like into the filler under a nitrogen atmosphere at normal pressure (non-pressurized). However, according to the researchers of the present invention, there are issues with the silicon powder filler being uneven or having residual pores. Furthermore, when molten aluminum is permeated into this filler under non-pressurized conditions, problems arise such as cracking, defects, or the inability to obtain a filler that is sufficiently and uniformly filled with silicon powder. Therefore, when using the aforementioned non-pressurized permeation method with the filler, it is impossible to produce a metal powder-aluminum composite with a high and uniform metal composition ratio as required for the product.

[0013] Furthermore, Patent Document 2 describes a method of obtaining a molded or calcined body of metal powder by adding PVA (polyvinyl alcohol) as a binder to metal powder such as silicon powder, and then permeating molten aluminum or other metals into the resulting molded or calcined body of metal powder in a non-pressurized manner. Its embodiments describe using silicon powder with an average particle size of 20 μm, a material containing PVA as a binder, to press and form a molded body, and then using a nitrogen atmosphere furnace containing magnesium to permeate molten Al alloy into the resulting molded body under normal pressure to obtain a composite metal. This method also involves using two types of metal powder, such as ceramic powder mixed with metal powder. However, as can be seen from the technique described in Patent Document 2, which involves mixing ceramic powder with metal powder, it is not a technique aimed at setting a high metal content in the molded or calcined body of metal powder, which is the object of non-pressurized permeation for composite formation of molten metal.

[0014] According to the research of the inventors, when Al alloys are impregnated under high pressure or without pressure into a filler containing silicon powder at a high content, stress may occur at the contact surface between the filler and the Al alloy during impregnation, or cracking may occur in the metal powder molded body during the impregnation of the molten Al alloy, or capillary action may be damaged due to cracking, resulting in defects such as incomplete impregnation. While the aforementioned prior art has studied how to obtain a high-metal powder-aluminum composite with minimal cracking and defects and a high metal content, it has not provided such a composite. For example, as with the aforementioned prior art, even in the case of a molded body formed by pressing an aluminum metal into a silicon powder filler without pressure, stress may occur at the contact surface between the silicon powder filler and the Al alloy, or cracking may occur during the impregnation of the molten Al alloy, or defects such as incomplete impregnation may occur.

[0015] The advantage of using the prior art to infiltrate molten Al alloys or the like into a filler or molded body without pressure is that, while maintaining the shape of a molded body (preform) obtained by pressing metal powder, the molten Al alloys or the like quietly infiltrate into the molded body using capillary action. After infiltration, a metal powder-aluminum composite with a shape close to that of the product can be manufactured. In other words, if a composite with a shape close to that of the product can be obtained after infiltrating the molten metal into the molded body, the subsequent necessary machining can usually be reduced, thus offering the advantage of lower manufacturing costs.

[0016] This means that if a robust molded body (preform) without cracking or defects is obtained by non-pressurized infiltration of molten Al alloys, the product value and cost advantage increase dramatically. Furthermore, if the content of silicon or other metal powder materials in the resulting metal powder-aluminum composite can be high, a metal powder-aluminum composite with even lower thermal expansion and higher Young's modulus can be obtained. For example, if a method for manufacturing silicon powder-aluminum composites with more than 50% silicon can be established, its applications will be significantly expanded.

[0017] Regarding the above, the preform manufacturing method using fine-particle-size metal powder to sinter a molded body at a temperature slightly lower than the melting temperature of the metal has been widely implemented. However, according to the research of the inventors, since the molded body (preform) is manufactured by sintering, the following situations occur: during sintering, the molded body shrinks and the preform deforms, or voids within the preform form closed pores isolated from the outside, resulting in poor impregnation in the subsequent impregnation process of Al alloys, etc., and the formation of an uneven aluminum powder composite.

[0018] Existing technical documents

[0019] Patent documents

[0020] Patent Document 1: Japanese Patent Application Publication No. 2005-036253

[0021] Patent Document 2: Japanese Patent Application Publication No. 2004-052011 Summary of the Invention

[0022] The problem the invention aims to solve

[0023] Therefore, the object of the present invention is to establish a robust molded body (preform) for manufacturing metal powders, such as silicon, aluminum-silicon alloys, iron, titanium, copper, nickel, ferrosilicon, etc., and to provide a technique for manufacturing preforms with high metal powder content, which can improve the metal powder filling rate according to target performance and have very few internal defects. The technique also provides a technique for obtaining an aluminum composite containing high metal powder with very few cracks and defects and a high metal content, in either case of high-pressure impregnation or non-pressurized infiltration of Al alloys into the obtained preform.

[0024] Solution for solving the problem

[0025] The above objective is achieved through the following technique for manufacturing aluminum composites containing high-metal powder with a high metal content. Specifically, the present invention provides a method for manufacturing aluminum composites containing high-metal powder.

[0026] As a first invention, a manufacturing method is provided for obtaining an aluminum composite containing high-metal powder by high-pressure impregnation of Al alloys, etc.

[0027] [1] A method for manufacturing an aluminum composite containing high metal powder content, characterized in that it comprises: a preform manufacturing step for obtaining a metal powder molded body (preform) with high metal content; and an infiltration step for infiltrating or penetrating molten aluminum or aluminum alloy into the obtained preform.

[0028] In the aforementioned preform manufacturing process, two or more metal powder materials with different average particle sizes are selected from metal powder materials with an average particle size of 1 μm or more and 200 μm or less as metal raw materials for the preform. A mixed organic-inorganic binder is added to the metal raw materials to obtain a mixture. The obtained mixture is used to form a molded article, and the obtained molded article is calcined at a temperature of 300°C or more and 800°C to obtain a metal powder molded article with a metal raw material content (volume fraction) of 55 vol% or more.

[0029] In the aforementioned infiltration process for aluminum, etc., molten aluminum or aluminum alloy is infiltrated into the metal powder molded body obtained through the aforementioned preform manufacturing process under a high pressure of 10 MPa to 200 MPa.

[0030] In particular, the aforementioned organic-inorganic binders can be liquid or in a liquid state, and can be selected from at least one of the group consisting of organosilicon resins, Si alkoxides and Al alkoxides.

[0031] As a second invention, a method for manufacturing an aluminum composite containing high-metal powder is provided by non-pressurized infiltration of Al alloys, etc.

[0032] [2] A method for manufacturing an aluminum composite containing high metal powder content, characterized in that it comprises: a preform manufacturing step for obtaining a metal powder molded body (preform) with high metal content; and an infiltration step for infiltrating or penetrating molten aluminum or aluminum alloy into the obtained preform.

[0033] In the aforementioned preform manufacturing process, two or more metal powder materials with different average particle sizes (excluding Mg powder, AlMg powder, ZnMg powder, ZnAl powder, and Mg2Si powder) are selected as the metal raw materials for the preform. Relative to 100 parts by mass of the metal raw materials, one or more powders selected from the group consisting of Mg powder, AlMg powder, ZnMg powder, ZnAl powder, and Mg2Si powder are added in an amount ranging from 0.2 to 5 parts by mass. A mixed organic-inorganic binder is further added to obtain a mixture. The mixture is then molded, and the resulting molded article is calcined at a temperature below 500°C to obtain a metal powder molded body with a metal raw material content (volume percentage) of 55 vol% or more.

[0034] In the aforementioned impregnation process of aluminum, aluminum or aluminum alloy is impregnated into the metal powder molded body obtained through the aforementioned preform manufacturing process in a non-pressurized manner.

[0035] In particular, the aforementioned organic-inorganic binders can be liquid or in a liquid state, and can be selected from at least one of the group consisting of organosilicon resins, Si alkoxides and Al alkoxides.

[0036] The following are preferred embodiments of the method for manufacturing the aluminum composite containing high metal powder of the present invention described above.

[0037] [3] The method for manufacturing an aluminum composite containing high metal powder according to [1] or [2] above, wherein the aforementioned metal powder is selected from silicon powder or silicon alloy powder containing silicon, titanium powder, iron powder or iron alloy powder containing iron and nickel powder or nickel alloy powder containing nickel.

[0038] [4] The method for manufacturing an aluminum composite containing high metal powder according to any one of [1] to [3] above, wherein the volume content of the metal powder in the aluminum composite containing high metal powder is 55v% or more and 85v% or less.

[0039] [5] The method for manufacturing an aluminum composite containing high metal powder according to any one of [1] to [4] above, wherein the two or more metal powders with different average particle sizes contain at least metal powder A with an average particle size of 10 μm or less and metal powder B with an average particle size of 40 μm or more, and the total amount of metal powder contains at least 3% of the aforementioned metal powder A and at least 50% of the aforementioned metal powder B by mass.

[0040] [6] The method for manufacturing an aluminum composite containing high metal powder according to any one of [1] to [5] above, wherein the aforementioned organic-inorganic binder is at least one selected from the group consisting of Si alkoxides and Al alkoxides.

[0041] In addition, as another embodiment, the present invention provides a method for manufacturing the following preform suitable for use in the manufacturing method of the aluminum composite containing high metal powder of the aforementioned first invention.

[0042] [7] A method for manufacturing a preform, characterized in that it is a metal powder molded body (preform) with a high metal powder content used in obtaining an aluminum composite metal containing high metal powder by impregnating molten aluminum or aluminum alloy under high pressure.

[0043] Two or more metal powder materials with different average particle sizes are selected as metal raw materials for preforms, wherein the two or more metal powder materials with different average particle sizes contain at least metal powder A with an average particle size of 10 μm or less and metal powder B with an average particle size of 40 μm or more. The metal powder A contains at least 3% and at least 50% of the metal powder B in the total amount of metal powder, based on a mass basis. A mixed organic-inorganic binder is added to the metal raw materials to obtain a mixture. The mixture is used to form a preform, and the preform is calcined at a temperature of 300°C or higher and 800°C or lower to obtain a metal powder molded body with a metal raw material content (volume fraction) of 55v% or higher.

[0044] In particular, the aforementioned organic-inorganic binders can be liquid or in a liquid state, and can be selected from at least one of the group consisting of organosilicon resins, Si alkoxides and Al alkoxides.

[0045] In addition, as another embodiment of the present invention, a method for manufacturing the following preform suitable for use in the manufacturing method of the aluminum composite containing high metal powder of the aforementioned second invention is provided.

[0046] [8] A method for manufacturing a preform, characterized in that it is a metal powder molded body (preform) with a high metal powder content used in obtaining an aluminum composite metal containing high metal powder by non-pressurized infiltration of molten aluminum or aluminum alloy.

[0047] Two or more metal powder materials with different average particle sizes are selected as the metal raw materials for the preform, which are metal powder materials with an average particle size of 1 μm or more and 200 μm or less (excluding Mg powder, AlMg powder, ZnMg powder, ZnAl powder and Mg2Si powder). The two or more metal powder materials with different average particle sizes contain at least metal powder A with an average particle size of 10 μm or less and metal powder B with an average particle size of 40 μm or more. Based on a mass basis, the metal powder contains at least 3% of the aforementioned materials. Metal powder A, and containing more than 50% of the aforementioned metal powder B, are added in an amount ranging from 0.2 to 5 parts by mass relative to 100 parts by mass of the metal raw material, along with one or more powders selected from the group consisting of Mg powder, AlMg powder, ZnMg powder, ZnAl powder, and Mg2Si powder. A mixed organic-inorganic binder is further added to obtain a mixture. The mixture is then molded, and the resulting molded article is calcined at a temperature below 500°C to obtain a metal powder molded body with a metal raw material content (volume percentage) of 55% or more.

[0048] In particular, the aforementioned organic-inorganic binders can be liquid or in a liquid state, and can be selected from at least one of the group consisting of organosilicon resins, Si alkoxides and Al alkoxides.

[0049] In addition, as another embodiment of the present invention, an aluminum composite containing high metal powder is provided.

[0050] [9] An aluminum composite containing high metal powder, characterized in that it is an aluminum composite containing high metal powder with very few internal defects such as pores, and is obtained by the manufacturing method of aluminum composite containing high metal powder by high pressure impregnation as described in any one of [1], [3] to [6] above.

[0051]

[10] An aluminum composite containing high metal powder, characterized in that it is a near-final aluminum composite containing high metal powder in a form close to the product shape, obtained by the manufacturing method of aluminum composite containing high metal powder using non-pressurized infiltration as described in any one of [2] to [6] above.

[0052] The effects of the invention

[0053] According to the present invention, for example, in the fabrication of molded articles (preforms) of metal powders represented by powders such as silicon, aluminum-silicon alloys, iron, titanium, copper, nickel, and ferrosilicon alloys, the volumetric filling rate of the metal powder can be increased to 55% or more according to the target performance, and it is possible to achieve minimal and uniform internal defects in the obtained preform. As a result, according to the present invention, an excellent method for manufacturing aluminum composites containing high-metal powder is provided, which can obtain high-quality aluminum composites containing high-metal powders with reduced cracking and defect generation, high metal volumetric filling rate, and high quality when Al alloys or the like are impregnated into the preform under high pressure or without pressure. Furthermore, according to the present invention, high-quality aluminum composites containing high-metal powders with minimal internal defects such as pores are provided. These composites can be used, for example, as vacuum components in semiconductor, liquid crystal manufacturing apparatus, electron microscopes, and optical communication packaging. Furthermore, according to the present invention, it is also possible to manufacture aluminum composites containing high metal powder in a near-finish manner that closely resembles the shape of a product. Therefore, it is possible to reduce the cost of subsequent machining processes and the associated machining processes, and thus to increase the size of the composite. Therefore, its use as a large structural component, such as a robotic arm, a shape measuring device base, or an XY worktable, is promising. Attached Figure Description

[0054] Figure 1(A) is a schematic diagram illustrating the step of pressurized infiltration, in which molten Al alloy or the like is pressurized into a preform, in the method for manufacturing an aluminum composite containing high-metal powder according to the first invention. It is a schematic diagram showing the pouring of molten Al alloy or the like 2 into a frame-type metal mold 3 of a high-pressure infiltration press containing the preform 1.

[0055] Figure 1(B) is a schematic diagram illustrating the state in which a punch is provided at the opening of a frame-type metal mold 3, which is filled with molten material such as preform 1 and Al alloy 2, obtained through the operation shown in Figure 1(A).

[0056] Figure 1(C) is a schematic diagram showing how the molten metal in the frame-shaped metal mold 3 in the state of Figure 1(B) is subjected to a load (high pressure) so that the molten Al alloy 2 is impregnated into the preform 1.

[0057] Figure 2(A) is a schematic diagram illustrating the process of manufacturing an aluminum composite containing high-metal powder according to the second invention, in which molten Al alloy or the like is infiltrated into a preform using a non-pressurized infiltration method via capillary action. It is also a schematic diagram showing the configuration of the preform 1 and the Al alloy or the like 2 filled into a carbon container 5.

[0058] Figure 2(B) is a schematic diagram showing how the Al alloy 2 in the carbon container 5 forms a molten liquid and the molten liquid permeates into the permeation channel 4 of the supporting preform 1 in a non-pressurized manner.

[0059] Figure 2(C) is a schematic diagram showing how the molten Al alloy 2 permeates into the carbon container 5 in a non-pressurized manner through the permeation channel 4 supporting the preform 1.

[0060] Figure 2(D) is a schematic diagram showing the overall appearance of the preform 1 after the molten Al alloy 2 has been permeated into the carbon container 5 in a non-pressurized manner. Detailed Implementation

[0061] The present invention will be described below with reference to preferred embodiments. The present invention is not limited to these embodiments.

[0062] Fabrication of metal powder molded bodies (preforms)

[0063] In view of the above-mentioned prior art, the inventors have conducted in-depth research on a method for manufacturing a uniform aluminum composite containing high metal content powder with high metal volume content and few internal defects, which is expected to be used for various applications. The important conclusion is that a method for easily manufacturing metal powder molded articles (preforms) with high metal volume content and few internal voids has been established. Furthermore, the inventors first discovered that, in order to obtain a metal preform with few voids, which is the cause of defects in the final composite material, it is effective to use a material composed of two or more metal powders with different average particle sizes, rather than using metal powders of the same particle size. That is, if configured in this way, fine particles with small average particle sizes will enter between particles with large average particle sizes, resulting in the effects of the present invention. In the present invention, two or more metal powders with different average particle sizes are selected, and a mixture formed by mixing them is used as the metal raw material for the preform.

[0064] (Metal powder materials)

[0065] In this invention, the metal powder material used for manufacturing the preform is a material with an average particle size in the range of 1 μm or more and 200 μm or less. Preferably, metal powders in the range of 3 μm or more and 180 μm or less are used, and more preferably, metal powders in the range of 3 μm or more and 100 μm or less are used. The preform of this invention needs to be manufactured by mixing two or more metal powders with different average particle sizes selected from metal powders having such an average particle size range. When only a material with an average particle size of less than 1 μm is used, the particles are too fine, resulting in an increase in the surface oxide phase of the metal powder, which may reduce the performance of the metal powder. On the other hand, if the metal powder used is only larger than 200 μm, the particle size is too large, resulting in poor particle filling properties for pressing, CIP molding, sedimentation molding, etc., which is not preferred.

[0066] In this invention, when selecting two or more metal powder materials with different average particle sizes for manufacturing the preform, it is preferable to use a mixture of metal powders with large and small particle sizes. For example, it is preferable to contain at least metal powder A with an average particle size of 10 μm or less and metal powder B with an average particle size of 40 μm or more, wherein, by mass, the total amount of metal powder contains at least 3% of the aforementioned metal powder A and at least 50% of the aforementioned metal powder B.

[0067] For example, when silicon powders of 45 μm and 5 μm with different average particle sizes are pressed separately, their volume filling rates (v%:Vf) are 47% and 52%, respectively. According to the research of the inventors, by mixing 45 μm and 5 μm silicon powders at a mass ratio of 70:30 and pressing the mixture, a molded body with a Vf of 73v% can be obtained. Similarly, by mixing 70 μm, 25 μm, and 5 μm silicon powders at a mass ratio of 70:25:5 and pressing the mixture, a silicon molded body with a Vf of 78v% (volume %) can be obtained.

[0068] Since the filling rate of metal powders such as silicon powder varies depending on their average particle size, particle shape, and particle size distribution, methods for obtaining a desired high volumetric filling rate (v%) include, for example, adding them to a carbon container or similar material to achieve the highest possible filling rate, and then carefully applying vibration to form the filled material in a way that minimizes voids. However, according to the research of the inventors, it is not easy to obtain a filler with a metal powder content of 55v% or more when using this vibration method. Furthermore, even if it is obtained, cracking or streaking defects may occur when molten Al alloy or similar materials are subsequently impregnated into the filler under high pressure, thus failing to obtain a high-quality aluminum composite with a high metal powder content.

[0069] Based on the above findings, the inventors conducted in-depth research and discovered the following: By mixing two or more metal powder materials with different average particle sizes to obtain a mixed powder, and using forming methods such as compression molding, CIP molding, and sedimentation, the metal powder is incorporated as seamlessly as possible to form the resulting mixed powder. This allows for the production of robust preforms with a higher filling rate of 55% or more of the metal raw material, which can withstand even high-pressure impregnation of molten Al alloys, etc. Furthermore, it was found that the strength of the preform is further improved by adding a mixed organic-inorganic binder to the metal powder mixture as described above, and then firing the molded article formed from the resulting mixture at a temperature of 300°C or higher and 800°C or lower. Details of these points are described below.

[0070] Furthermore, the inventors conducted in-depth research on the fabrication of preforms containing 55% or more of a metal powder raw material capable of penetrating molten Al alloys, etc., without pressure. The results showed that using a mixture, based on a mass basis, of 0.2 to 5 parts by mass of one or more powders selected from magnesium alloys such as metallic Mg powder, Al-Mg alloy powder, Zn-Mg alloy powder, and Zn-Al alloy powder, or Mg2Si powder with high magnesium content (also referred to as Mg-containing metal powders, or sometimes described as Mg component) relative to 100 parts by mass of the metal powder material is effective. It was also found that by adding a specific organic-inorganic binder to this mixture, calcining the molded article formed from the mixture at a temperature below 500°C to obtain a preform, and using this preform, molten Al alloys, etc., can be penetrated in a good state without pressure, resulting in a high-quality aluminum composite containing high amounts of metal powder. That is, for example, the Mg component present in the preform generates Mg3N2 in a nitrogen atmosphere during the non-pressurized infiltration process described later. Furthermore, the metal oxides on the surface of the metal powder are reduced and metallized through the thermite reaction of Mg, improving the wettability of the metal powder with the molten Al alloy, etc. It is believed that through the functions of these Mg components constituting the present invention, it is possible to achieve good infiltration of the molten Al alloy, etc., into the manufactured preform under non-pressurized conditions.

[0071] The Mg-containing metal powders listed above are preferably powders with an average particle size of 0.5 μm or more and 150 μm or less. Powders larger than 150 μm are too coarse and may not mix evenly with the aforementioned metal powder materials, which is not preferable. Furthermore, if the particle size is coarse, the surface area of ​​the Mg component decreases, and the amount of Mg3N2 formed after the Mg contained in the preform reacts with the nitrogen in the atmosphere is reduced. If the amount of Mg3N2 formed is low, the penetration rate of Al alloys into the preform is slower, which is also not preferable. On the other hand, the finer the Mg component, the larger the surface area, making it easier to be oxidized by oxygen in the air to form MgO, thus reducing the amount of Mg, which is also not preferable. Therefore, Mg-containing metal powders with an average particle size of 0.5 μm or more are preferred. In addition, when the average particle size exceeds 150 μm, the overall surface area decreases, and as mentioned above, the amount of Mg3N2 formed decreases, which is also not preferable.

[0072] The amount of Mg-containing metal powder or the like added, based on mass, is in the range of 0.2 to 5 parts by mass relative to 100 parts by mass of the metal powder, converted to Mg content. More preferably, it is in the range of 0.5 to 5 parts by mass. If the amount of Mg-containing metal powder or the like is less than 0.2 parts by mass, the amount of Mg3N2 generated decreases, and the penetration rate of the molten Al alloy or the like cannot be sufficiently promoted, which is not preferable. On the other hand, if the amount of Mg-containing metal powder or the like exceeds 5 parts by mass, the distribution of Mg in the preform made from these raw materials increases locally, and the amount of Al alloy or the like that penetrated may become uneven, which is also not preferable. When using Mg-based alloys or Mg-containing compounds as previously listed, the mixing amount can be determined by converting them to the Mg content they contain.

[0073] The metal powder used in this invention is not particularly limited, and examples include, for instance, silicon powder, silicon-aluminum alloy powder, silicon-iron alloy powder, iron or iron-based powder, titanium powder, nickel or nickel-based powder, etc. As previously mentioned, in order to allow the molten Al alloy, etc., to infiltrate the preform in a good state under non-pressurized conditions, it is preferable to have a Mg component present in the preform. Therefore, in the mixture used for preform production in non-pressurized infiltration, in addition to the metal powders listed above, it is necessary to add one or more Mg-containing metal powders in an amount ranging from 0.2 to 5 parts by mass, and then calcine the formed article at a temperature below 500°C. Therefore, when producing preforms used for non-pressurized infiltration, it is necessary not to use any of the two or more metal powder materials with different average particle sizes, such as Mg-containing metal powders.

[0074] In contrast to the above, when the preform is used for high-pressure impregnation, two or more metal powder materials with different average particle sizes can be used as the preform manufacturing process, such as Mg-containing metal powders. It should be noted that in this case, the preform is manufactured by firing the molded article formed from the mixture at a temperature of 300°C to 800°C. Therefore, when firing at temperatures exceeding 500°C, for example, Mg in the Mg-containing metal powder is oxidized to form MgO, and the Mg component, which is important during non-pressure impregnation, is absent in the preform. Furthermore, at temperatures exceeding 800°C, the metal powder is oxidized, damaging the original properties of the metal.

[0075] (Organic-inorganic binders)

[0076] Since molten Al alloys or the like are impregnated into a preform under high pressure or in a non-pressurized manner, the preform used needs to have the strength to withstand the stress generated by the impregnation / permeation of the molten Al alloys or the like. In the first invention of the present invention, it is necessary to impregnate the molten Al alloys or the like under high pressure, specifically, to impregnate the molten Al alloys or the like at tens of MPa. Therefore, especially for the preform used in this case, a higher strength capable of withstanding high pressure is necessary. In addition, even when molten Al alloys or the like are permeated into the preform of the second invention of the present invention in a non-pressurized manner, stress will be generated at the surface where the molten Al alloys or the like come into contact with the preform. According to the research of the present inventors, if molten Al alloys or the like permeate into a filling phase of metal powder filled by methods such as vibration under high pressure or in a non-pressurized manner, cracks and defects will occur. Therefore, when molten Al alloys or the like are impregnated / permeated by any method, it is desirable to construct the preform in a way that produces a more robust preform and infuses the Al alloys or the like into the preform.

[0077] Typically, to produce high-strength preforms from ceramic powders and the like, and to obtain ceramic-Al alloy composites, it is necessary to add an inorganic binder such as mixed colloidal silica to the ceramic, form it, and then calcine the resulting formed body at a temperature of approximately 1000°C or higher to produce the preform. However, the composite of the present invention is a composite of metal powder and Al alloys, and the aforementioned prior art cannot be used. That is, in order to obtain a high-strength preform, if the formed body obtained by adding an inorganic binder to the metal powder is calculated at a temperature of 1000°C, the metal powder will be oxidized, damaging its properties as a metal, and therefore the conventional method cannot be used. In contrast, in the present invention, by adding an organic-inorganic binder to the metal powder to obtain the formed body as specified in the present invention, a strong preform containing a high content of metal powder can be produced by calcination in a low temperature range of 300°C to 800°C, resulting in the significant effects of the present invention.

[0078] To achieve the aforementioned goal, the inventors conducted intensive research and development, and discovered that using a mixture of two or more metal powder materials with different average particle sizes, as described above, to add a mixed organic-inorganic binder, is an effective means of obtaining a more robust preform. The reasons for this will be explained.

[0079] To ensure the preform is strong, it is desirable to pack metal powder as tightly as possible using methods such as pressing, CIP, and sedimentation, and then apply pressure to form the preform, while adding a binder to the raw metal powder mixture. Typically, organic binders, such as polyvinyl alcohol (PVA) and polyvinyl butyral (PVB), are used as binders in the forming of ceramics and the like. However, if molten Al alloys are impregnated under high pressure or non-pressurized methods into preforms made using these organic binders, gas is generated, potentially hindering the impregnation of the Al alloys. To prevent this problem, the preform must be pre-fired to remove the organic binder, which would be a source of gas generation. This means that organic binders such as PVA and PVB cannot function as binders to strengthen the preform after firing, and therefore cannot be used. On the other hand, it is considered that adding inorganic binders such as colloidal silica and colloidal alumina to the metal powder material, forming it using methods such as pressing and CIP, and then firing it can strengthen the preform. Furthermore, to obtain preforms that exhibit strength using these inorganic binders, the preforms need to be fired at temperatures above 1000°C. However, at this temperature, the metal powder, which is the main raw material, is oxidized, thus impairing its function as a metal. Therefore, common inorganic binders such as colloidal silica and colloidal alumina cannot be used.

[0080] In contrast to the above, the inventors conducted in-depth research and found that by forming a mixture of two or more metal powder materials with mixed organic and inorganic binders, and then firing the resulting molded article at a specific temperature according to the impregnation method of molten Al alloy or the like, a strong preform can be obtained that can be impregnated in a good manner by pressure or non-pressure methods with molten Al alloy or the like.

[0081] As the organic-inorganic binder used in this invention, silicone resins, silicon-organic derivatives such as Si alkoxides having a Si-OR (R: organic) chemical structure, or aluminum-organic derivatives such as aluminum alkoxides having an Al-OR (R: organic) chemical structure can be used. According to the researchers of the present invention, a strong molded article can be formed at room temperature by first using a mixture of metal powders containing the aforementioned organic-inorganic compounds as binders. Next, according to the researchers of the present invention, a preform is formed by calcining the obtained molded article at a temperature between 300°C and 800°C (below 800°C) where the metal powder will not be oxidized. Thus, although the organic components in the aforementioned molded article are removed by calcination, a strong metal powder molded article (preform) is obtained after calcination. The researchers of the present invention believe the reason for obtaining this effect is as follows. First, the aforementioned organic-inorganic compounds, when added to metal powder for molding, exhibit strength at room temperature as a so-called paste, similar to ordinary organic binders. Furthermore, if heated to above 300°C, the organic components of the organic-inorganic compound are burned off, and the inorganic components in the structure of the organic-inorganic compound function as an inorganic binder, thus making the preform obtained after calcination strong. That is, by calcining at a temperature above 300°C, the organic components in the aforementioned molded article are removed, and the inorganic components function as an inorganic binder, resulting in a metal powder molded body with a metal raw material content (volume fraction) of 55% or more. The effects obtained by using an organic-inorganic binder will be explained in more detail below.

[0082] As previously mentioned, conventional inorganic binders such as colloidal silica and colloidal alumina, if not calcined at temperatures above 1000°C, cannot contribute to the strength of the preform. On the other hand, the organic-inorganic binder used in this invention, after calcination at temperatures above 300°C, removes the organic components, leaving the residual SiO2 and Al2O3 components in an amorphous state bonded to the metal powder. Therefore, even at low temperatures around 300°C, the calcined preform exhibits strength. Furthermore, according to the researchers, even at high calcination temperatures below 800°C, the metal powder is not oxidized, thus enabling the manufacture of sufficiently strong preforms. Additionally, since the organic-inorganic binder described above decomposes and removes the organic components at 300°C, it is advantageous that no organic gases are generated during the impregnation of molten Al alloys, etc. The reasons for these effects are as follows. In other words, the organic and inorganic binders used in this invention, such as Si alkoxides, have a Si-OR (R: organic) molecular structure. Therefore, compared to conventional organic binders, even at temperatures of 300–800°C, the organic components are less prone to carbonization and residue, and are easily removed by combustion. Thus, they function as inorganic binders of SiO2 in the calcined molded body, resulting in improved strength of the preform. Furthermore, the inorganic and organic binders used in this invention can be used in organic solvents such as ethanol, IPA, and toluene, thus suppressing degradation caused by the reaction of metal powder with water.

[0083] As described above, in either the first or second invention of the present invention, the organic components are decomposed and removed at a relatively low temperature, resulting in a robust preform. This is an important factor for ensuring that molten Al alloys, etc., are properly impregnated into the obtained preform under high or no pressure, as described below. Specifically, in the case of high-pressure impregnation in the first invention, the preform is preheated at a temperature below 800°C, and then molten Al alloys, etc., at a temperature of 700°C to 800°C are impregnated into the preform under high pressure. The preform constituting the present invention exhibits sufficient strength even with such high-temperature molten liquids. Furthermore, in the present invention using a unique preform, since there are no generated gases that are difficult to remove from the interior of the preform, molten Al alloys, etc., can impregnate into the interior.

[0084] On the other hand, in the case of non-pressurized infiltration in the second invention of the present invention, a preform manufactured as described below is used. As previously described, in the second invention, the preform is constructed by mixing a predetermined amount of Mg-containing metal powder into it. These Mg-containing metal powders, such as metallic Mg powder or Mg-containing alloy powder, are oxidized to MgO at temperatures exceeding 500°C, therefore the preform needs to be calcined at a temperature below 500°C. Furthermore, according to the research of the present inventors, in addition to calcining the preform at a low temperature below 500°C, a desired amount of the organic-inorganic binder described above is added when mixing the metal powder material to obtain the molded article. This allows the manufacture of a robust preform in which the Mg-containing metal powder is not oxidized when the molded article is calcined, and the molten Al alloy does not deform during non-pressurized infiltration.

[0085] When the organic-inorganic binder used in this invention is in solid form, it can be added by dissolving it in organic solvents such as ethanol and IPA. Alternatively, in liquid form, it can be added directly or by diluting it with organic solvents such as ethanol and IPA. Ethanol, IPA, or other organic solvents can be added in appropriate amounts to facilitate mixing of the metal powder raw material and the organic-inorganic binder. Preferably, the organic-inorganic binder used in this invention is added in an amount equivalent to SiO2 and Al2O3, approximately 0.3 to 5.0 parts by mass relative to 100 parts by mass of the metal powder raw material. Adding amounts less than this range may result in insufficient strength of the preform and inadequate acquisition of the desired preform strength. Adding amounts exceeding this range result in a higher content of inorganic substances such as SiO2 and Al2O3 in the final aluminum composite, potentially failing to achieve the high metal content of the aluminum composite with high metal powder content desired by this invention, thus reducing product performance and is therefore not preferred.

[0086] (Manufacturing method of shaped objects)

[0087] In this invention, two or more metal powder materials with different average particle sizes are selected as metal raw materials for preforms. An organic-inorganic binder as listed above is added to the metal raw materials to obtain a mixture. The resulting mixture is then molded to obtain a molded article. The molded article is then fired at a specific temperature, thereby producing a high-strength preform. Specifically, a molded article is obtained by molding a metal powder mixture formed by mixing two or more metal powder materials with different average particle sizes and the aforementioned organic-inorganic binder.

[0088] The forming method for the molded article is not particularly limited, and examples include the following: Methods such as drying a metal powder mixture and then pressing it, or dry forming (CIP) to obtain a molded article; methods such as forming a slurry of the metal powder mixture using an organic solvent and then vibratory settling molding, or casting using a plaster mold to obtain a molded article; and so on. When forming a slurry of the metal powder mixture, it is preferable to reduce the amount of water used and to use an organic solvent to form the slurry. This is because if there is too much water, the metal powder may react with water, or the metal powder may deteriorate by changing into hydroxides, etc. For example, if the metal powder is silicon powder, the silicon may deteriorate if the following reaction occurs.

[0089]

[0090] Furthermore, when the metal powder is titanium powder, the following reaction occurs, potentially causing titanium to deteriorate. Specifically, titanium forms oxides due to the reaction Ti + 2H₂O → TiO₂ + 2H₂. Other metal powders also react with water to form oxides, therefore water is generally not preferred. To suppress this problem, organic solvents such as alcohols are used, or mixed solvents of water and hydrophilic organic solvents such as alcohols are used. In this case, to suppress the above-mentioned reaction, it is also preferable to reduce the water content in the mixed solvent. According to the researchers of the present invention, if the water content is 30 parts by mass or less relative to 100 parts by mass of the organic solvent, the above-mentioned reaction will not occur.

[0091] When a metal powder mixture is dried and then subjected to dry forming processes such as compression molding or CIP (Compact In-Place Molding), the aforementioned problems do not occur. The desired molded article can be easily obtained using compression molding, a common method for obtaining molded articles from powder materials. Furthermore, CIP molding allows for the homogenization of the density of the resulting molded article; therefore, obtaining the molded article using CIP molding is also preferred. For example, pre-forming using compression molding followed by CIP molding is also a preferred method.

[0092] (Cooking of the shaped object)

[0093] In this invention, the molded article obtained as described above is calcined to obtain a metal powder molded body (preform) with a high metal content. In this case, when molten Al alloy or the like is impregnated into the preform under a high pressure of 10 MPa to 200 MPa, it is calcined at a temperature of 300°C or higher and 800°C or lower. Alternatively, when molten Al alloy or the like is impregnated into the preform in a non-pressurized manner, it is calcined at a temperature of 500°C or lower, for example, 300°C or higher and 500°C or lower. First, by calcining the molded article at the above-mentioned temperatures, organic components such as organic and inorganic binders contained in the molded article are removed. If organic components remain in the molded article, when Al alloy or the like is impregnated into the molded article, the high-temperature molten Al alloy or the like comes into contact with the organic components and generates gas, which may hinder the impregnation of Al alloy or the like. Therefore, it is necessary to remove the organic components by calcination.

[0094] Furthermore, by firing the molded article at the aforementioned temperature to produce a preform, sufficient strength can be provided when the molten Al alloy or the like is impregnated into the preform under either high pressure or no pressure, as is the original objective of this invention. Additionally, as previously stated, the present invention allows for the manufacture of aluminum composites containing high-metal powder in a near-finish form, closely resembling the product shape, which significantly reduces processing costs and is therefore highly useful. To achieve this, it is necessary to ensure that the preform possesses machinable strength before impregnating the molten Al alloy or the like; therefore, firing the molded article to produce the preform is also crucial for achieving this.

[0095] The temperature conditions for obtaining a metal powder molded body (preform) with a high metal content vary depending on the method used in subsequent processes to impregnate the preform with molten Al alloy, etc., whether high-pressure impregnation or non-pressurized impregnation is performed. When obtaining a preform for high-pressure impregnation, the molten Al alloy, etc., is impregnated under a relatively high pressure of approximately 10 MPa to 100 MPa; therefore, the preform used needs to withstand this pressure. However, according to the present invention, if the calcination temperature is too high, the metal powder used as the raw material for the preform will oxidize; therefore, to suppress oxidation, calcination is required at a temperature below 800°C. Furthermore, to sufficiently remove organic components from organic-inorganic binders, etc., added to the metal powder, calcination is required at a temperature above 300°C. According to the present invention, when obtaining a preform for high-pressure impregnation, calcination is preferably performed at a temperature exceeding 500°C and below 800°C. More preferably, calcination can be performed at a temperature above 700°C and below 800°C.

[0096] According to the research of the inventors, when a preform for non-pressurized infiltration is obtained, stress is generated in the part of the preform that comes into contact with the molten Al alloy, etc., due to non-pressurized infiltration, thus requiring a preform strength capable of withstanding this. Therefore, similar to the preform for high-pressure infiltration, calcination is performed to remove organic components from the formed product and improve the strength of the obtained preform. However, in the case of non-pressurized infiltration, as previously explained, in order to allow the molten Al alloy, etc., to infiltrate in a good state under non-pressurization, the preform for infiltration needs to be in a state containing Mg-containing metal powder, such as the Mg metal powder previously explained. In contrast, for example, Mg metal powder reacts with oxygen in the air at temperatures above 500°C to form MgO, and the Mg content required for non-pressurized infiltration is insufficient. Therefore, it is necessary to carry out the process at a calcination temperature below 500°C. According to the research of the inventors, in the case of non-pressurized permeation, organic components can be fully removed by calcination at a temperature of 300°C or higher and 450°C or lower, and preforms with high metal content can be made strong enough to withstand non-pressurized permeation.

[0097] [Preparation of aluminum composites containing high levels of metal powder]

[0098] Next, the infiltration process of aluminum or the like when obtaining the aluminum composite containing high metal powder of the present invention will be described. In this process, molten Al alloy or the like is infiltrated or permeated into a preform with high metal content and excellent strength obtained by the structure described above. The high-pressure infiltration method and the non-pressurized infiltration method will be described below respectively.

[0099] (High-pressure impregnation method for isotropic Al alloy preforms)

[0100] Figures 1(A) to 1(C) A schematic diagram illustrating the concept of high-pressure impregnation is provided. As shown in Figure 1(A), a preform 1 with a high metal content is heated to 300°C to 800°C and filled into a preheated frame-type metal mold 3 of a press. The reason for filling the preform 1 in a preheated state is that if the temperature of the preform 1 is low when the molten Al alloy 2 is impregnated into the preform 1 under high pressure, the Al alloy 2 may cool and solidify during the high-pressure impregnation process, preventing it from penetrating into the interior of the preform 1. This problem is prevented. Similarly, to prevent the Al alloy 2 from cooling and solidifying during impregnation, the frame-type metal mold 3 can be heated (preheated) to 200°C to 400°C using a burner or the like.

[0101] Molten Al alloy 2, at 600°C to 800°C, is poured into a frame-shaped metal mold 3 containing the preform 1 as described above. As shown in Figures 1(B) and 1(C), a load is applied using an upper punch to stamp the material, isotropically penetrating the molten Al alloy 2 into the preform 1. The stamping pressure is between 10 MPa and 200 MPa. Pressures below 10 MPa are too low, and the molten Al alloy 2 may not penetrate the preform 1, which is therefore undesirable. Penetration can be performed at higher pressures exceeding 200 MPa, but a stamping pressure within the above range is sufficient for the apparatus used to obtain the composite of the present invention. The resulting stamped and infiltrated body is cooled, and the aluminum surrounding the preform is removed to form the aluminum composite containing high-metal powder as the objective of the present invention.

[0102] (Non-pressurized infiltration method for isotropic Al alloy preforms)

[0103] Figures 2(A) to 2(D) A conceptual diagram illustrating the non-pressurized percolation stage is shown below. First, a preform 1 with a high metal content, such as Mg metal powder, is prepared and loaded into an electric furnace (not shown) where a nitrogen atmosphere can be maintained, as described below. A small piece of the same material as the preform 1 is preferably placed at the lower part of the preform 1 as a percolation channel 4. Additionally, a solid Al alloy or similar material 2, which is supplied for percolation, is placed nearby without contacting the preform 1. The preform 1 and the Al alloy or similar material 2 are loaded into the electric furnace in a manner that prevents them from reacting with the components inside the furnace, as shown in Figure 2(A), while being placed inside a carbon container 5.

[0104] After the preform 1 and solid Al alloy 2 are prepared and loaded into the electric furnace as described above, the temperature is slowly increased while maintaining a nitrogen atmosphere inside the furnace, and held at 700-900°C for 2-5 hours. During this period, if... Figures 2(B) to 2(D) As shown in the schematic diagram in stages, the molten Al alloy 2 permeates into the preform 1 in a non-pressurized manner through the permeation channel 4 to obtain an aluminum composite containing high metal powder.

[0105] The following explanation uses Mg powder as an example of a case where the metal powder containing Mg is Mg. The principle behind obtaining an excellent aluminum composite with high metal powder content through non-pressurized infiltration as described above is as follows. It is believed that Mg reacts with nitrogen to form Mg3N2, which precipitates within the preform, improving wettability with Al alloys, etc.; or Mg reacts with thermite to reduce the surface oxides of the metal powder constituting the preform, further improving wettability between the metal powder and Al alloys, etc. As previously explained, in the prior art, the following method is used: a molded article obtained by pressing, etc., is used for non-pressurized infiltration without firing; in the case of non-pressurized infiltration of Al alloys, etc., a molded article without Mg powder is placed in a nitrogen atmosphere containing magnesium vapor to allow Al metal infiltration. However, according to the research of the present inventors, if this method is used, Mg vapor in the atmosphere reacts with nitrogen to form Mg3N2 on the surface of the preform. In this state, Al alloys, etc., infiltrate, thus requiring a long time for aluminum to permeate the entire preform. In addition, since Mg3N2 is not uniformly generated on the surface of the preform, the uneven penetration of Al alloys and other materials may result in uneven infiltration into the entire preform.

[0106] According to the technology of the present invention, unlike the prior art described above, Mg powder can be uniformly mixed within the preform, thus Mg3N2 is formed throughout the preform. Therefore, the impregnation rate of Al alloys, etc., increases dramatically while uniformly impregnating the entire preform. Furthermore, by utilizing non-pressurized impregnation, Al alloys, etc., can be directly impregnated in the shape of the preform, thus offering the significant advantage of reducing secondary processing, allowing for the near-finished manufacturing of aluminum composites containing high levels of metal powder in a manner close to the product shape.

[0107] [Example]

[0108] The following examples and comparative examples illustrate further specific embodiments of the aforementioned one implementation method, but the present invention is not limited to these examples. In this document, w% refers to a mass basis, and v% refers to a volume basis. The average particle size in this specification is a value measured using a laser diffraction particle size distribution analyzer.

[0109] [Example 1] (Using high-pressure impregnation method)

[0110] First, a metal powder molded body (preform) with a high metal content is prepared through the following steps. In this embodiment, to prepare the preform, three types of silicon powder with different average particle sizes are combined and mixed as follows. Specifically, a mixture of 1820g of silicon powder with an average particle size of 45μm, 780g of silicon powder with an average particle size of 25μm, and 100g of silicon powder with an average particle size of 5μm, totaling 2700g, is prepared. 130g of ethyl silicate, containing 40w% silicon (SiO2 equivalent) as an organic-inorganic binder, is added to this mixture, and the mixture is further stirred for 15 minutes using a mixer to obtain the mixed powder used in this embodiment.

[0111] The total amount of the mixed powder obtained above is added into a pressing metal mold with an inner size of 200mm × 200mm × 150mm (depth), and pressed at 300kg / cm². 2 The material was pressed at a total pressure of 120t. The resulting pressed part was then placed in an electric furnace and heated to 700°C at a rate of 50°C / hr. This temperature was maintained for 3 hours, and then cooled to room temperature to produce a silicon metal preform. The weight and dimensions of the preform were measured, and the bulk density was calculated, resulting in a silicon preform with a volume filler content (Vf) of 77%.

[0112] The preform obtained above is preheated to 500°C in an electric furnace. The preheated preform is then loaded into a 300mm x 250mm deep frame-shaped metal mold heated to 250°C by a burner in a high-pressure impregnation press. Molten aluminum alloy (AC4C) at 750°C is added to the frame-shaped metal mold up to approximately 20mm above the mold. A punch is then inserted into the frame-shaped metal mold from above, and the mold is held at a pressure of 100MPa for 10 minutes, allowing the molten aluminum to be high-pressure impregnated into the previously obtained silicon preform (see reference). Figures 1(A) to 1(C) ).

[0113] After cooling, the aluminum surrounding the aforementioned preform is removed by machining, and the silicon-aluminum composite product section is taken out. This product section is a silicon-aluminum composite (hereinafter also referred to as silicon-aluminum composite) uniformly impregnated with aluminum, free of small pores (pores) and cracks. The bulk density was calculated by weight and dimensional measurements, resulting in a silicon-aluminum composite of 78 vol% silicon and 22 vol% aluminum alloy.

[0114] [Example 2] (Using non-pressurized osmosis)

[0115] The high-metal-content metal powder molded body (preform) used in this embodiment is prepared by the following steps: 50g of Mg powder with an average particle size of 80μm is added to a total of 2700g of three different silicon powders weighed in the same manner as the mixture used in Example 1. Then, 130g of ethyl silicate is added to the mixture in the same manner as in Example 1, and the mixture is stirred for 10 minutes using a mixer.

[0116] The total amount of the mixed powder obtained above is added into a pressing metal mold with an inner size of 200mm × 200mm × 150mm (depth), and pressed at 150kg / cm². 2 A total pressure of 60t was applied for pressing. The pressed product was removed from the metal mold and placed in a conventional air-atmosphere electric furnace, heated to 450°C at a rate of 50°C / hr, held at this temperature for 3 hours, and then cooled to produce a preform. The bulk density was calculated in the same manner as in Example 1, resulting in a volume filler ratio (Vf) of 73%.

[0117] The preforms obtained above are used to become Figures 2(A) to 2(D) The carbon container 5 is arranged in a manner schematically shown in the "non-pressurized permeation principle diagram". Specifically, four permeation channels 4, each 30mm × 30mm × 30mm in size and made of the same material as the preform 1, are placed in a grounded state under the preform 1. 2500g of solid aluminum alloy (AC4A) 2 is then placed next to the preform 1. Next, the carbon container 5, with the preform 1 and the like arranged as described above, is placed entirely into a nitrogen atmosphere furnace, heated at 50°C / hr, held at 800°C for 5 hours, and then cooled.

[0118] After cooling, the infiltration channel 4 was removed, and the surface and interior of the preform 6 after infiltration were processed and observed. The results confirmed that the silicon-aluminum composite was in a state where aluminum was completely infiltrated into the preform. The bulk density calculated from the measured values ​​of the weight and shape of the obtained silicon-aluminum composite showed that the composite was a silicon-aluminum composite with 73% silicon and 26% aluminum alloy, and was free of pores and cracks.

[0119] [Example 3] (Using high-pressure impregnation method)

[0120] The high metal content metal powder molded body (preform) used in this embodiment was prepared by the following steps. A mixture of three silicon powders with different average particle sizes, totaling 2700g, was prepared by mixing 1820g of silicon powder with an average particle size of 80μm, 780g of silicon powder with an average particle size of 25μm, and 100g of silicon powder with an average particle size of 3μm. 180g of an isopropanol solution containing silicone resin (Shin-Etsu Chemical Co., Ltd., trade name: KR-220L) dissolved in the mixture at a concentration of 30 wt% was added. After stirring for 15 minutes, the total volume was filled into a metal mold in the same manner as in Example 1, and pressed under the same conditions as in Example 1. The resulting pressed product was then placed in an electric furnace and heated to 750°C at a heating rate of 70°C / hr, and calcined at this temperature to obtain a preform with a volume filler of 78 wt%. It should be noted that the volume filler was obtained in the same manner as in Example 1.

[0121] The molten aluminum alloy was impregnated into the preform obtained above using a high-pressure impregnation press under the same conditions and steps as in Example 1. After cooling, the surrounding aluminum was removed, the product was taken out, and its weight and shape were measured to calculate the bulk density. The results confirmed that the obtained composite was a silicon-aluminum composite with 78% silicon and 22% aluminum alloy, and was free of pores (gases) and cracks.

[0122] [Example 4] (Using non-pressurized osmosis method)

[0123] The high-metal-content metal powder molded body (preform) used in this embodiment is manufactured through the following steps. A preform containing Mg powder and with a shape of 200mm × 200mm × 40mm, manufactured using the same steps as in Example 2, is machined using a milling cutter. Specifically, a preform with a rib-like structure in which four cavities of 75mm × 75mm × 25mm (depth) are evenly arranged in the preform obtained above is obtained. The resulting preform is a robust preform with strength sufficient for machining.

[0124] Using the preform obtained above, non-pressurized permeation of aluminum alloy (AC4A) was performed through a permeation channel disposed beneath the preform within a carbon container, similar to Example 2. Then, as in Example 2, the permeation channel was removed, and the bulk density was measured. The results confirmed the formation of a silicon-aluminum composite with 73 vol% silicon and 27 vol% aluminum alloy, free from pores and cracks. Furthermore, no aluminum alloy exudation occurred within the cavity, allowing the silicon-aluminum composite to be manufactured in a near-finished manner while still retaining the shape of the preform.

[0125] [Example 5] (Using high-pressure impregnation method)

[0126] The high-metal-content metal powder molded body (preform) used in this embodiment is prepared by the following steps: 1400g of iron powder with an average particle size of 80μm and 600g of iron powder with an average particle size of 10μm are added to 80g of ethyl silicate containing 40w% silicon (SiO2 equivalent), and the mixture is stirred for 15 minutes. This mixed powder is then added to a metal mold with internal dimensions of 200mm × 200mm × 150mm (depth) and pressed at 150kg / cm². 2 The powder was pressed into shape under a total pressure of 60t. The pressed product was then placed in an electric furnace and heated to 700°C at a rate of 50°C / hr, held at that temperature for 3 hours, and then cooled to room temperature to produce a preform of ferrous metal. The weight and dimensions of the obtained preform were measured, and the bulk density was calculated, resulting in a preform of ferrous powder with a volume filler content (Vf) of 73%.

[0127] The preform obtained above is preheated to 500°C in an electric furnace and then filled into a 300mm Φ×250mm deep frame-shaped metal mold heated to 250°C by a burner in a high-pressure impregnation press for high-pressure impregnation. Molten aluminum alloy (AC4C) at 750°C is added to the frame-shaped metal mold up to approximately 20mm above the mold. A punch is then inserted into the mold from above, and the mold is impregnated under a pressure of 100MPa for 10 minutes.

[0128] After cooling, the surrounding aluminum is removed, and the product section of the iron-aluminum alloy composite (hereinafter also referred to as the iron-aluminum composite) is taken out. This product section is an iron-aluminum composite made of a preform with uniform aluminum impregnation into iron powder, free of small pores (pores) and cracks. The bulk density is calculated by weight and dimensional measurement, and the result is an iron-aluminum composite with 73 vol% iron and 27 vol% aluminum alloy.

[0129] [Comparative Example 1] (Using high-pressure impregnation method without adhesive)

[0130] The same silicon powder mixture and weight as in Example 1 were added as powder to a 200mm×200mm×100mm iron box without the addition of silicone resin, ethyl silicate, or other binders. The box was then placed on a vibratory mixer and vibrated for 20 minutes to fill the box. The box was then subjected to high-pressure aluminum impregnation, just as in Example 1. After cooling, the composite was cut out.

[0131] Observation of the machined surface of the cut composite revealed numerous striped aluminum defects. This is believed to be due to cracking of the metal powder filler during high-pressure infiltration, into which the aluminum alloy penetrates. The uncracked portion was cut out, and its bulk density was calculated. The silicon filling rate was found to be 62 v%, lower than that of the preform in Example 1. These results indicate that when silicon powder particles are directly filled, the silicon filling rate is low, and the strength of the silicon filler phase is insufficient. During high-pressure infiltration of the molten aluminum, the filler phase cracks, resulting in aluminum infiltration defects.

[0132] [Comparative Example 2] (Precast parts are made by compression molding without the use of adhesives)

[0133] Tetraethyl silicate was not added to the same mixture and weight of the silicon mixed powder as in Example 1, and the same compression molding process was performed using the mixed powder. However, the resulting molded body lacked strength, distorted upon removal from the metal mold, and could not be used to produce preforms suitable for composite manufacturing. The above results indicate that when using silicon mixed powder materials for compression molding, a binder must be added to the powder material.

[0134] [Comparative Example 3] (Precast components are produced by sedimentation molding without the use of adhesives)

[0135] Using the same formulation and weight of silicon mixed powder as in Example 3, without adding binders such as silicone resin or ethyl silicate, a slurry was prepared, and sedimentation molding was performed using this slurry. After drying, the resulting molded body lacked strength and was so fragile that it immediately crumbled when touched. Furthermore, heating a portion of the molded body to 700°C in the same manner as in Example 1 resulted in almost no strength; it was so fragile that it immediately crumbled, making it unsuitable for high-pressure impregnation or non-pressurized infiltration.

[0136] [Comparative Example 4] (Preforms were made using organic binders, through compression molding, and firing)

[0137] For the silicon mixed powder of Example 1, an ethanol solution of polyvinyl butyral (hereinafter referred to as PVB) with a solid content of 20 wt% was added relative to the silicon mixed powder at a ratio of 2 wt% PVB formation. The resulting molded article was then formed by compression molding using the same procedure as in Example 1. The molded article was calcined at 750°C, and the result was so fragile that it deformed upon touch. This is believed to be because the PVB, which functions as a binder for the silicon mixed powder at room temperature, burned off during calcination. The above results confirm that organic binders can be used to maintain the shape of compressed molded articles, but the strength of the preform cannot be maintained due to subsequent calcination processes.

[0138] [Comparative Example 5] (Preforms were made using organic-inorganic binders and calcined at 850°C)

[0139] An equal amount of ethyl silicate, an organic-inorganic binder, was added to a mixture of three silicon powders with different average particle sizes used in Example 1. The mixture was stirred to produce a silicon mixed powder. Using the same amount of silicon mixed powder, the powder was pressed into shape using the same method as in Example 1. The resulting pressed product was placed in an electric furnace and heated to 850°C at a heating rate of 50°C / hr. It was then held at this temperature for 3 hours for calcination and then cooled to room temperature to produce a silicon preform.

[0140] Observing the surface of the calcined body obtained above, it was found that silicon was oxidized to form SiO2, which turned white. In addition, the silicon increased in volume as it formed SiO2, thus generating stress on the surface and creating tiny cracks, making it impossible to obtain a defect-free preform.

[0141] [Comparative Example 6] (Preforms were prepared by calcining Mg powder and organic-inorganic binders at 570°C using a non-pressurized infiltration method)

[0142] Mg powder with an average particle size of 80 μm was added to three types of silicon powder with different average particle sizes, similar to those used in Example 2. Ethyl silicate was added to the mixture, and the mixture was stirred to obtain a final product. The final product was then pressed and shaped in the same manner as in Example 2 to obtain a pressed article. The pressed article was then calcined at 570°C for 3 hours to remove excess oil and produce a preform (calcined body).

[0143] The preform (calcined body) obtained above was then subjected to non-pressurized infiltration using the same method as in Example 2, through molten aluminum alloy. However, the aluminum alloy did not infiltrate the preform (calcined body) in a non-pressurized manner. The reason for this is believed to be that the Mg added to the pressed product during calcination at 570°C oxidizes and forms MgO, thus failing to contribute to non-pressurized infiltration.

[0144] [Comparative Examples 7-9] (Preforms were fabricated using silicon powder of each average particle size alone)

[0145] 2700g of silicon powders with average particle sizes of 45μm, 25μm, and 5μm, used individually in the silicon powder mixture of Example 1, were pressed and molded using the same steps as in Example 1, and the pressed articles were then calcined to produce preforms. The volume fill rate (Vf) of the preforms obtained using only the silicon powders with average particle sizes of 45μm, 25μm, and 5μm was calculated in the same manner as in Example 1. The results showed that the fill rate was 50v% for the preform using 45μm silicon powder, 52v% for the preform using 25μm silicon powder, and 53v% for the preform using 5μm silicon powder. Compared to the preforms of the Examples, the fill rate of any preform obtained by using silicon powders with different average particle sizes individually was found to be lower. This indicates that to produce preforms with high fill rates, it is necessary to mix and use metal powders such as silicon with different average particle sizes.

[0146] Table 1 summarizes the manufacturing conditions of the preforms, the impregnation methods of Al alloys, etc., and the properties of the resulting aluminum composites containing high metal powders in the examples and comparative examples.

[0147] Table 1: Manufacturing conditions and properties of the resulting composite materials in the examples and comparative examples

[0148]

[0149] Explanation of reference numerals in the attached figures

[0150] 1: Precast components

[0151] 2: Al alloys, etc.

[0152] 3: Frame-type metal mold

[0153] 4: Infiltration Channel

[0154] 5: Carbon-based containers

[0155] 6: Precast components after impregnation

Claims

1. A method for manufacturing an aluminum composite containing high levels of metal powder, characterized in that, It includes: a preform fabrication process to obtain a metal powder molded body with a high metal content, i.e., a preform; and an aluminum or aluminum alloy infiltration process to infiltrate or penetrate molten aluminum or aluminum alloy into the obtained preform. In the preform manufacturing process, two or more metal powder materials with different average particle sizes are selected from metal powder materials with an average particle size of 1 μm or more and 200 μm or less as metal raw materials for the preform. A mixed liquid organic-inorganic binder selected from the group consisting of Si alkoxides having a Si-OR structure and Al alkoxides having an Al-OR structure is added to the metal raw materials to obtain a mixture. The mixture is then used to form a molded article, which is calcined at a temperature of 300°C or higher and 800°C or lower. This removes the organic components from the molded article, and the inorganic components function as an inorganic binder, resulting in a metal powder molded body with a metal raw material content of 55 vol% or more, where R represents organic matter. In the aluminum or aluminum alloy impregnation process, molten aluminum or aluminum alloy is impregnated into the metal powder molded body obtained through the preform manufacturing process under a high pressure of 10MPa to 200MPa. The two or more metal powders with different average particle sizes contain at least metal powder A with an average particle size of less than 10 μm and metal powder B with an average particle size of more than 40 μm. Based on mass, the total amount of metal powder contains at least 3% metal powder A and at least 50% metal powder B. The metal powder is at least one selected from the group consisting of silicon powder, silicon-aluminum alloy powder, silicon-iron alloy powder, iron powder, iron-containing iron alloy powder, titanium powder, nickel powder, and nickel-containing nickel alloy powder.

2. A method for manufacturing an aluminum composite containing high levels of metal powder, characterized in that, It includes: a preform fabrication process to obtain a metal powder molded body with a high metal content, i.e., a preform; and an aluminum or aluminum alloy infiltration process to infiltrate or penetrate molten aluminum or aluminum alloy into the obtained preform. In the preform manufacturing process, two or more metal powder materials with different average particle sizes are selected from metal powder materials with an average particle size of 1 μm or more and 200 μm or less as metal raw materials for the preform. The two or more metal powders with different average particle sizes contain at least metal powder A with an average particle size of less than 10 μm and metal powder B with an average particle size of more than 40 μm. Based on mass, the total amount of metal powder contains at least 3% metal powder A and at least 50% metal powder B. The metal powder is at least one selected from the group consisting of silicon powder, silicon-aluminum alloy powder, silicon-iron alloy powder, iron powder, iron-containing iron alloy powder, titanium powder, nickel powder, and nickel-containing nickel alloy powder. Relative to 100 parts by mass of the metal raw material, one or more powders selected from the group consisting of Mg powder, AlMg powder, ZnMg powder, ZnAl powder, and Mg2Si powder are added in an amount ranging from 0.2 to 5 parts by mass. Further, at least one organic-inorganic binder selected from the group consisting of Si alkoxides having a Si-OR structure and Al alkoxides having an Al-OR structure is added in a mixed liquid state to obtain a mixture. The mixture is then molded, and the resulting molded article is calcined at a temperature of 300°C to 500°C, thereby removing the organic components from the molded article and allowing the inorganic components to function as an inorganic binder, resulting in a metal powder molded article with a metal raw material content of 55 vol% or more, where R represents organic matter. In the aluminum or aluminum alloy impregnation process, aluminum or aluminum alloy is impregnated into the metal powder molded body obtained through the preform manufacturing process in a nitrogen atmosphere without pressure.

3. The method for manufacturing an aluminum composite containing high levels of metal powder according to claim 1, wherein, The content is 55% or more and 85% or less by volume.

4. The method for manufacturing an aluminum composite containing high levels of metal powder according to claim 2, wherein, The content is 55% or more and 85% or less by volume.

5. A method for manufacturing a precast component, characterized in that, It is used to obtain a metal powder molded body, i.e. a preform, with a high metal powder content when molten aluminum or aluminum alloy is impregnated under high pressure to obtain an aluminum composite metal containing high metal powder. Select two or more metal powder materials with different average particle sizes from those with an average particle size of 1 μm or more and 200 μm or less, as the metal raw materials for the preform. The two or more metal powder materials with different average particle sizes contain at least metal powder A with an average particle size of less than 10 μm and metal powder B with an average particle size of more than 40 μm. Based on mass, the total amount of metal powder contains at least 3% metal powder A and at least 50% metal powder B. The metal powder is at least one selected from the group consisting of silicon powder, silicon-aluminum alloy powder, silicon-iron alloy powder, iron powder, iron-containing iron alloy powder, titanium powder, nickel powder, and nickel-containing nickel alloy powder. A mixture of at least one organic-inorganic binder selected from the group consisting of Si alkoxides having a Si-OR structure and Al alkoxides having an Al-OR structure is added to the metal raw material to obtain a mixture. The mixture is then used to form a molded article, which is then calcined at a temperature of 300°C or higher and 800°C or lower to obtain a metal powder molded article with a metal raw material content of 55% or higher by volume, wherein R represents an organic compound.

6. A method for manufacturing a precast component, characterized in that, It is used to obtain a metal powder molded body, i.e. a preform, with a high metal powder content when molten aluminum or aluminum alloy is non-pressurized infiltrated in a nitrogen atmosphere to obtain an aluminum composite metal containing high metal powder. Select two or more metal powder materials with different average particle sizes from those with an average particle size of 1 μm or more and 200 μm or less, as the metal raw materials for the preform. The two or more metal powder materials with different average particle sizes contain at least metal powder A with an average particle size of less than 10 μm and metal powder B with an average particle size of more than 40 μm. Based on mass, the total amount of metal powder contains at least 3% metal powder A and at least 50% metal powder B. The metal powder is at least one selected from the group consisting of silicon powder, silicon-aluminum alloy powder, silicon-iron alloy powder, iron powder, iron-containing iron alloy powder, titanium powder, nickel powder, and nickel-containing nickel alloy powder. Relative to 100 parts by mass of the metal raw material, one or more powders selected from the group consisting of Mg powder, AlMg powder, ZnMg powder, ZnAl powder and Mg2Si powder are added in an amount ranging from 0.2 to 5 parts by mass. Further, at least one organic-inorganic binder selected from the group consisting of Si alkoxides having a Si-OR structure and Al alkoxides having an Al-OR structure is added in a mixed liquid state to obtain a mixture. The mixture is then used to form a molded article, and the molded article is calcined at a temperature of 300°C or higher and 500°C or lower to obtain a metal powder molded article in which the content of the metal raw material is 55% or higher by volume, wherein R represents an organic compound.

7. An aluminum composite containing high levels of metal powder, characterized in that, It is an aluminum composite containing high metal powder, which is obtained by the manufacturing method of aluminum composite containing high metal powder by high pressure impregnation as described in claim 1 or 3.

8. An aluminum composite containing high levels of metal powder, characterized in that, It is a near-finished aluminum composite containing high-metal powder in a manner close to the product shape, obtained by the manufacturing method of aluminum composite containing high-metal powder in a nitrogen atmosphere by non-pressurized infiltration as described in claim 2 or 4.

Images