Manufacturing method of metal matrix composite material and manufacturing method of preform

Abstract

A method for dramatically improving the penetration of a molten solution of an Al alloy or the like into a preform obtained by molding / hardening ceramic powder under non-pressure conditions. Regarding the technology of "metal matrix composites containing ceramic powder and Al alloy or the like" for more simply and stably obtaining an overall uniform state, there is provided "a method for manufacturing a metal matrix composite and a method for manufacturing the following preform. In this manufacturing method, a mixture containing magnesium-containing powder and ceramic powder and further containing any one of an inorganic binder or an organic-inorganic binder that hardens by heating at 500 °C or lower is molded to obtain a mixture, and the mixture is calcined at a temperature of 500 °C or lower to manufacture a preform, and an Al alloy or the like is infiltrated into the obtained preform in a non-pressure manner to manufacture a metal matrix composite containing aluminum and ceramic".

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a composite material for obtaining a metal matrix composite material containing ceramic powder and metallic aluminum (Al) or an Al alloy, and a method for manufacturing a preform that can be used in this manufacturing method. Specifically, it relates to a technology that can dramatically improve productivity and quality for a metal-ceramic composite material obtained by compositing ceramic powder as a reinforcing material in an aluminum-based metal matrix. Background Art

[0002] In recent years, aluminum-based metal matrix composite materials obtained by compositing ceramics such as Al alloys have been widely used as mechanical components such as semiconductor liquid crystal manufacturing devices and robotic arms due to their light weight, high strength, and high rigidity. In addition, as high thermal conductivity and low thermal expansion materials, they are widely used in heat sinks, heat dissipation diffusers, etc.

[0003] A composite material containing ceramic powder and an Al alloy, etc. is a type of so-called MMC (Metal Matrix Composites), and is usually manufactured by methods such as high-pressure infiltration method, casting method, non-pressure infiltration method, etc.

[0004] The high-pressure infiltration method is a method of forcibly infiltrating a melt of an Al alloy, etc. into ceramic powder or a formed body (preform) of ceramic powder by high-pressure pressing to composite the ceramic powder and the Al alloy, etc. Since the high-pressure infiltration method infiltrates a molten Al alloy, etc. using high pressure, it requires expensive devices such as a press. Furthermore, when using a normal method, it is not possible to infiltrate in the product shape, so it is necessary to remove the product by processing from the pressure-infiltrated product surrounded by the Al alloy, etc., and there is a problem of incurring processing costs for forming the product shape.

[0005] When using the casting method, ceramic powder such as silicon carbide or alumina is vigorously stirred in a melt of an Al alloy, etc. to produce an Al alloy melt containing the ceramic powder, and the composite of the ceramic and the Al alloy, etc. is manufactured by casting in a commonly used mold such as a sand mold, a metal mold, or a lost wax mold. When using this method, since the fluidity of the melt deteriorates as the content of the ceramic powder in the metal matrix increases, the content of the ceramic powder in the composite is usually limited to 30 v%, and there is a problem of a low content rate of the ceramic in the composite.

[0006] The non-pressure infiltration method is a method of obtaining a composite by infiltrating a melt of an Al alloy or the like into a packed body or a formed body (preform) of ceramic powder, such as an infiltration into a preform, etc., in an atmosphere of Mg and nitrogen under non-pressure. For example, a packed body of ceramic powder such as SiC, alumina, etc., or a preform is obtained by adding an inorganic binder such as silica to ceramic powder, molding, and firing. For this preform, in an atmosphere of nitrogen and Mg evaporation, at a temperature of about 700 °C or higher at which the Al alloy or the like melts, under non-pressure, the melt of the Al alloy or the like is infiltrated into the gaps between the ceramic powders to manufacture a composite of ceramic powder and Al alloy or the like. The principle of this non-pressure infiltration method is that by forming an atmosphere of Mg and nitrogen, the wettability between the ceramic and the Al alloy or the like is improved, and the so-called capillary phenomenon is promoted, so that the melt of the Al alloy or the like is infiltrated into the gaps (voids) of the packed body and the preform under non-pressure.

[0007] When using the non-pressure infiltration method, by increasing the ceramic filling rate and reducing the voids, the filling rate of the ceramic in the composite can be increased, and a composite (MMC) of ceramic and Al alloy with high physical property values such as Young's modulus, thermal conductivity, and coefficient of thermal expansion can be manufactured. In addition, when using a preform for manufacturing, the Al alloy can still be infiltrated in the shape of the preform. Therefore, it has attracted attention as a method for manufacturing MMC composites in a near-net shape close to the product shape without large processing.

[0008] Various studies have been conducted on the non-pressure infiltration method. For example, Patent Document 1 proposes that when manufacturing a metal matrix composite by infiltrating a molten Al alloy into a permeable material using a ceramic filler material by natural infiltration, the Al alloy contains at least 3% by weight of magnesium. In addition, since the Al alloy containing magnesium wets the ceramic, good bonding between the metal and the ceramic is expected.

[0009] In addition, Patent Document 2 proposes that when a source of matrix metal is substantially adjacently disposed to a non-reactive filler and the matrix metal spontaneously infiltrates into the filler, there is a penetration promoter precursor. Among them, when the infiltration atmosphere contains nitrogen, a substance selected from calcium, magnesium, and strontium is used as the penetration promoter precursor. Thus, by providing such a penetration promoter to the spontaneous system, spontaneous infiltration can be performed.

[0010] Prior Art Documents

[0011] Patent Documents

[0012] Patent Document 1: Japanese Patent Publication No. 2641901

[0013] Patent Document 2: Japanese Patent Publication No. 2930991 Summary of the Invention

[0014] Problems to be Solved by the Invention

[0015] In the above prior art, the present inventors have focused on a non-pressure infiltration method that can increase the content rate of ceramic powder in a composite without using expensive devices such as a press used in the high-pressure infiltration method, and can manufacture a metal matrix composite (MMC composite) in a near-net shape close to the product shape. It is recognized that if this manufacturing method can be made more excellent, the further utilization of "metal matrix composites containing ceramic powder and Al alloy, etc." can be promoted.

[0016] Therefore, an object of the present invention is to particularly improve by leaps and bounds a method of infiltrating a melt of metallic Al or an Al alloy (such as an Al alloy) into a preform obtained by molding / hardening ceramic powder under non-pressure, and to develop an improved technique for a non-pressure infiltration method that can more simply and stably provide an overall uniform state of "metal matrix composites containing ceramic powder and Al alloy, etc.". For the object of the present invention, among them, by using a simple method of molding a mixture containing ceramic powder, roasting, and hardening (curing) the obtained molded product, a manufacturing technique for a preform applicable to the non-pressure infiltration method and capable of manufacturing a metal matrix composite more effectively than conventional methods is provided.

[0017] Solution to the problem

[0018] The above object is achieved by the following method for manufacturing a composite material. That is, the present invention provides the following method for manufacturing a composite material containing a metal matrix composite of an Al alloy, etc. and ceramic.

[0019] [1] A method for manufacturing a composite material, characterized in that an organic solvent, or a mixed solvent of an organic solvent with reduced water content and water is further added to a mixture containing a magnesium-containing powder and a ceramic powder, and further containing any one binder of an inorganic binder or an organic-inorganic binder that hardens by heating at 500°C or lower, to obtain a mixture, the obtained mixture is used for molding to obtain a molded body, the molded body is roasted at a temperature of 500°C or lower to produce a preform, and metallic aluminum or an aluminum alloy is infiltrated into the obtained preform under non-pressure in a nitrogen atmosphere to manufacture a metal matrix composite containing aluminum and ceramic.

[0020] As a preferred embodiment of the method for manufacturing the composite material of the present invention described above, the following can be cited.

[0021] [2] The method for manufacturing a composite material according to the above [1], wherein the magnesium-containing powder is at least any one selected from the group consisting of metallic magnesium, magnesium alloy, and magnesium silicide, and has an average particle size of 0.5 μm or more and 150 μm or less.

[0022] [3] The manufacturing method of the composite material according to [1] or [2] above, wherein, in the aforementioned mixture, based on 100 parts by mass of the aforementioned ceramic powder, the aforementioned magnesium-containing powder is contained in a range of 0.3% or more and 10% or less in terms of magnesium conversion by mass.

[0023] [4] The manufacturing method of the composite material according to any one of [1] to [3] above, wherein the aforementioned inorganic binder is water glass, and the aforementioned organic-inorganic binder is any one selected from the group consisting of silicone resins, Si alkoxides, and Al alkoxides.

[0024] [5] The manufacturing method of the composite material according to any one of [1] to [4] above, wherein the aforementioned mixed solvent with reduced water content contains water in a range of 100 parts by mass or less relative to 100 parts by mass of the organic solvent.

[0025] In addition, as another embodiment of the present invention, a manufacturing method of the following preform is provided.

[0026] [6] A manufacturing method of a preform, characterized in that it is used to manufacture a ceramic preform applicable to the manufacture of an aluminum-based metal matrix composite material using the non-pressure infiltration method. A mixture containing a magnesium-containing powder, a ceramic powder, and also containing any one binder of an inorganic binder or an organic-inorganic binder that hardens by heating at 500°C or lower is further added with an organic solvent, or a mixed solvent of an organic solvent with reduced water content and water to obtain a mixture. The obtained mixture is molded to obtain a mixed body, and the obtained mixed body is calcined at a temperature of 500°C or lower to obtain a preform. Preferably, the aforementioned mixed solvent with reduced water content contains water in a range of 100 parts by mass or less relative to 100 parts by mass of the organic solvent.

[0027] Effects of the Invention

[0028] According to the present invention, particularly, the manufacturing method of a composite material in which a melt such as an Al alloy penetrates into a preform obtained by molding / hardening a ceramic powder under non-pressure is remarkably improved, and a technology can be provided to more simply and stably provide a "metal matrix composite material containing a ceramic powder and an Al alloy, etc." that is uniformly integrated. According to the present invention, a novel preform manufacturing technology is provided by a simple method of molding a mixture containing a ceramic powder, firing, and hardening (curing) the obtained molded product, which can be applied to the non-pressure infiltration method and thereby effectively and stably manufacture a metal matrix composite material in a good state. Description of the Drawings

[0029] Figure 1 It is a schematic diagram for explaining the arrangement state inside a container used in the non-pressure infiltration method used in the manufacturing method of the composite material of the present invention.

[0030] Figure 2(a) is the first schematic diagram for explaining the state before the molten metal penetrates and infiltrates into the preform by the non-pressure infiltration method carried out in the manufacturing method of the composite material of the present invention.

[0031] Figure 2(b) is the second schematic diagram for explaining the state where the molten metal begins to penetrate and infiltrate into the preform by the non-pressure infiltration method carried out in the manufacturing method of the composite material of the present invention.

[0032] Figure 2(c) is the third schematic diagram for explaining the state where the penetration and infiltration of the molten metal into the preform progress by the non-pressure infiltration method carried out in the manufacturing method of the composite material of the present invention.

[0033] Figure 2(d) is the fourth schematic diagram for explaining the state where the molten metal has penetrated and infiltrated into the entire preform by the non-pressure infiltration method carried out in the manufacturing method of the composite material of the present invention. Detailed Embodiments

[0034] The preferred embodiments of the present invention will be described below, but the present invention is not limited by these embodiments.

[0035] First, a summary of the usual sequence of the conventional non-pressure infiltration method using a preform for manufacturing a metal matrix composite material (hereinafter also simply referred to as a composite material or a composite) containing ceramic powder and Al alloy, etc., studied in the present invention, will be described. First, an organic binder such as polyvinyl alcohol and polyvinyl butyral is added to the ceramic powder, and an inorganic binder such as colloidal silica and colloidal alumina is added as needed to prepare a mixed raw material. Then, the above mixed raw material is formed by methods such as press molding, casting molding, extrusion molding, and vibration method to obtain a mixture. Then, the obtained mixture is calcined at a temperature of about 800°C to 1200°C to produce a preform.

[0036] Using the preform obtained as described above, a metal matrix composite material is manufactured by the non-pressure infiltration method as follows. As Figure 1 shown in FIG. 2(a), the preform 1 and the Al alloy 4, etc. are arranged in a container 3 made of carbon or the like, and this container 3 is placed in a box furnace (not shown) into which metal Mg powder is inserted. Nitrogen is circulated into this box furnace, and it is heated to form a temperature of about 700°C or more. While evaporating the Mg arranged in the box furnace, the state of the nitrogen atmosphere is formed and maintained in the box furnace. Thus, as Figures 2(b) to 2(d) shown, the Al alloy 4, etc. melts by heating, and the molten liquid penetrates into the gaps of the preform 1 through the penetration channels 2, and an MMC composite 5 in which the Al alloy 4, etc. is infiltrated into the preform 1 is obtained.

[0037] The principle of the non-pressure infiltration method used in manufacturing the MMC composite is described below. In an atmosphere where molten Al alloy or the like is infiltrated into the above-mentioned preform, Mg powder evaporates and reacts with nitrogen to form Mg3N2. The formed Mg3N2 deposits on the surface of the ceramic powder of the preform in a container placed in a box furnace. The wettability of the ceramic powder with the melt of Al alloy or the like is generally poor. However, if Mg3N2 is present on the surface of the ceramic powder, the wettability improves dramatically. As a result, the melt of Al alloy or the like is wetted by the ceramic powder constituting the preform and infiltrates into the gaps (voids) of the ceramic powder constituting the preform by capillary action without pressure. In addition, the formed Mg3N2 reacts with aluminum metal to produce the reaction of Mg3N2 + Al → Mg + AlN, and an ultra-thin AlN phase is formed on the ceramic surface. This AlN phase also improves the wettability of the melt of Al alloy. The Mg vapor generated by this reaction penetrates into the interior of the preform, repeats the same reaction, and the molten Al alloy or the like infiltrates into the preform in sequence. In this way, the melt of Al alloy or the like infiltrates into the whole preform in a non-pressure manner and infiltrates into the ceramic powder.

[0038] However, according to the research of the present inventors, the above method has the following problems. First, the above reaction does not occur in the whole preform from the start of infiltration. That is, at the start of infiltration, the reaction initially occurs on the surface of the preform where both Mg and N2 are present and proceeds to the interior of the preform in sequence. Therefore, it takes a long time for the melt of Al alloy or the like to infiltrate into the whole surface and interior of the preform, and there is a problem that the manufacturing efficiency deteriorates. In addition, there are parts in the preform where Mg3N2 is not formed, and Al alloy or the like does not infiltrate into the whole preform, so an uneven infiltration body of Al alloy or the like is formed, and it may not be possible to manufacture a good composite material.

[0039] In order to solve these problems, the present inventors have made a dramatic improvement to the method of infiltrating the melt of Al alloy or the like into the preform obtained by molding and hardening the ceramic powder, and have developed a technology that can rapidly infiltrate the melt into the preform and stably provide a "composite material containing ceramic powder and Al alloy or the like" with improved uniform quality, and have conducted in-depth research. As a result, the present invention has been achieved.

[0040] The manufacturing method of the composite material of the present invention is characterized in the following aspects. First, it is characterized in being configured in the following manner: The raw materials used are a mixture containing magnesium-containing powders such as metallic Mg powder and ceramic powder, and also containing any one of an inorganic binder or an organic-inorganic binder having the property that the mixture exhibits strength upon heating below 500 °C. The mixture is formed to obtain a formed body. As the above-mentioned "property that the mixture exhibits strength upon heating below 500 °C", examples include "the property of hardening upon heating below 500 °C". Furthermore, it is characterized in that the formed mixture is calcined at a temperature below 500 °C to produce a preform, and a melt of an Al alloy or the like is infiltrated into the obtained preform in a non-pressurized manner to manufacture a composite body of aluminum alloy and ceramic. In particular, the present invention is characterized in that, through the above configuration, a new manufacturing method for obtaining a useful preform with a configuration not previously available is discovered. That is, by using the preform configured as above, a melt of an Al alloy or the like can be rapidly infiltrated into the preform in a non-pressurized manner, realizing the manufacture of a composite body in which the Al alloy or the like is uniformly infiltrated into the preform. The following specifically describes each process of the manufacturing method of the composite material of the present invention.

[0041] <Manufacture of a mixture containing magnesium-containing powder and ceramic powder>

[0042] The mixture used in the manufacturing method of the present invention contains magnesium-containing powders such as metallic Mg powder and ceramic powder, and also contains any one of an inorganic binder or an organic-inorganic binder having the property that the mixture exhibits strength upon heating below 500 °C. The following describes these raw materials.

[0043] (Ceramic powder)

[0044] The ceramic powder used in the present invention is not particularly limited, and the following examples can all be used. For example, common ceramic powders such as silicon carbide (SiC), tungsten carbide (WC), and titanium carbide (TiC), oxides such as aluminum oxide (Al2O3), titanium dioxide (TiO2), and aluminum borate, and nitrides such as aluminum nitride (AlN) and silicon nitride (Si3N4) can be used.

[0045] The particle size of the above-listed ceramic powder is not particularly limited. For example, a ceramic powder with an average particle size of 1 μm or more and about 200 μm or less is suitable. When using a ceramic powder with an average particle size less than 1 μm, for example, in a mixture obtained by pressing and forming, etc., and in a preform obtained by baking the mixture, the gaps (pore diameters) formed are too small, and it is possible that molten Al alloy, etc. may not penetrate, so it is not suitable. That is, when using the non-pressure infiltration method, it is necessary for molten Al alloy, etc. to naturally penetrate into the gaps by capillary action in a non-pressure manner. However, if the gaps (pore diameters) between the ceramic powder particles are too small, the infiltration becomes insufficient. On the other hand, when the average particle size of the ceramic powder exceeds 200 μm, the particle size is too large, so it is not the most suitable in the following aspects. If the ceramic powder is too large, when forming a mixture using the mixture containing it, it is difficult to perform particle filling by pressing and forming or vibration forming, and it is difficult to achieve the subsequent forming of the mixture. In addition, when using a too-large ceramic powder, if the gap between the particles is more than several tens of μm, the gap interval becomes too large, so it is not easy to generate the aluminum infiltration utilizing capillary action, which is important in the non-pressure infiltration method.

[0046] In the manufacturing method of the present invention, it is also a preferred method to adjust the size of the ceramic powder used and obtain a preform having the necessary physical property values. For example, by appropriately mixing ceramic powders of large particles and small particles according to the use, manufacturing a mixture, and appropriately controlling the filling state of the ceramic powder when obtaining a mixture based on the obtained mixture, a preform having the necessary physical property values can be obtained.

[0047] (powder containing magnesium)

[0048] In the manufacturing method of the present invention, as the powder containing magnesium, for example, at least any one powder selected from the group consisting of metallic magnesium, magnesium alloy, and magnesium silicide can be used. Specifically, for example, in addition to the metallic magnesium powder described previously, powders such as Al-Mg-based alloys, Al-Mg-Si-based alloys and other magnesium alloys, and compounds such as Mg2Si with a high magnesium content can also be used.

[0049] In addition, it is preferable to use magnesium-containing powder with an average particle size of 0.5 μm or more and 150 μm or less. For powders exceeding 150 μm, they are too coarse and may not be uniformly mixed with the previously described ceramic powder, so they are not preferred. Furthermore, if the particle size is coarse, the surface area of the Mg-containing powder decreases, and the amount of Mg3N2 generated after the Mg contained in the preform reacts with nitrogen in the atmosphere and is nitrided decreases. Here, if the amount of Mg3N2 generated is small, the infiltration rate of aluminum into the preform becomes slow, so it is not preferred. On the other hand, the finer the Mg-containing powder, the larger the surface area, and it is easily oxidized by oxygen in the air to form MgO, resulting in a decrease in the amount of Mg, so it is not preferred. Therefore, it is preferable to use Mg-containing powder with an average particle size of 0.5 μm or more. In addition, when the average particle size exceeds 150 μm, the overall surface area decreases, and as previously described, the amount of Mg3N2 generated decreases, so it is not preferred.

[0050] As the mixing amount of the Mg-containing powder, it is preferably used in the range of 0.3% or more and 10% or less in terms of mass basis, in terms of Mg conversion, relative to 100 parts by mass of the ceramic powder. It is more preferably used in the range of 0.5% or more and 7% or less, and further 0.5% or more and 5% or less. If the mixing amount of the Mg-containing powder is small and less than 0.3%, the amount of Mg3N2 generated decreases, and the infiltration rate of the melt such as Al alloy cannot be sufficiently promoted, so it is not suitable. On the other hand, if the mixing amount of the Mg-containing powder exceeds 10%, the distribution state of the Mg-containing powder in the preform made of these raw materials locally increases, and the amount of the infiltrated Al alloy may become uneven due to this, so it is not suitable. When using the previously listed Mg alloys and Mg-containing compounds, the mixing amount can be determined by converting to the Mg contained in them.

[0051] (Binder)

[0052] The present invention is characterized in that, as the mixture used in the production of the preform, a mixture containing any one of an inorganic binder or an organic-inorganic binder having the property that the mixture exhibits strength by heating at 500 °C or lower is used in the above-mentioned Mg-containing powder and ceramic powder. Examples of the organic-inorganic binder having the above property include silicone resin, Si alkoxide, Al alkoxide, etc. In addition, examples of the inorganic binder include water glass, alumina cement, etc.

[0053] In the manufacturing method of the present invention, in subsequent processes, it is necessary to bake the mixture obtained by molding the mixture containing these binders at a temperature of 500°C or lower to manufacture a preform. Therefore, a binder having the property that the mixture exhibits strength upon heating at 500°C or lower is used, so that the preform exhibits strength at a baking temperature of 500°C or lower. In the present invention, organic binders such as polyvinyl alcohol, polyvinyl butyral, and cellulose can be further added to the mixture in a manner that easily molds the mixture containing the above binder. These organic binders are burned through the subsequent baking process at a temperature of 500°C or lower and do not contribute to the strength performance of the preform. Therefore, in the manufacturing method of the present invention, it is inevitable to use an inorganic-organic binder and an inorganic binder having the above properties in the manufacture of the mixture.

[0054] Examples are given to illustrate the binder that can be suitably used in the present invention having the above properties. The silicone resin has a polysiloxane structure composed of Si (silicon), oxygen, and an organic compound represented by the chemical formula "Si-O-R" (R is an organic substance), functions as an organic binder at low temperatures, and functions as an inorganic binder after baking at high temperatures. In addition, Si-alkoxide represented by Si(OC2H5)4 forms a polymer (silicone resin) from monomers at low temperatures. Therefore, when molding the mixture to form a mixture, the mixture can maintain the molding strength, and after baking the mixture, SiO2 is finally formed and functions as an inorganic binder. When using a solid silicone resin, it is dissolved in alcohols such as ethanol and isopropyl alcohol (IPA), and organic solvents such as xylene and toluene for use. The polymer of Si-alkoxide is a liquid and can be used directly or after dilution. In the manufacturing method of the present invention, substances in which the silicone resin is pre-dissolved in an organic solvent and substances in which the silicone resin itself is in a liquid state can be used directly. The above binder can be diluted with an organic solvent or water as needed for use. This will be described later.

[0055] In the present invention, water glass (sodium silicate) can be suitably used as the inorganic binder. At this time, it is preferable to use an inorganic binder in a solution state, so-called No. 1 water glass, No. 2 water glass, and No. 3 water glass, so as to be easily mixed with other materials. In addition, when using alumina cement as the inorganic binder, it is preferable to dissolve the alumina cement in a small amount of water and mix it with other raw materials such as ceramic powder.

[0056] The amount of the above binder used in the present invention depends on the forming method for making the mixture and is not particularly limited. When using either an inorganic binder or an organic-inorganic binder, when the mixture is calcined to form a preform, inorganic oxides such as SiO2 are formed and remain in the preform and are contained in the composite. Therefore, it is preferable to appropriately select the type of binder in consideration of the ceramics used in the composite raw materials. For example, in the case of using non-oxide ceramics such as SiC and Si3N4, or in the case of using oxide ceramics such as Al2O3 and TiO2, there is no problem with using silica-based binders such as silicone resin and water glass. The amount of the binder can be appropriately determined in consideration of the workability when forming the mixture, the hardness of the preform after calcination, etc. For example, it is preferably added and used in an amount of 0.3 parts by mass or more and about 110 parts by mass or less relative to 100 parts by mass of the ceramic powder.

[0057] (solvent)

[0058] The mixture containing the above raw materials constituting the present invention is used to form a mixture by molding the mixture, and the mixture is calcined at a temperature of 500 °C or lower to produce a preform. Therefore, in order to improve the moldability of the mixture, etc., in addition to the above materials, an organic solvent, water, or a mixed solvent of water and an organic solvent can also be used. As the organic solvent, lower alcohols such as ethanol and isopropyl alcohol, linear alkanes such as n-hexane, etc. can be used. In addition, in the present invention, a mixed solvent of water and these organic solvents can also be used.

[0059] However, according to the research of the present inventors, when using water, although it also depends on the amount used, Mg in the Mg-containing powder in the mixture reacts with water to form a hydroxide, which may impair the function as a penetration (infiltration) promoter necessary in the preform. That is, for example, when using metallic Mg powder, if there is a large amount of water, the Mg powder in the mixture undergoes hydrolysis through the reaction of Mg + 2H2O → 2Mg(OH)2 + H2. As a result, Mg3N2, which is useful in non-pressure infiltration, is not generated, and the effect of promoting the infiltration of the molten Al alloy may be impaired. Therefore, it is preferable that the solvent used in the mixture is an organic solvent not containing water or a mixed solvent with a reduced water content so that the Mg-containing powder constituting the mixture does not hydrolyze. Specifically, when using a mixed solvent of water and an organic solvent, it is important to reduce the amount of water used to 100 parts by mass or less relative to 100 parts by mass of the organic solvent. According to the research of the present inventors, in the case of the above-listed organic solvents, needless to say, when using a mixed solvent with a reduced water content, the Mg-containing powder in the mixture hardly reacts with water and still exists in the form of the Mg-containing powder in the mixture formed by molding the mixture. Therefore, by calcining the mixture, a preform applicable to non-pressure infiltration can be manufactured.

[0060] <Fabrication of Composite and Preform>

[0061] In the present invention, a composite is obtained by molding a mixture having the above-described composition, and the composite is calcined at a temperature of 500°C or lower to fabricate a preform. In the present invention, a composite is obtained using a mixture having the composition described above, and the obtained composite is calcined at a temperature specified in the present invention to obtain a preform. Thus, when used in the following non-pressure infiltration process, a useful preform that contains Mg powder in a state where the function as an infiltration (impregnation) promoter can be stably and sufficiently exhibited is provided, which is not available in the prior art. This will be described below.

[0062] When producing an MMC product containing an Al alloy or the like and a ceramic by non-pressure infiltration method, it is considered that in the production of a simple-shaped product, for example, a mixture containing ceramic powder and Mg powder can be added to a carbon box or the like, and the molten Al alloy or the like can be infiltrated into the mixture in the box. On the other hand, when producing a complex-shaped MMC product, a production method is sought in which a mixture containing ceramic powder is molded and hardened to produce a preform close to the shape of the product, or the preform obtained as described above is machined as needed to be a preform closer to the shape of the product, and the molten solution of the Al alloy or the like is infiltrated into these preforms. That is, if the Al alloy or the like can be infiltrated into a preform close to the shape of the product to produce the product, the processing cost of the product can be reduced, and further the product cost can be reduced, and the product can be provided at a low price.

[0063] However, in the prior art, when producing an MMC product using a preform close to the shape of the product by non-pressure infiltration method, a preform containing metallic Mg powder or the like is not used. As described above, in the prior art, a preform close to the shape of the product obtained by molding a mixture containing ceramic powder is used, and Mg exists as an infiltration (impregnation) promoter in the atmosphere of non-pressure infiltration. In a nitrogen atmosphere, the molten Al alloy is infiltrated into the above preform in a non-pressure manner to obtain an MMC product. According to the research of the present inventors, in the prior art, the reason for not using a preform containing metallic Mg powder or the like is as follows. In the prior art, when implementing the non-pressure infiltration method, the development of a preform containing metallic Mg powder or the like that can stably and sufficiently exhibit the function as an infiltration (impregnation) promoter cannot be achieved. The present invention is proposed in view of the above technical problems. According to the present invention, a preform that can be suitably used in the non-pressure infiltration method, has sufficient strength, and contains Mg powder in a state where the function as an infiltration (impregnation) promoter can be stably exhibited can be provided by a simple means.

[0064] (Manufacturing Process of the Composite Body)

[0065] In the manufacturing method of the present invention, the method of using a mixture containing the aforementioned raw material components to obtain a composite body with a desired shape is not particularly limited. For example, commonly used methods such as press molding, CIP molding (cold isostatic pressing), casting molding, and vibration molding can be used. As previously described, the mixture constituting the present invention contains any one of the inorganic binder or the organic-inorganic binder that exhibits strength characteristics such as hardening by heating below 500°C. Therefore, the obtained composite body, and further the preform obtained by baking the composite body thereafter, have excellent operability and are easy to handle. Furthermore, especially when the preform obtained by baking the composite body is infiltrated (impregnated) with molten Al alloy at high temperature by the non-pressure infiltration method, the preform does not deform and has excellent properties of being firmly solidified.

[0066] In the manufacturing method of the present invention, as an example when manufacturing the composite body, the following method can be cited. It can be cited that first, an organic-inorganic binder such as silicone resin is added to the ceramic powder and metal Mg powder as described above, and further an organic solvent such as alcohol or a mixed solvent containing a small amount of water as needed is added, and they are uniformly mixed to prepare a slurry. Then, the slurry obtained as described above is cast and molded in a plaster mold, a metal mold, a rubber mold, a resin mold, etc. to obtain a composite body, or after vibration sedimentation molding, the solvent is dried and removed and molded to obtain a composite body. In addition, according to the manufacturing method of flowing the above slurry into a plaster mold, the solvent in the mixture can be absorbed into the plaster mold to mold the composite body. In any case, as described later, after removing the composite body from the mold, the composite body is baked under specific temperature conditions, whereby a preform that can be suitably used in the manufacturing method of the present invention can be produced. In addition, not limited to these methods, the method of drying, pulverizing, etc. the slurry obtained as described above to manufacture a mixed powder, filling the mixed powder into a metal mold, and performing press molding or CIP molding to obtain a composite body can also be effectively utilized.

[0067] A more specific description of the above method for manufacturing the composite body will be given.

[0068] "Pressing, CIP Molding Method"

[0069] The slurry containing the mixture described previously is dried at a temperature of 150°C or lower. After drying, it is disassembled or gently pulverized in a manner that is easy to mold to manufacture the powder raw material for press molding. The obtained powder raw material for press molding is added to a press mold, a load is applied, and press molding or CIP molding is performed. In this case, when it is difficult to mold the composite body only with the inorganic binder, an organic binder can be appropriately used in the above slurry.

[0070] "Water Glass Hardening Method"

[0071] When sodium silicate is used as an inorganic binder, a mixture can be obtained as described below. After adding a mixture of ceramic powder, sodium silicate, and Mg powder to a mold and pressing it tightly, carbon dioxide is blown in for hardening, whereby a firmly solidified mixture can be formed. This method is a method used to form a gravity casting mold from sand such as silica. In the manufacturing method of the present invention, a mixture is obtained by this method, and then the mixture removed from the mold is calcined to obtain a preform.

[0072] "Vibration sedimentation method"

[0073] A slurry containing the previously described mixture is added to a rubber mold or the like and vibration molded. After removing the solvent on the upper part, it is dried to produce a mixture. The obtained mixture is calcined to form a preform, whereby a preform that can be preferably used in the manufacturing method of the present invention is formed.

[0074] (Manufacturing process of preform)

[0075] The manufacturing method of the present invention is characterized in that after removing a mixture having a desired shape obtained as described above and containing specific raw materials defined in the present invention from a mold, drying is performed as needed, and it is calcined at a temperature of 500 °C or lower to obtain a preform. Using the obtained preform, a molten metal such as an Al alloy is infiltrated (impregnated) into the preform in a non-pressurized manner to obtain a metal matrix composite containing aluminum and ceramic. In the present invention, a preform is produced by calcining and hardening a mixture having a specific composition at a temperature of 500 °C or lower in air. According to the research of the present inventors, it is necessary to avoid the calcination temperature exceeding 500 °C. That is, when the calcination temperature exceeds 500 °C, the Mg-containing powder contained in the mixture is oxidized in air to form 2Mg + O2 → 2MgO, and in the subsequent process of infiltrating / impregnating a molten metal such as an Al alloy into the preform using the calcined preform, the Al infiltration promoting effect cannot be exerted.

[0076] According to the research of the present inventors, when using an organic-inorganic binder such as silicone resin or silicate as the binder, at around 500 °C, the organic matter in its structure burns and decomposes to form amorphous silica SiO2. As a result, the obtained preform exhibits strength. On the other hand, when using water glass or alumina cement as the binder, the mixture hardens at room temperature, but sufficient strength cannot be obtained during hardening at room temperature. In contrast, in the manufacturing method of the present invention, since roasting is performed at a temperature below 500 °C, unnecessary moisture and organic matter are removed from the mixture while hardening, forming amorphous silica and alumina, so that the strength of the preform obtained after roasting can be sufficient. Therefore, in the non-pressure infiltration process at high temperature thereafter, the melt of Al alloy or the like rapidly infiltrates the preform, and when the melt infiltrates integrally, it exhibits sufficient strength and can provide a composite material in a state of overall uniformity.

[0077] The reason for the remarkable effect of the present invention that cannot be obtained by the conventional manufacturing method will be described below. That is, the roasting temperature of the mixture formed by molding a mixture composed of a specific raw material containing ceramic powder having the characteristics of the present invention is set below 500 °C to produce a preform for the non-pressure infiltration method.

[0078] Generally, a ceramic preform is produced by the following method. Usually, an inorganic binder such as colloidal silica or colloidal alumina and, if necessary, an organic binder are added to and mixed with ceramic powder, and a molded body is produced by molding such as pressing. Then, the molded body is roasted at a high temperature of 900 °C or higher to develop the strength of the preform. According to the research of the present inventors, when using the above-mentioned conventional method, if a molded body is made of ceramic powder containing Mg-containing powder as the raw material and roasted, the contained Mg-containing powder is oxidized to form MgO. Therefore, in the non-pressure infiltration process, Mg3N2 that can significantly improve the wettability with the Al alloy cannot be generated for the ceramic powder constituting the preform. Therefore, in the case of a preform obtained by the above-mentioned conventional method, the melt of Al alloy or the like cannot be infiltrated in a non-pressure manner.

[0079] Here, as a method for preventing the oxidation of Mg, roasting the above-mentioned formed body in an inert atmosphere such as argon is also considered. However, according to the research by the present inventors, at a temperature of 600 °C or higher, Mg in the formed body evaporates, and a prescribed amount cannot remain in the preform after roasting, reducing the effect achieved by adding Mg-containing powder to the raw material of the formed body. In addition, roasting the formed body in a nitrogen atmosphere furnace is also considered. However, according to the research by the present inventors, Mg3N2 is generated at about 550 °C, and when the preform is taken out of the furnace into the air after roasting, it reacts with the moisture in the air to form Mg(OH)2. Similarly, in this case, the amount of Mg that can function as an infiltration (impregnation) promoter in the preform is reduced. On the other hand, when an organic binder is added to the manufacturing raw material of the formed body and used in combination, the organic matter reacts with Mg to form MgO, and in the subsequent non-pressure infiltration process, Mg3N2 that can function effectively cannot be generated. As described above, there has been no prior art for manufacturing a preform containing Mg-containing powder in a state that can function as an infiltration (impregnation) promoter capable of dramatically improving the wettability between a ceramic preform and a melt such as an Al alloy in a non-pressure infiltration process.

[0080] In contrast to the above prior art, as described above, in the manufacturing method of the present invention, for a mixture (formed body) of ceramic powder containing Mg-containing powder such as metallic Mg powder, the roasting temperature during the production of the preform is set to 500 °C or lower, thereby achieving the remarkable effect of the present invention. That is, by setting the roasting temperature to 500 °C or lower, components such as metallic Mg powder contained in the mixture before roasting will not oxidize and evaporate during roasting, so the generation of Mg3N2 necessary for the subsequent non-pressure infiltration process proceeds well. This can be confirmed by the fact that a composite body obtained by using the manufacturing method of the present invention forms a composite body in which the melt of an Al alloy infiltrates well into the ceramic preform. Specifically, in the manufacturing method of the present invention, it can be confirmed that the non-pressure infiltration rate of Al into the ceramic preform increases dramatically, and the obtained composite body is a composite body in which the molten Al alloy or the like uniformly infiltrates the entire preform and has a good infiltration state.

[0081] <Non-pressure infiltration process>

[0082] The preform produced by the method as described above also depends on the forming method, but is removed from the mold and used directly, or is machined as needed to form a preform shape closer to the product shape and then used in the non-pressure infiltration process. The non-pressure infiltration process in the manufacturing method of the present invention is the same as the usual method except for the following differences: a mixture containing the materials specified in the present invention is formed to obtain a mixture, and the mixture is calcined at 500 °C or lower to obtain a preform having sufficient strength to withstand the non-pressure infiltration process. This preform is used, and a Mg-containing powder that functions as an infiltration (impregnation) promoter is contained in the preform.

[0083] As Figure 1 shown in the operation of Fig. 2(a), the preform 1 having a specific structure with the characteristics of the present invention and the Al alloy 4, etc. are loaded into a container 3 made of carbon or the like, and the container 3 is placed in a furnace (not shown) that can control the atmosphere. Then, as Figures 2(b) to 2(d) shown in the operation, the container 3 is held in a nitrogen atmosphere furnace at 700 to 900 °C for about 2 to 10 hours, and the molten Al alloy 4, etc. penetrates and impregnates into the gaps of the preform 1 through the infiltration channels 2. The amount of the Al alloy 4, etc. disposed in the container 3 needs to be more than the volume of the gaps (voids) between the particles of the preform 1. Usually, it needs to be more than about 1.2 times the voids. As shown in Fig. 2(d), after the Al alloy 4, etc. impregnate into the entire gaps of the preform 1, cooling and the treatment of removing the residual Al alloy 4, etc. (not shown) are performed to obtain a composite (MMC) 5 in which the Al alloy 4, etc. are impregnated into the preform 1. The composite obtained by the manufacturing method of the present invention forms a composite without voids and containing ceramics and the Al alloy, etc.

[0084] In the manufacturing method of the present invention, since a preform containing Mg-containing powder in a state where it functions as an infiltration (impregnation) promoter is used, the infiltration rate of an Al alloy or the like into the preform is significantly faster than that of conventional methods. According to the research of the present inventors, for example, even for preforms having a thickness of 50 mm or 100 mm, uniform infiltration can be achieved in 2 to 7 hours. In contrast, when using a preform of a conventional method that does not contain Mg, the infiltration rate is slow, and in order to infiltrate a molten solution of an Al alloy or the like into a preform having the same shape as the preform of the present invention used in the present invention by the conventional method, an infiltration time about 3 to 10 times longer is required. In addition, when using the conventional method, since the infiltration rate into the interior of the preform is slow, a state is formed in which the entire periphery of the preform except for the inlet for infiltration (impregnation) of the Al alloy or the like is surrounded, and thus, after infiltration, there is also a problem that it is difficult to remove excess Al alloy or the like from the obtained composite. In contrast, according to the manufacturing method of the present invention, the molten Al alloy or the like infiltrates only from the inlet portion of the preform in a short time, so the surrounding of the obtained composite surrounded by the Al alloy or the like that does not contribute to infiltration is significantly reduced. Thus, according to the manufacturing method of the present invention, a composite (MMC) can be produced in a near-net shape, the load of subsequent processing and the like can be reduced, and the productivity can be improved dramatically.

[0085] Examples

[0086] Examples and comparative examples are listed below to illustrate further specific examples of the foregoing embodiment, but the present invention is not limited to the following examples. In the text, w% refers to the mass basis, and v% refers to the volume basis. The average particle size in this specification is a value measured using a laser diffraction particle size distribution analyzer.

[0087] [Example 1]

[0088] Silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KR-220L) was previously dissolved in isopropyl alcohol (IPA) to prepare a 30 w% binder solution. As the ceramic powder, 4000 g of SiC powder with an average particle size of 50 μm and 1200 g of SiC powder with an average particle size of 14 μm were used. 104 g of Mg powder with an average particle size of 75 μm was added at a ratio of 2 w% relative to the above ceramic powder (SiC powder) to form a mixture containing Mg powder and ceramic powder. 346 g of the previously prepared 30 w% binder solution was further added to this mixture at a ratio of 2 w% silicone resin relative to the above ceramic powder. Then, 1300 g of IPA was further added thereto, and the mixture was uniformly mixed using a ball mill to produce a slurry. The obtained slurry was added to a stainless steel container and naturally dried to substantially remove IPA, and then further dried in a dryer at 60 °C for 8 hours. After drying, the dried product was pulverized (crushed) using a ball mill with 20 mmΦ plastic balls to produce a powder raw material for press molding.

[0089] 1000 g of the powder raw material for press molding obtained above was added to a mold with dimensions of 100 mm × 100 mm × depth 100 mm, and press-molded at a pressure of 150 kg / cm 2 to obtain a mixture with dimensions of 100 mm × 100 mm × 50 mm. The mixture obtained as described above was placed in an electric furnace in an air atmosphere, heated to 500 °C at a rate of 50 °C / hour, held at 500 °C for 4 hours for roasting, and then cooled to produce a preform. The filling rate of SiC powder in the obtained preform was 63 v%.

[0090] As Figure 1 shown, the preform 1 (hereinafter referred to as the preform body 1) manufactured above was placed in a carbon container 3 with dimensions of 200 mm × 200 mm × 80 mm depth. At this time, three infiltration channels 2 were provided under the preform body 1. For these infiltration channels 2, they were obtained by cutting / processing a preform made of the same material and using the same method as the preform body 1, with dimensions of 20 mm × 20 mm × height 20 mm, and were used for infiltrating Al alloy, etc., to form a state of supporting and floating the preform body 1. 1000 g of AC3A as the Al alloy 4 with adjusted weight by cutting was placed beside the preform body 1 thus placed in the container 3, and the container 3 was placed in a nitrogen atmosphere furnace with internal dimensions of 600 mm × 600 mm × height 500 mm. Then, while flowing nitrogen into this atmosphere furnace at a rate of 5 L / minute, the temperature was raised from room temperature to 800 °C at a rate of 10 °C / minute, and held at this temperature for 5 hours.

[0091] After maintaining at 800 °C for 5 hours and cooling to room temperature, the composite (MMC) in which the Al alloy penetrates the preform is taken out from the atmosphere furnace. Next, the three infiltration channels 2 used to support the preform body 1 are removed, and the composite (MMC) 5 in which the Al alloy 4 penetrates the preform body 1 is obtained. As described above, in the container 3 provided in the nitrogen atmosphere furnace maintained at 800 °C for 5 hours, the AC3A of the Al alloy 4 disposed in the container 3 melts, and the melted Al alloy 4 penetrates into the preform body 1 as a porous body through the infiltration channels 2 in a non-pressurized manner.

[0092] For the composite of this embodiment obtained as described above, the bulk density is measured by the Archimedes method. In addition, the interior is cut with a diamond cutter, and the cut surface is observed under a microscope. As a result, it was confirmed by observing the cut surface that the Al alloy was completely infiltrated into the gaps of the preform body. In addition, it was confirmed from the calculation result of the bulk density that it was a composite (MMC) with 63 v% SiC and 37 v% AC3A.

[0093] [Example 2]

[0094] To 4000 g of alumina powder with an average particle size of 15 μm, 120 g of Mg powder with an average particle size of 75 μm is added in an amount of 3 w% relative to the above alumina powder to form a mixture containing Mg powder and ceramic powder. Using this mixture, a slurry is further manufactured in the same manner as in Example 1. Specifically, as described below, for the mixture obtained above, a slurry is manufactured using a binder solution. In this embodiment, 400 g of a 30 w% binder solution of the same silicone resin as that used in Example 1 is added in an amount of 3 w% of the silicone resin, and further 1400 g of IPA is added, and the mixture is uniformly mixed by a ball mill using the same method as in Example 1 to produce a slurry.

[0095] Approximately 1 / 4 of the slurry prepared above is added to a gypsum mold of 110 mm × 110 mm × depth 60 mm, and while applying vibration for about 30 minutes, the gypsum mold absorbs the solution in the slurry and the solution is removed from the slurry. Then, it is dried at 60 °C for about 8 hours for curing, and the mixture containing Mg powder and ceramic powder is taken out from the gypsum mold. The obtained mixture is calcined at a temperature of 500 °C under the same conditions as in Example 1. As a result, a calcined product of 100 mm × 100 mm × 50 mm is obtained. The weight and shape of the obtained calcined product are measured, and the bulk density is measured. As a result, a preform with 50 v% alumina is obtained.

[0096] The preform obtained above was placed in a carbon container in the same state as in Example 1, with the preform body floating by means of the infiltration channels, and the same Al alloy was infiltrated in the same manner as in Example 1 to obtain a composite. For the obtained composite, the interior was cut, and the cut surface was observed under a microscope. Additionally, the bulk density was measured. As a result, it was confirmed by observing the cut surface that the Al alloy was completely infiltrated into the gaps of the preform body. Additionally, from the calculation results of the bulk density, it was confirmed that the composite (MMC) was composed of 50 v% alumina and 50 v% Al alloy.

[0097] [Example 3]

[0098] To 2000 g of SiC powder with an average particle size of 50 μm and 600 g of SiC powder with an average particle size of 14 μm, 78 g of Mg powder with an average particle size of 75 μm was added, and further 80 g of liquid water glass No. 3 was added, and the mixture was stirred using a stirrer. The obtained mixture was added to a mold made of silicone resin with a depth of 100 mm × 100 mm × 100 mm, and filled while gently tapping with a tamper. Carbon dioxide was sprayed onto the filler, and infiltration and curing were performed to obtain a mixture with dimensions of 100 mm × 100 mm × 52 mm. The obtained mixture was dried at 60 °C for approximately 8 hours. Then, the temperature was raised to 450 °C at a rate of 50 °C / hour and maintained for 4 hours for roasting of the mixture. Except for this, a preform was produced in the same manner as in Example 1.

[0099] For the preform obtained above, the melt of the Al alloy was infiltrated in the same manner as in Example 1 to obtain a composite. Then, for the obtained composite, the interior was cut, and the cut surface was observed under a microscope. Additionally, the bulk density was measured. As a result, from the calculation results of the bulk density, it was confirmed that a composite (MMC) with a SiC filling rate of 54 v% and 46 v% Al alloy could be manufactured. Additionally, by observing the cut surface, it was confirmed that even in this example where a preform cured with water glass used as a binder was used, a composite (MMC) in which the Al alloy was completely infiltrated into the gaps of the preform body could be manufactured.

[0100] [Examples 4 and 5]

[0101] For the preform with a filling rate of 63 v% of SiC powder produced in the same manner as in Example 1, instead of AC3A of the Al alloy used in Example 1, AC4C of the Al alloy was used in Example 4, and Al-3Mg, an Al alloy containing magnesium, was used in Example 5. Using the same method as in Example 1, the Al alloy was infiltrated into the preform body in a non-pressurized manner through the infiltration channels. As a result, in any of the examples, a composite (MMC) in which the Al alloy was completely infiltrated to a height of 50 mm was obtained in the same manner as in Example 1. In addition, from the calculation results of the bulk density, it was confirmed that in any of the examples, a composite (MMC) with 60 v% SiC and 40 v% Al alloy was obtained.

[0102] [Example 6]

[0103] In the same manner as the substances used in Example 1, 4000 g of SiC powder with an average particle size of 50 μm and 1200 g of SiC powder with an average particle size of 14 μm were used as the ceramic powder, and 52 g of Mg powder with an average particle size of 75 μm was added in an amount of 1 w% relative to the ceramic powder to form a mixture containing Mg powder and SiC powder. As the organic-inorganic binder, an oligomer of tetraethyl orthosilicate Si(OC2H5)4 (containing 40 w% in terms of SiO2) was used, and 260 g of this organic-inorganic binder was added to the mixture in an amount of 2 w% in terms of SiO2 relative to the above ceramic powder. Then, 1200 g of isopropyl alcohol (IPA) was further added, and using the same method as that carried out in Example 1, the mixture was uniformly mixed using a ball mill to prepare a slurry.

[0104] Using the slurry obtained above, by the same operation as in Example 1, drying and crushing (grinding) were carried out to prepare a powder raw material for press molding. Then, using the obtained powder raw material for press molding, a mixture with a shape of 100 mm × 100 mm × 50 mm was press-molded in the same manner as in Example 1. The obtained mixture was placed in an electric furnace in an air atmosphere and calcined at 430 °C to prepare a preform. Using the obtained preform, the AC3A of the aluminum alloy was infiltrated into the preform in a non-pressurized manner under the same operation and conditions as in Example 1 to obtain a composite. From the calculation results of the bulk density, it was confirmed that the obtained composite was an MMC with 64 v% SiC and 36% AC3A.

[0105] [Comparative Example 1]

[0106] A preform was produced in the same manner as in Example 1 except that Mg powder was not added when preparing the powder raw material for press molding. Next, the obtained preform was used to infiltrate Al alloy using AC3A of Al alloy in a non-pressurized manner by the same procedure as that performed in Example 1. As a result, the Al alloy did not infiltrate the preform.

[0107] [Comparative Example 2]

[0108] A preform of 100 mm × 100 mm × 50 mm was prepared in the same manner as in Example 1 except that Mg powder was not added when preparing the powder raw material for press molding. Next, the Al alloy AC3A was used to infiltrate the preform obtained above in a non-pressurized manner as described below. Specifically, the preform was Figure 1 When the preform is placed in the container 3 as shown, Mg powder 5g (not shown) is placed under and around the preform, and the Al alloy is infiltrated into the preform in the same manner as in Example 1. The above method has been conventionally performed and is called the direct oxidation method (Lanxide process).

[0109] The state of the preform was observed after the above infiltration process. As a result, in the preform with a thickness of 50 mm, the Al alloy infiltrated from the bottom to about 8 mm (16%), but did not infiltrate the entire preform. In addition, the Al alloy surrounded the periphery of the preform, which was not a near-final state.

[0110] [Comparative Example 3]

[0111] The Al alloy was infiltrated into the preform by using the direct oxidation method (Lanxide process) in the same manner as in Comparative Example 2. Specifically, the preform obtained in the same manner as in Comparative Example 2 without adding Mg powder was used, and the preform was Figure 1 When the preform is placed in the container 3 as shown, 100 g of SiC powder mixed with 5% Mg is laid under the preform, and the Al alloy is infiltrated into the preform by the same method as in Example 1.

[0112] After the above infiltration process, the state of the preform was observed under a microscope. As a result, in the preform with a thickness of 50 mm, the Al alloy infiltrated from the bottom to about 10 mm (20%), and there was no infiltration gap as a whole. In addition, the Al alloy surrounded the periphery of the preform, and the MMC in a near-final state was not obtained.

[0113] [Comparative Examples 4 and 5]

[0114] In this comparative example, the powder raw material for press molding obtained by the same method as in Example 1 was used, and a mixture of 100 mm × 100 mm × 50 mm was obtained in the same manner as in Example 1. The obtained mixture was placed in an electric furnace in an air atmosphere and dried at 60°C for 8 hours, and then calcined to manufacture a preform. At this time, the calcination temperature when manufacturing the preform in Example 1 was set to 550°C in Comparative Example 4 and 600°C in Comparative Example 5, and in any case, the preform was calcined at a temperature higher than the temperature specified in the present invention. As described above, preforms obtained by separately changing the calcination temperature were used, and in addition, by the same method as in Example 1, AC3A of the Al alloy was infiltrated into each preform.

[0115] After the above infiltration process, the states of the preforms used separately were observed. As a result, in the case of the preform in any example, the Al alloy did not penetrate into the gaps at all. The inventors considered that this was because, especially when the preform was calcined at a temperature exceeding 500°C, Mg contained in the mixture was oxidized, and the effect of promoting infiltration by the presence of Mg in the preform was impaired.

[0116] [Comparative Example 6]

[0117] As the binder used when producing the powder raw material for press molding, alcoholic colloidal silica (5 mμ) was used instead of silicone resin, and it was added and mixed so as to form a concentration of 5% with respect to the ceramic powder. In addition, a preform was tried to be produced by the same method as in Example 1. Specifically, colloidal silica was used as the binder, and in addition, the same compounded mixture as in Example 1 was used. The mixture was press-molded to obtain a mixture, and the obtained mixture was calcined at 500°C. However, it did not harden at a temperature of 500°C, and a preform that could be used for the non-pressure infiltration method could not be produced.

[0118] [Comparative Example 7]

[0119] Using the mixture with colloidal silica as the binder obtained in Comparative Example 6, the calcination temperature was changed and calcined at 1000°C. As a result, it hardened and a preform could be produced. However, using the obtained preform, an attempt was made to infiltrate the melt of the Al alloy with AC3A of the Al alloy in the same manner as in Example 1 by non-pressure, but the Al alloy did not penetrate at all. It was considered that this was because when calcined at 1000°C, Mg in the mixture was completely oxidized and Mg did not exist in the preform.

[0120] Table 1: Manufacturing conditions of preforms in Examples and Comparative Examples and properties of the obtained composite materials

[0121]

[0122] Explanation of reference numerals

[0123] 1: Prefabricated part or prefabricated part body

[0124] 2: Penetration path

[0125] 3: Container made of carbon or the like

[0126] 4: Al alloy or the like

[0127] 5: Composite (MMC) (Prefabricated part impregnated and compounded with Al alloy or the like)

Claims

1. A manufacturing method of a composite material, characterized in that, To a mixture composed of a magnesium-containing powder and a ceramic powder, any one of an inorganic binder or an organic-inorganic binder that hardens by heating below 500 °C is added, and further an organic solvent or a mixed solvent in which the water is 100 parts by mass or less relative to 100 parts by mass of the organic solvent is added to obtain a mixture. The obtained mixture is used for molding to obtain a green body, and the green body is calcined in air at a temperature below 500 °C to produce a preform. Metal aluminum or an aluminum alloy is non-pressure infiltrated into the obtained preform in a nitrogen atmosphere to manufacture a metal matrix composite containing aluminum and ceramics. The inorganic binder is water glass, and the organic-inorganic binder is any one selected from the group consisting of an organosilicon resin, an Si alkoxide, and an Al alkoxide. In the mixture composed of a magnesium-containing powder and a ceramic powder, the magnesium-containing powder is contained in a range of 0.3% or more and 5% or less on a mass basis in terms of magnesium conversion relative to 100 parts by mass of the ceramic powder.

2. The manufacturing method of the composite material according to claim 1, wherein, The magnesium-containing powder is a powder having an average particle diameter of 0.5 μm or more and 150 μm or less, which is at least any one selected from the group consisting of metallic magnesium, a magnesium alloy, and a magnesium silicide.

3. A manufacturing method of a preform, characterized in that, It is used for producing a ceramic preform applicable to the manufacture of an aluminum-based metal matrix composite using a non-pressure infiltration method. To a mixture composed of a magnesium-containing powder and a ceramic powder, any one of an inorganic binder or an organic-inorganic binder that hardens by heating below 500 °C is added, and further an organic solvent or a mixed solvent in which the water is 100 parts by mass or less relative to 100 parts by mass of the organic solvent is added to obtain a mixture. The obtained mixture is used for molding to obtain a green body, and the obtained green body is calcined in air at a temperature below 500 °C to obtain a preform. The inorganic binder is water glass, and the organic-inorganic binder is any one selected from the group consisting of an organosilicon resin, an Si alkoxide, and an Al alkoxide. In the mixture composed of a magnesium-containing powder and a ceramic powder, the magnesium-containing powder is contained in a range of 0.3% or more and 5% or less on a mass basis in terms of magnesium conversion relative to 100 parts by mass of the ceramic powder.

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