JP4167317B2 - Method for producing metal / ceramic composite material for casting - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a metal-ceramic composite material in which a reinforcing material is combined with a metal, and more particularly to a method for producing a metal-ceramic composite material for casting.
[0002]
[Prior art]
Ceramics and metal composites reinforced with ceramic fibers or particles combine the properties of both ceramics and metals. For example, this composite material has excellent ceramic properties such as high rigidity, low thermal expansion, and wear resistance. It has excellent properties and characteristics of metals such as ductility, high toughness, and high thermal conductivity. Thus, since it has the characteristics of both ceramics and metal, which have been considered difficult, it has been attracting attention as a next-generation material from industries such as machine equipment manufacturers.
[0003]
As a method for producing this composite material, particularly a composite material using aluminum as a matrix as a metal, methods such as a powder metallurgy method, a high-pressure casting method, and a vacuum casting method have been conventionally known. However, these methods are not possible due to the reason that the content of ceramics as a reinforcing material cannot be increased, a large pressure device is necessary, or near-net molding is difficult, and the cost is extremely high. It was not satisfactory.
[0004]
Thus, recently, a non-pressurized metal infiltration method developed by Rankside, Inc. of the United States has attracted particular attention as a manufacturing method for solving the above problems. In this method, an aluminum ingot containing Mg is brought into contact with a preform formed of a ceramic powder such as SiC or Al ₂ O ₃ , and this is heated to 700 to 900 ° C. in an N ₂ atmosphere to melt the aluminum alloy. Is a method in which a preform is impregnated. This is an excellent method in which the metal can be impregnated into the preform without applying pressure by improving the wettability of the molten metal to the ceramic powder by utilizing a chemical reaction between Mg and N _2. .
[0005]
There has also been proposed a method for producing a metal / ceramic composite material for casting, in which the composite material produced by this production method is further melted and diluted to the extent that it can be cast with a molten aluminum alloy. The composite material for casting produced by this method can be remelted and cast into a mold to produce a composite material having a larger size or a more complicated shape. For casting, almost any casting method generally used for aluminum casting, such as gravity casting using a sand mold / mold, precision casting represented by lost wax, die casting, etc., is possible.
[0006]
[Problems to be solved by the invention]
However, in the production of this metal-ceramic composite material for casting, a penetration enhancer is used to promote metal penetration, and the penetration enhancer uses Mg powder of 250 μm or less. There is a problem that Mg powder is extremely difficult to obtain in Japan. This is because fine Mg powder of 250 μm or less is hardly commercially available because it explodes easily. If this is made rough so as to be easily obtained, metallic spots called metal spots are generated in the composite material, resulting in failure.
[0007]
The present invention has been made in view of the problems of the above-described method for producing a metal / ceramic composite material for casting, and the object thereof is to use a penetration enhancer having the same effect without using Mg powder. An object of the present invention is to provide a method for producing a casting metal-ceramic composite material.
[0008]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventors have obtained the knowledge that if Al—Mg alloy powder is used instead of Mg powder, the present invention is completed with the knowledge that it has the same acceleration effect as Mg powder. It came to do.
[0009]
That is, the present invention includes (1) Al—Mg alloy powder added to 0.5 to 6.0% by weight in terms of Mg and mixed with SiC, Al ₂ O ₃ , and AlN ceramic powder as reinforcing materials, and the mixed powder A composite material is prepared by impregnating aluminum alloy in a nitrogen atmosphere at a temperature of 700 to 1000 ° C. with no pressure, and then a predetermined amount of the composite material and a predetermined amount of aluminum alloy are melted and stirred. metal and wherein the - claims a method of producing a ceramic composite material (claim 1), and (2) fineness of the Al-Mg alloy powder, characterized in that it is a 5~250μm an average particle size The gist of the present invention is the method for producing a casting metal-ceramic composite material according to claim 1. This will be described in more detail below.
[0010]
As the manufacturing method, a manufacturing method of a powder of a ceramic powder, Al ₂ O _3, SiC, a ceramic powder such as AlN, was added 0.5 to 6.0 wt% of Al-Mg alloy powder Mg terms used (Claim 1). The reason why Al-Mg powder was used instead of Mg powder is that this alloy powder is easy to obtain without risk of explosion, and the same effect as Mg powder is obtained, and further, there is no problem of melting into the aluminum matrix. by.
[0011]
The fineness of the alloy powder was 5 to 250 μm in average particle size (Claim 2). Even though the fineness of the alloy powder is coarse, no metal spots such as Mg powder are observed, so there is no particular limitation as long as there is no problem due to the fineness of the alloy powder in producing a composite material. Considering the uniform dispersibility in the ceramic powder, 5 to 250 μm is preferable.
[0012]
The amount to be added is preferably 0.5 to 6.0% by weight in terms of Mg. If the amount is less than 0.5% by weight, the metal permeation rate becomes slow. This is because the speed is too fast, or unevenness in the permeation speed occurs and a portion that does not permeate is generated, and an unpermeated portion is generated inside the composite material.
[0013]
The aluminum alloy to be permeated is not necessarily an alloy having the same composition as the aluminum alloy to be diluted. However, when the ceramic powder is SiC, an Si component must be included in the alloy. The reason for this is that molten aluminum reacts with SiC during penetration to produce aluminum carbide (Al ₄ C ₃ ), which reacts with moisture in the air and easily turns into aluminum hydroxide, resulting in defects. Therefore, it is for preventing the production | generation by including Si. As for the amount thereof, it is desirable to adjust the Si amount in the alloy so that the Si content in the composite material is 8% by weight or more based on the alloy.
[0014]
It is desirable that one of the aluminum alloys for dilution contains Si. This is because the molten metal has good fluidity, is easy to cast, and hardly causes defects such as casting cracks. The amount to be diluted may be an appropriate amount so as to obtain a desired powder filling rate. The agitation method / condition during dilution is a very important factor. That is, a stirring speed that prevents separation of ceramic particles and maintains sufficient dispersion is required, but bubbles should not be involved in the molten metal. It is necessary to conduct experiments thoroughly and carefully determine the stirring conditions. The diluted molten metal may be cast as it is to produce the target composite material, or may be once formed into an ingot shape and then melted again to produce the target composite material.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The production method of the present invention will be described in more detail. First, ceramic powder such as SiC, Al ₂ O ₃ , and AlN is prepared as a reinforcing material. Al-Mg alloy powder having an average particle diameter of 5 to 250 μm is added thereto and mixed in an amount of 0.5 to 6.0% by weight in terms of Mg. The obtained mixed powder is filled in a container, and an aluminum alloy ingot is placed on the container. The aluminum alloy is infiltrated at a temperature of 700 to 1000 ° C. in a non-pressurized atmosphere in a nitrogen atmosphere, and cooled to produce a composite material. To do.
[0016]
The obtained composite material is remelted in a crucible at a predetermined temperature, and a predetermined amount of a molten aluminum alloy is added thereto, and the mixture is sufficiently stirred and diluted with a stirrer. There is no problem even if a predetermined amount of the composite material and the ingot of the aluminum alloy are put in a crucible and melted at a predetermined temperature and then stirred with a stirrer. If this is cooled and a metal-ceramic composite material for casting is produced, and this is further remelted and cast, a desired composite material such as a complex shape product can be obtained. Alternatively, a desired composite material can be obtained by casting as it is without cooling.
[0017]
When a metal-ceramic composite material for casting is produced by the above method, a metal-ceramic composite material for casting equivalent to that produced using Mg powder can be obtained.
[0018]
【Example】
Examples of the present invention will be specifically described below together with comparative examples to describe the present invention in more detail.
[0019]
(Examples 1-4)
(1) Production of composite material As commercially available SiC powder having an average particle diameter of 15 μm as a reinforcing material, Al—Mg (Al: Mg = 4: 6) having an average particle diameter of 150 μm is converted into 0 according to the order of the examples. 0.5, 1.0, 2.0, and 3.0% by weight were added and mixed for 15 minutes with a V-type mixer. Each of the obtained mixed powders was filled in a 200 x 200 x 200 mm depth container made of a graphoil, and then an ingot of an aluminum alloy (Al-10Si) 1.2 times as much as the mixed powder was placed on the container. Set. This was held at 790 ° C. for 12 hours in a N ₂ air stream, allowed to infiltrate the aluminum alloy under no pressure, and then cooled to produce a composite material.
[0020]
(2) Production of casting composite material A predetermined amount of the obtained composite material and the ingot of the above aluminum alloy were placed in a crucible so that the filling rate of SiC powder in the casting composite material would be 30 vol%, and then 610 It was melted at a temperature of 0 ° C. and stirred for 2 hours to prepare a molten composite material for casting. The molten metal was raised to 720 ° C. without cooling and further stirred, cast into a sand mold, and the cast was used for evaluation.
[0021]
(3) Evaluation The bulk density of the obtained casting was measured by the Archimedes method to determine the powder filling rate. As a result, the powder filling rate was 30 vol% and was diluted as intended. Moreover, the casting was cut | disconnected and the cut surface was observed visually and the dispersion | distribution condition of SiC powder was investigated. As a result, the SiC powder was dispersed without any problems, and there were no defects such as pores, non-penetrating portions, or metal spots. This indicates that the Al—Mg alloy powder has the same function as the Mg powder and has good wettability to the SiC powder.
[0022]
(Comparative Examples 1 and 2)
For comparison, in Comparative Example 1, except that the Al—Mg alloy powder was not added, in Comparative Example 2, the Al—Mg alloy powder was added except 6.5% by weight outside the scope of the present invention. A casting was prepared and evaluated in the same manner as in Example 1. As a result, in Comparative Example 1, because the wettability to the SiC powder was not good, the SiC powder floated on the upper part of the molten metal during dilution, and a molten material suitable for casting could not be obtained. Further, in Comparative Example 2, since there was too much Al—Mg alloy, a portion that did not penetrate due to uneven permeation rate occurred, and a small amount of SiC powder floated on top of the molten metal during dilution, and the casting was not impregnated. Part was recognized.
[0022]
【The invention's effect】
As described above, according to the method for producing a casting metal-ceramic composite material of the present invention, an equivalent casting metal-ceramic composite material can be obtained by using Al-Mg alloy powder without using Mg powder. It has become possible to provide a manufacturing method that can As a result, the production of composite materials for casting has become much easier than before.

Claims (2)

SiC is a reinforcing _material, an Al-Mg alloy powder was mixed with 0.5 to 6.0 wt% in terms of Mg to the ceramic powder of the Al ₂ O 3, AlN, to the mixture powder of aluminum alloy in a nitrogen atmosphere A casting metal characterized by melting a predetermined amount of the composite material and a predetermined amount of an aluminum alloy and stirring the composite material after making a non-pressurized infiltration at a temperature of 700 to 1000 ° C. A method for producing a ceramic composite material.   The method for producing a metal / ceramic composite material for casting according to claim 1, wherein the fineness of the Al-Mg alloy powder is 5 to 250 µm in average particle diameter.