JPH0693354A - Production of composite light metallic material - Google Patents

Abstract

PURPOSE:To uniformly disperse different kinds of metals such as ceramics or the like into the molten metal of a light metallic material. CONSTITUTION:A vessel 2 in which covers 4 and 6 are constituted of aluminum allay is filled with alumina powder 12, and the inside of the vessel is exhausted from an exhaust port 8 by a vacuum pump. After that, fusing is executed, and the exhaust port 8 is sealed. The vessel 2 is charged to the molten metal of aluminum allay contg. calcium and is sunk to melt the covers 4 and 6 of the vessel and to infiltrate the molten metal into the vessel 2. In this way, the alumina powder can uniformly be dispersed into the molten metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light metal material such as an aluminum alloy or a magnesium alloy used for parts such as transportation machines and home electric appliances, and in particular, such a light metal material in which different materials such as ceramic particles are dispersed. The present invention relates to a method for manufacturing a composite light metal material.

[0002]

2. Description of the Related Art Aluminum alloys and magnesium alloys have been variously improved to improve wear resistance and heat resistance. For example, an aluminum alloy has been tried to be improved by a quenched powder aluminum alloy, but this is still problematic in terms of cost performance. As another improvement, a method of first forming a ceramic preform and impregnating it with an aluminum alloy by a squeeze or the like is performed, and this method is put to practical use for pistons and the like. However, this method requires a step of forming a preform made of ceramic short fibers, which increases costs and significantly improves the performance of the aluminum alloy, but inevitably increases costs.

Another improvement method is to uniformly disperse short fibers and particles having good wear resistance and heat resistance in an aluminum alloy. As an example of this, Duralcan (registered trademark of Alcan (Asia Limited)), which is a composite alloy in which up to 20% by volume of silicon carbide is dispersed in an aluminum alloy, is about to be marketed. Also in magnesium and magnesium alloys, it is considered to improve wear resistance and heat resistance by dispersing particles of silicon carbide or ceramics.

When short fibers or particles having good wear resistance and heat resistance are dispersed in a light metal, depending on the short fibers or particles used, the wettability with the molten metal may be poor and the dispersion may be difficult. Therefore, it has been proposed to improve wettability by adding a small amount of various metals and salts thereof, including calcium metal, to a molten metal (Japanese Patent Laid-Open No. 57-169033).
JP, JP-A-57-169034, JP, JP-A-60
-159137, JP-A-60-194039, etc.).

[0005]

Even if various metals or salts thereof are added to the molten metal in order to improve the wettability,
It is difficult to disperse different materials evenly throughout the melt,
For example, in addition to the molten metal part in which the different materials are uniformly dispersed, the upper part of the molten metal contains more than a predetermined amount of the different material, resulting in poor fluidity, and the ratio is 5 to 15% by weight. There arises a problem that different kinds of materials charged in coexistence are not uniformly dispersed throughout the molten metal. Such a problem occurs not only when the matrix is a melt of aluminum or an aluminum alloy, but also when the matrix is a melt of magnesium or a magnesium alloy. Further, this tendency becomes stronger as the particle diameter becomes smaller and the short fibers become smaller. This tendency does not change even if the amount of the wetting improving agent added is increased.
The present invention has an object to uniformly disperse different kinds of materials such as ceramics in the molten metal when manufacturing the molten metal of the composite light metal material.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have found out that air adheres to different materials such as ceramics to be added to the molten metal, and that the air prevents uniform dispersion of the different materials in the molten metal. The present invention has been made. That is, the present invention is a method in which, when a different material is added to the molten metal, the air adhering to the different material is added in a state where the air is removed so that the different material is uniformly dispersed in the molten metal.

If a method of removing air from different materials such as ceramics is to remove the air of the entire system including the molten metal after adding the different materials and stirring, the equipment becomes huge. When the pressure is reduced, the molten metal rises like a carmel and closes the vacuum system or adheres to the wall of the crucible, which not only increases the manufacturing cost but also makes maintenance difficult. Even if different materials and light metal alloys are put in a crucible and decompressed or vacuumed before melting, the equipment will become huge and some of the light metal material components will be vaporized and the material components will change. The problem arises.

Therefore, in the present invention, at least a part of the molten metal component or the main component of the molten metal component is filled with a different material in a container having a vacuum exhaust port, and the interior of the container is exhausted through the vacuum exhaust port. After evacuation, the container is submerged in the molten metal with the evacuation port sealed, and the dissimilar materials in the container are dispersed in the molten metal. The degree of vacuum in the container in which the different materials are sealed is preferably high vacuum, and at least the degree of vacuum at which the air adhering to the different materials can be removed is required. The required degree of vacuum may be determined according to the shape and size of the different materials to be enclosed.

A container for enclosing different kinds of materials and submerging in molten metal is
When a part is composed of the molten metal component or a main component of the molten metal component, for example, when the molten metal is an aluminum alloy, a part of the container can be composed of aluminum or an aluminum alloy. The other parts of the container must be made of a material having a melting point higher than that of the molten aluminum alloy. This is because if the portion other than the aluminum or aluminum alloy portion of the container melts at a temperature lower than the temperature of the molten metal, they become part of the molten metal component, which is not preferable. Iron or stainless steel is preferable as the high melting point material forming the container. However, in the case of molten aluminum alloy, iron is melted, so if necessary, titania or the like applied to the ladle of an automatic die-cast water heater may be applied to the iron portion in advance. When the container is immersed in the molten metal, the aluminum or aluminum alloy forming a part of the container melts at the temperature of the molten metal,
The molten metal that is the matrix invades from the open part,
The action of the wetting improver added to the molten metal causes the molten metal to become compatible with the different material, and the stirring action of the molten metal thereafter causes the different material to be uniformly dispersed. At this time, the molten metal may be stirred by using a stirrer. However, for example, when the container for enclosing different materials is provided with a handle, the molten metal may be stirred vertically and horizontally with the handle. However, it is preferable to stir the molten metal with a stirrer or the like, because a portion where the different materials have a high content ratio may partially occur in the molten metal only by moving the container.

When the entire container for enclosing different materials is made of the same material, if the molten metal is an aluminum alloy, it is easy to weld when sealing the vacuum exhaust port of the container after accommodating the different materials in the container. The material is preferably made of pure aluminum. When the entire container for enclosing different kinds of materials is made of aluminum and different kinds of materials such as ceramics are enclosed in the container, when the container is put into the molten metal, the specific gravity may be smaller than that of the molten metal and may float. That is, when the container is an aluminum alloy, the specific gravity of the ceramics is about 3 to 4, but the filling rate in the container is as low as about 1/3, and therefore the apparent specific gravity of the entire container is about 1. Is. In that case, it is necessary to add a weight to the container or put the container in a stainless steel basket and push it down.

Similarly, particles of different materials or short fibers may be added to magnesium or magnesium alloy to form a composite material. When the molten metal is magnesium or a magnesium alloy, it is desirable that the molten metal be flame-retarded by adding an alkaline earth metal such as calcium so that it can be operated in the atmosphere.

The shape of the container is preferably an ampoule type or a cylindrical type as long as the whole is made of the same material. When a part of the container is made of the same light metal as the molten metal, the body is cylindrical and both bottom surfaces are the same as the molten metal. The body is made of, for example, iron, and a pipe for vacuum evacuation is welded to this, and a different material is sealed in a container and melt-fused in a state of vacuum evacuation to seal the pipe. When joining the body and the bottom surface when using different materials, configure both bottom parts into a dish and press fit into the body, or attach a flange to the body and attach the bottom material with a gasket (packing). The lid can also be bolted to the flange or screwed. An adhesive may be used as a supplement. However, when the decomposed gas may lower the degree of vacuum inside the container when the adhesive is decomposed, it is better not to use the adhesive.

As the short fibers to be added, inorganic fibers such as silica, alumina, alumina silica, SiC and carbon fibers, or whiskers thereof can be used.
The size is 1 cm or less in length, preferably 0.5 cm or less, and the shorter one has no problem up to submicron.
When the length is 1 cm or more, the dispersion is possible, but the viscosity increase due to the entanglement becomes large, the fluidity becomes poor at the time of casting, and it becomes substantially impossible to contain a large amount of the reinforcing material. When it is desired to contain a large amount of fibrous reinforcing material, a preform is first formed and then impregnated with a squeeze. As the granular powder, alumina, SiC, alumina silica, aluminum nitride, boron nitride, tungsten carbide, spinel or the like can be used. It is appropriate that the particle size is in the range of 0.1 μm to 3000 μm, and if it becomes fine powder from 0.1 μm, it may float partly, and the viscosity may increase and castability may be poor. become. If it is more than 3000 μm, the uniformity of the composite material will be problematic. Some of these dissimilar materials react with magnesium, and in that case, a few percent of calcium may be added to the molten metal. The maximum content of these different materials is 35% by volume, and it is difficult to fill more than this.

As a method of improving the wettability between these different materials and the molten metal, a method of adding calcium to the molten metal is known. In addition to Ca, Bi, Sn, Cd, Sb, I
n, Ba, Sr, Ra, Ti, Cr, Mg, V, Zr,
Nb, Mg, Li, Ce, Be or the like may be added (JP-A-57-169033, JP-A-57-16).
9034, JP-A-60-159137, JP-A-60-194039 and the like). Further, once a dissimilar material such as ceramics is immersed in a solvent such as alcohol, the bulkiness is reduced and the wettability and dispersibility with the molten metal tend to be improved. The kind and size and amount of different materials to be dispersed, the kind of wetting improver, etc., and the degree of effectiveness can be easily judged by visually observing the state of the molten metal, so preliminary evaluation is possible. The applicable range may be determined. The matrix material, the size and content of different materials to be added and dispersed, the type of wetting improver, etc. can be selected easily by visually observing the state of the molten metal. The applicable range may be determined from.

[0015]

According to the present invention, the following industrial advantages can be achieved. (1) Since the container filled with different materials is simply put into the molten metal, the existing melting equipment can be used as it is. (2) Since the dissimilar materials are uniformly dispersed, it is possible to greatly improve the characteristics of the composite light metal material. (3) The present invention can be generally applied regardless of the kind of the wetting improver, the matrix material, and the different materials to be added and dispersed. As a result, it is not necessary to select a special material according to the required performance of the parts, but it is possible to meet the required performance by adding different kinds of materials required for general mass production materials, and it is possible to reduce costs accordingly. , The scope of application is expanded. (4) Since mass production is easy and the characteristics are improved as compared with conventional light metal materials, it is possible to replace iron material parts with composite light metal parts. As a result, for example, it is possible to reduce the weight of a vehicle and improve fuel efficiency.

[0016]

【Example】

(Examples 1 and 2) Alumina powder was weighed so that the alumina content was 12% by volume of the molten metal, and the alumina powder was filled in a cylindrical container having both ends screwed as shown in FIG. In the container shown in FIG. 1, the body 2 is made of iron, and the outer surface and the inner surface are coated with titania. Lids 4 and 6 inwardly threaded with an aluminum alloy having the same composition as the molten metal were formed so as to close both openings of the cylindrical body, and screwed with a pyrene to seal. An exhaust port 8 of an iron tube connected to a vacuum pump is welded to the body portion 2 in advance, and a handle 10 is welded to the body portion 2. Two types of alumina powder having a particle size of 4 μm (Example 1) and 7 μm (Example 2) (both are products of Sumitomo Chemical Co., Ltd.) were used. After filling and exhausting the inside of the container from the exhaust port 8 with a vacuum pump, it was fused and the exhaust port 8 was sealed. Reference numeral 12 represents the enclosed alumina powder. Since the specific gravity of the filled alumina powder was about 1.3, the thickness of the iron in the body 2 was about 6
It was made to be able to be completely immersed in the molten metal as mm.

Separately, calcium was added to the aluminum alloy AC8A so as to be 2% by weight and melted. The molten metal (alloy weight 1.0 kg) was charged into the above-mentioned container filled with alumina. At this time, the temperature of the molten metal was 740 ° C., and both bottom surfaces 4 and 6 of the container melted in about 20 minutes after being charged,
The molten metal entered the container. Body 2 with handle 10 in molten metal
By shaking, the alumina was made to fit into the molten metal, and the body 2 was pulled up. After that, the molten metal was stirred with a stirrer and cast into an ingot. This molten metal had no bad fluidity, all of the molten metal could be cast into an ingot, and the effect of adding calcium as a wetting improver was that alumina was uniformly dispersed.

(Comparative Examples 1 and 2) Composite alloys were prepared in the same manner as in Examples 1 and 2. However, alumina was added and dispersed as follows, without using the container as shown in FIG. That is, while agitating the molten metal at 100 rpm, a predetermined amount of alumina was gradually added to the molten metal over a period of about 5 minutes and added, and cast into an ingot. However, a part of the molten metal had a poor fluidity and remained in the crucible, and its weight was about 9% in Comparative Example 1 using alumina having a particle diameter of 4 μm, and alumina having a particle diameter of 7 μm was used. In Comparative Example 2, which was about 7.5%.

Example 3 Magnesium alloy AZ91 was further mixed with 4.9% by weight of calcium and 5% by weight of zinc and blended to obtain a molten metal which does not burn even in the air, and a particle diameter of 1 μm for polishing instead of alumina. A molten metal was prepared in the same manner as in Examples 1 and 2 except that the silicon carbide of Example 1 was added as a different material, the addition amount was 20% by volume, and the temperature of the molten metal was 700 ° C. As in the results of Examples 1 and 2, all the melts had good fluidity, could be cast into ingots, and silicon carbide was uniformly dispersed. In this embodiment, the body 2 of the container for enclosing silicon carbide is made of iron, and the lids 4 and 6 for closing both openings of the body are made of magnesium alloy having the same composition as the molten metal.

(Comparative Example 3) By the same method as shown in Comparative Examples 1 and 2, a melt of a composite alloy having the same composition as shown in Example 3 was prepared. However, the fluidity was poor, and the weight remaining in the crucible was about 13%. (Example 4) As a container for separating different materials from air and charging them into a molten metal, for example, as shown in FIG. 2, the whole is formed into a capsule shape made of a molten metal component or a material of a main component of the molten metal component. Then, a heterogeneous material 12 such as ceramics powder may be filled in the inside thereof, and the exhaust port 16 connected to the vacuum pump may be melted and blown to make the inside of the container into a vacuum state and sealed. Since some parts of this container may float on the surface of the molten metal when it is poured into the molten metal, it may be placed in a basket made of stainless steel or the like and forcibly submerged in the molten metal.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a container used for adding different kinds of materials to a molten metal in Examples.

FIG. 2 is a cross-sectional view showing another example of a container used for adding different materials to a molten metal in Examples.

[Explanation of symbols]

 2 Body of container 4,6 Bottom of container 8,16 Exhaust port 10 Handle 12 Alumina powder

Claims (5)

[Claims] 1. A method of adding a heterogeneous material to a melt of a light metal material to obtain a composite light metal material melt, enclosing the heterogeneous material in a container having at least a part of the melt component and having a vacuum exhaust port, After exhausting from the vacuum exhaust port to evacuate the inside of the container, the container is submerged in the molten metal with the vacuum exhaust port sealed, and dissimilar materials in the container are dispersed in the molten metal. Manufacturing method of composite light metal material. 2. The composite light metal material according to claim 1, wherein a part of the container is made of a molten metal component or a main component of the molten metal component, and the other part of the container is made of a material having a higher melting point than that. Production method. 3. The method for producing a composite light metal material according to claim 1, wherein the specific gravity of the container is higher than the specific gravity of the molten metal in the state where the different material is filled in the container. 4. The method for producing a composite light metal material according to claim 2, wherein the container is provided with a handle for moving the container from the outside of the molten metal. 5. The container is entirely composed of a molten metal component or a main component of the molten metal component, and after the container is filled with the different material, the container is forcibly submerged in the molten metal. Item 2. A method for manufacturing the composite light metal material according to Item 1.