JPH07138675A - Process and apparatus for production of oxide particle dispersed composite material - Google Patents

Abstract

PURPOSE:To provide the composite material applicable to members for which high strength, high wear resistance and high heat resistance are required by blowing oxygen to molten metal or solid-liquid coexisting material while stirring this molten metal or material, and then forming the oxide particles of a base phase metal. CONSTITUTION:Oxygen is blown from a hole bored in a revolving shaft of a stirrer to oxidize base phase metal elements, while the molten metal or the molten metal contg. a solid phase is kept stirred by using this stirrer. The high rotation, wide area and high shearing strength of the stirrer disperse the oxides uniformly into the molten metal. As a result, the oxide particles of the base phase metal or the multi component oxide particles mainly consisting of the oxides of the base phase metal are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an oxide particle composite material (metal or alloy) which can be applied to any member requiring high strength, high wear resistance and high heat resistance, and its production. It relates to the device.

[0002]

2. Description of the Related Art (A) Powder metallurgy method and (B) molten metal method have been already developed as methods for producing oxide particle-dispersed composite materials (metals or alloys). It has not been put to practical use except for special uses that ignore sex. That is, in (A) powder metallurgy, (1) a method of mixing metal or alloy powder and oxide particles, pressing and then sintering, and (2) pressing metal or alloy powder having an oxide surface coating. After that, there is a method of hot extruding, but each has the following drawbacks. (A) The powder manufacturing cost is high. Moreover, the manufacturing process of parts is complicated, and the total manufacturing cost is significantly increased. (B) In the powder, foreign matters are often mixed, and the chemical change of the powder surface is likely to occur. (C) The powder is contaminated due to the wear of the equipment for mixing the powder. (D) The mechanical strength is low because there are many internal defects.

In the (B) molten metal method, (1) oxide particles are placed on the surface of a molten metal in a molten state or a solid-liquid coexisting state of a metal or alloy, and stirred to disperse the oxide particles inside the molten metal. Method and (2) a method of blowing oxygen while stirring a molten metal or a solid-liquid coexistence body containing a base element to oxidize the base metal to generate and disperse oxide particles (JP-A-4-9437). Gazette). The molten metal method does not have the drawbacks of the powder metallurgy method. However, the dispersion strengthening, abrasion resistance and heat resistance are higher as the volume ratio of the dispersed particles is smaller, the diameter of the particles is smaller, the dispersity of the particles is larger, and the interfacial strength between the particles and the dough is larger. Become effective. Therefore, the method (1) has the following drawbacks. (A) The dispersion state of oxide particles is not so good. (B) The smaller the particle size of the oxide particles, the more difficult it becomes to mix with the molten metal, and even if they are mixed, the dispersity is very poor. (C) When the particle size is large, the wear resistance is improved,
Mechanical strength does not increase. (D) Additives must be selected because the interfacial strength does not increase even if oxide particles are simply mixed. Next, the method (2) is a method in which a base metal element is alloyed in a noble metal melt, and only the base element is converted into an oxide by blowing oxygen, and the present invention is the principle. Is completely different.

[0004]

The conventional method and its drawbacks relating to the method for producing the oxide particle-dispersed composite material have been described above.
It is an object of the present invention to eliminate these drawbacks. The important points are listed below. (1) Raw materials and manufacturing equipment are inexpensive. (2) The material manufacturing process is simple and the manufacturing cost is low. (3) To provide a material having not only mechanical strength but also excellent wear resistance and heat resistance by uniformly dispersing fine oxides. (4) Parts can be manufactured with near net shape without requiring much machining. (5) The heat treatment can strengthen the dough in the material without destroying the oxide dispersion strengthening.

[0005]

[Means for Solving the Problems] As a manufacturing method of the present invention,
Of a dispersed composite material (metal or alloy) in which oxygen is blown into a molten metal or solid-liquid coexistent while stirring to generate oxide particles of a matrix metal or composite oxide particles mainly containing an oxide of a matrix metal It is a manufacturing method. The apparatus of the present invention includes a container for molten metal or solid-liquid coexisting body, a stirrer rotatable in the container, and a gas inlet and a gas inlet for blowing oxygen gas into the liquid phase in the container. Equipped with,
The gas is blown through a hole formed in the rotary shaft of the stirrer to blow gas into the liquid phase and to effectively shear the molten metal, so that the area facing the stirrer and the container is widened. It is an apparatus for producing an oxide particle-dispersed composite material.

Here, as the metal serving as the matrix phase, all metal materials are targeted, but in particular, either aluminum or magnesium or an alloy thereof is effective for the present invention. These alloys are all practical aluminum alloys as well as all practical magnesium alloys.

The physical and chemical conditions for performing the above-mentioned oxidation to generate and disperse the oxide and the conditions that the apparatus should have are as follows. (1) To oxidize the entire melt, blow oxygen gas to the bottom of the melt. In particular, a rotating stirrer should be placed at the bottom of the melt, and the bottom of the stirrer should have an oxygen gas outlet. (2) In order to prevent the agglomeration of the oxide, the distance between the stirring bar and the inner wall of the container is made small, and a large shear strain is applied to the molten metal containing the oxide. In addition, the surface where the stirrer and the container face each other should be large so that the shearing area becomes large. (3) As long as the molten metal does not overflow from the container by centrifugal force, the shearing action increases as the rotating speed of the stirrer increases, so that the rotating speed can be controlled. (4) The temperature inside the container must be equal to or higher than the melting temperature of the metal or alloy or the solid-liquid coexisting temperature. (5) Since the amount of oxide produced depends on the oxidation time or the amount of oxygen blown, it is possible to control the oxygen gas blowing rate.

[0008]

[Function] With the metal or alloy melted, a stirrer is inserted into the container to start stirring. While stirring, oxygen is blown into the molten metal to oxidize the matrix metal elements. In the case of an alloy, if the affinity of the alloying element with oxygen is the same as that of the matrix metal element, a composite oxide of the oxide of the matrix metal and the oxide of the alloy element is formed. When producing an oxide-dispersed alloy, the alloying element may be added during or after the oxidation without using the alloy from the beginning of melting.

In this stirring, a sufficiently fast rotation of the stirrer breaks the oxygen bubbles blown from the bottom of the stirrer into fine bubbles to form fine oxides. The sufficiently fast rotation of the stirrer and the large area and strong shearing disperse the oxide uniformly in the molten metal. This shearing occurs in the molten metal between the stirrer and the container, destroys the agglomeration of the oxide, and helps the uniform dispersion of the oxide. When the oxidation is complete, normal casting can be done using a sand mold or mold. However, if the volume ratio of the generated oxide to the molten metal is large, or if the volume ratio of the oxide and the solid phase generated in the solid-liquid coexisting body to the liquid phase is large, the viscosity of the molten metal becomes high, so pressure is applied. A new casting method is required.

[0010]

The present invention will be described in detail below with reference to its examples.
FIG. 1 shows an apparatus used in an embodiment of the present invention, in which 1 is a container, the inner wall of which is formed in a concavo-convex shape so that the surface facing the stirrer is wide. There is a notch. Reference numeral 2 is a stirrer having two multi-stage blades facing the irregularities of the inner wall of the container. The stirrer can be removed from the container by passing through the cut by rotating the blades of the stirrer 90 degrees. The container 1 and the stirrer 2 may be made of any material that does not react with the molten metal and has sufficient strength to stir the molten metal. In the figure, 3 is a rotary shaft having an oxygen gas passage in the center, 4 is an oxygen gas inlet, 5 is an oxygen gas inlet, 6 is an upper bearing, 7 is a lower bearing, and 8 is a belt for transmitting rotation from the transmission. The car, 9 is the surface of the molten metal.

Experiments were conducted using the above-mentioned apparatus and the following eight kinds of materials. That is, (1) pure aluminum, (2) 1
An aluminum alloy containing ~ 6 wt% magnesium,
(3) Aluminum alloy containing 12 wt% silicon,
(4) Aluminum alloy containing 6 wt% magnesium and 1 wt% silicon, (5) Aluminum alloy containing 5 wt% copper and 1 wt% magnesium, (6) Pure magnesium (7) Magnesium alloy containing 10 wt% aluminum (8) A magnesium alloy containing 8 wt% aluminum and 1 wt% zinc.

Melting, stirring, oxidizing and casting were performed using the above metal or alloy, but the conditions were all the same and were as follows. (A) The dissolved amount was 270 g. (B) The melting temperature was 700 to 1000 ° C., and the melting was carried out in an argon atmosphere. (C) After the melting, the stir bar is immersed in the molten metal, and 300 to 100
The molten metal was stirred at a rotation speed of 0 rpm. (D) Simultaneously with the start of stirring, oxygen gas is blown into the molten metal at a rate of 10 cc to 50 cc / min in the aluminum alloy, and 500 cc per minute in the magnesium alloy.
A mixed gas of argon gas and 1 to 100 cc oxygen gas was blown into the molten metal to oxidize the molten metal. (E) Oxidation time was 0.5 to 3 hours. (F) After the oxidation was completed, it was cast in an iron mold at 200 ° C.

The results obtained are summarized as follows. (A) All the samples were sound with no cracks. (B) No void (or void) was observed with an optical microscope. It was confirmed by optical microscope observation and chemical analysis that the amount of (C) oxide increased with the increase of oxidation time and oxygen gas. It was confirmed by electron microscope observation that the oxide particles (D) were fine with an average diameter of 3 μm and were dispersed uniformly. (E) Particularly containing aluminum and magnesium (2),
In the alloys (4), (5), (7) and (8), the degree of dispersion of oxide particles was extremely high. This is because the spinel type composite oxide of aluminum oxide and magnesium oxide identified by X-ray analysis was formed. The volume ratio of (F) oxide particles is about 30 in the alloy of (2).
%, And the hardness was twice as high as the hardness before oxidation. That is, it shows that the oxide dispersion has an extremely large effect on the improvement of the mechanical strength. (G) By heat treatment after casting (4),
The alloys of (5), (7) and (8) showed age hardening.

Although the present invention has been described in detail with reference to specific embodiments relating to a light metal material, the present invention is not limited to these, and various embodiments are possible within the scope of the present invention. Is clear.

[0015]

As described above, according to the manufacturing method of the present invention, the mechanical properties, wear resistance and heat resistance of a metallic material are improved, and the apparatus of the present invention has a simple structure and oxide particles. Very useful for the production of dispersed composites (metals or alloys).

[Brief description of drawings]

FIG. 1 is a sectional view of an apparatus used in an embodiment of the present invention.

[Explanation of symbols]

 1 Container 2 Stirrer 3 Rotating Shaft 4 Oxygen Gas Inlet 5 Oxygen Gas Inlet

Claims (2)

[Claims] 1. A method of blowing oxygen into a molten metal or a molten metal containing a solid phase while stirring to generate oxide particles of a matrix metal or composite oxide particles mainly containing an oxide of a matrix metal. And a method of manufacturing a dispersed composite material. 2. A container for molten metal containing a molten metal or a solid phase, a stirrer rotatable in the container, and a gas inlet and a gas blowing port for blowing oxygen gas into the liquid phase in the container. In order to blow gas into the liquid phase and effectively shear the molten metal, the area facing the stirrer and the container is widened by performing the gas blowing through the hole formed in the rotary shaft of the stirrer. An apparatus for producing an oxide particle-dispersed composite material, which has a shape.