JPH0421731A - Manufacture of al or al alloy matrix composite and device therefore - Google Patents

Abstract

PURPOSE:To manufacture an Al material matrix composite in which particles are uniformly dispersed by pouring ceramic particles into the molten metal of an Al material while this molten metal is mechanically convected, simultaneously generating a turbulent flow and, by its shearing force, increasing the wettability of the particles and the molten metal. CONSTITUTION:An Al alloy is melted in a crucible 1 and is set in a chamber 7, and a guide cylinder 2 in which the inside face is provided with annular ruggedness 2b is inserted into the crucible 1, and joining is executed by a flange 2a. Next, a rotary shaft 6 fitted with a propeller 4 and a fin 3 is inserted into the guide cylinder 2 and is rotated. The molten metal 11 is flowed into the crucible 1 from the lower end of the guide cylinder 2, and the raised molten metal 11 is circulated in the guide cylinder 2 via a hole 10. Then, its rotating speed is increased while SiC particles are intermittently charged to the guide cylinder 2. After the whole quantity of the SiC particles is charged, a cap 8 is set on the chamber 7, and its rotating speed is increased as deaeration is executed via a deaerating pipe 9 to uniformly disperse the SiC particles into the molten metal 11. After the stirring is finished, the molten metal 11 is cast in a mold, by which the Al alloy matrix composite in which the SiC particles are suitably dispersed can be obtd.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method and method for producing an Al or Al alloy matrix composite material in which Al or an Al alloy is used as a matrix and ceramic particles or ceramic whiskers are dispersed as a reinforcing material. It is related to the device.

[Prior Art] Al and Al alloys (hereinafter referred to as Al alloys) have the characteristics of being lightweight and having high specific strength.

However, since they are generally soft and have poor heat resistance and abrasion resistance, their field of application has been severely limited. However, recently, fine ceramic particles or ceramic whiskers (hereinafter sometimes referred to as ceramic particles) have been dispersed in Al alloys as reinforcing materials, and Al alloys have improved physical properties such as strength, rigidity, heat resistance, and wear resistance. Alloy composite materials have been developed and are expected to significantly expand their application fields.

However, when producing Al alloy matrix composite materials,
Since there is a problem of poor wettability between the molten Al alloy and the ceramic particles, the expected dispersion effect cannot be obtained by adding the ceramic particles into the molten Al alloy and stirring it in a car. Therefore, as an alternative to the method of stirring and mixing using molten Al alloy, the following methods 1 to 2 have been used.

■Powder metallurgy method in which Al alloy powder and ceramic particles are mixed and then molded under high temperature and pressure.■Al alloy is brought into a semi-molten state (that is, a state in which liquid and solid phases are mixed), and ceramic particles are mixed while stirring. Compocast method, which involves mixing; ■ Squeeze cast method, which involves making a preform from ceramic particles and injecting molten Al alloy into it.

[Problems to be Solved by the Invention] However, each of the above methods (1) to (3) has the following problems. First, according to the method (2) above, the manufacturing process becomes complicated because the Al alloy needs to be powdered and a molding device is required, which increases the manufacturing cost of the composite material. Its uses are limited. In addition, method (1) requires sophisticated temperature control, and method (2) requires a high-precision pressurized injection mechanism, which is a drawback in terms of production equipment.

Therefore, the method of adding and stirring ceramic particles into molten Al alloy was reconsidered, and in order to improve the wettability between the molten metal and ceramic particles, plating was applied to the particle surface, and Developing a new composition is being considered. However, there are problems in that the production cost increases due to the plating process and that the Al alloy composition is specified and lacks versatility.

The present invention has been made to solve these technical problems, and the purpose is to produce aluminum in a relatively simple process without plating or developing an Al alloy composition to improve wettability. A method for producing an alloy matrix composite material,
and manufacturing equipment.

[Means for solving the problem] The method of the present invention that achieves the above object is based on Al or A
l In producing alloy matrix composite material, A] or A]
While mechanically convecting the molten alloy, ceramic particles or ceramic whiskers are introduced into the molten metal, and in order to apply shear force to the molten metal by creating turbulence, the molten metal undergoing convection is repeatedly bent. This is a method for producing an Al or Al alloy composite material, the gist of which is to improve the wettability of the particles or whiskers and the molten metal and uniformly mix them by advancing the process.

In addition, as a device for carrying out the above method, Al or A
1 An apparatus for producing an alloy matrix composite material, comprising means for mechanically convecting Al or Al alloy molten metal, and for applying shearing force to the molten metal by creating turbulence,
A structure is proposed that includes means for advancing the molten metal so as to bend the molten metal repeatedly.

[Function] The present invention is constructed as described above, but in short, it includes a means for mechanically convecting the molten Al alloy, and a means for bending the molten metal in order to apply shear force to the molten metal by creating turbulent flow. It is possible to improve the wettability between the molten alloy and the ceramic particles using only a relatively simple mechanical mechanism that includes a means for advancing the ceramic particles. It was possible to produce an Al alloy matrix composite material by directly mixing ceramic particles into molten metal without developing the composition. In other words, by creating turbulence in the molten metal, a strong shearing force is applied, increasing the collision force of the molten metal against the ceramic particles, thereby increasing the wettability between the ceramic particles and the molten metal.

The structure, action, and effect of the present invention will be explained in more detail with reference to Examples below. However, the following Examples do not limit the present invention, and any design changes for the purpose of the above and below are within the scope of the present invention. It is within the technical scope of the invention.

[Example] Fig. 1 is a schematic explanatory diagram showing an example of an Al alloy matrix composite material production apparatus according to the present invention, in which 1 is a crucible, 2 is a guide cylinder, and 3 is a sintered body having tapered surfaces 3a on the top and bottom. Ball-shaped fin, 4 is a propeller with two twisting blades on the top and bottom, 6
7 is a rotating shaft, 7 is a chamber, 8 is a lid, 9 is a degassing pipe, 10 is a through hole provided intermittently in the circumferential direction on the upper circumferential surface of the guide cylinder 2, 11 is a molten metal, and 12 is a shaft of the rotating shaft 6. Each bearing is shown.

Using the manufacturing equipment shown in Figure 1, S
An iC particle reinforced (volume fraction 20%) 2024Al alloy matrix composite material was produced.

After melting 1,300 g of 2024Al alloy as a matrix in the crucible 1 (pre-installed with a disc-shaped bearing 12) in the apparatus of the present invention installed in a nichrome wire electric furnace (not shown), It was kept at ℃. After the melting was completed, the guide cylinder 2 having an annular unevenness 2b on its inner surface was inserted into the crucible 1. This guide cylinder 2 is provided with an outward flange 2a at the top, and this flange 2a is joined to the upper end of the crucible 1, so that the guide cylinder 2 can be stabilized in an appropriate position simply by inserting it into the crucible 1. It has a structure. Of course, a fixing structure may be provided on the upper surface of the crucible 1 to ensure stable holding.

Next, a propeller 4 for applying propulsive force to the molten metal 11 to cause convection and an inner circumference of the guide cylinder 2 are attached to the molten metal 11 along the uneven surface.
A rotary shaft 6 equipped with fins 3 for imparting shearing force to the molten metal by causing turbulent flow was inserted into the guide cylinder 2. The rotating shaft 6 is connected to a variable speed conductor (not shown) outside the furnace, and
It was configured to rotate in the direction of the arrow within a range of ~1500 rpm. As a result, a downward driving force is applied to the molten metal 11 in the guide cylinder 2, and the molten metal 11 swept downward through the guide cylinder 2 enters the crucible 1 from the lower end of the guide cylinder 2 and rises inside the crucible 1. . The molten metal 11 that has reached the through hole 10 then enters the guide cylinder 2 through the through hole 10, forming a circulating flow in the same manner.

Further, the propeller 4 is set to be located between the lower end of the through hole 10 and the upper end of the annular uneven part 2b of the guide cylinder 2, and is rotated so that the fin 3 fits into the recess of the uneven part 2b. The insertion depth of shaft 6 was set.

After inserting and positioning the rotating shaft 6 to which the propeller 4 and fins 3 were attached, rotation of the rotating shaft 6 was started. The rotational speed at this time was set to 500 rpm from the viewpoint of the minimum value necessary for convection of the molten Al alloy in the crucible 1.

After the convection of the molten metal 11 was started, 10 g of SiC particles having a particle size of 5 μm were intermittently introduced into the guide cylinder 2, so that the final amount introduced was 350 g. Furthermore, the SiC to be introduced at this time
The particles used were preheated by holding at 700° C. for 30 minutes. In addition, the procedure for introducing SiC particles is such that after the previously introduced SiC particles are completely engulfed in the molten metal, the next 10 g of SiC particles are introduced one after another, resulting in a situation where the SiC particles remain suspended on the surface of the molten metal for a long time. I tried not to.

It took 15 minutes until the entire amount of SiC was added.

The viscosity of the molten metal 11 tends to increase as the amount of SiC particles added increases, resulting in poor fluidity and difficulty in generating convection. Therefore, as the total amount of SiC particles added increased, the rotational speed of the rotating shaft 6 was increased to increase the driving force applied to the molten metal 11. However, if the rotation speed is increased too much, a vortex will be formed between the molten metal 11 and the rotating shaft 6, causing the molten metal 11 to
Since the atmosphere may be drawn in, it is necessary to gradually increase the rotational speed of the rotating shaft 6 according to the amount of particles input.

After charging the entire amount of SiC particles, the lid 8 is placed in the chamber 7.
was set, and the inside of the chamber was degassed via the degassing vibrator 9 to create a vacuum atmosphere of 10-27 orr. At the same time as the deaeration, the rotational speed of the rotating shaft 6 is increased to 1500 rpm,
Convection and stirring were continued for 15 minutes. At this time, Si
The air that has been somewhat trapped in the molten metal 11 along with the C particles is removed from the system, while the particles trapped in the molten metal 11 repeat convection within the crucible 1 and move between the fins 3 and the guide circle WJ2. The melt progresses as if repeatedly bent between the fins 3 and is stirred turbulently.
A shearing force is applied to the molten metal 1 and the molten metal 11 is uniformly dispersed.

After finishing the stirring under degassing, the lid 8, rotating shaft 6, and guide cylinder 2 are removed, the crucible 1 is taken out of the apparatus, and the obtained SiC particle-reinforced 2024Al alloy molten metal is cast into a mold and solidified. Molded. The obtained Al alloy matrix composite material is S
The wettability of iC particles and Al alloy is improved, and SiC
It had a structure in which the particles were moderately dispersed in the Al alloy matrix.

In the above example, SiC particles were used as the reinforcing agent and 2024Al alloy was used as the matrix Al alloy, but the materials used in the present invention are not limited to those mentioned above, and examples of the reinforcing material include TiC, ZrC, etc. particles and whiskers, and pure Al as a matrix Al alloy.
Of course, for example, 6061Al alloy and 7075Al
Various Al alloys such as alloys can be used.

In the manufacturing apparatus shown in FIG. 1, the fin 3 has a tapered surface 3a.
However, this shape is not limited to that shown in FIG. 1 as long as it applies shearing force while stirring the molten metal 1. For example, as shown in FIG. 2, the shape of the fin 3 may be configured to have a horizontal surface 3b.
The fins 3 may have a disc shape, a number of rods protruding radially, or various other modifications. In addition, Figure 2 shows the crucible 1. Main parts near the guide cylinder 2 and rotating shaft 6 are shown,
Other parts are omitted (the same applies to FIGS. 3 to 7 described below). Also, if the fin 3 has a disc shape as shown in FIG. Since the guide member 2 cannot be inserted into the guide cylinder 2, the guide member 2 is made into a half-split shape, and after the rotating shaft 6 is inserted into the guide member 2, the guide cylinder 2 is assembled into one body using a joining means such as a flange (not shown). All you have to do is match it.

Although the fins 3 are shown in two stages in FIGS. 1 and 2, the number of fins 3 is not limited to these. For example, as shown in FIG. 3, four stages may be formed. or even more.

Increasing the number of stages of the fins 3 increases the number of bends of the molten metal 11, which is preferable in principle, but in a small-scale device, the flow path of the molten metal 11 may become too narrow and cause clogging. There is. However, this problem can be corrected to some extent by increasing the size of the device or by devising a way to apply a strong downward propulsive force to the molten metal 11. Further, as shown in FIG. 4, the outer diameter of the fin 3 may be made to gradually increase as it goes downward. In this case, as shown in FIG. 4, the shape of the uneven portion 2b inside the guide cylinder 2 may be made to correspond to the shape of the fin 3, or as shown in FIG. The configuration may be such that the circumferential surfaces of the two circumferential surfaces gradually approach each other. however,
When adopting the configuration shown in Fig. 5, there may be places where sufficient turbulence does not occur and ceramic particles tend to stagnate (for example, parts A and B). As shown in FIG.
A configuration that reduces the number of recesses has also been proposed. Furthermore, molten metal 1
From the viewpoint of improving the downward flow of the guide cylinder 2, a configuration in which a tapered surface 15 is formed on the uppermost surface of the uneven portion of the guide cylinder 2 as shown in FIG. 7 is also exemplified.

FIG. 8 is a schematic explanatory diagram of still another embodiment of the present invention. In the embodiments shown in FIGS. 1 to 7, the fins 3 and propeller 4 are used to convect and stir the molten metal, but in this embodiment, a screw 20 is provided, and the same effect is achieved by this screw 20. are doing. The screw 20 attached to the rotating shaft 6 is formed in a tapered shape such that its outer diameter decreases as it goes downwards (toward the tip), and the guide cylinder 2 is also formed in a correspondingly tapered shape. Further, the screw 20 is configured to be able to move arbitrarily in the axial direction (vertical direction in FIG. 8), so that the clearance between the screw 20 and the guide cylinder 2 can be adjusted arbitrarily. When the molten metal 11 is introduced and the screw 20 is rotated, the molten metal 11 moves downward within the guide cylinder 2 due to the thrust of the screw 20, and convection occurs from below the guide cylinder 2 through the outer periphery and returns upward again. At this time, a flow velocity difference occurs in the molten metal in the clearance between the screw 20 and the guide cylinder 2, and a shearing force acts, and when ceramic particles or whiskers are introduced, they are dispersed appropriately.

In this embodiment, the clearance can be adjusted arbitrarily, so the shearing force can be adjusted as appropriate.

It is also recommended that the structure of the manufacturing equipment be designed to allow for internal pressurization.For example, if high pressure gas is introduced from the high pressure gas introduction vibrator 21 to pressurize the inside of the equipment, the dispersion of ceramic particles into the molten metal will be further promoted. be done. In FIG. 8, reference numeral 22 indicates a bearing for maintaining airtightness while maintaining rotation of the rotary shaft 6, and reference numeral 23 indicates a heating furnace for heating the crucible 1.

FIG. 9 shows another experimental example of the present invention, in which a pair of fully meshing screws 20a and 20b are installed in the crucible 1. Screws 20a, 20 in this experimental example
b rotates in a different direction. Although the screws 20a and 20b can be configured to rotate in the same direction, the sealing performance is better when they rotate in different directions. The cross section of the crucible has a binocular shape corresponding to the screws 20a, 20a. Therefore, the space 27 formed by the screws 20a, 20b and the inner wall of the crucible 1 becomes a C-shaped space that is isolated from the outside, and one space 27 is formed for each pitch of each screw. Screw 20a.

The molten metal (including ceramic particles) that has entered one C-shaped space at the base of 20b (upper part in Fig. 9) flows through the screws 20a and 2 without being mixed with the molten metal that has entered other spaces.
It is sent to the tip of 0b (lower part in Fig. 9). The flow path 28 through which the molten metal 11 sent to the lower part of the crucible 1 moves when it convects upward after being released from the screws 20a and 20b is formed by, for example, a labyrinth-shaped resistance member 25 to increase the flow resistance. Ru. Therefore, the pressure below the crucible 1 becomes high, and the ceramic particles become easily dispersed in the molten metal 11. In the configuration shown in FIG. 9 as well, high-pressure gas may be introduced from the vibrator 21 to pressurize the inside of the apparatus, similar to the configuration shown in FIG. 8. It is also possible to adopt a configuration in which the pitch of the screws 20a, 20b decreases toward the tip (downward). That is, if such a configuration is adopted, the internal volume of the C-shaped space can be gradually reduced toward the bottom, and the pressure of the molten metal can be increased, thereby further improving the dispersion effect of the ceramic particles.

The manufacturing apparatus according to the present invention, for example, as shown in FIG.
It is also possible to adopt a configuration in which a pair of rotors 30a and 30b having a substantially elliptical cross-sectional shape perpendicular to the axis and being twisted is installed.

[Effects of the Invention] As described above, according to the present invention, ceramic particles or whiskers can be introduced into a molten metal by a method without polishing the surface of the ceramic particles or whiskers or changing the Al alloy composition. It has become possible to obtain an Al alloy matrix composite material in which these are appropriately dispersed.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram showing an example of an Al alloy composite material manufacturing apparatus according to the present invention, Figs. 2 to 7 are schematic explanatory diagrams showing various configuration examples near the fin 3, and Figs. FIG. 2 is a schematic explanatory diagram showing various configuration examples of an Al alloy composite material manufacturing apparatus according to the present invention. 1... Crucible 2... Guide cylinder 3...
Fin 4... Propeller 6... Rotating shaft
7... Chamber 8... Lid body
9... Degassing vibrator lO... Through hole
11... Molten metal 12... Bearing

Claims (2)

[Claims] (1) In producing Al or Al alloy matrix composite material, while mechanically convecting Al or Al alloy molten metal,
Ceramic particles or ceramic whiskers are introduced into the molten metal, and the molten metal in the convection is repeatedly bent to create turbulence, thereby applying shearing force to the molten metal, and using this shearing force, the particles Alternatively, a method for producing an Al or Al alloy composite material, characterized in that whiskers and the molten metal are uniformly mixed by increasing their wettability. (2) An apparatus for producing an Al or Al alloy matrix composite material, which includes means for mechanically convecting molten Al or Al alloy, and making the molten metal advance in a repeated bending manner to generate turbulent flow. Al or A characterized in that it is provided with means for applying shearing force to the molten metal.
l Alloy matrix composite material manufacturing equipment.