JPS63241103A - Method for solidifying powder of metal or the like - Google Patents

Abstract

PURPOSE:To solidity powder of a quickly cooled and solidified metal or the like without impairing the characteristics thereof by pressing the powder of the metal, etc., by using a pressing member and rotating the pressing member around the axis of rotation in the same direction as the powder pressing direction. CONSTITUTION:One open end of a cylinder 2 is hermetically closed by a piston 3 and the powder 4 of the amorphous metal or fine crystalline metal produced by a quick cooling and solidifying method, etc., is packed into the inside space of the cylinder 2 by a piston 3. A piston 1 is then fitted into the cylinder 2 from the open end thereof and the powder 4 is pressed by a pressing face 1' at the front end thereof and is compressed between said face and a receiving face 3' of the piston 3. The piston 1 is rotated around the pressing direction simultaneously with such pressing. The metal powder 4 is, therefore, plastically deformed by the deformation applied from the relative rotation of the receiving face 3' at the front end of the piston 3 while the internal friction heat is generated, by which the powder particles are joined to each other and the powder 4 is solidified at the crystallization temp. or below. The solidification of the powder 4 is thereby permitted without impairing the excellent properties possessed by the powder 4.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing products by solidifying powder such as metal. By mechanically solidifying powders such as metals that would otherwise lose their properties under relatively low-temperature conditions, it is possible to maintain the properties of the metal powders and turn them into products. This invention relates to a method for forming metals, etc., which makes it possible to create composites made by mixing alloys of metals and ceramic materials.

[Prior art] It is well known that amorphous metals or microcrystalline metals produced by rapid solidification methods have excellent physical properties such as heat resistance, abrasion resistance, surface hardness, tensile strength, and magnetic properties. If this metal is commercialized, it can be applied in a very wide range of fields. However, these metals have problems with heat resistance, and when heated above the crystallization temperature, for example, about 300°C or above in the case of aluminum, the amorphous or microcrystalline structure is destroyed, and the superior properties of these metals are destroyed. Physical properties are lost. Therefore, when making the metal into a product, a method that requires heating like the manufacturing method of general metal products,
For example, methods such as hot pressing or casting cannot be adopted, and thin film-like amorphous Si metals, which are generally used in solar cells, can be created by glow discharge methods, etc., but in the case of rod-shaped, plate-shaped, or even larger products. cannot be created in this way. Therefore, in order to commercialize amorphous metals or microcrystalline metals while maintaining their properties, it is necessary to form rapidly solidified powders of the metals by mechanical means that do not require high-temperature heating.

Conventionally, methods for solidifying metal powder include extrusion, rolling, and Japanese Patent Publication No. 57-2441 and Japanese Patent Publication No. 60.
There is a known method of producing green compacts by transporting powder through a powder passage formed between a fixed wall and a driving wall by the movement of the driving wall, and compressing the powder, as shown in Japanese Patent No. 14082. It is being

[Problem that the invention seeks to solve]

In the conventional extrusion and rolling methods described above, powder particles of metal, etc. are bonded together by pressurizing and compressing them under temperature conditions caused by heating and frictional heat to increase their density. That is. However, with this method, it is difficult to firmly bond powder particles at processing temperatures below the metal's crystallization temperature, hardening is severe, sintering treatment such as annealing is required, and amorphous metals and It is impossible to maintain the microcrystalline structure of metals and commercialize them using the rapid solidification method. In addition, especially when the powder particle surface is covered with a strong oxide film such as aluminum powder, simply increasing the density will not allow the oxide film on the particle surface to act as a barrier and strengthen the bond between the powder particles. It cannot be bonded to and solidified.

In this way, when an oxide film is formed on the surface of metal powder particles, the powder particles are plastically deformed to destroy the strong oxide film on the particle surface and remove the clean parts inside the particles. The particles can be solidified by exposing them to the surface and firmly bonding the particles together using the clean surface. However, it is difficult to completely destroy such an oxide film on the surface of metal particles by compression alone, and even if the oxide film can be partially destroyed, the remaining oxide film layer will remain on the original particle. If it remains on the surface, the bonding strength on the surface will still be weak, and even if sintering by annealing is performed after molding, the oxide film remaining on the surface will act as a barrier and inhibit the bonding between powder particles.
This causes a decrease in the strength of the entire product.

In conventional extrusion methods, in order to increase the ability to plastically deform particles and destroy oxide films, the ratio of the pressing area to the area of the extruded area during extrusion, the so-called extrusion ratio, is set to a large value. It is possible to increase the amount of deformation of the resulting powder particles, but when the extrusion ratio is set to a large value, the fluidity of the powder must be increased.For this reason, in actual extrusion processing, In the case of aluminum alloy, it is heated to around 550°C.

This is because at temperatures above 550°C, the properties of rapidly solidified powder are lost due to coarsening of precipitates, etc., but in the case of aluminum, crystal grains grow at temperatures above about 300°C, resulting in a fine crystal structure. However, extrusion is difficult at temperatures below 300°C, and the strength of the compact is weakened due to insufficient adhesion between powder particles. In order to improve the adhesion of the powder, processing is carried out at a temperature of about 550° C. at the expense of the microcrystalline structure.

Furthermore, in the methods described in Japanese Patent Publication No. 57-2241 and Japanese Patent Publication No. 6014082, the adhesion between powder particles is achieved by utilizing the frictional heat generated between the fixed wall and the driving wall and the powder. However, similar to the extrusion method and rolling method described above, this compression processing method does not plastically deform the metal powder particles to solidify the powder. It is difficult, and the problems mentioned above have not yet been solved.

In view of the above-mentioned problems, the present invention aims to produce a product of metals that tend to lose their properties when heated, such as amorphous metals or microcrystalline metals. By plastically deforming the particles, even if an oxide film or the like is formed on the surface of the metal powder particles, the particles can be bonded together and solidified to improve the surface strength and
The object of the present invention is to provide a method for forming a powder surface of metal, etc., which can produce metal products having excellent physical properties such as wear resistance, tensile strength, and heat resistance, and which can be widely applied.

[Means for solving problems]

In order to solve the above problems, the present invention presses powder such as metal with a pressing member and rotates the pressing member around a rotation axis in the same direction as the powder pressing direction to shear the powder. It is an object of the present invention to provide a method for solidifying powder of metal or the like, which is characterized by crushing by applying force.

[Effect]

The method for solidifying powder such as metal of the present invention is as described above,
Powder such as metal is compressed by pressing it with a pressing member to increase its density, and at the same time, by rotating the pressing member around a rotating shaft in the same direction as the pressing direction, the powder particles are subjected to shearing force and frictional heat. It is possible to plastically deform powder particles such as metals to firmly bond between them, and solidify the powder at a temperature below the crystallization temperature without destroying the microcrystalline structure of amorphous metals or rapidly solidified metals. be.

[Details of the invention]

Next, the present invention will be further explained based on illustrated concrete examples.

The method for solidifying powder such as metal according to the present invention is, for example, as shown in FIG.
The internal space of the cylinder 2 is filled with powder 4 of metal or a mixture of different metal powders, and the powder 4 is pushed into the piston 3 by pressing it with the pressing surface 1' at the tip of the piston 1 inserted from the open end of the cylinder 2. By compressing the metal powder 4 between the receiving surface 3° and rotating the piston 1 in the pressing direction, that is, the longitudinal direction of the cylinder 2, the metal powder 4 is compressed by the relative rotation of the receiving surface 3° at the tip of the piston 3. Due to the deformation applied from the powder, the powder particles are plastically deformed with internal frictional heat, and the powder particles are bonded to each other, and the powder is solidified. In this case, the pressing force by the piston 1 is between the powder 4 and the pressing surface l°
This increases the frictional force between the two and prevents slippage between the two.
A sufficient pressure is required to transmit the shear force necessary for plastic deformation. As for such pressurizing force conditions, preferably a pressure equal to or higher than [yield pressure of the metal powder used at the processing temperature x pressurized area] is required, but even a pressure of about 0.7 times the pressurizing force may be used. Although slipping occurs, there is no practical problem with the adhesion of the powder particles.Furthermore, by processing under such pressure conditions, the stress that would normally cause cranking is generated inside the powder compact. Even if this occurs, it is possible to prevent the occurrence of cranks and obtain a uniform solidified product. Also,
Even if an oxide film is formed on the surface of the powder particles of aluminum or the like, the shear force applied to the powder 4 from the pressing surface 1' of the piston 1 due to the rotation of the piston 1 as a pressing member The strong oxide film on the particle surface is destroyed,
A clean part inside the particle is exposed on the particle surface, and the particles can be firmly bonded to each other at the clean part. In addition, the plastic deformation of the particles of the powder 4 in this case is not only caused by compression due to the pressure of the piston 1; the shear force applied to the powder 4 is caused by the pressure of the piston 1, This is caused by the frictional force between the powder 4 and the receiving surface 3'' at the tip of the piston 3, which holds the powder against the pressure of the piston 1 with the other end closed, and the inner wall 2'' of the cylinder 2. The stroke 1 is not directly related to the shearing force applied to the powder, and may be a short stroke depending on the configuration of the device.

As described above, the method for solidifying powder such as metal of the present invention not only compresses the powder 4 and increases its density by applying pressure with the piston 1 as a pressing member (but also uses the piston 1 coaxially with the pressing direction). By applying shear force to the powder 4 by rotating the powder 4, the powder particles are plastically deformed between the pressing surface 1° of the piston 1 and the receiving surface 3' of the piston 3, and an oxide film is formed on the surface of the powder particles. Even when the oxide film is formed, the oxide film is destroyed and the internal clean part is exposed to enable strong bonding using the clean surface.In addition, the temperature conditions in this case include the shear force There is no need to heat the metal powder particles to a high temperature as it can assist in plastic deformation of the powder particles. It is possible to increase the fluidity of powder and solidify it efficiently, and it can be applied to various metals by appropriately setting conditions such as rotation, pressure, and temperature depending on the type of powder to be solidified. be.

Furthermore, as mentioned above, the method for solidifying powder such as metal according to the present invention involves applying shearing force to the powder under pressure above a certain level to plastically deform the powder particles and bonding the particles together. Even in the case of extrusion molding, there is no need to heat the powder to a high temperature to improve fluidity during extrusion, and various extrusion moldings can be performed under relatively low temperature conditions. For example, the example of the extrusion device shown in FIG. An opening communicating from the internal space of the cylinder 13 to the outside is formed in the cylinder 13 to serve as a powder supply hole 14 (FIG. 2(A)). The piston 11 has its rear end connected to a hydraulic cylinder (not shown) so that it can be moved under pressure within the cylinder 13, and the piston 11 is connected to a pulley p,
Drive means such as a motor (not shown) via a belt V etc.
The piston 12 is also connected to a hydraulic cylinder (not shown) so that it can be moved under pressure within the cylinder 13. To solidify powder using this device, first place the pistons 11 and 12 in the cylinder 13 so that their tip surfaces 11
', 12'' are provided in the cylinder 13. Powder supply hole 1
Powder 15 such as metal is fed into cylinder 1 from powder supply hole 14 by leaving an internal space S between 4 parts and facing each other.
Fill it within 3. Next, the piston 11 is pressed in the direction of the piston 12 and rotated by the driving means (FIG. 2 (a)), thereby compressing the powder 15 between the piston 11 and the piston 12 and rotating the piston 11. As a result, a shearing force is applied to the powder 15, and the powder particles are plastically deformed, thereby solidifying the powder 15. At this stage of solidification, pressure is applied to the piston 12 by a hydraulic cylinder associated with the piston 12 in opposition to the pressing force of the piston 11 to compress the powder 15 within the cylinder 13. If the pressure is made slightly lower than the pressure exerted by the piston 11, the powder will solidify and the solidifying powder 15 will be held between the pressing surface 11° of the piston 11 and the receiving surface 12° of the piston 12. When the powder 15 is solidified by moving it in the direction of the piston 12, the end face of the solidified material 15 on the pressing surface 11' side is located closer to the piston 12 than the position of the powder supply hole 14 in the cylinder 13. Figure 2 (c)).

In this state, if the piston 11 is moved backward from the position of the powder supply hole 14, the solidified powder 15" and the piston 11
A supply hole 14 is provided in the space S' formed between the pressing surfaces 11'.
Further powder can be fed into the cylinder 13 from.

By repeating the above operations (FIG. 2 (d) and (e)), the newly supplied powder 15 can be continuously solidified at the rear end of the already solidified powder 15. Moreover, the previously solidified portion 15" and the current solidified portion 15" are simultaneously kneaded with shearing force applied by the rotation of the piston 11, so that they are molded as one piece.By repeating the above operations in sequence, It is possible to form the powder 15 into a continuous long object (FIG. 2(f)).

Furthermore, since the method for solidifying powder such as metal of the present invention applies compression by pressing force to the powder as well as shearing force, the receiving side does not necessarily need to be closed with the piston 12 as shown in FIG. Instead, after the initial solidification stage is completed, in the next stage, as shown in FIG. By providing a nozzle 16 having a diameter of 15 mm, the pressure and rotational force of the piston 11 can be countered by the anti-deformation force and frictional force of the solidified powder 15'' near the outlet e, thereby eliminating the need for the receiving piston 12. By applying shear force to the powder, it is possible to solidify the powder, and it is possible to produce a continuous solidified product of 15 degrees as in ordinary extrusion molding.Also, as shown in Fig. 4, the inside of the nozzle 16 is formed with a two-stage tapered surface. and the first tapered surface A
The powder may be plastically deformed and extruded from the second tapered surface B. In the case shown in FIG. 3 or 4 above, the shape of the outlet e of the nozzle 16 can be made into a desired product shape. Furthermore, according to the present invention, powder particles are joined together by compressing the powder and applying shearing force, so that even when extrusion molding is performed, the internal cross-sectional area of the cylinder 11 and the cross-sectional area of the outlet are The ratio increases the frictional force between the powder 4 and the pressing surface 11° of the piston 11 by pressurizing the piston 11, prevents slipping between them, and provides the powder 4 with the shearing force necessary for plastic deformation. As a result, even if the powder has an oxide film formed on its surface, it can easily be plastically deformed and solidified by joining the powder particles, and it can also be hardened by bonding the powder particles, which would otherwise cause cracks. Even if stress is generated inside the powder, it is possible to prevent the occurrence of cranks.

Instead of the nozzle 16, as shown in FIG. 5, rollers 17 and 17 are provided to clamp the solidified powder solidified and extruded out of the outlet of the cylinder 13, and by applying a brake to the solidified material, the piston It is also possible to substitute 12.

In the case shown in FIG. 6, a rotating die 18 is provided at the outlet of the cylinder 13, and the rotation of the rotating die 18 causes the powder to be
5 is compressed and extruded by applying shear force, the solidified powder is given a very large deformation near the exit by the rotation of the rotating die 18, and can be extruded as a strong solid. By forming the two-step tapered surface A1B inside the nozzle 16 as shown in FIG. 7, it is possible to prevent the pressurizing force at the portion A from escaping from the outlet e to the outside. In the method shown in FIGS. 3 to 7, the outlet of the nozzle 16 or the rotary die 18 may be closed by appropriate means at the beginning of solidification.

The method shown in FIG. 8 is a method of applying hydrostatic pressure to the tip of the rotary die 18 to prevent the pressure applied to the portion A from escaping to the outside.

In addition, it is desirable to be able to control the temperature of the powder due to frictional heat or heating during the above operation depending on the metal powder used, especially for amorphous metals whose properties change greatly depending on temperature. Temperature control is important in these cases.

A solid sample was prepared by the method shown in FIG. 1 using pure aluminum with a purity of 99.9% and containing 95% of 250 meshes or more produced by the air atomization method as a raw material powder. The pressure applied by the pressing member was approximately 10 t/eta, and a solid aluminum material with a diameter of 25 m and a thickness of 5 days was applied by applying rotational shearing force of approximately 3 rotations per crane in an unheated state while maintaining the pressure. It was created.

As a result of physical property tests of the solid sample thus obtained, it showed a tensile strength of 60.6 kg/m'' and a high Vickers hardness of Hv135.

For comparison, samples were prepared using conventional powder metallurgy methods for aluminum, and physical property tests were conducted.

That is, pure aluminum powder produced by the air atomization method is pressurized at a pressure of about 20 tons/-, and
Sintering was carried out at 0° C. in a nitrogen gas stream for 2 hours. The tensile strength of this product was approximately 4.3 kgA1. In addition, when we measured the tensile strength of aluminum alloy 2014 manufactured by the air atomization method and processed it using the same method, it was 5.
．． 2 +r/l, 2.

As mentioned above, those made using conventional powder metallurgy methods exhibited extremely brittle physical properties, but as a result of observing the state of these fractured surfaces, the cause of this was found to be due to the adhesion between powder particles. It was assumed that this was due to the low area and adhesive strength.

As is clear from these results, conventional general powder metallurgy methods have a basic problem of adhesion of powder in the case of aluminum-based materials, but the solidification method of the present invention solves this problem. This problem is solved, and the powder particles are strongly bonded.

In the above example, although frictional heat was generated from the sample during processing, it was assumed that the temperature did not rise above 300°C. The heat generated by the friction described above can be controlled by the rotational speed of the pressing member.

In addition, the deformation given to the particles of raw material powder depends on the pressing force, rotation speed, and rotation time, but under ideal conditions, there will be no slip between the pressing member and the raw material powder, and the pressing member will The applied rotation is directly consumed by the deformation of the particles. Furthermore, it is thought that the particles at the outer periphery in the cylinder under the conditions of the above-mentioned example were elongated by about 160 times, and the surface of the powder particles was substantially free of oxide film.
It has a clean surface. The strengthening mechanism of this material is, as mentioned above, in addition to the material strengthening brought about by the fine crystals of the powder obtained by rapid solidification, processing strengthening provided by the deformation of the strength, and the oxide film that formed the surface of the powder particles. That is, this is dispersion strengthening obtained by dispersing aluminum oxide in the matrix. Especially regarding the crystal structure, the crystal grain size is 1 μm.
It was observed that it consisted of uniform ultrafine crystal grains smaller than a crane.

In addition, no grain boundaries of the granules were observed at all when the fracture surface was observed, and it was confirmed that the adhesion of the raw material powder had completely failed. Furthermore, there are no pores between powder particles,
In this method, the raw material powder behaves as a powder only at the initial stage of processing, and after solidifying to a certain extent, it is considered to be in a kind of metal flow state, and the powder behaves like a powder that flows due to the deformation of the strength. It is thought that the body particles completely filled the pores.

As described above, according to this method, metals can be strengthened without alloying.

〔Effect of the invention〕

As described above, in the method for solidifying powder such as metal according to the present invention, powder such as metal is pressed by a pressing member, and the pressing member is rotated around a rotation axis in the same direction as the powder pressing direction. It is characterized by crushing the powder by crushing the powder, and commercializes amorphous metals or microcrystalline metals whose properties are lost due to changes in the crystal structure due to heating, such as the rapidly solidified powders mentioned above. In this process, the metal powder particles are kneaded and pressure-welded under temperature conditions such as frictional heat or low-temperature heating. The surface oxide film is destroyed by plastic deformation, and the particles are bonded by the internal clean surface, so it is possible to create an alloy in which the particles are firmly bonded to each other. Even in the case of metals other than crystalline metals, such as lithium, which has a low melting point and cannot be heated to high temperatures during alloy creation, aircraft can be created by kneading the powder of each metal at low temperatures and solidifying it. It is possible to create lithium alloys etc. that are useful as materials. It is also possible to create composites of dissimilar metals that are difficult to coexist due to their different melting points, specific gravity, etc., or of metals and ceramics. For example,
Heat-resistant, lightweight alloys such as Al-Pe alloys, aluminum and silica.

It is also possible to create composites with ceramics such as alumina.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an apparatus showing an embodiment of the method for solidifying powder of metal, etc. according to the present invention, and Fig. 2 (a) to (e) show continuous solidification by the above-mentioned solidification method. Explanatory drawings showing the method, FIGS. 3 to 8 are explanatory drawings showing other examples of apparatuses using the method of the present invention. 1: Piston, 2 Niji cylinder - 13: Piston, 4: Powder, 11: Piston, 12: Piston, 13 Niji cylinder - 114: Powder supply hole, 15: Powder, 16: Nozzle, 1
7: Roll, 18: Rotating die, V: Belt, p: Pulley, e: Exit, S: Space. Patent applicant Idea Research Ltd. Figure 6 Figure 7 Figure 8 Figure 3 Figure 4

Claims (1)

[Claims] 1) Powder such as metal is pressed by a pressing member and the pressing member is rotated around a rotating shaft in the same direction as the powder pressing direction to apply shear force to the powder and crush it. A method for solidifying powder such as metals.