JPH0617490B2 - Solidification method of crushing / fixing powder containing mainly metal - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a product or the like by solidifying a powder containing a metal, and more specifically, to a powder obtained by heating at high temperature such as a rapidly solidified powder. By mechanically solidifying a metal powder that loses its properties under relatively low temperature conditions, it is possible to commercialize the product while maintaining the properties of the metal powder, and with different properties. The present invention relates to a solidification method of crushing and adhering powder of metal or the like, which enables the production of an alloy of different metals or a composite of a metal and a ceramic material.

[Conventional technology]

It is well known that amorphous metals or microcrystalline metals produced by the rapid solidification method have excellent physical properties such as wear resistance, surface hardness, tensile strength, and magnetic properties. If this is done, application in a very wide field is possible. However, these metals have a problem in heat resistance, and are higher than the crystallization temperature, for example, 300 ° C in the case of aluminum.
When heated to a certain degree or more, the amorphous structure or the microcrystalline structure is destroyed and the excellent physical properties are lost. Therefore, in order to commercialize such a metal, a general method that requires heating, for example, a method such as hot pressing or casting cannot be adopted. Thin-film amorphous Si metal or the like used for solar cells and the like can be prepared by the glow discharge method or the like, but in the case of rod-shaped or plate-shaped or larger products, it cannot be prepared by such a method.

For this reason, when an amorphous metal or a microcrystalline metal is manufactured while maintaining its characteristics, it is necessary to use a rapidly solidified powder of the metal by mechanical means that does not require high temperature heating. Conventionally known methods for solidifying metal powder include extrusion method, rolling method, and Japanese Patent Publication No. 57-2.
As can be seen in the 441 publication and the Japanese Patent Publication 60-14082 publication,
There is a method of manufacturing a green compact by transporting the powder through a powder passage formed between the drive walls of the fixed wall, passing through the powder passage by the movement of the drive wall, and compressing the powder.

[Problems to be solved by the invention]

The conventional extrusion method and rolling method as described above, the powder particles such as metal are pressed under the temperature condition by heating and friction heat,
It is intended to join the powder particles by compressing and increasing the density. However, with such a method, it is difficult to firmly bond the powder particles at a processing temperature lower than the crystallization temperature of the metal, the curing is violent, and the sintering treatment such as annealing is required. It is impossible to maintain the microcrystalline structure of metal by the rapid solidification method and to commercialize it.

Further, particularly in the case of metal powder in which the surface of powder particles such as aluminum is covered with a strong oxide film, simply increasing the density causes the oxide film on the particle surface to act as a barrier and to prevent the powder particles from being separated from each other. It cannot be firmly bonded and solidified. When an oxide film is formed on the particle surface of such metal powder, the powder particle is plastically deformed to destroy the strong oxide film on the particle surface, and the clean part inside the particle is surfaced. It is possible to solidify the particles only by exposing them to the surface and firmly bonding the particles to each other by the washed surface. However, it is difficult to completely destroy the oxide film on the surface of such metal particles only by compression by pressure, and even if the oxide film can be partially destroyed, the remaining oxide film layer is the original particle. If it remains on the surface, the surface bonding strength is still weak, and even if sintering treatment by annealing is performed after molding, the oxide film remaining on the surface acts as a barrier and hinders the bonding between powder particles, reducing the strength of the entire product. Cause of.

Further, in the conventional extrusion method, in order to increase the ability to plastically deform the particles to destroy the oxide film, the ratio of the pressing area and the extrusion area at the time of extrusion, that is, the so-called extrusion ratio is set to be large in the vicinity of the die. The amount of deformation of the powder particles generated may be increased, but when the extrusion ratio is set large in this way, the fluidity of the powder must be increased. Therefore, in the actual extrusion process, the aluminum alloy is heated to around 550 ° C. This is 550 ℃
This is because at the above temperatures, the characteristics of the rapidly solidified powder are lost due to coarsening of precipitates and the like. However, in the case of aluminum, the crystal grains grow at a temperature of about 300 ° C. or higher and the fine crystal structure is destroyed. However, 300 ℃
At the temperatures below, extrusion is difficult and the adhesion between powder particles is insufficient, so the strength of the molded product becomes weak. For this reason, in the conventional processing and sintering by the extrusion method, in order to enhance the adhesiveness of the powder, the processing is performed at a temperature of about 550 ° C. at the sacrifice of the fine crystal structure.

Further, the above-mentioned Japanese Patent Publication No. 57-2241 and Japanese Patent Publication No. 601408.
In the method disclosed in Japanese Patent Publication No. 2 as well, adhesion between powder particles utilizes frictional heat generated between the fixed wall and the driving wall and the powder,
Although a powder is manufactured by compressing powder by extrusion, the metal powder particles are plastically deformed to solidify the powder by a processing method that merely compresses like the above-mentioned extrusion method and rolling method. However, the above-mentioned problems have not been solved yet.

In view of the above problems, the present invention produces a metal whose properties are likely to be lost by heating an amorphous metal or a fine crystalline metal, and powder particles of these metals under relatively low temperature conditions. Even when plastically deformed and an oxide film or the like is formed on the particle surface, the powder particles are crushed and bonded to each other,
By fixing and solidifying, it has excellent properties such as surface strength, wear resistance, tensile strength and heat resistance, and it can obtain widely applicable metal products. It is intended to provide a solidification method for fixing.

[Means for solving problems]

In order to achieve the above object, the present invention provides a powder containing mainly an amorphous metal or a microcrystalline metal to the extent that it can be crushed between the end pressing surface of the pressing member and the end receiving surface of the receiving member. The powder is pressed with a yield pressure of 0.7 times or more of the metal powder particles under the processing temperature while the receiving member is housed and the movement of the receiving member is regulated so as to support the crushing movement from the pressing member. Crystallization of these metals by rotating the pressing member while pressing the receiving surface of the receiving member with the pressing surface of the member, and simultaneously applying a pressing force and a shearing force to the powder to the extent that the powder can be crushed. It is intended to provide a solidification method for crushing and fixing powder containing mainly a metal, which is characterized in that powder particles are crushed at a temperature equal to or lower than a temperature and fixed to each other to be solidified.

[Action]

The method of solidifying powder mainly containing metal according to the present invention is as described above, and the powder mainly containing amorphous metal or microcrystalline metal is compressed by the pressing of the pressing member to increase the density and at the same time press the powder. The powder particles are plastically deformed and crushed by the shearing force and frictional heat generated by the rotation of the members, and the powder particles are firmly bonded and fixed to each other, so that the amorphous structure of the amorphous metal or the fine solidification of the rapidly solidified metal is obtained. The powder can be solidified at a temperature below the crystallization temperature without destroying the crystal structure.

[Detailed Description of the Invention]

 The invention will now be further described on the basis of the illustrated embodiment.

As shown in FIG. 1, for example, as shown in FIG. 1, the method for solidifying powder of metal or the like according to the present invention is performed by sealing one opening of the cylinder 2 with a piston 3 as a receiving member to seal the cylinder 2. A pressing surface 1'at the tip of the piston 1 as a pressing member which is filled with a powder 4 to be solidified such as a metal powder or a mixture of different metal powders and is inserted from the other opening.
The powder 4 inside the cylinder 2 is compressed by pressing it against the receiving surface 3'of the piston 3 with the piston 1
The powder 4 is rotated by rotating the end face of the piston 3
3 ′ is deformed by the rotation in the shearing direction under compression and is plastically deformed and crushed with internal frictional heat, and the powder particles are bonded and fixed to each other. The body 4 is solidified.

The pressure applied by the piston 1 in this case is such that the frictional force between the powder 4 and the pressing surface 1 ′ is increased to prevent slippage between the two and to transmit the shearing force necessary for plastic deformation to the powder 4. Is required. As such a pressing force condition, it is preferable that the pressure is equal to or more than [yield pressure at the processing temperature of the used metal powder particles × pressurized area]. However, in practice, there is no problem with the adhesive strength of the powder particles. Here, the yield pressure of the metal powder particles means the pressure at which the metal powder particles undergo plastic deformation beyond elastic deformation when subjected to pressure. Further, by processing under such a pressure condition, even if a stress that would cause a crack in a normal state occurs inside the green compact, the generation of a crack can be prevented and a uniform solidified product can be obtained. Moreover, even in the case of a powder such as aluminum having an oxide film formed on the surface of the particle, the rotation of the piston 1 as a pressing member causes the shearing force applied to the powder 4 from the pressing surface 1 ′ to strengthen the surface of the particle. The oxide film is destroyed, the clean portion inside the particle is exposed to the surface of the particle, and the particles are firmly bonded and fixed to each other in this clean portion.

Incidentally, the plastic deformation of the particles of the powder 4 in this case does not depend only on the compression by the pressing of the piston 1, but the pressing force of the piston 1 closes the other end of the cylinder 2 to make the pressure of the piston 1 A shear force is applied to the powder 4 by the frictional force between the powder 3 and the receiving surface 3'of the tip of the piston 3 that supports the powder 4 against the powder 4, and the inner wall 2'of the cylinder 2 and the piston 4, The stroke of 1 is not directly related to the shearing force applied to the powder 4. Therefore, the stroke of the piston 1 may be short depending on the configuration of the device.

Further, the processing temperature condition in this case does not need to be heated to a high temperature because it can assist the plastic deformation of the powder particles by the shearing force, but it can be heated depending on the properties of the powder used. In this case, it is possible to raise the fluidity of the metal powder particles by appropriate heating to solidify them efficiently, and set the conditions such as rotation, pressurization and temperature appropriately according to the type of powder to be solidified. By doing so, it can be applied to various metals.

As described above, the method for solidifying powder of metal or the like according to the present invention not only compresses the powder 4 by pressurizing the piston 1 as a pressing member to increase the powder density but also presses the piston 1. The powder particles are plastically deformed between the pressing surface 1'of the piston 1 and the receiving surface 3'of the piston 3 by applying a shearing force to the powder 4 by rotating so as to push in the same direction. Even if an oxide film etc. is formed on the surface of the powder particles, the oxide film is destroyed to expose the internal clean part, so that the hard part of the powder particles can be firmly bonded and fixed. is there.

Further, as described above, the method for solidifying a powder mainly containing a metal according to the present invention is a method in which a shearing force is applied to a powder under a certain pressure or more to plastically deform the powder particles to bond the particles together. Therefore, even in the case of extrusion molding, it is not necessary to heat the powder to a high temperature in order to improve the fluidity at the time of extrusion, and various extrusion molding can be performed under relatively low temperature conditions below the crystallization temperature.

For example, the one shown in FIG. 2 is an example of an extrusion apparatus utilizing the present invention. Here, the piston 11 and the piston 12 are fitted through the openings at both ends of the cylinder 13 so that the tip surfaces 11 'and 12' of both pistons face each other, and the powder supply that communicates from the inside of the cylinder 13 to the outside is provided on the wall surface of the cylinder 13. Hole 14
Are formed (Fig. 2 (a)). The piston 11 is associated with a hydraulic cylinder (not shown) at its rear end so as to be capable of pressurizing and moving in the cylinder 13, and is also associated with a driving means (not shown) such as a motor through a pulley p, a belt v, and the like. Cylinder 13 can be rotated by attaching the piston 12 to a hydraulic cylinder or the like (not shown).
The inside can be moved by pressure.

In order to solidify the powder using this device, first, the tip surface 1 of the piston 11 and the piston 12 in the cylinder 13
The 1 ', 12' are positioned so as to face each other with the space s left inside with the powder supply hole 14 interposed therebetween, and the powder 15 such as metal to be solidified from the powder supply hole 14 into the cylinder 13. Supply. Next, with the movement of the piston 12 regulated, the piston 11
By pressing the powder 15 toward the piston 12 and rotating the piston 11 (Fig. 2 (b)), the powder 15 is compressed between the piston 11 and the piston 11, and the piston 11 rotates. Thereby, a shearing force is applied to the powder 15, the powder particles are plastically deformed and crushed, the particles are bonded and fixed to each other, and the powder 15 is solidified. At this solidification stage, the piston 12 is pressed by the hydraulic cylinder associated with the piston 12 against the pressing force of the piston 11 to compress the powder 15 in the cylinder 13. The pressure of the piston 12 is higher than the pressure at which the powder 15 can be crushed between the piston 12 and the piston 12.
If the pressure is made slightly weaker than the pressure generated by 11, the pressing surface 11 ′ of the piston 11 and the receiving surface 1 of the piston 12 as the powder 15 solidifies.
The powder 15 that is solidifying between 2'moves in the direction of the piston 12, and when the solidification of the powder 15 is completed, the solidified product
15 'can be positioned closer to the piston 12 than the powder supply hole 14 of the cylinder 13. In this state, when the piston 11 is retracted rearward from the powder supply hole 14, the solidified powder
Space s' formed between 15 'and the pressing surface 11' of the piston 11
Further, powder can be further supplied into the cylinder 13 from the supply hole 14 (Fig. 2 (C)). By repeating the above-mentioned operation in this way (FIG. 2 (d) (e)), the powder 15 newly supplied to the rear end surface of the powder 15 'which has already been solidified is continuously integrated. It can be solidified. Moreover, the previously solidified portion 15 ′ and the currently solidified portion 15 are pistons at the same time.
A shearing force is applied by the rotation of 11, and they are kneaded, and both are molded as a completely integrated body. By repeating such an operation in sequence, the powder 15 can be molded as a continuous long product (Fig. 2 (f)).

Further, the method of solidifying powder mainly containing metal of the present invention applies compression to the powder by pressing force and applies shear force to the powder by rotation of the pressing member, but the receiving side is not necessarily shown in FIG. It is not necessary to completely close the piston 12 as. That is, at the next stage after the completion of the initial solidification stage, for example, as shown in FIG. 3, a nozzle having an outlet e smaller than the inner diameter of the cylinder 13 at the end of the cylinder 13 instead of the receiving piston 12 is provided. 16 is provided so as to oppose the pressing force and rotational force of the piston 11 by the anti-variation stress and frictional force of the solidified powder 15 ′ near the outlet e, and the solidified powder 15 ′ is used as a powder for the receiving member. It is also possible to apply a pressing force and a shearing force at the same time to solidify, and to manufacture this as a continuous solidified product 15 'as in ordinary extrusion molding.

In the above case, the inside of the nozzle 16 is formed into a two-step tapered surface as shown in FIG.
Alternatively, the powder may be plastically deformed and then extruded on the second tapered surface B. In the case of FIG. 3 or FIG. 4, the shape of the outlet e of the nozzle 16 is set to a desired product sectional shape. Further, according to the present invention, since the powder particles are bonded and fixed to each other by compressing the powder and applying a shearing force to the powder particles to crush the powder particles, the piston 11 is pressed. The frictional force between the powder 15 and the pressing surface 11 'of the piston 11 can be increased by this to prevent slippage between them and to give the powder 4 the shearing force necessary for plastic deformation. Even if an oxide film is formed on the surface, it can be easily plastically deformed to destroy the oxide film and firmly bond and fix the powder particles to the inner clean part to solidify it. In addition, even if the extrusion ratio of the inner cross-sectional area of the cylinder 13 and the cross-sectional area of the outlet e is such that cracks are generated inside the powder in the usual method, the generation of cracks can be prevented.

As shown in FIG. 5, instead of the nozzle 16, rollers 17 and 17 are provided outside the exit of the cylinder 13 to hold solidified and extruded powder solid matter, and brake the solidified matter. This is an example in which the piston 12 is substituted by.

The one shown in FIG. 6 is one in which a rotary die 18 is provided at the outlet of the cylinder 13, the powder 15 is compressed by the rotation and a shearing force is applied, and extrusion molding is carried out. The rotation of 18 gives a very large deformation in the vicinity of the outlet, and it can be extruded as a solid solid material.

Further, as shown in FIG. 7, the two-step tapered surfaces A and B are formed inside the die 18 to prevent the pressing force at the portion A from the outlet e from escaping 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 an appropriate means at the beginning of solidification.

Then, the method shown in FIG. 8 is a method for preventing the pressure applied to the portion A from escaping to the outside by applying hydrostatic pressure to the tip of the rotary die 18.

The temperature of the powder due to frictional heat or heating during the above solidifying operation is preferably controlled at a temperature not higher than the crystallization temperature by appropriately controlling it according to the metal powder used, and in particular the physical properties greatly change depending on the temperature. In the case of a metal such as an amorphous metal, temperature control during this processing is important.

Example A solidified material sample was prepared by the method shown in FIG. 1 using pure aluminum having a purity of 99.9% containing 95% of 250 mesh or more produced by the air atomization method as a raw material powder. The pressure applied by the pressing member is about 10 t / cm ² , and while maintaining the applied pressure, a rotary shearing force of about 3 rotations is applied for a diameter of 25 mm and a meat pressure of 1 mm to a solid aluminum product having a meat pressure of 5 mm. Created. As a result of the physical property test of the sample solid thus obtained, the tensile strength was 60.6 kg / mm ² , and the Vickers hardness was a high value of Hv135.

Comparative Example For comparison, a conventional general powder metallurgy method was used for aluminum to prepare a sample, and a physical property test was performed.
That is, a powder of pure aluminum produced by the air atomizing method is pressed at a pressure of about 20 t / cm ² , and 510
Sintering was carried out in a nitrogen gas flow at 2 ° C for 2 hours. The tensile strength of this product was about 4.3 kg / mm ² . Further, the tensile strength of an aluminum alloy 2014 manufactured by the air atomizing method prepared and processed by the same method was measured and found to be 5.2 kg / mm ² .

As described above, the materials prepared by the conventional general powder metallurgy method showed very brittle physical properties. The cause is that the adhesion of the powder particles to each other was observed as a result of observing the state of these fracture surfaces. It was speculated that the area and adhesive strength were both low.

As is clear from this result, the conventional general method of powder metallurgy has a basic problem of adhesion of powder in the case of aluminum-based material, but according to the solidification method of the present invention, This problem is solved and the powder particles are strongly bonded together.

In the above examples, it was estimated that frictional heat was generated from the sample during processing, but the temperature did not rise above 300 ° C. The heat generated by this friction can be controlled by the rotation speed of the pressing member. Further, the deformation imparted to the particles of the raw material powder depends on the pressing force, the rotation speed, and the rotation time, but under ideal conditions, no slip occurs between the pressing member and the raw material powder, and The given rotation is consumed by the deformation of the particles. Further, the particles in the outer peripheral portion in the cylinder under the conditions of the above-mentioned example are about 16
It is considered that the powder particles have been stretched to 0 times, and the surface of the powder particles is a clean surface with substantially no oxide film. The strengthening mechanism of this material is, in addition to the material strengthening brought about by the fine crystals of the powder obtained by rapid solidification as described above, the processing strength given by the deformation of the strength and the oxide film constituting the powder particle surface. That is, it is dispersion strengthening obtained by dispersing aluminum oxide in the matrix. In particular, it was observed that the crystal structure consisted of uniform ultrafine crystal grains with a grain size of 1 μm or less. Further, no grain boundaries of the granules were observed at all as long as the fracture surface was observed, and it was confirmed that the raw material powder was completely adhered. Furthermore, there are no pores between the powder particles at all, and in this method, the raw material powder behaves as a powder only in the initial stage of processing, and after solidification to some extent, it seems to be a kind of metal flow. It is considered that this is a state, and it is considered that the powder particles, which flow due to the strong deformation, fill the pores.

As described above, according to this method, it is possible to strengthen the metal not by alloying.

〔The invention's effect〕

As described above, the method for solidifying powder according to the present invention is performed by pressing powder containing mainly amorphous metal or microcrystalline metal with a pressing member at a pressure higher than a predetermined pressure and rotating the pressing member. By crushing, the metal powder particles are crushed to be bonded and fixed to each other. An amorphous metal whose crystal structure is changed by heating and loses its characteristics such as rapidly solidified powder. Alternatively, in producing a microcrystalline metal as a product, a strong oxide film is formed on the surface of the powder particles by kneading and pressure-contacting the metal powder particles under a temperature condition equal to or lower than the crystallization temperature such as frictional heat or low temperature heating. Even in the case of the formed aluminum alloy, the particles are plastically deformed to destroy the surface oxide film, and the internal clean surface bonds and fixes the particles, so that an alloy in which the particles are strongly bonded can be created. It is a function. Furthermore, according to the method of the present invention, it is possible to prepare different metals which are difficult to coexist because of different properties such as melting point and specific gravity, or a composite of a metal and a ceramic, for example, an Al-Fe alloy. Heat resistance, etc.
It is also possible to make a lightweight alloy or a composite of aluminum and a ceramic such as silica or alumina.

[Brief description of drawings]

FIG. 1 is an explanatory view of an apparatus showing one embodiment of a method for solidifying powder of metal or the like according to the present invention, and FIGS. 2 (a) to (f) are methods for continuously solidifying by the solidifying method. An explanatory diagram showing
3 to 8 are explanatory views showing another example of the apparatus using the method of the present invention. 1: Piston, 2: Cylinder, 3: Piston, 4: Powder, 11: Piston, 12: Piston, 13: Cylinder, 14: Powder Supply Hole, 15: Powder, 16: Nozzle, 17: Roll, 18 : Rotary die, v: belt, p: pulley, e: exit, s: space.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-4003 (JP, A) JP-A-63-169301 (JP, A) Actually opened 62-287002 (JP, U) JP-B-59- 32521 (JP, B2)

Claims (1)

[Claims] Claim: What is claimed is: 1. A crushing method for crushing a powder containing mainly an amorphous metal or a microcrystalline metal to such a degree that it can be crushed is contained between the end pressing surface of the pressing member and the end receiving surface of the receiving member. With the movement of the receiving member restricted so as to be able to support the movement, the receiving member is pressed by the pressing surface of the pressing member by a pressure of 0.7 times or more the yield pressure of the metal powder particles at the processing temperature of the powder. The pressing member is rotated while being pressed against the receiving surface of the powder, and the pressing force and the shearing force that are capable of crushing the powder are simultaneously applied to the powder, so that the powder is heated at a temperature not higher than the crystallization temperature of these metals. A solidification method of crushing and fixing powder containing mainly metal, characterized by crushing particles and fixing them to solidify each other.