JPS61194222A - Production of metallic filament - Google Patents

Abstract

PURPOSE:To obtain continuously a metallic thin filament having spherical section, from a metallic melt having amorphous phase forming ability or crystallite forming ability, by setting a means to accelerate a liquid medium in the middle of a quenching zone. CONSTITUTION:The metal 1 melted under heating is jetted from the spinning nozzle 4 into a filament by a pressurizing device, and introduced into a quenching zone of the cooler 6. The flow velocity of a cooling medium in the cooling pipe 7 is accelerated by high-pressure water jetted from the jet pump 9 and reaches >=10m/s, the jet flow of the molten metal 1 is rapidly quenched, and solidified, to give the thin filament 5. Water is usually used as the cooling medium.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a method for manufacturing metal fibers by rapid solidification.

[Background of the invention]

Recently, instead of the conventional production of metal fibers by die drawing, various methods have been studied to obtain fibers at high speed by directly solidifying into a linear shape from a jet stream of molten metal fluid. If a device using this method is completed, it will not only be possible to produce metal fibers in large quantities at low cost, but also to produce fibers of materials that have low ductility and are difficult to draw with a die. Since it is crystalline, a metal fiber with unique properties not found in conventional crystalline metal fibers can be obtained. However, the so-called melt direct spinning method, in which fibers are obtained by directly solidifying a jet stream of molten metal fluid into a linear shape, poses a big problem. In general, metals have low viscosity and high surface tension in their molten state. Therefore, the six-fold (@-shaped) molten metal jet stream ejected from the nozzle at high speed cannot maintain its own shape, becomes constricted within a short period of time, and eventually becomes droplets. Therefore, in order to produce continuous metal fibers using the direct melt spinning method, it is necessary to devise ways to complete the solidification of the jet flow before the shape is destroyed.

Many attempts have been made so far, and considerable progress has been made technically. Highly feasible means to complete the solidification of the jet flow before the shape is destroyed can be broadly classified into two types.

One idea is to improve the low viscosity and strong surface tension that are characteristic of molten metal, and to prevent the formation of constrictions or droplets during the time until solidification is complete. Specifically, the jet stream is ejected into a gaseous atmosphere that causes a chemical reaction with one or more components of the jet stream, forming a solid film of oxides etc. on the liquid jet stream, lowering the surface tension and further removing the oxides. The viscosity is improved by diffusing and distributing it in the molten jet liquid. Another method uses electrostatic charges to stabilize and maintain the shape of the jet stream. However, when a reactive element is added to the molten metal to create a reaction product with the atmospheric gas, the mechanical
Adversely affects electrical or other physical properties. Sixth, it is extremely difficult to stabilize the formation of molten metal using this method alone, and even if a solid film is formed, the molten metal will continuously deform due to its own weight, and a continuous metal surface will be created. In extreme cases, there will be areas where the coating is formed, and areas where the coating is insufficient or not formed at all, resulting in non-uniformity in the resulting thin metal wire that is inconvenient for use. , which also leads to breakage of the jet stream. Furthermore, in order to stabilize the jet flow using static electricity, it is necessary to apply a high voltage, which causes many problems and drawbacks.

Glass's viscosity decreases at high temperatures, and it has the property of becoming a thin thread when stretched. The glass-coated melt-spinning method takes advantage of the spinnability of glass.The metal to be spun is placed in a predetermined glass tube, and the metal is melted by high-frequency heating, which also softens the glass tube and is wound at high speed. In particular, glass-coated metal fibers are obtained. Mechanical or chemical methods are used to remove glass, but it can be removed by immersing it in an aqueous hydrofluoric acid solution. However, this process is also quite complicated, the production cost is high, and it is difficult to stably produce high-quality metal fibers in large quantities.

In contrast to the above-mentioned methods, another approach has been attracting attention in recent years, in which metal fibers are created by rapidly cooling and solidifying a molten metal jet stream before its shape changes.

The challenge with this idea was to establish a technology to rapidly cool and solidify a circular cross-section while maintaining a constant thickness.
(circa 1996) attempted cooling with a mist of vaporized liquid dispersed in a gas or a gas-solid dispersion. However, the cooling rate of these cooling media is slow, and in order to stably solidify the jet flow and obtain a continuous, uniform thickness, and high quality metal a@, the above-mentioned concept, that is, chemical or electrostatic stabilization is required. It is necessary to use them together. In order to increase the cooling rate, it is necessary to select a medium that removes heat from the molten metal fluid. Recently, a method has been developed in which a jet stream is ejected onto the surface of a metal roll that rotates at high speed and has high thermal conductivity to rapidly cool it (roll method).
, as well as a submerged spinning method in which a jet stream is ejected into the original medium (coolant) typified by water to rapidly cool the medium.

Since the roll method has a high cooling rate of 108 to 10 deg/s, ribbon-shaped high-quality metal fibers, that is, fine crystalline or amorphous metal fibers can be stably obtained. However, since the metal molten fluid is solidified on a rotating metal roll, it is not always possible to obtain a flat cross-sectional shape, and a round line cannot be obtained. However, it is not used for anything other than special purposes.

The submerged spinning method is circular! #? It is a method that can obtain a thin wire with a flat surface or a thin wire close to it, and among them, the rotating liquid spinning method disclosed in Japanese Patent Application Laid-Open No. 55-64948 has a circular cross section because the cooling liquid is stabilized by a long distance force and the cooling rate is fast. Suitable for manufacturing small quantities of metal filaments. This is a method in which molten metal ejected from a nozzle is guided into a rotating body containing a cooling liquid and cooled and solidified. However, in this method, the cooling liquid layer is maintained in the rotating cylinder by centrifugal force, and the cooled and solidified metal wire is continuously collected and wound on the inner wall of the rotating cylinder, so the depth of the cooling liquid layer and the winding speed are , the temperature of the cooling liquid changes, and there are many problems involved in continuously manufacturing large quantities of thin metal wires of constant quality. Furthermore, since there are restrictions on the size and width of the rotating cylinder, patch operation is always required and continuous production operation on an industrial scale is difficult.

On the other hand, Japanese Patent Publication No. 59-26685 proposes a method of solidifying a molten metal stream by passing it through a quenching zone made of a raw medium in order to obtain a thin metal wire with a circular cross section. This is ■
The molten metal jet flow ejected from the nozzle in the quenching zone and the cooling raw medium are cocurrent, and the velocities of the molten metal jetted from the nozzle and the cooling raw medium in the quenching zone are the same; The velocity of the original cooling medium is determined by the rate of fall of its own weight. This method uses circulating cooling water to rapidly solidify the molten metal, making it possible to continuously manufacture thin wires.
Recovery is relatively easy and mass production is high.

However, the flow velocity of the cooling water can only be increased to a maximum of about 3 m/8 because it utilizes the falling phenomenon of its own weight, and the cooling rate is insufficient, so the kinetic energy is small, and the molten metal and cooling water Collision of the cooling water, boiling of the cooling water, evaporation, and convection cause the cooling water or the liquid surface to be disturbed, making it impossible to obtain high-quality fine crystals with a circular cross section or amorphous metal wire.

[Purpose of the invention]

The object of the present invention is to produce high quality gold 11EMfil wires with a circular cross section directly and continuously on an economical industrial scale from a melt of a metal with the ability to form an amorphous state or a metal with the ability to form a microcrystalline state. The goal is to provide a way to do so.

[Summary of the invention]

A feature of the present invention is that a means for accelerating the raw medium is provided in the middle of the quenching zone.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of one embodiment of the present invention.

Gold 11i put in crucible 2! 1 is a high frequency induction coil 3
or by heating and melting by other suitable methods. The metal 1 heated to a predetermined temperature is ejected in the form of a thread from the spinning nozzle 4 by a pressurizing device (not shown). The pressurizing device uses an inert gas such as hydrogen gas or argon gas, or a reducing gas. The diameter of the nozzle 4 is made equal to or slightly larger than the diameter of the desired thin wire.

The jet stream of molten gold Is1 is introduced into the quench zone of the cooling device 6 located directly below the nozzle 4. The quenching zone is composed of a cooling pipe 7, a jet pump 9, and a cooling medium 8, and the cooling medium 8 flows through the cooling pipe. The flow rate of the jet stream of molten metal 1 is determined by the pressurizing conditions of the pressurizing device. The flow rate of the cooling medium in the cooling pipe 7 is determined by the ejection conditions of the jet pump 9. 11 is jet pump 9
It is a pump that operates the Accelerated by the high-pressure water ejected from the jet pump 9, the flow rate of the cooling medium in the cooling pipe 7 reaches 1Qm/s or more, and the jet stream of the molten metal 1 is rapidly cooled and solidified to become the thin wire 5. 12 is a circulation path for the cooling medium, 10 is a cooler for cooling the cooling medium, and the cooled cooling medium passes through the filter 13 and returns to the cooling device 6.

The cooling rate of the molten metal l is determined by the jet speed and the heat transfer coefficient with the cooling medium. The higher the jet speed, the more
The higher the heat transfer coefficient, the higher the cooling rate. but,
If the speed of the cooling medium is slow, the shape of the molten metal will be disturbed before it solidifies, leading to constriction and fracture. Therefore, it is necessary to set the speed of the cooling medium to be equal to or slightly faster than the jet flow speed. In Japanese Patent Publication No. 59-26685, since the falling speed of the coolant due to its own weight is used, the increase can only be increased by about 3 m/@ at most, but in the present invention, the flow rate of the coolant is adjusted to match the speed of the metal jet stream. It can be set using the pump 9. Therefore, fine metal wires can be stably and continuously produced by the melt spinning method. The heat transfer coefficient between the molten metal and the cooling medium can be increased by selecting the temperature and composition of the cooling medium, but a detailed explanation will be omitted here. Generally, water is used.

FIG. 2 shows another embodiment of the invention. The cooling medium and flowing wire 711 are jetted out from the cooling pipe 7 at high speed and captured by the rotating wheel 15. As shown in FIG. 3, the rotary wheel 15 consists of a gate 14 that collects the thin wire by centrifugal force, blades 14a that generate rotational force by the fluid force of the cooling medium, and a shaft 15a. The fine wires can be continuously collected. In the present invention, the jet pump 9
The cooling medium is accelerated by not only increasing the flow velocity in the cooling pipe 7 but also imparting kinetic energy to the cooling medium,
While overcoming the flow path resistance, the collection device 15 is driven once, and the centrifugal force in the collection device traps the thin wire in the gate 14. The kinetic energy of the cooling medium is absorbed by the collection device and it falls downward.
The coolant is recovered and circulated by a cooling medium recovery device (not shown).

Note that the gate 14 can be divided into two parts in the axial direction, and the collected fine wire can be efficiently taken out.

FIG. 4 shows an embodiment in which the cooling pipe 7 is formed with a vortex preventer 7at. Liquid flowing at high speed through a pipe is susceptible to various turbulences. In the melt spinning method, macroscopic disturbances are extremely harmful until the molten metal has completely solidified. Vortices are most likely to occur in the cooling pipe 7, and when these vortices occur, the molten metal is twisted and bent, and the shape is no longer circular, making it impossible to obtain a satisfactory thin wire. Since vortices are generated when the cooling medium in the pipe has a rotational component, an effective means to prevent this is to provide a continuous protrusion in the longitudinal direction toward the axis of the pipe as shown in Figure 4. It is. The vortex generation preventer 7a is most effective when applied to the portion of the cooling pipe 7 where molten metal solidifies, but it is also effective when applied to the position of the jet pump 9 where the high-pressure cooling medium is jetted. The generation of vortices leads to the waste of kinetic energy of the high-pressure fluid, which reduces the rate at which it acts on the acceleration of the cooling medium, reducing efficiency.

The vortex generation preventer has the effect of preventing this phenomenon and increasing the flow velocity of the cooling medium in the cooling pipe 7, which is accelerated by the jet pump.

FIG. 5 shows another embodiment of the invention. A plurality of small holes 7b are provided that penetrate the cooling pipe 7 from the inside to the outside and are inclined in the direction of the flow of the cooling medium. As the flow velocity increases, the flow in the pipe changes from laminar to turbulent, and as the flow velocity increases, the turbulence increases.

As mentioned above, this turbulence is detrimental to the solidification of the molten metal. When there is a flow in a pipe, a boundary layer is generated near the entrance of the pipe, and the boundary layer grows and becomes thicker as it goes inside. There is a flow velocity distribution inside the boundary layer, and where the boundary layer is thick, the flow velocity is faster in the center. This is because the average flow velocity in the pipe must be constant if the pipe diameter is constant. There is a velocity distribution as shown in FIG. 6, and at the five points where the boundary layer is thick, u6h at the center is faster than IQ. In this way, if the flow velocity differs from the center toward the pipe wall at one point in the tube, or if the flow velocity differs in the longitudinal direction at u(, u6.), the cooling medium will This disturbs the molten metal jet, making it impossible to obtain a fine wire.In other words, the molten metal jet ejected from the nozzle enters the cooling medium in the cooling pipe and is cooled, and the cooling medium is cooled while the jet slows down and solidifies. The flow velocity must be the same at every point in the cooling pipe. By satisfying this condition, fine wires with a constant shape and high quality can be obtained.

In Fig. 5, the small holes 7b provided in the cooling pipe 7 allow a small amount of cooling medium to flow in, which has the effect of reducing the thickness of the boundary layer that begins to grow in the cooling pipe, and keeps the flow velocity constant at most points. shall be.

〔Effect of the invention〕

According to the present invention, high-quality thin metal wires having a circular cross section can be produced directly and continuously on an industrial scale using the melt spinning method.

[Brief explanation of drawings]

Fig. 1 is a sectional view of an embodiment of the present invention, Fig. 2 is a partial sectional view of the vicinity of the recovery device, Fig. 3 is a perspective view of the recovery device, and Figs. 4 and 5 are partial sectional views of the cooling pipe. , FIG. 6 is an explanatory diagram of a boundary layer generated in a flow in a pipe. 1... Molten metal, 2... Crucible, 3... Heater, 4
... Spinning nozzle, 5... Thin wire, 6... Cooling device,
7... Cooling pipe, 8... Cooling medium, 9... Jet pump, 10... Cooler, 11... Pump, 1
2...Cooling medium circulation path, 13...Filter, 1
5... Thin wire collection device.

Claims (1)

[Claims] 1. Molten metal is ejected from a spinning nozzle to form molten fibers, and the molten fibers are passed through a liquid quenching zone, which quenches a liquid medium cocurrent with the fibers introduced therein. A method for producing metal fibers comprising recovering solidified fibers, characterized in that the liquid medium is accelerated in the middle of the quenching zone. 2. In claim 1, the liquid quenching zone is filled with a flow of the liquid medium, and in the middle of the liquid quenching zone there is a high-speed drive of the same type as the liquid medium flowing in parallel with the fibers. A method for producing metal fibers, comprising ejecting a raw medium in the same direction as the liquid medium. 3. The method for producing metal fibers according to claim 1 or 2, characterized in that the solidified fibers are driven and recovered by the liquid medium flowing out together with the solidified fibers. 4. The method for producing metal fibers according to claim 1, wherein the flow velocity is monitored at a plurality of locations in the liquid quenching zone to control the driving force of the liquid medium. 5. A portion of the liquid quenching zone into which the molten fibers flow;
2. The method for producing metal fibers according to claim 1, further comprising: preventing rotational components of the liquid medium at a portion where the driving liquid medium is ejected. 6. The method for producing metal fibers according to claim 1, wherein the flow rate is reduced in order to obtain a uniform flow of the liquid quenching medium at a portion of the liquid quenching zone into which the molten fibers flow.