JPS6360052A - Production of rapidly cooled metal - Google Patents

Abstract

PURPOSE:To simply prevent development of deteriorated ribbon by detecting unstabilization or droplet of molten metal jetting and blowing away rapidly cooled solidified material toward reversing direction to flying direction. CONSTITUTION:In order to detecting the condition, which the molten metal jetting becomes to the unstabilization or droplet, a flood-light 10 for photoelectric switch is arranged at gas injecting pipe 8 side and on the other side, a receiver 12 for photoelectric switch is arranged as facing at a receiving vessel 9 side. When the molten metal jetting becomes to the droplet, it is detected as photoelectric change, and by opening a solenoid valve 14 arranged to the gas injecting pipe 8 through a controller 13, inert gas is injected from the gas injecting pipe 8, to receive the droplet in the vessel 9 by flying away. In this way, the mixing of the deteriorated ribbon into good quality ribbon or of slow cooling powder is prevented by simple equipment.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an improvement in a method for producing solidified materials (ribbons, tapes, flakes, etc.) in which molten metal is rapidly cooled by injecting it onto a rotating roll using a small-diameter nozzle. It is something.

(Prior art and its problems) Compared to the conventional melting and casting method (hereinafter abbreviated as 1/M method), the method of manufacturing various products by rapidly cooling and solidifying molten metal and solidifying and molding the obtained rapidly solidified material is , (1) The types and amounts of alloying elements added can be greatly increased, and (2) crystal grain refinement and fine dispersion of second phase particles are promoted, which cannot be obtained with the conventional 11M method. Recently, it has been attracting particular attention as it is expected to lead to the development of new alloys that cannot be used.

By the way, what is particularly important in promoting this type of rapid solidification technology is how to efficiently produce the rapid solidification material, which is the raw material, in large quantities and stably. Various methods and devices have been proposed for this purpose.

Currently, the single-roll method and the twin-roll method are relatively widely used, and the single-roll method in particular is the most commonly used because it is relatively simple in terms of equipment.

To briefly explain the principle of the trial decision and how to use it, the fifth
As shown in the figure, first, the metal melt fhl is melted in a closed crucible 4 equipped with a heating device 5 such as an induction heating coil or a heating heater.
(Using an inert gas such as N) 3 is pressurized by an inert gas introduced through a small diameter nozzle 2 (usually 0.2~
1,0 miφ) to form a molten metal jet 6. Molten metal jet (hereinafter referred to as jet)
6 is stretched into a thin strip on the surface of a rotating roll 7 placed directly below the nozzle 2, and at the same time is rapidly solidified by the rapid heat removal effect from the roll to form a ribbon R. After that, the ribbon R is stored in a collection container or rolled. It is sent to a collecting device and collected (generally, melt spinning
ng) law).

In such a single roll method, one of the important factors is how to form a stable jet in order to manufacture a homogeneous continuous ribbon using the melt spinning method. It is normal to operate with the distance (12) as small as possible.

Furthermore, in order to increase productivity, as shown in FIG. 8, a plurality of nozzles are used to obtain a large number of ribbons R at the same time.

However, this kind of nozzle diameter is 0.2~1,0II
Because of its small diameter of IIIlφ, it is very easily clogged, and is relatively frequently clogged by inclusions (oxides, refractory materials, oxide films, etc.) contained in the molten metal. In addition to the above, causes of blockage include oxidation of the molten metal near the nozzle due to air flowing through the nozzle during melting and holding in the crucible before injection starts.

If the nozzle becomes clogged (part or all of the nozzle) due to these reasons, the ejected jet will become unstable, such as ■ Fluctuations in flow velocity ■ Reduction in flow diameter ■ Fluctuations in injection angle (Figure 6 (a)) ) ■ No jet is formed and a dripping state occurs (Fig. 6(b)) ■ Phenomena such as complete blockage and inability to inject occur. As a result, in the case of minor cases of ■ to ■, a ribbon with a quality different from the initial purpose may be formed, and in the case of severe cases of ■ to ■, or in the case of ■, the ribbon may not be formed, as shown in Figure 7. As shown in Fig. 8, unstable jets or dripping droplets are repelled and scattered as small droplets on the roll surface, and when multiple nozzles are used as in the case of Fig. 8, some of them may adhere to adjacent healthy ribbons. In addition, some of it will end up in the collection container or winding device. Such scattered droplets are not rapidly solidified on the roll surface, but are solidified by heat absorption by the surrounding atmospheric gas during reflection flight on the roll surface, so the cooling rate is very slow (hereinafter referred to as slow droplets). Ribbons to which slow-cooled powder (referred to as cold powder) and slow-cooled powder are attached or mixed cause structural non-uniformity in the solidified molded material thereafter, causing property deterioration and making it impossible to obtain a good final product.

In particular, when producing a continuous ribbon using a multi-hole nozzle, if even one of the multiple nozzles becomes clogged as described above and the jet becomes unstable (Figure 8), the remaining normal nozzles will be used to produce a continuous ribbon. The quality of even the ribbons used will deteriorate. To this end, we have taken measures such as discarding all the products obtained from the charge, or immediately stopping operations if a blockage (or jet instability) is discovered. It was a major cause of sexual decline. This decrease in productivity was particularly significant for highly oxidizing active metals such as AQ and Mg.

Therefore, in order to prevent a drop in productivity, it is necessary to close the blocked nozzle where the jet has become unstable. However, if a slide nozzle or immersion stopper is used to open and close the molten metal nozzle, the former will close between the nozzle and the roll. It is necessary to install a driving nozzle in a small gap (usually 10 mm or less), which requires advanced stopper processing technology and its driving technology, although it is technically impossible, which leads to a rise in equipment costs. Become. Particularly in recent years, in order to suppress ribbon oxidation due to demands for improved quality, it has become necessary to manufacture ribbons in an inert gas atmosphere inside an airtight chamber. Needless to say, it is becoming increasingly difficult to set up and control the equipment, and expensive equipment is required. Furthermore, in order to further improve productivity, it is clear that installing drive stoppers independently to each of a large number of nozzles, such as 10 holes and 20 holes, will also lead to a rise in equipment costs.

Similarly, in the latter case, arranging a large number of vertically driven stoppers independently for each nozzle increases the complexity of the equipment.
This will lead to high prices.

Furthermore, in either the former or the latter case, it is undeniable that productivity decreases due to troublesome maintenance such as replacing the stopper after the end of the operation.

Furthermore, in both methods, when trying to increase productivity with a very large number of nozzles, such as several tens of holes, the nozzle gap must be set to 10mm+ or 20mm due to the provision of stoppers.
m, which has the disadvantage of increasing the size of the crucible, melting furnace, etc.

(Object of the invention) The present invention uses a melt spinning method or the like to inject molten metal in a crucible as a molten metal jet from a small diameter nozzle, rapidly solidify it on a rotating roll placed directly below the nozzle, and produce ribbons, tapes, flakes, etc. To provide a technology with excellent productivity and yield by preventing the occurrence of defective ribbons due to jet instability caused by nozzle blockage in the production of coagulated materials in an extremely simple and low-cost equipment. The purpose is to

(Means for Achieving the Object of the Invention) The present invention involves injecting molten metal in a crucible as a molten metal jet from a small-diameter nozzle, rapidly solidifying it on a rotating roll placed directly below the nozzle, and forming ribbons, tapes, flakes, etc. In producing the coagulating material, detecting when the molten metal jet becomes unstable or turning into droplets, and injecting gas between the nozzle and the rotating roll parallel to and in the opposite direction to the coagulating material flying direction, By preventing the unstable molten metal jet or droplets injected from the above nozzle from being blown away in the opposite direction to the flight direction of the rapidly solidified material, it is extremely easy to prevent the generation of defective ribbons due to instability of the jet caused by nozzle blockage. It was discovered that this can be prevented using low-cost equipment.

Hereinafter, the present invention will be described in detail based on specific examples shown in the accompanying drawings.

(Example) FIG. 1 is a schematic elevational view of an apparatus for carrying out the method of the present invention. Similar to the conventional single roll method shown in FIG. metal molten ti
hl is a gas introduction pipe (usually Ar).

(Using an inert gas such as N1) 3 is pressurized by the inert gas introduced through the small diameter nozzle 2 (usually 0.2 to 1
．． The molten metal jet (hereinafter referred to as jet) 6 that is injected and formed through the nozzle 2 is stretched into a thin strip on the surface of the rotating roll 7 placed directly below the nozzle 2, and at the same time is rapidly deprived of the roll. After being rapidly solidified by thermal effects, it is sent to a collection container or winding device and collected. However, Figure 1.2 is an example in which multiple nozzles are employed.

In the present invention, as shown in FIGS. 1 and 2,
Each of the above nozzles 2. ... and the rotating roll 7, a small-diameter gas injection pipe 8 is installed parallel to the ribbon flight direction, that is, perpendicular to the roll rotation axis direction, and with the injection port in the opposite direction to the ribbon flight direction. ..., while the gas injection pipe 8
Container 9 to receive and store droplets blown away from the
will be established.

The diameter of the injection tube 8 is of course smaller than the nozzle/roll distance g set during operation, but it also prevents the ribbon from flying while the ribbon is being formed normally from the target nozzle. All you have to do is choose the pipe diameter within the range.

Regarding the mounting position, it is best to install it as close to the nozzle side as possible so as not to interfere with the flight of the ribbon, and in short, it can be placed between the nozzle and the roll as long as it does not become an obstacle. Furthermore, to explain the tip position and injection pressure of the injection tube 8, firstly, it is preferable that the tip position be as close to the nozzle as possible in order to efficiently and reliably blow away unstable jets or dripping droplets. If it becomes necessary to maintain a certain distance due to constraints such as the diameter, equipment structure, installation method, or nozzle monitoring for operation, the injection gas from the injection pipe may act on the jet of the adjacent nozzle. All you have to do is move it back to a range that does not disturb the stability of the jet. In addition, it is advantageous to increase the pressure of the gas introduced into the injection tube 8 in order to reliably blow off unstable jets or dripping droplets in the opposite direction to the ribbon flight direction, but if it is too high, the pressure of the introduced gas Since waste, adverse effects on adjacent jets, and contamination of the blown fine powder into the ribbon due to unnecessary gas convection within the chamber occur, a pressure that can reliably feed the powder into the storage container 9 may be selected. However, if the pressure is too low, the blowing will not be sufficient and some or all of the jet or dripping droplets will fall onto the roll surface, causing the above-mentioned problems, so care must be taken.

On the other hand, in order to detect when the molten metal jet becomes unstable (FIG. 6(a)) or becomes droplets (FIG. 6(b)), a photoelectric switch floodlight IO is installed on the gas injection pipe 8 side. is placed, while a photoelectric switch receiver 1 is placed on the side of the storage container 9.
2 are placed facing each other. When the molten metal jet turns into droplets,
Such a state is detected as a change in the amount of light, and the control device I3
The electromagnetic valve 14 provided in the gas injection pipe 8 is opened via the gas injection pipe 8 to inject inert gas from the gas injection pipe 8, and the droplets are blown away and stored in the container 9. In the drawing, the projector 10 is housed in a gas injection tube, and a pipe 15 for supplying inert gas is provided in front of the receiver 12 in order to cool the projector and receiver and to avoid adhesion of splashed powder. In addition, II is a power source for light projection.

Instead of the photoelectric detection described above, an infrared imaging device 20 may be used as shown in FIGS. 3(a) and 3(b).

In this case, if the camera section is placed above the front of the roll and the temperature of multiple ribbons is constantly measured, the roll surface temperature (normally due to the water cooling effect) when droplets are generated (Fig. 3 (b)) 200-250°C) is measured.
Since the surface temperature of the flying ribbon (normally 300 to 500° C.) is lower than that in FIG. 3(a), it is possible to detect when a droplet is generated by image analysis.

Note that the device structure may be appropriately determined depending on the type of metal and operating conditions (nozzle diameter, nozzle/roll distance, distance between adjacent nozzles, etc.).

Although the present invention has been explained above in the case of a single roll method, it can also be applied to a double roll method when the nozzle is placed above the top surface of the roll as shown in Fig. 4. . Identical members are given the same numbers and their explanations will be omitted.

(Manufacturing example) Ribbon manufacturing conditions and quality of ribbon are manufactured using the method of the present invention using the 8ρ-8%Fe-8% (La%Ce) alloy, and when the present invention is not applied. The results of a comparative investigation are shown in the table below.

The main conditions for conducting this study are as follows.

(a) Ribbon manufacturing conditions: melting amount = 3, 9 nozzle diameter = 0.
5 to φ Number of nozzles, nozzle spacing = above-mentioned front roll diameter = 300 mm φ Roll rotation speed = 2500 rpm Nozzle/roll distance = 7 mm (b) Present invention implementation conditions: Gas injection diameter - 3 curved gas injection pipe tip position = nozzle center 2mm Injection pressure = 2, 0 kg/mm” Injection gas = Ar (Operations and Effects of the Invention) As is clear from the above explanation, according to the present invention, unstable jets or dripping droplets caused by nozzle blockage are reduced to ribbons. By blowing in the opposite direction to the flight direction, we have made it possible to prevent inferior quality ribbons or slow-cooled powder from mixing with good quality ribbons using extremely simple equipment, even in cases where conventionally the entire amount had to be disposed of or operations had to be discontinued. Since the operation can be continued as is and only high-quality ribbons can be recovered, the quality and productivity of rapidly solidified ribbons can be significantly improved.

[Brief explanation of the drawing]

Fig. 1 is an elevational view schematically showing an apparatus for carrying out the method of the present invention, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 shows the state of droplet generation using an infrared imaging device. An explanatory diagram of the operation in the case of detection, FIG. 4 is an elevation view showing the outline of the device when the present invention is applied to the twin roll method, and FIG. 5 is an elevation view showing the device configuration of the conventional single roll method. FIGS. 6(a) and (b) are explanatory diagrams showing the injection angle fluctuation state of the molten metal jet and the droplet drop phenomenon, respectively. FIG. 7 is an explanatory diagram showing the state of droplet formation due to droplet formation, and FIG. FIG. 2 is an explanatory diagram showing a phenomenon in which adjacent ribbons are deteriorated due to the formation of droplets (slowly cooled powder). ■...Metal molten metal, 2...Small diameter nozzle, 4...Sealed crucible, 6...Metal molten metal jet, 7...Rotating roll, butt...Gas injection pipe, IO...Floodlight, 12 ...
Receiver, 20... Infrared imaging device, R... Ribbon, L... Droplets. Patent applicant: Aluminum powder metallurgy technology research association.

Claims (1)

[Claims] (1) The molten metal in the crucible is injected as a molten metal jet from a small-diameter nozzle, and is rapidly solidified on a rotating roll placed directly below the nozzle to produce solidified materials such as ribbons, tapes, and flakes. If the molten metal jet becomes unstable or becomes droplets, this is detected, and gas is injected between the nozzle and the rotating roll in parallel to and opposite to the flight direction of the solidified material, and the gas is injected from the nozzle. A method for producing rapidly solidified metal, which comprises blowing out unstable molten metal jets or droplets in a direction opposite to the flight direction of the rapidly solidified material.