JPH0655247A - Nozzle for spinning metallic fiber - Google Patents

Abstract

PURPOSE:To provide the nozzle for spinning for stable production of a metallic fiber by increasing the melting temp. of the metal as high as possible, thereby lowering the viscosity of a molten alloy and preventing nozzle clogging and nozzle failure. CONSTITUTION:This nozzle for spinning the metallic fiber consists of the nozzle constituted by laminating plates A, B consisting of at least two kinds of ceramics and is formed by inserting a material, such as graphite, molybdenum, tungsten, platinum or tantalum, as a plate heater C and a packing material between these plates. As a result, the nozzle clogging in melt spinning is eliminated and the stable and safe spinning of the metallic fiber having a truly circular shape in section is possible; in addition, the nozzle is extremely simple in construction and is easy to use.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal fiber spinning nozzle capable of safely and stably spinning a metal fiber by a melt spinning method.

[0002]

2. Description of the Related Art Conventionally, when producing a metal fiber having a small diameter, the diameter of the metal fiber is usually reduced by passing through a die, and the desired number of times of passing through the die is repeated to produce the desired metal fiber having a small diameter. It was generally done. However, since the above method requires a lot of man-hours and accordingly the cost of the final product is high, a method for producing a metal fiber having a small wire diameter at a lower cost has been studied, and the metal fiber is produced by the melt spinning method. It came to be. (JP-A-3-2075
(No. 58)

The present invention is completely different from the above-mentioned invention and provides a method for continuously and safely producing metal fibers by using a simple spinning nozzle. As a result of many years of research on the production of fine metal fibers by the melt spinning method, the present applicant has found that the molten metal is made into a continuous fiber having a small variation in the cross-sectional area in the longitudinal direction and a uniform crystal orientation. A method and an apparatus for producing a continuous metal fiber having a structure have been completed. That is, the molten metal is jet-jetted from an orifice to a gas cooling cylinder, the metal sprayed in the gas cooling cylinder is solidified, and then the metal fiber obtained by solidification is wound into a rotary drum, and a method for producing the same. The present invention relates to a manufacturing device. (JP-A-3-243246)

[0004]

However, according to the results of studies by the present inventor, the biggest problem in the melt spinning method for metal fibers according to the invention of the present applicant lies in the nozzle in the metal fiber spinning apparatus. found. For example, when manufacturing metal fibers, especially steel fibers with a diameter of 100 μm or less, unless the melt spinning temperature is maintained at a high temperature of 1500 ° C, the viscosity of the molten metal is too high to produce metal fibers with a perfect circular cross section. Is extremely difficult.

However, when the melt spinning temperature is raised to 1500 ° C. or higher, the surface of the molten metal reacts with the ceramics nozzle plate in contact with the molten metal or the surface is oxidized by air to cause nozzle clogging, and finally a uniform metal fiber is spun. It can be difficult. Alternatively, when the molten metal is heated and melted at a high temperature as described above, when the molten metal is jetted from the nozzle, there is a risk that the nozzle may be damaged due to a sudden change in the nozzle temperature, and therefore, the temperature is usually 1500 ° C. or higher as described above. Melt spinning of metals does not occur at elevated temperatures. Therefore, as described above, it has been extremely difficult to stably spin a metal fiber having a perfect circular cross section.

In view of the above, in order to solve the various problems described above, the present invention reduces the viscosity of the molten alloy by raising the melting temperature of the metal as much as possible, and prevents clogging of the nozzle and damage to the nozzle. Another object of the present invention is to provide a spinning nozzle for stably producing metal fibers. .

[0007]

In order to solve the above problems and to achieve the above object, the present invention comprises a nozzle formed by laminating plates made of at least two kinds of ceramics, The present invention relates to a metal fiber spinning nozzle in which a high melting point substance such as graphite, molybdenum, tungsten, platinum or tantalum is inserted between the at least two ceramic plates as a plate heater and a packing material. Graphite is particularly suitable as a plate heater and a packing material.

The present invention will now be described with reference to the drawings. [FIG. 1] is a tank for storing the molten metal used in the metal fiber spinning apparatus of the above-mentioned JP-A-3-243246 of the present applicant.
FIG. 3 is a schematic cross-sectional view of an embodiment of a discharge portion of a spinning device including (1). The molten metal (1) is in a molten state in the crucible (2) by the high frequency induction coil (5) and is discharged from the discharge part (3) by applying pressure (P) to the upper part (4) of the crucible. When using the crucible having the structure shown in FIG. 1, it is necessary to consider the material of the crucible (2) itself. That is, there is a possibility that the crucible (2) may be damaged by the heat shock due to the temperature difference between the portion in contact with the molten metal and the non-contact portion in the crucible. Moreover, since the pressure of the injection gas is applied to the side wall of the crucible itself, strength at high temperature is also required. Further, when it is desired to produce metal fibers having a diameter of 100 μm or less, it is difficult to process the discharge part on the crucible. Generally, a quartz pipe is heat-deformed to process the discharge portion, and is used as a crucible.

FIG. 2 is a schematic cross-sectional view of one embodiment showing the material of the nozzle portion used in the metal fiber spinning nozzle used in the present invention. That is, as shown in FIG. 2, the nozzle portion is constructed by laminating plates made of two ceramic materials (A) and (B) in a direction perpendicular to the flow direction of the molten metal. . In this case, it is preferable that the plate (A) contains, as a main component, one kind selected from metal oxides such as alumina, magnesia, calcia and beryllia, which have low reactivity with molten metal. The plate (B) is the plate.
As the support plate of (A), silicon nitride, aluminum nitride, or the like, which has high strength at high temperature, is preferably used.

When spinning the molten metal using the nozzle as described above, the problem is that the molten metal reacts with the nozzle plate (A) at a high temperature or nozzle clogging occurs due to air oxidation of the molten metal. It's a problem. The molten metal varies depending on its kind, but unless the temperature is raised to a high temperature of 1500 ° C. or higher, the viscosity is high and there is a possibility that stable melt spinning cannot be performed. However, the higher the temperature, the higher the activity of the metal and the formation of a reaction product with the nozzle plate. Generally, the melting point of these reactants or the oxide of the metal itself generated at high temperature is about 20 to 50 ° C higher than the temperature of the molten metal, so even if the metal is kept above the melting point Metal oxides can clog the nozzle and often make injection impossible. In addition, the nozzle blade transfers heat by heat conduction in the vertical direction from the contact surface with the molten metal, but at the tip of the nozzle, the temperature decreases due to heat dissipation to the atmosphere, which promotes the formation of reactants or oxides. There is. Furthermore, the nozzle plate (A) often uses dense ceramics to prevent reaction with the molten metal, and since a heat shock is generated by a slight temperature difference, the contact surface with the molten metal is not It often breaks due to the temperature difference from the contact surface.

In view of the above situation, the present inventor has conducted earnest research on a nozzle for spinning a metal fiber from molten metal, and as a result, finally reached the above-mentioned nozzle for a metal fiber of the present invention. A sectional view of one embodiment of the constitution is shown in FIG.

In order to avoid the above-mentioned nozzle clogging and perform safe spinning, it is necessary to heat the tip temperature of the nozzle plate to the temperature of the molten metal or higher. Therefore, in the present invention,
As shown in FIG. 3, it has a thickness of 0.5 to 5 mm, which is formed so as to completely contact the lower surface of the nozzle plate (A) in the gap between the nozzle plate (A) and the nozzle plate (B). By inserting a ring-shaped high melting point self-induction heating element (C) of graphite, molybdenum, tungsten, platinum, tantalum, etc., the nozzle plate (A) lower surface is heated by this planar heater. It was composed. By adopting this structure, the surface heater (C) generates heat by self-induction, so the lower surface of the nozzle plate (A) becomes equal to or higher than the temperature of the molten metal, and the tip of the nozzle plate is The formation of reactants or oxides is prevented, and stable spinning is possible. Further, since it has a function of alleviating the temperature difference generated in the vertical direction of the nozzle plate (A), it also prevents damage due to heat shock. Furthermore, since the surface heater (C) generates heat by self-induction as described above, unlike ordinary electric heating heaters, no lead wire or the like is required, and it is extremely simple in terms of equipment. It is easy to use and useful.

[0013]

The present invention will be described below with reference to examples. [Example 1] Using a nozzle as shown in Fig. 3, commercially available iron was melted by induction heating. Nozzle plate
A dense alumina plate having pores with a diameter of 100 μ was used as (A), and a dense silicon nitride plate was used as nozzle plate (B). A circular ring made of molybdenum having a thickness of 1 mm was inserted into the surface heater (C), and a molten metal was discharged from a nozzle for 15 minutes by pressurizing with 20 kg / cm ² of argon gas in the crucible. It was confirmed that the discharged molten metal fluid was discharged as a continuous fluid near the nozzle. Moreover, when the temperature was measured, the temperature of the molten metal in the crucible was 1500 ° C, whereas the temperature of the lower surface of the nozzle plate (A) was 1550 ° C, indicating that the temperature was reversed between the upper surface and the lower surface. confirmed. The nozzle maintained its original shape without being damaged even after ejection.

Comparative Example 1 Using a nozzle as shown in FIG. 2, commercially available iron was melted by induction heating. As the nozzle plate, an alumina plate and a silicon nitride plate were used as in the examples. Although the molten metal was pressed at a temperature of 1600 ° C in the same manner, the metal fluid was no longer discharged 90 seconds after being discharged. After the ejection, the metal oxide layer was confirmed by observing the tip of the nozzle plate. Moreover, when the temperature inside the crucible was measured, the temperature of the lower surface of the nozzle plate (A) was 1380 ° C, which was 220 ° C lower than that, although the temperature of the molten metal was 1600 ° C.

[0015]

The effects of the present invention are summarized as follows. (A) According to the present invention, graphite, molybdenum, and tungsten, which are self-induction heating elements, are provided between the upper and lower nozzle plates.
By inserting a self-induction heating element having a high melting point, such as platinum or tantalum, as a plate heater and a packing material, the nozzle plate can be heated and there is no nozzle clogging during spinning of molten metal, which is stable. As a result, it is possible to safely spin a fine metal wire having a perfect circular cross section. (B) Further, the plate (C) inserted between the nozzle plates (A) and (B) is composed of a high melting point self-induction heating element such as graphite, tungsten, platinum or tantalum. Therefore, there is an advantage that a lead wire is not required and the apparatus is extremely simple and easy to use.

[Brief description of drawings]

FIG. 1 is a schematic view of a conventionally known metal fiber spinning device.

FIG. 2 is a schematic cross-sectional view of an embodiment of a nozzle portion composed of two types of plates used in the present invention.

FIG. 3 is a schematic sectional view of an embodiment of the nozzle of the present invention.

[Explanation of symbols]

 1. Molten metal 2. Crucible 3. Discharge unit 4. Pressure unit 5. High frequency induction coil A, B. Ceramics nozzle plate C. Face Heater

Claims (1)

[Claims] 1. A nozzle formed by laminating plates made of at least two types of ceramics, wherein graphite, molybdenum, and tungsten are provided between the plates.
Plate heat-resistant materials such as platinum and tantalum
A nozzle for spinning a metal fiber, characterized by being inserted as a target and a packing material.