JPS60161490A - Apparatus for producing magnetic fluid - Google Patents

Abstract

PURPOSE:To convert a ferromagnetic substance to a highly stable colloid, and to obtain a magnetic fluid having excellent thermal and electrical conductivity, by evaporating a ferromagnetic substance with a heater, and contacting the vapor with a liquid containing a surfactant to effect the condensation of the ferromagnetic substance. CONSTITUTION:A crucible 7 is placed in a cylindrical drum 1, and the drum 1 is evacuated to high vacuum or substituted with an inert gas or oxygen gas having low pressure. A ferromagnetic metallic element such as Fe, a ferromagnetic alloy containing a metal such as Cr or a ferromagnetic compound (hereinafter referred to as ferromagnetic substance) 8 is charged in the crucible 7. A liquid 6 containing a surfactant is poured to the bottom of the cylinder 1 as the medium of the magnetic fluid. The drum 1 is revolved, and the liquid 6 is developed over the inner wall of the drum 1 to form a coating film. The vapor of the ferromagnetic substance evaporated by heating is made to condense on said coating film to form a ferromagnetic colloid. The operation is repeated until the objective magnetic fluid is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for producing magnetic fluid. It is known that most of the magnetic fluids that have been developed so far have magnetic fluids as a dispersed phase.

The method for producing magnetite colloidal magnetic fluid is as follows: (1) Magnetite lumps are ground for a long time (5 to 20 weeks) using a ball mill in a mixed solution of water, a colloidal dispersion medium such as kerosene, and a surfactant. Wet method (2) to separate large particles and create a magnetic fluid (2) After adding an alkali to a mixed aqueous solution of ferrous and ferric salts to coprecipitate fine magnetite particles, a surfactant is used to create a magnetic fluid. A wet precipitation method was used to peptize the material and create a magnetic fluid.

However, the wet pulverization method requires a long pulverization time and a step of separating coarse particles after pulverization, resulting in extremely low production efficiency and poor raw material utilization efficiency due to the separation of coarse particles. In principle, the particle size of the pulverized particles is distributed over a wide range, making it difficult to control the properties of the magnetic fluid and control its quality. Furthermore, the magnetic material of the magnetic fluid that can be applied to this method is limited to soft and brittle materials such as magnemate, and has many drawbacks such as being difficult to apply to sticky metals or alloys.

On the other hand, the wet precipitation method utilizes a co-precipitation reaction of iron salts, so
The target is limited to ferromagnetic liquefied substances such as magnetite, and it is difficult to apply it to a wide range of ferromagnetic substances. Further, although the particle size of the fine particles obtained by this method is uniform in the range of 100 to 200X, there is a further drawback that it is difficult to obtain particles with a smaller particle size.

The most important factor that characterizes the performance of a magnetic fluid is the magnitude of its magnetization. A magnetic fluid using magnetite colloid has a performance of K11 degrees because the magnetite itself has a small magnetization value.

The fundamental solutions to this problem are iron, which has high magnetization, ferromagnetic metals such as conort, iron-cobalt alloys, iron-cobalt alloys, iron-cobalt alloys,
Use a colloid made of a ferromagnetic alloy such as a nickel alloy or a ferromagnetic compound such as a Laves phase compound. Further, in this case, the particle size of the colloidal particles is made uniform to 20 to 100X.

As a conventional technique in this direction, a method is known in which a magnetic fluid made of cobalt colloid is produced by thermally decomposing conocarbonyl (C-(CO)S) in toluene.However, according to this method, The resulting cobalt colloid particles had a particle size of about 200×, and had the disadvantage that they tended to aggregate in a colloid solution.

The present invention was made to eliminate the drawbacks of these conventional methods, and its purpose is to use a highly magnetized ferromagnetic metal element,
Fine particles of ferromagnetic alloys and ferromagnetic compounds can be obtained as a dispersed phase, and the particle size of these fine particles is 20 to 100X.
It is an object of the present invention to provide an apparatus for easily and efficiently producing a colloidal magnetic fluid having high stability against agglomeration.

To explain the magnetic fluid manufacturing apparatus of the present invention based on the drawings, FIG. 1 is a schematic explanatory diagram of an embodiment of the magnetic fluid manufacturing apparatus of the present invention, and (a) of FIG. 1 is an inner drum method, (
b) shows the outer drum method, and (c) shows the belt method. FIG. 2 shows a partially cut section of an apparatus according to an embodiment of the inner drum method.

To explain in Fig. 1(a), a horizontal cylindrical drum l
The interior is set to a high vacuum or low pressure inert gas or low pressure oxygen gas atmosphere. The cylindrical drum 2 is configured to be able to slowly rotate multiple times or reciprocate. A refractory crucible 7 made of, for example, beryllia (BeO) or alumina (AlffiOs) is installed in the center of the cylindrical drum l, and the nuclear crucible 7 is heated with a heater made of tungsten, tantalum, etc., and Fe, Co, A ferromagnetic alloy or ferromagnetic compound 8 (hereinafter collectively abbreviated as ferromagnetic material) containing at least one metal selected from ferromagnetic metal elements such as Ni and cadmium, Cr, Mn, and rare earth elements is loaded. . The heating may be high frequency heating, infrared or laser heating, electron beam heating, or arc plasma heating.

Further, a liquid 6 containing a surfactant and serving as a medium for magnetic fluid is placed at the bottom of the cylindrical drum 1. The medium constituting the liquid includes a low vapor pressure liquid such as alkylnaphthalene,
Examples include low vapor pressure hydrocarbons, alkyldiphenyl ethers, polyphenyl ethers, diesters, silicone oils, fluorocarbon oils, and the like. However, it is not limited to these. The surfactant is preferably a surfactant that is soluble in the medium, has a lower surface tension than the medium, and has a functional group that exhibits strong adsorption to ferromagnetic substances. For example, soaps that are salts of carboxylic acids and metals or amines, sorbitan oleate, pentaerythritol oleate, polyhydric alcohol fatty acid esters, alkylaryl sulfonates, sulfonates such as octadecylbenzene sulfonate, and other phosphoric acids. Examples include salts, phosphate esters, amine derivatives, and the like. However, it is not limited to these.

When the cylindrical drum 1 is rotated, the liquid spreads along the inner wall of the cylindrical drum to form a film. The vapor of the ferromagnetic substance evaporated by heating condenses and adheres to this film to form a ferromagnetic colloid. The generated ferromagnetic colloid is transported to the bottom of the cylindrical drum.

By repeating this process, a magnetic fluid with a desired concentration can be obtained. In the figure, 13 is a round heat insulating plate that prevents the temperature of the liquid containing the surfactant from increasing due to heat radiation from the crucible 7. Further, it is preferable to cool the outer periphery of the cylindrical drum and the heating electrode portion with water to prevent the temperature of the liquid from rising.

Figure 1(b) shows a rotating cylindrical drum 1 and a liquid tank containing a surfactant installed in a container 1' whose interior is in a high vacuum, low pressure inert gas, or low pressure oxygen gas atmosphere. This is a device in which the lower part of a cylindrical drum 1 is immersed in a liquid 6 and rotated to form a liquid film on the surface of the drum, and evaporated matter of a ferromagnetic substance is condensed on the film.

In addition, FIG. 1(e) shows the rotating cylindrical drum I in FIG. 1(b).
Instead of K, a belt 15 rotated by rollers 16, 16' and 16'' is used.

An embodiment of the present invention is illustrated in FIG. 1, and the gist thereof is to generate vapor of a ferromagnetic substance in a high vacuum or low pressure inert gas or oxygen gas atmosphere, and to generate a magnetic fluid containing a surfactant. The apparatus continuously produces a colloidal liquid by forming a film of a liquid serving as a medium, and while circulating this film, it is brought into contact with and condensed with the vapor of the ferromagnetic substance. Therefore, its aspects may vary.

According to the magnetic fluid manufacturing apparatus of the present invention, the following excellent effects can be achieved. .

(1) In order to make a colloidal liquid by contacting and condensing the vapor obtained by evaporating a ferromagnetic substance with a liquid that is a medium for a magnetic fluid containing a surfactant, in addition to magnetite and cobalt in the conventional method, , as well as other ferromagnetic metals,
Ferromagnetic alloys and ferromagnetic compounds containing at least one of iron, cobalt, nickel, manganese, lithium, europium, samarium, gadolinium, neodymium, and praseodymium can be produced.

Therefore, the saturation magnetization, which could not be obtained with the conventional method, is 2000
It is possible to obtain a magnetic fluid exhibiting Gaussian behavior, and it can also be made to have excellent thermal conductivity and electrical conductivity.

(2) By changing the atmosphere and K, a sulfuric fluid consisting of ferromagnetic metal oxides can be created. For example, by providing an appropriate amount of oxygen atmosphere, it is possible to produce not only a conventional magnetic fluid made of magnetite colloid but also a magnetic fluid made of multi-element ferrite colloid.

(3) The particle size of the colloidal particles obtained is 20 to 50X, and the particle size can be controlled by mutually adjusting the rotation speed of the cylindrical drum and the amount of evaporation of the ferromagnetic substance. The resulting magnetic fluid is unlikely to cause agglomeration or precipitation, exhibits high stability, and appears to have low viscosity.

(4) Since uniform particles can be easily obtained, there is no need for particle sorting in conventional methods, which simplifies the manufacturing process, yields high yields, and provides excellent production efficiency.

(5) Ferrofluid can be easily manufactured continuously, the manufacturing process is automatic, and quality control is also easy, making it suitable for industrial production.

etc., can produce excellent effects that cannot be obtained with conventional methods.

Example The apparatus shown in FIG. 2 was used. 1 is a drum made of Pyre Tutus glass and fixed to a metal flurry 2, and the nuclear drum 1 is rotated at a speed of 2 revolutions per minute by a pulley 4 while keeping it airtight through a vacuum rotary seal 3. Ta. The system was evacuated to high vacuum through flange 5. Alkylnaphthalene28. A liquid 6 consisting of F and alkylpropylene diamine 2f was placed at the bottom of the drum 1. By rotating the drum 1, the liquid was spread in a film on the inner wall of the drum and returned to the bottom, and this process was continuously repeated.

A current is passed through the tungsten wire heater through the spirally wound tungsten wire heater, and cobalt particles 8
was heated and evaporated. Its current value was 40 amperes. The evaporated cobalt atoms fly in the vacuum, condense and adhere to the surface of the liquid film at the upper part of the inner wall of the drum 2, producing a metallic cobalt colloid, and as the drum rotates, a magnetic fluid is produced in the reservoir at the bottom of the drum. did.

In addition, in order to prevent heating due to radiant heat from the heating crucible 7, the drum 1 is cooled by flowing water from the nozzle 11 into several spaces.
The rotary shaft seal was cooled by low-temperature gas injection from the nozzle 12, and a reflective plate 13 was provided to insulate it. Further, the cock 14 is used to block the insertion of the cobalt particle raw material and liquid and the outlet for the produced magnetic fluid.

By performing the above operation for 30 minutes, 200 Gauss1
A cobalt ferrofluid with a magnetization of 0.00 was obtained. Also by increasing the amount of cobalt or using other ferromagnetic alloys or compounds! D1600 It is possible to manufacture a magnetic fluid with a magnetization of about 100 Gauss.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1(a)
(b) and (e) are explanatory diagrams of apparatuses for the inner drum method 3, the outer drum method, and the belt method, respectively, and FIG. 2 is a partially cut section of the embodiment apparatus. 1 Ni drum 1' Vacuum container 2: Flange 3: Vacuum rotating shaft seal 4: Pulley 5 = Flange 6: Liquid containing surfactant 7: Crucible 8: Ferromagnetic material raw material 9: Current introduction terminal 1O: Electrode 1: Cooling Water nozzle 12: Low temperature gas injection nozzle 13:
Reflector plate 14: Cock 15: Rotating belt 16. 16', 16'': Roller Patent applicant Science and Technology Agency, Metals Materials Technology Research Institute

Claims (1)

[Claims] 1. A heating evaporation device for a ferromagnetic metal element, ferromagnetic alloy, or ferromagnetic compound is installed in a container with a high vacuum or low pressure inert gas or oxygen gas atmosphere, and a magnetic material containing a surfactant is installed. A liquid is contained as a fluid medium, a film of the liquid is formed, and the liquid film is circulated and brought into contact with the vapor of the evaporated ferromagnetic metal element, ferromagnetic alloy, or ferromagnetic compound to condense it. A magnetic fluid manufacturing device characterized by: