JPS6379924A - Manufacture of fibrous integrated body and equipment therefor - Google Patents

Abstract

PURPOSE:To obtain a fibrous integrated body capable of improving strength and also of inhibiting thermal expansion when used in manufacturing a fiber-reinforced metal, by pouring a fibrous suspension into electric fields between plural couple of anodes and cathodes in a vertical cylindrical space, by subjecting the fibers to electrostatic orientation in the tangential direction of circumference and to bridging, and then by settling and integrating the above fibers in succession. CONSTITUTION:The fibrous suspension in which discontinuous fibers of short fiber of Al2O3, etc., are dispersed in a dielectric liquid such as CCl4, etc., is alternately poured into the electric fields respectively generated between plural couple of anodes 4 and cathodes 5 in foil condition, etc., from the upper part of the vertical cylindrical space 3. The poured fibers mentioned above are subjected to dielectric polarization in the dielectric liquid and electrostatically oriented in the tangential direction of circumference, and many of the above fibers form bridging and increase their mass and then settle while keeping the state of orientation in the tangential direction of circumference. These oriented and bridged fibers 10 are successively integrated on a filter 7 by means of filtrate discharge from a conduit 8 which is carried out parallel to the pouring of the above suspension, so that fibrous integrated body 11 of prescribed thickness is formed and this integrated body 11 is taken out after the discharge and removal of the residual liquid.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method and apparatus for producing a fiber aggregate, and more particularly, it relates to a method and an apparatus for producing a fiber aggregate, and more particularly, it relates to a method and an apparatus for producing a fiber aggregate, particularly for producing fiber-reinforced metals in which most of the miscellaneous materials are oriented in the tangential direction of the circumference. The present invention relates to a method and apparatus for obtaining a suitable cylindrical fiber aggregate.

[Prior Art] Conventionally, in order to obtain an aggregate of relatively short fibers such as short fibers or whiskers used in the production of fiber-reinforced metals, a fiber dispersion liquid is placed in a porous cylinder lined with a filtration membrane. A centrifugal molding method (Japanese Patent Laid-Open No. 60-65
200) and a suction molding method in which a fiber dispersion supplied into a cylinder is pressurized with a plunger, and the filtrate is actively discharged from the bottom via a filter material.

However, in the fiber aggregate formed by the above-mentioned molding method, many of the fibers are oriented in two-dimensional or three-dimensional directions, and the volume fraction of fibers is low. However, when it comes to suppressing thermal expansion, very unsatisfactory results were obtained.

[Problems to be Solved by the Invention] In order to obtain a fiber aggregate in which most of the fibers are one-dimensionally oriented, the present invention involves creating a fiber suspension in which fibers are dispersed in a dielectric liquid between positive and negative electrodes. It is based on the technical idea that the fibers are injected into an electric field to electrostatically align and bridge the fibers at the same time, and the tags with the same orientation are sequentially sedimented and accumulated.

However, there are many problems that arise when implementing such basic technology industrially.

For example, when a fiber suspension is injected into an electric field created between positive and negative electrodes arranged in parallel to electrostatically orient the fibers, most of the fibers become aggregates oriented in one dimension, that is, in a straight line. is obtained, and the aggregate is quite useful as such. However, many of the functional parts to which fiber-reinforced metals are applied are cylindrical or cylindrical, and there is a problem in that the linearly oriented fiber aggregate cannot be suitably used for such functional parts.

The technical problem to be solved by the present invention is to obtain a cylindrical fiber aggregate in which most of the discontinuous fibers are oriented in the tangential direction of the circumference.

[Means for Solving the Problems] In order to solve the above problems, the present invention creates an electric field between multiple pairs of positive and negative electrodes arranged alternately in the normal direction of the circumference in an upright cylindrical space, and A miscellaneous suspension in which discontinuous fibers such as miscellaneous fibers and whiskers are dispersed in a dielectric liquid is injected into the above electric field to electrostatically orient the fibers in the tangential direction of the circumference, and at the same time bridge the fibers to achieve the same orientation. I! A novel structure is adopted in which the webs are allowed to settle and accumulate in sequence.

A particularly important feature of the invention is the electrostatically orienting reservoir electrode, which is disposed in the normal direction of the circumference within the upright cylindrical space and extends vertically so that its pole There is no particular limit to the number, but the number of positive and negative electrodes is equal,
In addition, positive electrodes and negative electrodes are arranged alternately in the circumferential direction. The most preferable form is that the upright cylindrical space is divided into an even number of equal parts in the horizontal plane by each electrode.In other words, the dimensions of each fan-shaped cross-sectional space divided by the electrodes are approximately equal, so that each divided area is divided into equal parts. The strength of the electric field created is approximately uniform.

Since the above-mentioned electrode is arranged in a form that divides the oriented fibers in an upright cylindrical space, it is preferable to make it as thin as possible in order to reduce the part where the oriented fibers are separated. It is desirable to have a shape such as a mesh shape, a mesh shape, or a combination thereof.

The surfaces of the positive and negative electrodes are coated with a diaphragm that prevents short-circuiting of the conductive fibers and suppresses turbulent flow of the fiber suspension. The diaphragm can be a filter paper, but it is preferable to use an ion exchange membrane that prevents turbulence of the fiber suspension. In that case, an anion exchange membrane is provided on the surface of the positive electrode. A cation exchange membrane is coated on the surface of the negative electrode.

As a result, the anion exchange membrane prevents cations generated on the positive electrode side from permeating into the my orientation, and similarly, the cation exchange membrane prevents anions generated on the negative electrode side from entering the fiber orientation region. In order to prevent permeation, ion-induced disturbances of the fiber suspension are effectively prevented.

The production of the $l miscellaneous material begins with dispersing fibers such as short fibers and whiskers in a dielectric liquid to form a fiber suspension.

As the above vaN, anything that falls within the range of short fibers and whiskers can be used, and the diameter and length thereof are not particularly limited. The fibers may be made of any material that electrostatically aligns in a dielectric liquid when injected as a fiber suspension into a predetermined electric field, such as alumina, silica, alumina-silica, beryllia, carbon, In addition to silicon carbide, silicon nitride, and glass, various metals can be used. Ma-6= In addition, two or more of the #&chicks may be used in combination.

The above-mentioned dielectric liquid refers to a liquid that exhibits dielectric properties upon application of voltage, and examples thereof include carbon tetrachloride, fluorochlorine-substituted hydrocarbons, n-hexane, and cyclohexane. Among these dielectric liquids, carbon tetrachloride is particularly preferred, and fluorochlorine-substituted hydrocarbons are superior in handling safety.

In order to disperse the fibers as uniformly as possible in the dielectric liquid, it is generally desirable to add a suitable amount of a surfactant, particularly a nonionic surfactant.

Next, an electric field is created between a plurality of pairs of positive and negative electrodes arranged alternately in the normal direction of the circumference in the upright cylindrical space, and the fiber suspension is injected into the electric field, so that the fiber suspension is injected into the dielectric liquid. Then, the individual w4 navy blue is oriented in the circumferential tangential direction with one end facing the positive electrode and the other end facing the negative electrode, and at the same time, it is sedimented with bridging.

The strength of the electric field t created by applying a voltage between the positive and negative electrodes is typically 0.5 to 5 kv/cm, which is Q, 2k.
If it is less than about 10 kv/cm, the electrostatic orientation of the fibers will not be sufficient, and if it is more than about 10 kv/cm, the fiber suspension will be disturbed and the precision of fiber orientation will deteriorate. The most preferred electric field strength is about 1 to 2 kv/cm. The strength of the electric field is set to the most preferable value depending on the type of fibers used, the dielectric properties of the dielectric liquid, the thickness of the fiber assembly to be produced, and the like. The settled oriented fibers are accumulated in the lower part of the upright cylindrical space, but the injection of the fiber suspension continues until the desired thickness is reached, and approximately the same amount of liquid is poured from the bottom wall of the container. Evacuation takes place.

In this case, it is important to be careful when draining the liquid, and after adjusting the flow rate to a level that does not cause mechanical disturbance to the liquid, it is desirable to allow it to drain naturally or by suction.

It is effective to perform the above-mentioned flow discharge through a filter disposed at the bottom of the upright cylindrical space, not only to adjust the flow rate but also to prevent fiber leakage and liquid turbulence. For example, porous ceramic can be used.

In addition, the electrode in the lower part of the upright cylindrical space, that is, at least in the part corresponding to the accumulation height of the settled taIll, has a relatively sparse needle line shape or net shape,
It is desirable to cancel the division of the orientation #A miscellaneous by the electrode.

The cylindrical fiber aggregate taken out after the accumulation is completed and the residual dielectric liquid is discharged and removed is used as a woven base molded body for fiber-reinforced metal of a cylinder or a functional part formed in a cylindrical shape. It is something.

For carrying out the method of the invention, for example, an apparatus as schematically shown in FIGS. 1 and 2 is used. In the figure, 1 is the outer cylinder 1a.
An inner cylinder 2 arranged concentrically with the outer cylinder 1a is supported on the inner bottom surface of the bottomed container 1 by, for example, three legs 2a, and the outer cylinder 1a and the inner cylinder An upright cylindrical space 3, which serves as a fiber orientation region, is formed between the fiber orientation region 2 and the fiber orientation region. Inside the upright cylindrical space 3, a foil-like or mesh-like positive electrode 4 and a negative electrode 5 are arranged so as to equally divide the space 3 in the normal direction of the circumference and extend in the vertical direction. A plurality of pairs, for example, three each, are provided alternately.

The bottom part of the negative electrode 4.5, that is, at least the part corresponding to the accumulation height of sedimented II, is formed into a relatively sparse needle line shape 6, and its lower end is connected to the upright cylindrical space 3. It is tied to a filter body 7 disposed throughout the lower part, and the upper part is supported under tension in the vertical direction by a holder (not shown). The surfaces of the positive and negative electrodes 4.5 are coated with negative and positive ion exchange (not shown), and the master and negative electrodes 4.5 are placed between the positive and negative electrodes 4.5. It is connected to a voltage application device (not shown) for creating an electric field. In addition, the bottom of the bottomed container 1 is provided with a draining means consisting of a conduit 8 and a cock 9 which can also be connected to a suction device.

[Effects of the Invention] The method for producing m-miscellaneous aggregates of the present invention creates an electric field between a plurality of pairs of positive and negative electrodes arranged alternately in the normal direction of the circumference in an upright cylindrical space, and produces short fibers, A suspension of lIn, in which discontinuous fibers such as whiskers are dispersed in a dielectric liquid, is injected into the above electric field to electrostatically orient the fibers in the tangential direction of the circumference, and the fibers are sedimented and accumulated to form cylindrical fibers. Since it is designed to obtain an aggregate, it can be used as an I of a cylindrical or cylindrical functional component.
When used as a miscellaneous reinforced metal molded body, it exhibits the excellent effects listed below.

(1) Since many of the discontinuous II fibers in the fiber-reinforced metal are well oriented in the tangential direction of the circumference, the fibers sufficiently bear the stress in the same direction, greatly improving the strength of the reinforced metal. At the same time, especially I! Because the fiber orientation and expansion direction match,
Thermal expansion of the reinforced metal can be effectively suppressed.

(2) In comparison with continuous reinforcing metals wound in the circumferential direction, continuous fibers are susceptible to thermal cycling, and fibers and matrix metals are susceptible to peeling and buckling due to the difference in thermal expansion. However, in the case of discontinuous #& miscellaneous fibers oriented in the circumferential tangential direction, the matrix metal near the fiber end surface absorbs the strain caused by the thermal expansion of both, so the above defects do not occur.

(3) There is no need to compare reinforced metals made of discontinuous fibers oriented two-dimensionally or three-dimensionally randomly, but the strength It is extremely superior in terms of thermal expansion.

Furthermore, in the apparatus for manufacturing fiber aggregates of the present invention, the electrodes arranged in the normal direction of the circumference in the upright cylindrical space are shaped like thin foils, nets, or wires, and are oriented in the tangential direction of the circumference. Because it is designed to prevent rupture due to the electrode as much as possible,
It has an even more remarkable effect on improving the strength of fiber-reinforced metals.

[Example] The present invention will be explained below with reference to Examples.

(First Example) In the apparatus shown in FIGS. 1 and 2, positive and negative electrodes 4.5
were arranged alternately in a foil shape with a width of 15 mm at equal intervals, and the interval between adjacent electrodes was set to 55 mm at the center.

First, short alumina fibers (average fiber diameter: approximately 3 μm, average fiber length: 10 to 500 μm) without surface treatment were added to a carbon tetrachloride dielectric liquid along with a very small amount of nonionic surfactant, and these were stirred. A fiber suspension was prepared by dispersing 1&II.

An electric field of about 1 kv/cm is applied to each positive and negative electrode of the above device.
= All electrodes 4 from above the upright cylindrical space 3.
The w4 fiber suspension was injected between 5 and 5 days.

The injected fibers are dielectrically polarized in the dielectric liquid and electrostatically oriented in the circumferential tangential direction, and then many of them form bridges to increase mass and settle while maintaining the circumferential tangential orientation.

The above-mentioned oriented bridges eiiio are sequentially accumulated on the filter body 7 by discharging the filtrate from the conduit 8 in parallel with the injection of the fiber suspension, and after forming the fiber aggregate 11 of a predetermined thickness, the remaining liquid is discharged and removed.

This fiber aggregate has a cylindrical shape, and most of the fibers are well oriented in the tangential direction of the circumference, and the inner circumference has a somewhat larger fiber volume percentage than the outer circumference. However, the upright cylindrical space 3
By supplying a fiber suspension with a higher concentration in the outer peripheral region, it is possible to obtain an aggregate having substantially the same fiber volume percentage as a whole.

In this example, since the filter body 7 is provided in the entire lower part of the upright cylindrical space 3, there is almost no turbulence caused by the flow and discharge of the liquid, and most of the mI miscellaneous particles are very well oriented in the tangential direction of the circumference. Fiber aggregate! You can create if.

Since most of the fibers in this fiber aggregate are well oriented in the circumferential tangential direction, when this is used for fiber-reinforced metals,
Since the reinforced metal has high strength in the direction normal to the circumference and low thermal expansion, it can be effectively used in various pistons, etc., for example.

(Second Example) In this example, two positive and negative electrodes 4.5 are arranged in the form of a mesh (#4) at equal intervals, and the dielectric liquid is a fluorine-chlorine substituted hydrocarbon,
The fibers were made of silicon carbide whiskers (average fiber diameter: 0.7 μm, average fiber length: 50 μm), and the electric field strength was set to 1.5 kV.
An mi aggregate was manufactured in the same manner as in the first example except that the thickness was set to /cm.

In this example as well, I! A fiber aggregate was obtained in which most of the miscellaneous particles were well oriented in the circumferential tangential direction.

[Brief explanation of the drawing]

FIG. 1 is a sectional view taken along line J-r in FIG. 2, schematically showing an embodiment of the apparatus of the present invention, and FIG. 2 is a plan view thereof.

Claims (5)

[Claims] (1) An electric field is created between multiple pairs of positive and negative electrodes arranged alternately in the normal direction of the circumference in an upright cylindrical space, and discontinuous fibers such as short fibers and whiskers are dispersed in the dielectric liquid. A method for producing a fiber aggregate, in which a fiber suspension is injected into the electric field to electrostatically orient the fibers in a circumferential tangential direction and simultaneously bridge the fibers, thereby sequentially settling and accumulating the oriented fibers. (2) A bottomed container having an upright cylindrical space formed therebetween by concentric inner and outer cylinders, and a plurality of pairs arranged alternately in the normal direction of the circumference within the upright cylindrical space, and in the vertical direction. Extended foil-shaped positive and negative electrodes, a filter disposed at the bottom of the upright cylindrical space, a drainage means provided on the bottom wall of the bottomed container, and each of the electrodes. A fiber assembly manufacturing device comprising a connected voltage application device. (3) The device according to claim 2, wherein the upright cylindrical space is divided into an even number of equal parts by each of the electrodes in a horizontal plane. (4) The device according to claim 2 or 3, wherein the electrode is formed in a net shape. (5) The device according to claim 2, 3, or 4, wherein a lower part of the electrode is formed in the shape of a relatively sparse needle line.