JPH06138077A - Instrument and method for measuring relative permittivity of powder - Google Patents

Abstract

PURPOSE:To accurately measure the relative permittivity of powder to be measured by uniformly scattering the powder in a liquid medium and forming a homogeneous composite system containing the powder between a pair of electrodes. CONSTITUTION:Powder whose relative permittivity is to be measured is uniformly scattered in a liquid medium by fluidizing the mixture 2 of the powder and liquid medium by utilizing the rotation of stirring blades 9 between outer and inner electrodes 6 and 7 facing each other at a fixed interval. Then, after measuring the relative permittivity of the composite system of the power and medium, the relative permittivity of the powder is found. Therefore, the relative permittivity of the powder can be accurately measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for measuring the relative permittivity of powder, and in particular, the formula is applied after measuring the relative permittivity of a composite system of the powder and some medium. The present invention relates to an apparatus and a method for measuring the relative permittivity of powder, in which the relative permittivity of powder is obtained.

[0002]

2. Description of the Related Art As a method for measuring the relative permittivity of powder,
For example, there is a method in which a powder is put between a pair of electrodes facing each other at a constant interval and compressed, and the capacitance between the electrodes is measured.

[0003]

However, in the above-mentioned method, since the powder is put between the pair of electrodes and compressed,
When the physical properties of the powder change due to compression, accurate measurement of the relative dielectric constant could not be performed.

Further, in order to accurately measure the relative dielectric constant,
The voids between the powders must be completely removed by compaction, which is virtually impossible. Therefore,
From this point of view, the relative permittivity of the powder could not be accurately measured.

Therefore, an object of the present invention is to provide a measuring apparatus and a measuring method for the relative permittivity of powder, which can accurately measure the relative permittivity of powder.

[0006]

In the present invention, attention is paid to an equation that can approximately calculate the relative permittivity of a mixed material.

That is, according to the present invention, an apparatus for measuring the relative permittivity of powder is provided. This measuring device is a container that provides a pair of electrodes facing each other at regular intervals and a channel for a mixture of a powder and a liquid medium whose relative dielectric constant is to be measured, between the pair of electrodes. And placed in this container,
And a stirring means for uniformly dispersing the powder in the liquid medium.

Further, in the method for measuring the relative permittivity of powder according to the present invention, the relative permittivity of the powder whose relative permittivity is to be measured is known between a pair of electrodes facing each other with a constant interval. First, the relative permittivity of the mixture uniformly dispersed in the liquid medium is measured. Then, the measured value ε of the relative permittivity is expressed by the following equation:

[0009]

[Equation 2]

Where ε _{1 is} the relative permittivity of the powder, ε _{2 is} the relative permittivity of the liquid medium, v _{1 is} the volume ratio of the powder, v _{2 is} the volume ratio of the liquid medium, and v _{0 is the} constant. The relative permittivity ε _{1 of} is calculated.

[0011]

In the present invention, since the powder whose relative dielectric constant is to be measured is uniformly dispersed in the liquid medium, a homogeneous composite system containing the powder can be realized between the pair of electrodes.

[0012]

Therefore, according to the present invention, the relative permittivity of the mixture of the powder and the liquid medium can be accurately measured without compressing the powder, and as a result, the relative permittivity of the powder can be measured. The rate can be calculated accurately.

According to the measuring device of the present invention,
Since the stirring means for uniformly dispersing the powder in the liquid medium is arranged in the container, the uniformly dispersed state of the powder can always be easily maintained during the measurement operation.

On the other hand, according to the measuring method of the present invention,
Since the object to be measured placed between the pair of electrodes is liquid, the object to be measured can be rapidly and uniformly introduced between the pair of electrodes as compared with the case where the object to be measured is powder alone. Therefore, the relative permittivity can be measured efficiently.

[0015]

EXAMPLES The method for measuring the relative permittivity of powder according to the present invention can be carried out using a measuring apparatus as exemplified below.

FIG. 1 is a schematic sectional view showing an apparatus 1 for measuring the relative permittivity of powder according to an embodiment of the present invention.

The measuring device 1 comprises a container 3 for containing a mixture 2 of powder and liquid medium whose relative dielectric constant is to be measured. Inside the container 3, cylindrical outer electrodes 6 and inner electrodes 7 are arranged, respectively, supported by insulating stands 4 and 5. The insulating table 5 that supports the inner electrode 7 has a structure that allows the mixture 2 to flow. The distance between the outer electrode 6 and the inner electrode 7 is kept constant.

Inside the inner electrode 7, a stirring blade 9 driven by a motor 8 is arranged. By the rotation of the stirring blade 9, a flow is given to the mixture 2 as indicated by an arrow 10, and the powder contained in the mixture 2 is uniformly dispersed in the liquid medium. Also, as a result of the flow of mixture 2 as described above, container 3 provides a flow path for mixture 2 between outer electrode 6 and inner electrode 7.

As the powder contained in the mixture 2 described above, any material whose relative dielectric constant is to be measured can be applied. For example, ceramics such as calcium titanate, and other inorganic dielectrics can be applied. The powder is preferably dispersed in a liquid medium with an average particle size of about 2 to 3 μm. On the other hand, as the liquid medium, it is preferable to use an insulating liquid such as kerosene, which is nonpolar and has a small relative dielectric constant.

The dielectric constant of the mixture 2 is measured using the measuring device 1 shown in FIG. Then, the relative permittivity ε of this mixture is calculated by the following equation:

[0021]

[Equation 3]

Here, ε ₁ : relative permittivity of powder to be obtained ε ₂ : relative permittivity of known liquid medium v ₁ : volume ratio of powder v ₂ : volume ratio of liquid medium v ₀ : constant Then, the relative permittivity ε ₁ of the powder is obtained.

The constant v ₀ depends on the powder and the jig, here, the measuring device. More specifically, it means the point at which the measured value and the value of each relative permittivity obtained by the equation of the Lichtnecker rotor intersect.

FIG. 2 is a schematic plan view showing a measuring device 11 according to another embodiment of the present invention.

The measuring device 11 comprises a container 12 which provides a flow path for a mixture of powder and liquid medium whose relative dielectric constant is to be measured.
The inner cylinder 13 is arranged in the center of the container 12.
The inner cylinder 13 is supported in the same manner as the inner electrode 7 shown in FIG. The outer electrode 14 is arranged on a part of the inner peripheral surface of the container 12, and the inner electrode 15 facing the outer electrode 14 is arranged on the outer peripheral surface of the inner cylinder 13. Other configurations are substantially the same as those of the measuring apparatus 1 shown in FIG.

FIG. 3 is a schematic sectional view showing a measuring device 16 according to still another embodiment of the present invention.

The measuring device 16 comprises a container 17 which provides a circulating flow path, and the mixture 18 contained in the container 17 is
It is circulated in the container 17 in the direction of the arrow 20 by the pump 19. By this circulation, the powder contained in the mixture 18 is uniformly dispersed in the liquid medium. A part of the flow path for the mixture 18 provided by the container 17 is provided with a pair of electrodes 21 and 22 facing each other at regular intervals.

The measuring device according to the present invention is as described above.
Although described in connection with some embodiments, various other variations are possible. For example, as the stirring means for uniformly dispersing the powder in the liquid medium, in addition to the stirring blade 9 or the pump 19 used in the illustrated embodiment, for example, ultrasonic vibration may be used.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a measuring apparatus 1 according to an embodiment of the present invention.

FIG. 2 is a schematic plan view showing a measuring device 11 according to another embodiment of the present invention.

FIG. 3 is a measuring device 1 according to still another embodiment of the present invention.
FIG. 6 is a schematic sectional view showing No. 6;

[Explanation of symbols]

 1,11,16 Measuring device 2,18 Mixture 3,12,17 Container 6,7,14,15,21,22 Electrode 9 Stirring blade 19 Pump

Claims (2)

[Claims] 1. A container for providing a pair of electrodes facing each other at a constant interval, and a channel for a mixture of a powder and a liquid medium whose relative dielectric constant is to be measured, between the pair of electrodes. An apparatus for measuring the relative permittivity of powder, comprising: and a stirring unit that is disposed in the container and that uniformly disperses the powder in the liquid medium. 2. A relative permittivity of a mixture in which a powder whose relative permittivity is to be measured is uniformly dispersed in a liquid medium whose relative permittivity is known between a pair of electrodes facing each other with a constant interval. Is measured, and the measured value ε is calculated by the following formula: Where ε _{1 is} the relative permittivity of the powder, ε _{2 is} the relative permittivity of the liquid medium, v _{1 is} the volume ratio of the powder, v _{2 is} the volume ratio of the liquid medium, and v _{0 is the} dielectric constant of the powder. A method for measuring the relative permittivity of powder, which is used to determine the coefficient ε ₁ .