SU1509715A1 - Method of measuring dielectric permittivity of dispersed loose dielectrics - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure the electrical parameters of dispersed bulk dielectrics. The purpose of the invention is to increase the reproducibility of measurement results. The method includes vibrating compaction of a dispersed friable dielectric in a flat-capacitor measuring cell in two stages. At the first stage, a free (without load) vibrational compaction is carried out, in this case there is a complete fractional separation of the bulk material according to the particle size by height. The second stage is carried out to obtain a compulsory douplotnenie dense packing under the influence of the load, which is selected from the weight ratio of M = ^K. @ ^. S, where K is an experimentally determined coefficient depending on the material and average particle size.

σ is the elastic limit of the sample material

S is the area of the upper electrode. The upper electrode serves as a load. An increase in the reproducibility of measurements is achieved due to the high repeatability of sample preparation for the measurement. 1 Cp f-crystals, 3 sludge.

Description

The invention relates to a measurement technique and can be used to measure the dielectric characteristics of dispersed bulk dielectrics.

The purpose of the invention is to increase the reproducibility of measurement results.

A dispersed, dielectric dielectric is a material formed by a combination of a larger number of particulates, a solid dielectric material (e.g., polyethylene, polystyrene, glass spheres, etc.) whose dimensions vary and vary within certain limits.

The method is based on the fact that during vibratory compaction of dispersed bulk material, especially when free, i.e. without a load, fractional separation of a dispersed friable dielectric by particle size in height occurs, with larger particles being forced upward and smaller particles downward. As a result, at some point in time after the start of vibrocompaction, a complete fractional separation of the sample occurs, i.e. it turns out that the largest particles are at the very top and the smaller the size

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SP

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particles, the lower (height) they are. The minimum size particles are at the lowest level. The most effective fractional separation occurs with a free (without a load, vibration effect in cylindrical bunkers.

After achieving a complete fractional separation of the dielectric with a free (without load) vibro-compaction, a forced vibratory compaction is performed under the action of the load in order to reduce the porosity of the test sample. The role of the load is performed by the upper electrode. In this case, the mass of the upper electrode is chosen from the ratio

m "K-CT S ,.

where S is the area of the electrode;

GI - material elastic limit

dispersed bulk dielectric;

K - coefficient, the value of which is obtained experimentally depending on the average particle size, based on the condition that there is no residual deformation of the particles of the bulk dielectric after the additional sealing.

In particular, the value of this coefficient for PSVS foam polystyrene granular medium (average particle diameter is .2.5 mm) is 0.002, and for low pressure polyethylene is low pressure (d 4 mm) is 0.001.

When the mass of the upper load electrode is greater than m, unrecoverable deformations and destruction of particles of the granular medium occur.

With a cargo weight less than t, incomplete consolidation occurs.

After such a two-stage vibration compaction, the dielectric constant is measured.

With this method, almost complete reproduction of the resulting packaging is achieved and, as a result, almost complete reproducibility of the results of electrical measurements is observed due to

reproducibility of packing particles of the sample bulk dielectric.

Figures M-3 show the steps for changing the state of a sample of a particulate material (Fig. 1).

15.4

It is first subjected to vibration without a load, as a result of which a complete fractional separation of a dispersed bulk dielectric is obtained according to the particle size by height (Fig. 2), and then additional consolidation is performed under the action of the load until a dense packing of particles is obtained (Fig. 3). The method is implemented as follows: In a measuring flat-capacitor cell, which is a cylinder of insulating material, the plates of which serve the bottom of the cylinder and the load, fill the sample with a dispersed bulk dielectric.

Then, the sample cell (without load) is mounted on the shaker and, under the action of vibration, a complete fractional separation of the bulk material in terms of particle size is achieved. After that, the top electrode, which serves as a load at the same time, is inserted into the cell, and the sample is forced to be compacted until a dispersed friable dielectric is tightly packed. Then electrical measurements are taken.

The proposed method can be used to control the moisture content of bulk materials, in particular silica gel, grain, fertilizers, etc.

about rmu l and

the invention

Claims (2)

1. A method for measuring the dielectric constant of dispersed bulk dielectrics using a capacitive sensor, which consists in carrying out a vibrating compaction of a sample, which is so that, in order to improve the reproducibility of measurement results, vibrational compaction is carried out without a load until complete fractional separation of the dispersed bulk material and then compulsory additional consolidation is carried out to obtain a tight package under the action of a load, the weight of which is chosen based on the ratio m, where K is an experimentally determined coefficient depending on the material and the average particle size; - material elastic limit samples; S is the area of the upper electrode of the sensor, 515097156 2. The method according to p. 1, about tl tf h and h- use the upper measuring u and so that as the load electrode of the sensor. Fke.2 phi.1 Fig.Z