SU1589172A1 - Method of determining critical temperatures of vitreous materials - Google Patents

Abstract

The invention relates to the field of physico-chemical analysis of materials, and specifically to methods for determining the critical temperatures of glassy materials. The purpose of the invention is to expand the scope of application of the method by determining the transformation temperature. The test specimen is fixed between electrodes made with the possibility of moving relative to each other. In this case, a pressure of 10 6 to 10 7 Pa is applied to the sample, which is transmitted through the electrodes under the action of a constant compressive load. In the process of heating a glassy sample, its conductivity is measured with simultaneous temperature recording. The abrupt change in the temperature coefficient of conductivity at the transformation temperature caused by the pressing of electrodes into the softened material due to the displacement of one of them under the action of a compressive load makes it possible to determine the transformation temperature of the studied glassy material. 1 ill., 1 tab.

Description

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The invention relates to physical. chemical analysis of materials, in particular, methods for measuring the electrical and thermal properties of substances, and can be used to determine the critical temperatures of glassy materials.

The aim of the invention is to expand the scope of application of the method by determining the transformation temperature.

The method is carried out as follows. in a way. i

The test specimen of glassy material is fixed between the electrodes, made with the possibility of moving relative to each other. At the same time, a pressure of 10 to 10 Pa is applied to the sample, which is transmitted through the electrodes under the action of a constant compressive load. In the process of heating “H

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The specimens of the sample measure its specific epithelpism with simultaneous recording of the temperature. From the obtained data, the critical temperatures are determined: T is the softening temperature, T is the transformer temperature.

 The ability to move one electrode relative to another allows for an increase in the contact area between the electrodes and the sample by three 1 changing the shape of the sample during the material softening process4. Constant pressure on the sample when the temperature Tg is reached promotes the pressure of the electrodes into the sample the onset of plastic flow of a glassy material, this increases the surface area of the contact of the electrode with the sample (S) and: the distance (1) between the electrodes decreases. According to the known shape e to pl resistance R / S (n - material resistivity) such modification 1 .i S leads to R Ryzkomu drop, i.e. increase conductivity O 5 The graph in logarithm

myic dependence (-IgG) on the inverse temperature (1 / T) there is a vertical rise of the curve up,

corresponding to the beginning of the current and allowing accurate recording of T ,.

Example. The critical temperatures Tn and T of the electronically conducting glass TlAsS, which does not crystallize in the course of the Elite experiment, have been determined. Four experiments were carried out: with the usual fixing of the sample between stationary electrodes (experiment 1) and the establishment of electrodes with the possibility of moving one electrode under the action. The effect of compressive pressure on the sample is 10, 5-tO

J5 and 10 Pa per unit electrode surface, if the sample surface is larger than the electrode surface (experiments 2-4). In the heating process, the electrical conductivity was measured.

20 (b) glassy material with simultaneous temperature recording (TC).

The drawing shows the dependence (-IgG) from 1 / T. Curve Numbers

25 correspond to experiments 1 (1) and 4 (2). The curves of experiments 2 and 3, within the limits of error, coincide with curve 2. The temperature T is determined by the inflection point of the curve, T. by the beginning of the total curve rise.

The results of determining the critical temperatures are presented in the table.

The table shows the average of 3 experiments, the values of temperature-GUR Tp and Tj ... The error is determined by the systematic measurement error and is + 2 °.

Claims (1)

Thus, in one experiment, both the softening temperature and the transformation temperature of TlAsS glass are determined simultaneously. The formula of the acquisition The method of determining the critical temperature glassy materials including fixing the sample between the electrodes, heating and measuring its electrical conductivity, which means that the sample is subjected to a constant compressive load with a pressure of 10 to expand the field of application of the method by determining the transformation temperature up to 10 Pa, transmitted through electrodes adapted to be moved relative to each other. SG / D L7