SU864057A1 - Method of determining electroconductive material thermal stability - Google Patents

Description

one

The invention relates to the study of the strength properties of material materials, and specifically to methods for determining the heat resistance of electrically conductive materials.

A known method for determining the heat resistance of electrically conductive materials, which consists in creating a temperature gradient across the thickness of a sample of a material when heated by passing an electric current pulse, measures the temperature of the sample and the time from the beginning of the current passing until the sample breaks.

The disadvantage of this method is the low accuracy of the determination of heat resistance.

The purpose of the invention is to improve the accuracy of determination.

This goal is achieved by measuring the time TplOg of the start of current flow until the beginning of the melting of the sample material and the time 1Gy from the time of the start of melting to the moment of the sample destruction, and the heat resistance is determined by the ratio Tp / t jy. In addition, the electrical conductivity and the level of acoustic emission of the sample are also measured, the occurrence of the initial melting of the material of the sample is judged by the jump in electrical conductivity, and the moment of destruction is determined by the change. the level of acoustic emission from the sample.

J The method is carried out as follows.

A test specimen manufactured in the form of two plates / clamped between two massive cooled

10 electrodes. When a pulse of electric current is passed through the sample, heat is generated at the contact resistance at the point of contact, which causes an abrupt rise in temperature, and the sample experiences thermal shock. After the end of the current pulse, the heated portion of the sample is cooled. During the test, the electrical conductivity of the sample material is measured. The moment when the sample material reaches the melting point is determined by the jump in electrical conductivity. The local melting of the sample material can be determined, for example, by the maximum of the oscillogram of the current pulse transmitted through the sample. The moment of destruction of the sample is determined by the change in the level of acoustic emission from the sample, which

also measured during the test. The heat resistance is determined by the ratio of the time from the beginning of melting to the moment of the destruction of the sample to the time from the beginning of the passage of current to the beginning and melting.

The proposed method for determining the heat resistance of electrically conductive materials improves the determination accuracy, taking into account the heating time of the material, which determines the rate of thermal destruction.

Claims (2)

1. A method for determining the heat resistance of electrically conductive materials, which consists in creating a temperature gradient across the thickness of a sample of a material when heated by passing an electric current pulse, measuring the temperature of the sample and the time from the beginning of the current to the moment of destruction of the sample. that, in order to improve the accuracy of the determination. measure time About the beginning of prop scanning current until the beginning of the melting of the sample material and the time fp from the beginning of the melting to the moment of destruction of the sample, and the heat resistance is determined by the ratio tp / C pl. 2. The method according to p. 1 / differs from the fact that the electrical conductivity and the level of acoustic emission of the sample are measured, the moment of the beginning of the sample material melting is judged by the jump in electrical conductivity, and the moment of destruction - by the change of acoustic emission level 5 . Sources of information taken into account in the examination 01. USSR author's certificate  484442, cl. G 01 N 3/18, 1973 (prototype).