METHOD FOR DETERMINING THE THERMAL CONDUCTIVITY COEFFICIENT AT TEMPERATURES UP TO 2800 K OF SEMICONDUCTOR, COMPOSITE MATERIALS Russian patent published in 2021 - IPC G01N25/18 

FIELD: physical quantities measurements.

SUBSTANCE: proposed invention relates to the field of measurements of physical quantities, in particular to thermophysical measurements of the properties of materials with a pronounced temperature dependence of characteristics, such as graphite, carbides and others. The method can find application in determining the properties of composite materials that are used in power engineering, aerospace, chemical and other branches of technology. A method for determining the thermal conductivity coefficient at temperatures up to 2800 K of semiconductor, composite materials, including heating the sample, measuring the values ​​of the current I, the voltage drop U and the true temperature of the external and internal surfaces of the sample, characterized in that the sample is heated by indirect heating, with heat transfer by radiation from a graphite cylindrical heater-core placed inside the cylindrical channel of the sample with a distance between the heater-core and the inner surface of the sample less than 0.5 mm, measure the volumetric heat release of the central part of the core and the temperatures at points of the sample located on the outer surface and at a depth in the channel wall, and the measurements are carried out under steady-state thermal conditions at various stages of stepwise heating of the sample from room temperature through a number of intermediate stages of interest to the researcher, temperatures up to 2800 K, in this case, the calculation formula for determining the coefficient of thermal conductivity was obtained on the basis of solving a stationary, one-dimensional equation of thermal conductivity in a cylindrical coordinate system with a known heat flux on the inner surface of the sample λ=IUln(R₀/(R₀-h))/(2πL(T_h-T₀)), where I, U are the current and the voltage drop across the heater, R₀ is the outer radius of the cylindrical sample, h is the depth of the hole in the wall of the sample, L is the length of the isothermal section, T_h, Т₀ is the temperature at the depth h and on the outer surface of the sample. In this case, the sample is a hollow one-piece cylinder or assembled from rings 20 mm wide and has special mounting through upper and lower

holes that are drilled in the center of the isothermal section, the distance of the thermostable zone located between the two upper and two lower mounting holes, where the voltage drop across the core is measured, is 20 mm.

EFFECT: allows the possibility of implementation in stationary conditions for the high temperature region. This corresponds to the maximum approximation to the real working conditions of high-temperature materials.

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