METHOD FOR DETERMINING THERMAL DIFFUSIVITY AND THERMAL CONDUCTIVITY COEFFICIENT Russian patent published in 2022 - IPC G01N25/18 

FIELD: measuring technology.

SUBSTANCE: invention relates to measuring technology, to the measurement of thermal properties of materials. A method for determining the thermal diffusivity and thermal conductivity coefficient is proposed, which consists in bringing the test sample into thermal contact with the first insulator in the form of a semi-infinite body, the surface of the test sample, opposite the first insulator, is brought into thermal contact with the second insulator in the form of a semi-infinite body. The surface of the test sample, mating with the first insulator, is subjected to constant thermal action, the temperature change is recorded. The first and second insulators are made of the same material as the test sample. The thickness of the experimental sample R is selected in the range of 0.03÷0.05 m, the thickness of the first insulator R₁ is selected, and the thickness of the second insulator R₂ from the condition: R₁= R₂=(1.2÷1.4) R, the diameters of the test sample are selected and two insulators equal and from the condition: D=(10÷15) R, the value of the constant specific heat flux q into the test sample is selected from the condition: q≈(2700-4800)λ, where λ=1 for refractories or λ=0.3 for heat insulators. A sensor for measuring temperature T₁ is placed in the center of the surface of the test sample in contact with the heat source, and a second sensor for measuring temperature T₀ is placed in the center of the surface of the second insulator in contact with the surface of the test sample. The initial temperature T_i is preliminarily set and the test sample and insulators are thermostated at a given initial temperature T_i. Registration of changes in temperatures T₁ and T₀ during thermal exposure to heat flow q is stopped at the time τ_к, when the temperature at the boundary of the surfaces of the test sample and the second insulator T0 exceeds the initial temperature T_i by 0.1 K. Calculation of the thermal diffusivity at,o of the test sample is carried out by solving nonlinear system of equations by selecting the Fourier number Fo, and the thermal conductivity coefficient λ_T is also calculated.

EFFECT: simplifying the method and improving the accuracy of the complex determination of the thermophysical characteristics of materials and providing the possibility of determining the thermophysical properties of the material depending on temperature.

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