The influence of non-ideal geometric shape on the uncertainty thermal conductivity measurements by a laser-flash method

The influence of the geometric shape of the samples on the uncertainty of the coefficient of thermal conductivity measurement of materials by the method of a laser flash has been studied. Using a method of mathematical modeling in the Comsol Multiphysics software, a model that simulates the process of measuring the coefficient of thermal conductivity of samples made of graphite, Mg$_{2}$Si$_{0.4}$Sn$_{0.6}$ and bismuth telluride using a laser flash method has been created. Samples of cylindrical shape with plane-parallel sides and samples in the form of a truncated cylinder, as well as samples in the form of a parallelepiped with a square base, were investigated. It is shown that the measurement uncertainty of samples with plane-parallel sides and sizes up to 12.7 mm, does not exceed 2%. For samples in the form of a truncated cylinder with a diameter of 3 mm and at an angle of $\varphi$ = 1.5$^{\circ}$, the measurement uncertainty does not exceed 3%. With an increase in the sample diameter and the $\varphi$ angle, the measurement uncertainty increases significantly.