Density study of thermoexpanded graphite samples by acoustic amplitude-shadow method

Abstract

The paper presents the results of the study of sensitivity of the acoustic method of density control for samples of expanded graphite based on registration of changes in the amplitude of the signal passed through the sample due to density changes. The results have shown that the limiting sensitivity of the method is commensurable with an error of density measurement by direct weight method and mass and equal to 26 kg/m3 and 0.02 g. The unevenness of the density distribution over the area of TEG samples of different thickness was evaluated, and the amplitude excursion of the signal transmitted through the sample, proportional to the density deviation, for some sheets reached up to 50%, for mats - 30%, and the smallest did not exceed 10%. In the process of scanning, an inversely proportional dependence of the amplitude of the passed acoustic signal on the average density of the samples was revealed, which is most expressed for small thicknesses of TEG mats and sheets.