Effect of expanded graphite particle size on the physical properties of compacted samples

Abstract

The compacted carbon samples were prepared with the help of the expanded graphite grinding. The different fractions were prepared using mechanical disintegration and separation of the powder. It was found that each fraction varies in its particles morphology which influences the powder internal elastic stresses, particles distribution, chaining and deposition in a cell. As a result, the anisotropy of electrical resistivity of the compacted expanded graphite reduces by the ~ 30%, when the dispersity of particles increases and their morphology tends to equiaxial. It was also shown that the expanded graphite with an average particle size of 120 μm has a high level of internal elastic stresses, an increased dislocation density and a significant lattice distortion. Therefore, the corresponding compacted samples have higher elastic characteristics and microhardness levels. The radial surface distribution of microhardness varies depending on the powder fraction in the compacted samples. It was found out that the values of microhardness are maximal in the central area of the samples. This may be caused by different densities of the compacted samples and different levels of the powder internal stresses.