Packing Density and Electrical Rresistivity of Mesocarbon Microbeads under Compression

Abstract

Packing behavior and electrical resistivity of the powder under compression up to 46.2MPa were investigated on mesocarbon microbeads (MCMB) heat-treated at temperatures from 1000°C to 2600°C. Packing density, packing height and electrical resistivity of the powder compacts were measured in relation with applied pressure. Shape of the particles was observed by scanning electron microscope. Value of n of the formula ρ=aP^-n+b (where ρ is electrical resistivity, P is an applied pressure, n, a and b are constant) was also estimated.
Deformation of the particles under the maximum applied pressure of 46.2MPa were observed for all MCMBs and particularly it was remarkable for graphitized MCMB particles heat-treated above 2400°C. The deformed particles reformed to the original spherical shape without fracture with release of pressure. However, packing behavior and electrical resistivity of MCMB under the cycles of applied pressure and unloading varied with heat-treatment temperature. Except for MCMB heat-treated at 1800°C, n values of the first unloading, which were thought to represent the characteristics of the packed bodies of each MCMB, were estimated about 0.4 for MCMBs heat-treated below 2200°C, and 0.8-0.9 for the ones heat-treated above 2400°C.