Quantitative micrography of carbon black microstructure

Abstract

The d-spacing distribution in a number of carbon blacks was accurately measured by means of an internal calibration standard. The distribution appears to be random, following a log-normal pattern for all blacks, except for thermal blacks, which are concentrically arranged around the particle nucleus. In all furnace blacks and in channel blacks the d-spacing are identical with an identical distribution pattern, regardless of particle size and degree of particle coalescence. Except for thermal blacks, all other carbon blacks investigated appear to be built up from layer planes oriented around a plurality of nuclei randomly distributed in the particles. Layer planes follow the particle contour, generally only at the periphery of the particle. Graphitization leads to growth as well as motion of layer planes, resulting in a marked narrowing of the d-spacing distribution without changing its log-normal character. It is shown that X-ray data are intrinsically restricted to a limited number of carbon planes, while electron micrography has no such restrictions in revealing the carbon black microstructure.