X-ray computed micro-tomography of reticulated vitreous carbon

Abstract

The 3D structure of various grades of reticulated vitreous carbon (RVC) is studied by X-ray computed micro-tomography (μCT). The settings required to estimate the bulk volumetric surface area, Ae, accurately are investigated and the results are compared to those obtained from scanning electron microscopy and from pressure drop measurements via the Ergun equation. A resolution in the order of 1.3 μm per voxel in μCT imaging is needed to determine the volumetric surface area, but its value is highly dependent on post-processing. In contrast, a resolution of 9.6 μm per voxel underestimated this characteristic by a factor of up to 0.64 due to an incomplete resolution of the cell struts. This latter resolution is, however, sufficient to establish the volumetric porosity and the relative density. Theoretical estimations of electrical resistivity using these properties are consistent with those reported in the literature. Cell volume and cell surface area distributions are then obtained from computational analysis of the digitally rendered structure of 100 ppi RVC. Both cases can be approximated by a gamma function. Suitable instrumental μCT conditions for performing metrological studies on bare and modified RVC are proposed. Opportunities for the modelling of decorated and coated digitally rendered RVC are discussed.