3-D ~1H NMR imaging of porosity in calcined needle cokes

摘要

The properties of calcined needle cokes, in particular the coefficient of thermal expansion (CTE), are important for the performance of graphite electrodes which contain calcined cokes as fillers. It is important to know, however, how the microstructure of calcined needle coke particles (especially that of coarse particles) affects their thermal expansion behavior. The microstructure of coke particles can be considered to consist of their optical texture and porosity, including microcracks. Some studies have been reported on characterization of coke texture and porosity which rely on optical microscopy and image analysis performed on polished sections which provide two-dimensional pictures of coke surfaces modified by polishing with abrasives. This communication reports, for the first time, a three-dimensional imaging of needle coke porosity using a non-invasive technique, ~1H NMR spin echo multislice imaging.