Ms. Seehra et As. Pavlovic, X-RAY-DIFFRACTION, THERMAL-EXPANSION, ELECTRICAL-CONDUCTIVITY, AND OPTICAL MICROSCOPY STUDIES OF COAL-BASED GRAPHITES, Carbon, 31(4), 1993, pp. 557-564
In this work, the properties of three graphites (WVU-1, WVU-2, WVU-3)
produced from solvent-extracted coal feedstocks are reported. The tech
niques of x-ray diffraction, thermal expansion, electrical conductivit
y, and optical microscopy were used for these measurements. Parameters
determined include crystallite sizes L(c) and L(perpendicular-to), cr
ystalline parameter d(002), Bacon anisotropy parameter, lattice strain
, degree of graphitization, longitudinal and transverse coefficients o
f thermal expansion (CTE), electrical conductivity and density. The lo
ng-range goal of this project is to produce a coal-based isotropic gra
phite comparable in properties to H-451, a commercially available grap
hite produced from petrocoke feedstocks. Therefore, the properties of
the WVU graphites are compared to those of H-451, and a high-purity gr
aphite powder is included in this study for reference. These compariso
ns show that the x-ray and the CTE anisotropy ratios of the WVU-1 and
WVU-3 graphites are comparable to those of H-451. However, WVU-2 is mo
re anisotropic because of the hydrogenation process used for the coal
feedstock. The electrical conductivities of the three WVU graphites ar
e about half that of H-451. The lower conductivities and lower densiti
es of the WVU graphites are due to lack of impregnation, a step which
needs to be included in future sample preparations.