The processes involved in the adsorption of oxygen on brown coal char

✍ Scribed by D.J. Allardice

• Publisher: Elsevier Science
• Year: 1965
• Tongue: English
• Weight: 350 KB
• Volume: 3
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(65)90052-7

✦ Synopsis

CARBON 215 ram was placed in the mold and the assembly compressed and heated according to standard techniques. The result was a Lucite cylinder with graphite flakes imbedded and oriented with their a-axes parallel, and in a plane perpendicular to the axis of the Lucite cylinder. The cylinder was sectioned perpendicular to the u-axis of the graphite flakes and each cut surface was polished. The edge cross-sections of several graphite flakes were located under a microscope and photographed at 5&1oooX magnification. A typical cross-section of a graphite flake from the 149-177 p sieve fraction is shown in Fig. 1. The results of the thickness measurements are shown in Fig. 2 on a log scale plot of the average sieve screen size vs. the average c-axis thickness. The thickness was found to be proportional to the average diameter of the flakes and could be expressed by the relation, t=0.07 a, where t is the thickness and a is the average sieve screen size. The decrease in thickness with decreasing flake diameter is reasonable. It is known that graphite crystals of high perfection are easily delaminated. Highly anisotropic, but less perfect graphites are stronger in the direction of the c-axis. It is, therefore, likely that natural graphite flakes are more perfect when they are smaller in diameter and, hence, are more readily delaminated. REFERENCES 1. UBBELOHDE A. R. and LEWIS F. A., Graphite and Its Crystal Compounds. Clarendon Press, Oxford. (1960). 2. SALZANO F. J. and ARONSON S., The Mechanism of Bromine Exchange in the Bromine-Graphite Lamellar Compounds, in preparation.