2002 Denver Annual Meeting (October 27-30, 2002)

Paper No. 2
Presentation Time: 8:00 AM-12:00 PM


CRELLING, John C., Southern Illinois Univ, 1259 Lincoln Dr, Carbondale, IL 62901-4324 and GRAY, Ralph J., 303 Drexel Dr, Monroeville, PA 15146-1511, jcrelling@geo.siu.edu

Although organic petrology is commonly used to study coals, cokes, and kerogens, there are a growing number of unconventional applications including the analysis of calcined and graphitized carbons, carbon fibers and carbon-carbon composite materials, and automobile and aircraft brakes. Other applications are found in forensic geology and archeology. Organic petrology of calcined carbons can be used to identify and quantify the microstructures and microtextures that calcination/graphitization imparts to the feed carbon materials. It is also being used to determine carbon fiber quality parameters including size, degree of anisotropy and the length and width of anisotropic domains. In carbon-carbon composites organic petrology can reveal the nature of the matrix carbon and the degree of bonding with the fibers as well as the nature and distribution of vapor deposited binder carbon. Because coal, coke, graphite, char, and carbon fibers are used in a wide variety of modern brakes for automobiles, trucks and aircraft, there are applications for organic petrology in the manufacture and use of these materials. The composition of these brakes is characterized by a petrographic point-count analysis in both white-light and blue-light. The blue light analysis is both necessary and possible because many of the plastics and fiber components, which are difficult to observe in white light, fluoresce distinctively when excited with blue light. Optical microscopy is used for quality control and troubleshooting in the production of these brakes. The ability to definitively identify and characterize coal has found applications in such fields as forensic geology and archeology. For example, in a murder case in the western USA, small fragments of coal found in the clothes of a suspect were matched to similar fragments found at the murder scene. It was later discovered that the site had once been used for the storage of coal. A wide variety of carved black artifacts from prehistoric times in Europe have proven to be made of coal or carbonaceous materials from specific geological localities.