Variation in the crystallinity of carbons deposited in fluidized beds

Abstract

A variety of carbons deposited in fluidized beds have been studied, using X-ray scattering techniques to determine the concentration of amorphous carbon and misaligned single layers in each. It was found that small amounts of amorphous carbon can be present in carbons deposited at 1400°C and that the amount present increases with the deposition rate. The concentration of misaligned single layers in these carbons varied from 23% in the low density carbon deposited from 5% methane to less than 2% in the high density anisotropic carbon deposited from 40% methane. This decrease in the concentration of single layers with methane concentration occurred regardless of a concomitant increase in deposition rate. The carbons deposited at 1650°C and above had no detectable amorphous carbon in their structures. The low density, isotropic carbon deposited at a very high rate at 1650°C was found to contain about 10% single misaligned layers compared with 1% to 2% in the carbons deposited at 1900° and 2000°C. Possible models of carbon deposition that are consistent with the observed variations in structure with deposition conditions are presented.