Shigeru Ando1, Norio Kurose2, Toshio Shimoo1 and Hiroshi Kimura1
1College of Engineering, University of Osaka Prefecture, Sakai
The carbon depositing behavior on iron in CO-H2 mixtures at 773 to 1273 K has been studied by means of metallography and thermogravimetry. Two types of carbon, laminar carbon and filamentous carbon, are observed to deposit on iron. The deposition of laminar carbon is predominant early in the reactions at all temperatures. The outward growth reaction of laminar carbon and the depositing behavior of filamentous carbon change definitely near A1 transformation temperature. These may be caused by the facts that CO gas is thermodynamically more unstable and easier to decompose with decreasing temperature, and that laminar carbon changes from turbostratic carbon towards graphitic carbon with increasing temperature and particularly at temperatures above A1 point it becomes a dense and filmy carbon which has almost the same crystallinity as natural graphite. Mechanisms are suggested for the deposition of these two types of carbon at temperatures below and above A1 point.
carbon deposition on iron, CO-H2 mixtures, laminar carbon, filamentous carbon, turbostratic carbon, graphitic carbon
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