773∼1273 Kに加熱した鉄表面におけるCO-H₂系ガスの熱分解反応による炭素析出

抄録

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.