CO2 corrosion of IG-110 nuclear graphite studied by gas chromatography

The CO2 corrosion behavior of IG-110 nuclear graphite has been investigated using the gas chromatography method which allows the continuous analysis of the CO2/CO gas mixture at the outlet of the corrosion chamber. The effects of temperature and initial CO2 concentration are studied based on the Arrhenius-type reaction model. From 745 to 995°C, the Arrhenius curve shows a linear behavior. For higher temperatures, a non-linear behavior is observed. The activation energy is calculated as 210 kJ/mole and is independent of the initial CO2 inlet concentrations of 10%, 14% and 17%. The corrosion behavior at 1145°C, in the diffusion-controlled regime, has also been investigated. At this temperature, the interior of IG-110 graphite is severely attacked by CO2, and the material's surface morphology is changed drastically. A measurement of the corrosion rate against corrosion time shows that the corrosion rate initially increases to a maximum value at a weight loss degree of 30%-35%, after which it begins to decline. (author)