adsorption de l'eau entre des degres hygrometriques allant de 0 a loo%, (2) en dosant l'eau extraite par un courant de gaz inerte set balayant le graphite port& a des temperatures croissantes (allant jusqu'a 900°C) nous avons mesure la quantite d'eau pouvant etre d&orb&es du graphite a chaque temperature and (3) nous avons CtudiC les quantites d'eau dCsorbCes dans de petits autoclaves remplis de gaz set sous diverses pressions (1, 25, 40 bars) a des temperatures voisines de 125°C.
- The effect of chlorofluoromethanes on graphite oxidation P. G. Pallmer (Battelle Memorial Institute, Richland, Washington). The effect of dichlorodifluoromethane on the air oxidation of nuclear graphite was studied by the continuous measurement of weight loss. One-half per cent CFaCla in air reduced the rate of oxidation of CSF and TSGBF nuclear graphites to about one-third the rate in air. The inhibition accompanying adsorption is not persistent, and larger concentrations do not increase the effectiveness proportionately. The pyrolysis of CFaClz produced both chlorine and CFsCl. Adsorption of chlorine can reduce the active sites available for oxidation, without changing the activation energy. Surface pitting was suppressed during inhibited oxidation, and greater BET area developed than during air oxidation. It is proposed that impurities react with CFzClz or CFsCl to form molten compounds which are more effective catalysts as liquids. These impurities, especially vanadium, were present in significant amounts in EGCR graphite. Its oxidation behavior, as a result, was drastically different from that of the other nuclear graphites.