Kinetics of high temperature oxidation of chromium rich HfC reinforced cobalt based alloys
Résumé
Mostly known to improve the high temperature oxidation resistance of superalloys hafnium may also form carbides. Several percents of Hf allow developing a dense carbide network to mechanically strengthen alloys. Here the high temperature oxidation behaviour of three HfC-containing cobalt alloys was characterized at all steps of a thermogravimetry test: heating, isothermal stage and cooling, with comparison with two Co-Cr-C model alloys. The five alloys were heated in synthetic air, maintained at 1200°C during 50 hours, then cooled. The mass gains were plotted versus time or according to {m × dm/dt = Kp-m × Kv} to specify the isothermal kinetic constants, or versus temperature to determine how oxidation acts during heating and oxide spallation occurs during cooling. Compared to the ternary alloys the oxidation of the HfC-reinforced alloys starts earlier but leads to lower mass gains during heating, the isothermal oxidation is faster and oxide spallation occurs later.
Fichier principal
CorrosionEngineeringScience&Technology2014p45.pdf (1.02 Mo)
Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)
Loading...