KINETICS OF HIGH-TEMPERATURE OXIDATION OF REFRACTORY CARBIDES

Data concerning the interaction with oxygen of refractory carbides suc h as TaC, TiC, NbC and VC is reported at the oxygen partial pressure o f 0.8 Pa in the temperature range from ambient to 400 degrees C. All t he carbides show consumption of oxygen around 350 degrees C. The amoun t of oxygen consumed is comparable with the amounts found previously o n various forms of carbon in the same experimental conditions. Detaile d results on TiC up to 1050 degrees C and at the oxygen partial pressu re ranging from 0.8 to 19 Pa are reported. In particular, it is shown that at the lowest oxygen partial pressure and around 890 degrees C, o xygen interacts with TiC without producing any gaseous product. This o ccurs at (O/C)=(2.7+/-0.3) x 10(-2). At the highest temperatures, the oxidation kinetics was found quite linear with activation energy of 18 0 +/- 10 kJ mol(-1).