Oxidation of powder and porous compacts of TiB2

The oxidation behavior of powders and porous powder composites on the base of titanium diboride used as the material for wettable cathode in aluminium electrolysis cells has been investigated in different gaseous atmospheres (air, argon, reducing atmosphere). In air at 800-1270 K materials were fully oxidized from several hours to ten days. In soft oxidizing atmosphere (volume content of O2 less then 0,002%) the important degradation has been also observed. The oxidation of TiB2 during heat treatment under reducing gaseous atmosphere has been studied. The mass of samples increases regularly with formation of TiO2, TiBO3, B2O3, oxicarbid TiCхОy, graphite depending of temperature and time of oxidation. The long-term service of wettable cathode comparable with lifetime of aluminium electrolysis cells (5-8 years) requires to reduce risks of oxidizing degradation.