OXIDATION OF MOLYBDENUM AND MOLYBDENUM-TUNGSTEN ALLOYS

The authors investigated the kinetics and mechanism of oxidation in air at 400-1100 degree . Alloying of molybdenum with tungsten increases its resistance to oxidation up to 600-700 degree ; at higher temperatures (800-1100 degree ) the favorable effect of tungsten is suppressed by intensive evaporation of MoO//3. The addition of carbon increases with oxidation rate due to formation of gaseous CO and CO//2 which disrupt the continuity of the oxide film. Small additions of zirconium and titanium have practically no effect on the oxidation rate of the alloys above 600 degree . At lower temperatures titanium reduces, and zirconium increases, the oxidation rate of molybdenum.