The corrosion of pure niobium in oxidizing, sulfidizing, and oxidizing-sulfidizing gas mixtures at 600-800 degrees C

The corrosion of pure niobium has been studied at 600-800 degrees C in various environments as part of a study of the corrosion resistance of its alloys with iron, cobalt, and nickel to atmospheres of low-oxygen and/or high-sulfur activities. The results have shown that not only the sulfidation but also the corrosion in mixed atmospheres and particularly the oxidation under low oxygen pressures of pure niobium are quire slow, with kinetics rather similar in the three types of gas mixtures used. The good corrosion resistance of niobium to attack by oxygen under low pressures is quite interesting because this element is corroded very vapidly by oxygen under high oxygen pressures, due to the formation of the nonprotective highest oxide Nb2O5 as a main corrosion product.