On the oxidation mechanism of pure tungsten in the temperature range 600-800 °C

The oxidation behavior of International Thermonuclear Experimental Reactor (ITER)-reference tungsten grade has been evaluated in dry air in the temperature range 600-800 degrees C. At 600 degrees C, the scale remained protective while the integrity of Wigaig layer was kept. Rapid increase in mass gain resulted from massive cracking at local areas in the W18O49 layer. Then, a coarse non-protective columnar WO2.92 scale was developed which favoured rapid inward oxygen transport into the alloy. At 700 and 800 degrees C, growth stresses in the scale were released through local cracking. At this stage, WO2.92 became progressively transformed into WO3 when the oxygen partial pressure increased across the scale thickness. (C) 2011 Elsevier Ltd. All rights reserved.