Oxidation behavior of pure W and W-0.5 wt% ZrC at 700 °C and 900 °C

This study investigates the oxidative behavior of pure tungsten and a W-0.5 wt% ZrC alloy (WZC05), was examined. Both materials were fabricated via sintering and hot rolling. The alloys were exposed to air at 700 degrees C for 20 h and to air at 900 degrees C for 8 h to analyze surface morphology, oxidation resistance, and oxidation behavior of pure tungsten and WZC05. WZC05 exhibited a significantly smaller grain size than pure tungsten. At 700 degrees C, the "positive effect of grain size," caused a higher oxidation rate in pure tungsten compared with that in WZC05. After air oxidation for 20 h at 700 degrees C, the thickness of the oxide layer on pure tungsten reached 320 mu m, whereas that on WZC05 was only 202 mu m. At 900 degrees C, the dense oxide layer was destroyed owing to the formation of volatile WO3, resulting in similar oxidation rates for pure tungsten and WZC05. Scanning electron micrographs revealed that the oxidized tungsten materials had a layered structure.