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Separating Test Artifacts from Material Behavior in the Oxidation Studies of HfB2–SiC at 2000°C and Above


  • This study was supported by the United States Air Force Contract # FA8650-10-D-5226.


Oxidation characteristics of HfB2-15 vol% SiC prepared by field-assisted sintering was examined at 2000°C by heating it in a zirconia-resistance furnace and by direct electrical resistance heating of the sample. Limitations of the material and the direct electrical resistance heating apparatus were explored by heating samples multiple times and to temperatures in excess of 2300°C. Oxide scales that developed at 2000°C from both methods were similar in that they consisted of a SiO2/HfO2 outer layer, a porous HfO2 layer, and a HfB2 layer depleted of SiC. But they differed in scale thicknesses, impurities present, scale morphology/complexity. Possible test artifacts are discussed.