Oxidation behavior of ZrB₂-SiC-ZrO₂ ceramic composites in the temperature range of 800-1200 °C

ZrB₂-10 vol.% SiC ceramics were hot pressed with addition of two contents of ZrO₂, i.e., 10 vol.% and 20 vol.%. Oxidation behavior of ZrB₂-SiC-ZrO₂ ceramics was investigated using muffle furnace in the temperature range of 800-1200 °C in air. With the increase in temperature and extension in holding time, two ceramics both presented more and more severe oxidation behavior. Comparatively, results of microstructure indicated that ceramic with 10 vol.% ZrO₂ always exhibited lighter variation in structure after oxidation. Further discussion showed that ceramic with 10 vol.% ZrO₂ also provided lower mass gain and thinner oxidized layer. Analysis of oxidation mechanism revealed that excessive addition of ZrO₂ brought much path to the inward transport of oxygen and therefore led to the serious oxidation for ZrB₂-SiC-ZrO₂ ceramics.