OXIDATION BEHAVIOR CHARACTERIZATION OF ZIRCONIUM DIBORIDE COMPOSITES AT ABOVE 2000℃

摘要

Because the highest temperature for most traditional testing systems is limited to below 2000℃, an apparatus capable of testing zirconium diboride based composites, the key members of ultra-high temperature ceramics, was built and applied based on rapid Joule heating in the ultra-high temperature range (above 2000℃). A novel method was introduced to measure the real-time temperature distribution along the length of a ribbon shaped specimen (ZrB_2-20 vol% SiC), which could be heated up to failure with the apparatus. The influence of oxidation on the temperature measurement was evaluated, which suggested that the bubble formation can significantly decrease the measuring temperature. A liquid phase would form at ～2300℃, which might be induced by the eutectic reaction of the ZrB_2 and SiC.