Preparation and Thermal Ablation Behavior of HfB_2-SiC-Based Ultra-High-Temperature Ceramics Under Severe Heat Conditions

摘要

HfB_2-SiC-based ultra-high-temperature ceramics with aluminum nitride (AlN) as a sintering aid were hot pressed at 1850℃. The sinterability and mechanical properties were investigated and compared with the composite without a sintering aid. It was shown that the addition of A1N greatly improved the powder sinterability and enabled the production of a nearly hill-dense composite. The mechanical properties, especially the flexural strength, were enhanced remarkably through the improvement in the sinterability and microstructure. The oxidation resistance of a composite doped with 10 vol% A1N was evaluated by a plasma arc heater and the ablation mechanism was discussed.