Thermal shock resistance of ultra-high temperature ceramics under active cooling condition including the effects of external constraints

摘要

A model has been established according to practical applications that ultra-high temperature ceramics are used as parts of the thermal protection system. Taking HfB2 as an example, the effects of convective heat transfer coefficient, thermal shock initial temperature and external constraints on the thermal shock resistance of ultra-high temperature ceramics under active cooling condition have been studied through numerical simulation. This model has also considered about sensitivities of thermo-physical properties to temperature changes. The results indicate that with the increase of thermal shock initial temperature and convective heat transfer coefficient, there are dangerous regions where the critical rupture temperature difference is the lowest. Some measures can be taken to pass the dangerous region safely in practical engineering applications. Besides, external constraints can improve the thermal shock resistance of ultra-high temperature ceramics under active cooling condition, which is very significant in practical applications. (C) 2016 Elsevier Ltd. All rights reserved.