Effects of LaB6 addition on arc-jet convectively heated SiC-containing ZrB2-based ultra-high temperature ceramics in high enthalpy supersonic airflows

The performances of a ZrB2-SiC-LaB6 ultra-high temperature ceramic (UHTC) was investigated in high enthalpy supersonic air flow. The UHTC material reached and maintained steady-state radiative surface temperature of 1973 K (monitored by pyrometer) for 5 min, and survived the arc-jet plasma exposure without any optical evidence of mechanical damage. The oxide scale covering externally the sample evolved into different textures. Transient thermal analysis processed via CFD provided a good agreement between the numerical steady-state temperature and the temperature distribution obtained experimentally. The contemporary addition of LaB6 and SiC to ZrB2 had a detrimental effect on the overall oxidation resistance.