Dynamic oxidation of ultra-high temperature ZrB2–SiC under high enthalpy supersonic flows

The dynamic response to oxidation of a hot-pressed ZrB2 + 15 vol%. SiC ceramic composite was studied under aero-thermal heating using a high enthalpy supersonic flow of a N2/O2 gas mixture in plasma wind tunnel. Microstructural features of the reaction scale developed upon oxidation were analyzed and correlated to test conditions through Computational Fluid Dynamics simulations. The significant heat flux and temperature gradients of the sample’s surface exposed to the highly energized N2/O2 gas stream led to the formation and evolution of distinct layered oxide sub-scales. The diffusion of oxidants through silica-rich 3D glassy network was proposed as the rate governing factor for oxidation.

Research highlights
► Hot-pressing of ZrB2–SiC sample without the assistance of any sintering additives.
► An extended stability domain of a silica-rich glass at very high temperature and dissociated oxygen.
► The inward diffusion of oxygen is the rate governing factor for oxidation.