Emissivity, catalycity and microstructural characterization of ZrB2-SiCfiber based UHTC at high temperature in a non-equilibrium air plasma flow

In this paper are presented and discussed the experimental results of emissivity and catalycity of two different UHTC materials based upon the ZrB2-SiCfiber composition with different sintering additives (Si3N4 or ZrSi2). Microstructural characterization by SEM, XRD and XPS have shown oxidation-induced surface modifications with oxide layers composed of silica with trace amounts of boron oxide and zirconia if the maximum reached temperature is lower than about 1800 K and only zirconia for higher temperatures. The differences in the oxide layer composition may account for the different thermal radiative properties and catalytic behavior.