Comparison of ZrB2-SiC, HfB2-SiC and HfB2-SiC-Y2O3 oxidation mechanisms in air using LIF of BO2(g)

•Investigation of the in situ oxidation of UHTC samples using LIF technique.•Detection of the BO2 radicals in the gas phase above three different UHTC materials during an oxidation run up to 1873K.•Determination of the volatile species in the gas phase and of the temperature of the first detection.•Description of the in situ oxidation mechanisms as a function of the composition.•Interest of additives on the oxidation behaviour.