High-temperature oxidation resistance of dense amorphous boron-rich SiBCN monoliths

High-temperature oxidation behavior of dense amorphous boron-rich Si2B1-4C2N monoliths in flowing air was studied in detail. The oxidation products are those of amorphous silica and cristobalite that control the diffusion of oxygen inward. Oxygen diffusion leads to a dense and passivating scale, which acts as a barrier to oxygen. Amorphous boron-rich monoliths oxidize through a classical parabolic manner. The amorphous nature, three-layers structure of oxide scale and varying chemical bonds are primarily responsible for the oxidation resistance with respect to the nano monoliths. The increase in boron content is revealed to weaken the oxidation resistance of the amorphous Si2B1-4C2N monoliths.