Heterogeneous oxidation of different atomic clusters in amorphous SiBCN ceramic associated with phase separation

In this study, the microstructure of amorphous SiBCN ceramic derived from polyborosilazane and the crystalline SiBCN ceramic heat treated at 1600 degrees C was investigated and their oxidation behavior and kinetics involving different atomic clusters or phases during the non-isothermal oxidation process up to 1500 degrees C were analyzed to obtain their different micro mechanisms. Due to higher oxidation activity, the atomic clusters in amorphous structure can be oxidized at lower temperatures and exhibit lower activation energy than the crystal phases in crystalline structure, but have much higher oxidation resistance due to the phase separation-coupled heterogeneous oxidation of different atomic clusters.