Study on the oxygen diffusion in the oxide layers of SiBCN ceramics by SIMS

SiBCN, SiC and SiC-BN ceramics/composites were prepared by mechanical alloyed combined hot-pressing sintering at 1900 °C, and the oxidation kinetics of SiBCN, SiC and SiC-BN were calculated based on the thickness of oxide layers at 1100∼1500 °C. The oxide layer can be divided into outer and inner parts under 1300 °C. At 1100 °C, the oxygen molecules diffused in SiC through the gaps in lattice, while diffused in SiBCN by substituting the O in SiO₂. Moreover, BN(C) phase in SiBCN can slow down the generation rate of gases such as CO, N₂, NO₂ and B₂O₃.