Comparative study on the microstructure evolution and crystallization behavior of precursor-derived and mechanical alloying derived SiBCN

In this study, the chemical reactions and structural change during the transformation of the precursor into PDCs-SiBCN ceramic were investigated. Besides, the crystallization behaviors of precursor-derived (PDCs-SiBCN) and mechanical alloying derived (MA-SiBCN) SiBCN ceramics at different temperatures (1200-1700 degree celsius) were compared. Due to different amorphous structures derived from pyrolysis and amorphization processes, the silicon atoms units bonded by sp(3) hybridization in PDCs-SiBCN and MA-SiBCN ceramics are SiC4 and SiC(4-x)Nx tetrahedral structure, respectively. Due to the phase separation of SiC(4-x)Nx tetrahedral structure at higher temperatures (>1400 degree celsius), PDCs-SiBCN ceramic has a higher resistance to crystallization but will suffer obvious carbothermal reduction process of Si3N4 during crystallization. Finally, the crystallization kinetics of SiC in MA-SiBCN ceramic were investigated. The temperature dependence of SiC crystallization in MA-SiBCN ceramic obeys the Arrhenius-type law with different activation energies in the low and high temperature ranges respectively due to the transition of the rate-controlling mechanisms.