Structural characterization and mechanical properties of SiBONC ceramics derived from polymeric precursors

SiBONC ceramics with specific structural characteristics were designed. Nano-sized amorphous SiBONC ceramic powders were prepared by pyrolysis of polymeric precursors synthesized from chloro-polysiloxane [(SiOClx)n], phenylamine (PhNH2) and boron trichloride (BCl3). Amorphous nano-sized powders were prepared through pyrolysis with designed compositions at Si/B molar ratios of 4:1. The density of the SiBONC ceramics is between 1.95 g/cm3 and 2.15 g/cm3, with the maximum bending strength of 150.50 MPa, Vickers-hardness of 3.78 GPa, fracture toughness of 2.10 MPa m1/2. SiBONC ceramics can keep amorphous state up to 1700 °C, nano-sized β-SiC and bamboo like BN/C filaments can be precipitated from amorphous matrix, which indicates that adulteration of B, C, N can obviously increase crystallization temperature and mechanical property of the SiO2-based ceramics.