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 SUB molar ratios of 4:1. The density of the SiBONC ceramics is between 1.95 g/cm(3) and 2.15 g/cm(3), with the maximum bending strength of 150.50 MPa, Vickers-hardness of 3.78 GPa, fracture toughness of 2.10 MPa m(1/2). SiBONC ceramics can keep amorphous state up to 1700 degrees C, nano-sized -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. (c) 2006 Elsevier B.V. All rights reserved.