Physical and surface characteristics of the mechanically alloyed SiBCN powder

A powder mixture of cubic silicon, hexagonal boron nitride and graphite, with the molar ratio of Si:BN:C=2:1:3, was high-energy ball milled for 40 h, under argon atmosphere. The physical and surface characteristics, the microstructures and the behavior on heating of the as-milled SiBCN powder were carefully studied by SEM, nitrogen adsorption–desorption isotherms, XPS, FT-IR, XRD, TEM and thermogravimetry-differential thermal analysis-mass spectrometry-infrared spectroscopy (TG–DTA-MS-IR). Results show that the as-milled powder is amorphous and mainly consists of near-spherical agglomerates, 6.6±5.3 μm in size deriving from the hard agglomeration of nano-primary particles. The specific surface area, the specific pore volume and the average pore diameter of the powder are 24.5 m2/g, 0.136207 cm³/g and 20.3 nm, respectively. The as-milled powder adsorbs water vapor, CO and CO2, and it is easy to oxidize. When heated in helium atmosphere, the powder desorbs water vapor, CO and CO2 at lower temperature, and rapidly degasifies CO and CO2 at temperatures approximately between 1350 °C and 1500 °C.