Physical and surface characteristics of the mechanically alloyed SiBCN powder

Abstract 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 m 2 /g, 0.136207 cm³/g and 20.3 nm, respectively. The as-milled powder adsorbs water vapor, CO and CO 2 , and it is easy to oxidize. When heated in helium atmosphere, the powder desorbs water vapor, CO and CO 2 at lower temperature, and rapidly degasifies CO and CO 2 at temperatures approximately between 1350 °C and 1500 °C.