“…The polyborosilazane precursor, made in Institute of Chemistry, Chinese Academy of Sciences, was synthesized by co-condensation reaction of boron trichloride (BTC, 1 M in hexane), methylvinyldichlorosilane (MVDCS), methyldichlorosilane (MDCS) and hexamethyldisilazane (HMDZ). The detailed process for the preparation and pyrolysis of the precursor used in this experiment has been reported by Zhang et al [16]. The polyborosilazane precursor treatment process was as follows: first, the precursor was crosslinked in a corundum tube up to 170 1C at a heating rate of 10 1C/min in nitrogen atmosphere for 2 h, second, the samples was once again pyrolysed in a corundum tube up to 1000 1C at a heating rate of 5 1C/min in argon atmosphere for 2 h, and third, the samples obtained in the previous step was crushed into powders, then the powders passed through a 75 μm sieve.…”