Preparation of hollow Si-B-N ceramic fibers by partial curing and pyrolysis of polyborosilazane fibers

摘要

Hollow silicon boron nitride (Si-B-N) ceramic fibers with composition of Si_(0.3)BN_(1.4) were prepared by melt-spinning, partial curing with trichlorosilane (HSiCl_3), and pyrolysis of a novel polyborosilazane under NH_3 up to 1000 ℃. The polyborosilazane fibers with low ceramic yield were partially cured to make sure the hollow Si-B-N ceramic fibers could be fabricated after pyrolysis. The hollow Si-B-N ceramic fibers were -16 μm in diameter with inner hollow pore diameter of ～4 μm, and showed good average tensile strength of 1.03 GPa and elastic modulus of 106 GPa. Moreover, the hollow Si-B-N ceramic fibers also exhibited excellent dielectric properties with the average dielectric constant real part and loss tangent about 3.06 and 0.0032 at 2-18 GHz, respectively, making them to be promising microwave-transparent materials.