Highly Ordered Macroporous BN-Based Ceramics Prepared from Templated Preceramic Polymers

摘要

Macroporous SiCBN and BCN ceramic were prepared by infiltrating these preceramic polymers into the colloidal silica crystalline array, followed by pyrolysis at 1400 deg C and subsequently etching off the silica spheres. It is generally observed by SEM and TEM that a highly ordered and interconnected 'honeycomb' pore structure was obtained by replicating the three dimensional close packed silica spheres which was fabricated by natural sedimentation. And BET surface areas in range 413 approx 315 m~2/g and pore sizes of 113 approx 395 nm in the porous materials were tailored by controlling the sacrificial silica sphere sizes in range 145 approx 500 nm even under volume shrinkage involved during pyrolytic step. The porous SiCBN ceramics and BCN ceramic showed a slight weight loss of 0.2 approx 0.8 percent and 4 percent, respectively, indicating excellent resistance to oxidation.