Fabrication of novel AlN-SiC-C refractories by nitrogen gas-pressure sintering of Al4SiC4

Novel AlN-SiC-C refractories were fabricated by nitrogen gas-pressure sintering using single Al4SiC4 as raw-material. The high nitrogen pressure is essential and effective for the nitridation because it contributes to the diffusion of the nitrogen atoms into the interior matrix of Al4SiC4 specimen. Different from traditional carbon-containing refractories and ceramic bonded carbon materials (CBCs), the resulted products possess a honeycomb microstructure consisting of interlocked structure of worm-like SiC and C particles with a AlN ceramic boundary. AlN-SiC nanoparticles and aluminum carbonitride particles (Al-C-Ns) were formed at the interface between AlN-rich and C/SiC-rich area, which acted as transition phases that make these two areas combined tightly. The as-prepared AlN-SiC-C refractories at 1700 ℃ by a 20 atm pressure showed a relative density of 75.8%, combining a bulk density of 2.20 g/cm3 with a flexural strength of 120.9 MPa. Furthermore, the potential reaction mechanism responsible for fabrication of AlN-SiC-C refractories was revealed.