A novel approach for preparation of dense TiC-SiC nanocomposites by sol-gel infiltration and spark plasma sintering

摘要

Dense TiC-SiC nanocomposite ceramics were prepared by infiltration of porous TiC scaffolds with a Si-O-C sol, followed by spark plasma sintering (SPS). The porous nano TiC scaffold was first synthesized by direct carbothermal reduction of a monolithic Ti-O-C precursor obtained from a controlled sol-gel process. The TiC scaffold was infiltrated with a Si-O-C sol and then the sample was aged in a container for 48 h at 80℃ to convert the sol into gel. After this, the sample was heated at 550℃ to remove the organic components and then 1350℃ to convert the Si-O-C gel to SiC by carbothermal reduction reaction. The cycle of the infiltration and carbothermal reduction was repeated several times to obtain relatively dense TiC-SiC composite samples. Dense TiC-SiC composite with a uniform nano-sized grain microstructure was obtained by spark plasma sintering at 1800℃ for 5min under 40MPa uniaxial pressure. Compared with conventional powder mixing methods, the sol-gel infiltration approach has shown distinct advantages of achieving dense TiC-SiC composites with uniform nano-sized grain structures.