Formation of high-density TiN/Ti5Si3 ceramic composites using preceramic polymer

The formation, microstructure and properties of high-density TiN/Ti5Si3 ceramic composites created by the pyrolysis of preceramic polymer with filler were investigated. Methylpolysiloxane was mixed with TiH2 as filler and ceramic composites prepared by pyrolysis at 1200A degrees C to 1600A degrees C under N-2, Ar and vacuum were studied. When a specimen with 70 vol.% TiH2 was pyrolyzed up to 1600A degrees C in a vacuum after a preheat treatment at 850A degrees C in a N-2 atmosphere and subsequently heat-treated at 1600A degrees C for 1 h under Ar at a pressure of 2 MPa, a ceramic composite with full density was obtained. The microstructure of the ceramic composite was composed of TiN and Ti5Si3 phases. Under specific pyrolysis conditions, a ceramic composite with a density of 99.2 TD%, a Vickers hardness of 18 GPa, a fracture toughness of 3.5 MPam(1/2), a flexural strength of 270 MPa and a electrical conductivity of 6200 ohm(-1)center dot cm(-1) was obtained.