| Title |
Effect of Transition Metal on Properties of SiC Electroconductive Ceramic Composites |
| Keywords |
{α}-SiC ; WC ; {β}-SiC ; TiB_2 ; Liquid forming additives ; YAG ; PTCR |
| Abstract |
The composites were fabricated, respectively, using 61vol.% SiC - 39vol.% TiB_2 and using 61vo1.% SiC - 39vo1.% WC powders with the liquid forming additives of 12wt% Al_2O_3＋Y_2O_3 by pressureless annealing at 1800°C for 4 hours. Reactions between SiC and transition metal TiB_2, WC were not observed in this microstructure. The result of phase analysis of composites by XRD revealed SiC(6H), TiB_2 and YAG(Al_{5}Y_3O_{12}) crystal phase on the SiC-TiB_2, and SiC(2H), WC and YAG(Al_{5}Y_3O_{12}) crystal phase on the SiC-WC composites. β →α-SiC phase transformation was ocurred on the SiC-TiB_2, but α →β-SiC reverse transformation was not occurred on the SiC-WC composites. The relative density, the vicker's hardness, the flexural strength and the fracture toughness showed respectively value of 96.2%, 13.34GPa, 310.19Mpa and 5.53Mpa·ml/2 in SiC-WC composites. The electrical resistivity of the SiC-TiB_2 and the SiC-WC composites is all positive temperature coefficient resistance(PTCR) in the temperature ranges from 25°C to 500°C. 2.64×10-2/°C of PTCR of SiC-WC was higher than 1.645×10-3/°C of SiC-TiB_2 composites.posites. |