| Title |
Properties of {β}-SIC TiB_2 Electroconductive Ceramic Composites Densified by Liquid-Phase Sintering(Ⅱ) |
| Authors |
신용덕(Shin, Yong-Deok) ; 임승혁(Yim Seung-Hyuk) ; 송준태(Song Joon-Tae) |
| Keywords |
YAG ; Pressureless Anealing ; Pressed Annealing ; Fracture Toughness ; PTCR |
| Abstract |
The mechanical and electrical properties of the hot-pressed and annealed {β}-SiC-TiB_2 electroconductive ceramic composites were investigated as function as functions of the liquid forming additives of Al_2O_3+Y_2O_3. The result of phase analysis of composites by XRD revealed {α}-SiC(6H), TiB_2 , and YAG(Al_5Y_3O_{12}) crystal phase. The relative density and the mechanical properties of composites were increased with increasing Al_2O_3+Y_2O_3 contents in pressureless annealing method because YAG of reaction between Al_2O_3 was increased. The flexural strength showed the highest value of 458.9 MPa for composites added with 4 wt% Al_2O_3+Y_2O_3 additives in pressed annealing method at room temperature. Owing to crack deflection, crack bridging, phase transition and YAG of fracture toughness mechanism, the fracture toughness showed 7.1 MPa · m^{1/2} for composites added with 12 wt% Al_2O_3+Y_2O_3 additives in pressureless annealing method at room temperature. The electrical resistivity and the resistance temperature coefficient showed the lowest value of 6.0×10^{-4} {Ω} · cm(25 '°C} and 3.0×10^{-3}/°C for composite added with 12 wt% Al_2O_3+Y_2O_3 additives in pressureless annealing method at room temperature, respectively. The electrical resistivity of the composites was all positive temperature coefficient resistance(PTCR) in the temperature ranges from 25 °C to 700 °C |