| Title |
Properties and Manufacture of β-SiC-ZrB_2 Composites Densified by Liquid-Phase Sintering(II) |
| Authors |
윤세원(Yoon, Se-Won) ; 황철(Hwang, Chul) ; 주진영(Ju, Jin-Young) ; 신용덕(Shin, Yong-Deok) |
| Keywords |
Fracture toughness ; Area fraction ; PTCR |
| Abstract |
The mechanical and electrical properties of the hot-pressed and annealed β-SiC+39vol. %ZrB2 electroconductive ceramic composites were investigated by adding 1, 2, 3wt% Al2O3+Y2O3(6:4wt%) of the liquid forming additives. In this microstructures, no reactions were observed between β-SiC and ZrB2. The relative density is over 90.8% of the theoretical density and the porosity decreased with increasing Al2O3+Y2O3 contents. Phase analysis of the composites by XRD revealed α-SiC(6H, 4H), ZrB2 and β-SiC(15R). Flexural srength showed the highest of 315.5MPa for composites added with 3wt% Al2O3+Y2O3 additives as room temperature. Owing to crack deflection and crack bridging of fracture toughness mechanism, the fracture toughness showed 5.5MPa.m1/2 and 5.3MPa.m1/2 for composites added with 2wt% and 3wt% Al2O3+Y2O3 additives respectively at room temperature. The area fraction of the elongated SiC grain in the etched surface of sample showed 65% and 65.1% for composite added with 2wt% and 3wt% Al2O3+Y2O3 additives respectively. The electrical resistivity at room temperature. The electrical resistivity of the composites wall all positive temperature coefficient(PTCR) against temperature up to 700°C. |