| Title |
Effect of In Situ YAG on Properties of the Pressureless-Sintered SiC-ZrB_2 Electroconductive Ceramic Composites |
| Authors |
신용덕(Shin, Yong-Deok) ; 주진영(Ju, Jin-Young) ; 고태헌(Ko, Tae-Hun) ; 이정훈(Lee, Jung-Hoon) |
| Keywords |
Electroconductive ceramic compositesAl_2O_3+Y_2O_3 sintering additives ; Pressureless-sintered ; In Situ YAG(Al_5Y_3O_{12}) ; NTCR |
| Abstract |
The effect of content of Al_2O_3+Y_2O_3 sintering additives on the densification behavior, mechanical and electrical properties of the pressureless-sintered SiC-ZrB_2 electroconductive ceramic composites was investigated. The SiC-ZrB_2 electroconductive ceramic composites were pressurless-sintered for 2 hours at 1,700[°C] temperatures with an addition of Al_2O_3+Y_2O_3(6 : 4 mixture of Al_2O_3 and Y_2O_3) as a sintering aid in the range of 8 ~ 20[wt%]. Phase analysis of SiC-ZrB_2 composites by XRD revealed mostly of α-SiC(6H), ZrB_2 and In Situ YAG(Al_5Y_3O_{12}). The relative density, flexural strength, Young's modulus and vicker's hardness showed the highest value of 89.02[%], 81.58[MPa], 31.44[GPa] and 1.34[GPa] for SiC-ZrB_2 composites added with 16[wt%] Al_2O_3+Y_2O_3 additives at room temperature respectively. Abnormal grain growth takes place during phase transformation from β-SiC into α-SiC was correlated with In Situ YAG phase by reaction between Al_2O_3 and Y_2O_3 additive during sintering. The electrical resistivity showed the lowest value of 3.l4×10^{-2}{Ω}·cm for SiC-ZrB_2 composite added with 16[wt%] Al_2O_3+Y_2O_3 additives at 700[°C]. The electrical resistivity of the SiC-TiB_2 and SiC-ZrB_2 composite was all negative temperature coefficient resistance (NTCR) in the temperature ranges from room temperature to 700[°C]. Compositional design and optimization of processing parameters are key factors for controlling and improving the properties of SiC-based electroconductive ceramic composites. |