• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.839-842
• /
• 2000

The mechanical and electrical properties of the hot-pressed and annealed $\beta$-SiC-ZrB$_2$ electroconductive ceramic composites were investigated as function of the liquid forming additives of $Al_2$O$_3$+Y$_2$O$_3$. Phase analysis of composites by XRD revelled $\alpha$ -SiC(6H), ZrB$_2$, and YAG(Al$_{5}$ Y$_3$O$_{12}$ ). Owing to crack deflection, crack bridging, phase transition and YAG of fracture toughness mechanism, the fracture toughness showed the highest value of 6.3MPa.m$^{1}$2/ for composites added with 24wt% $Al_2$O$_3$+Y$_2$O$_3$additives at room temperature. The resistance temperature coefficient respectively showed the value of 2.46$\times$10$^{-3}$ , 2.47$\times$10$^{-3}$ , 2.52$\times$ 10$^{-3}$ $^{\circ}C$ for composite added with 16, 20, 24wt% A1$_2$O$_3$+Y$_2$O$_3$additives. The electircal resistivity of the composites was all positive temperature coefficient resistance(PTCR) in the temperature range of $25^{\circ}C$ to 90$0^{\circ}C$.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.49 no.9
• /
• pp.510-515
• /
• 2000

The mechanical and electrical properties of the hot-pressed and annealed $\beta-SiC-TiB_2$ electroconductive ceramic composites were investigated as a function of the liquid forming additives of Al_2O_3+Y_2O_34. The result of phase analysis of composites by XRD revealed $\alpha-SIC(6H)\;TiB_2,\; and YAG(Al5Y3O12) crystal phase. The relative density and the mechanical properties of composites were increased with increasing $Al_2O_3+Y_2O_34 contents because YAG of reaction between $Al_2O_3\; and\; Y_2O_3$ was increased. The Flexural strength showed the highest value of 432.5MPa for composites added with 12wt% $Al_2O_3+Y_2O_34 additives at room temperature. Owing to crack deflection crack bridging phase transition and TAG of fracture toughness mechanism the fracture toughness showed 7.1MPa.m1/2 for composites added with 12wt% $Al_2O_3+Y_2O_34 additives at room temperature. The electrical resistivity and the resistance temperature coefficient showed the lowest of $6.0\times10-4\Omega.cm\; and\; 3.1\times10-3/^{\circ}C4 respectively for composite added with 12wt% \Omega additives at room temperature. The electrical resistivity of the composites was all positive temperature coefficient resistance (PTCR) in the temperature range of $25^{\circ}C\; to\; 700^{\circ}C$.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.49 no.9
• /
• pp.516-522
• /
• 2000

The mechanical and electrical properties of the hot-pressed and annealed $\beta-SiC-ZrB_2$ electroconductive ceramic composites were investigated as a function of the liquid forming additives of$Al_2O_3+Y_2O_3$ Phase analysis of composites by XRD revealed $\alpha-SiC(6H) ZrB_2\; and YAG(Al_5Y_3O_{12})$ The relative density of composites were increased with increased Al2O3+Y2O3 contents. The Flexural strength showed the highest value of 390.6MPa for composites added with 20wt% Al2O3+Y2O3 additives at room temperature. Owing to crack deflection crack bridging phase transition and YAG of fracture toughness mechanism the fracture toughness showed the highest value of 6.3MPa.m1/2 for composites added with 24wt% Al2O3+Y2O3 additives at room temperature. The resistance temperature coefficient showed the value of$ 2.46\times10^{-3}\;, 2.47\times10^{-3},\; 2.52\times10^{-3}/^{\circ}C$ for composite added with 16, 20, 24wt% Al2O3+Y2O3 additives respectively. The electrical resistivity of the composites was all positive temperature coefficient resistance(PTCR) in the temperature range of $256{\circ}C\; to\; 900^{\circ}C$.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.1545-1547
• /
• 2000

The mechanical and electrical properties of the hot-pressed and annealed $\beta$-Sic-$TiB_2$ electroconductive ceramic composites were investigated as function of the liquid forming additives of $Al_{2}O_{3}+Y_{2}O_3$. Phase analysis of composites by XRD revealed $\alpha$-SiC(6H), $TiB_2$, and YAG($Al_{5}Y_{3}O_{12}$). The relative density and the mechanical properties of composites were increased with increasing $Al_{2}O_{3}+Y_{2}O_3$ contents because YAG of reaction between $Al_{2}O_3$ and $Y_{2}O_3$ was increased. The Flexural strength showed the highest value of 432.5MPa for composites added with l2wt% $Al_{2}O_{3}+Y_{2}O_3$ additives at room temperature. Owing to crack deflection, crack bridging, phase transition and YAG of fracture toughness mechanism. the fracture toughness showed 7.1MPa${\cdot}m^{1/2}$. For composites added with l2wt% $Al_{2}O_{3}+Y_{2}O_3$ additives at room temperature The electrical resistivity and the resistance temperature coefficient respectively showed the lowest of 6.0${\sim}10^{-4}{\Omega}{\cdot}$ cm and 3.1${\times}10^{-3}/^{\circ}C$ for composite added with l2wt% $Al_{2}O_{3}+Y_{2}O_3$ additives at room temperature. The electrical resistivity of the composites was all positive temperature coefficient resistance(PTCR) in the temperature range of 25$^{\circ}C$ to 700$^{\circ}C$.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.50 no.6
• /
• pp.263-270
• /
• 2001

The mechanical and electrical properties of the hot-pressed and annealed ${\beta}-SiC-TiB_2$,/TEX> 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 ${\alpha}$-SiC(6H), $TiB_2$,/TEX>, 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 ${\cdot}\;m^{1/2}$ 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 $6.0{\times}10^{-4}\;{\Omega}\;{\cdot}\;cm(25\'^{\circ}C}$ and $3.0{\times}10^{-3}/^{\circ}C$ 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 $^{\circ}C$ to 700 $^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.05c
• /
• pp.15-18
• /
• 2001

The composites were fabricated 61 vol% $\beta$-SiC and $39vol%TiB_2$ powders with the liquid forming additives of 8, 12, 16wt% $Al_2O_3+Y_2O_3$ by hot pressing at $1730^{\circ}C$ and subsequent pressed annealing and pressureless annealing at $1750^{\circ}C$ for 4 hours to form YAG. The result of phase analysis of composites by XRD revealed $\alpha$-SiC(6H), $TiB_2$, and YAG($Al_5Y_3O_{12}$) crystal phase. The relative density of composites were increased with increasing $Al_2O_3+Y_2O_3$ contents. The fracture toughness showed the highest value of $7.77MPa{\cdot}m^{1/2}$ for composites added with 12wt% $Al_2O_3+Y_2O_3$ additives at room temperature. The electrical resistivity and the resistance temperature coefficient showed the lowest of $7.3{\times}10^{-4}{\Omega}{\cdot}cm$ and $3.8{\times}10^{-3}/^{\circ}C$, respectively, for composite added with 12wt% $Al_2O_3+Y_2O_3$ additives at room temperature. The electrical resistivity of the composites was all positive temperature coefficient resistance(PTCR) in the temperature range of $25^{\circ}C$ to $700^{\circ}C$.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.50 no.10
• /
• pp.500-503
• /
• 2001

The mechanical and electrical properties of the hot-pressed and pressureless annealed SiC+39vol.%$TiB_2$electroconductive ceramic composites were investigated as a function of the liquid additives of $Al_2O_3+Y_2O_3$. The result of phase analysis for the SiC+39vol.%$TiB_2$composites by XRD revealed $\alpha$-SiC(6H), $TiB_2$, and $YAG(Al_5Y_3O_{12})4 crystal phase. The relative density of SiC+39vol.%$TiB_2$ composites was increased with increased $Al_2O_3+Y_2O_3$. contents. The fracture toughness showed the highest value of $7.8 MPa.m^{1/2}$ for composites added with 12 wt % $Al_2O_3+Y_2O_3$. additives at room temperature. The electrical resistivity and the resistance temperature coefficient showed the lowest value of $7.3\times10_{-4}\Omega.cm\; and\; 3.8\times10_{-3}/^{\circ}C$ for composite added with 12 wt% $Al_2O_3+Y_2O_3$. additives at room temperature. The electrical resistivity of the SiC+39vol.%$TiB_2$composites was all positive temperature coefficient resistance(PTCR) in the temperature ranges from $25^{\circ}C\; to\; 700^{\circ}C$.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.49 no.7
• /
• pp.394-399
• /
• 2000

The mechanical and electrical properties of pressed and annealed $\beta-SiC-TiB_2$ electroconductive ceramic composites were investigated as a function of the liquid forming additives of $Al_2O_3+Y_2O_3$. Phase analysis of composites by XRD revealed $\alpha$-SiC(6H), TiB2, and (Al5Y3O12). Reaction between Al2O3 and $Y_2O_3$ formed YAG but the relative density decreased with increasing $Al_2O_3+Y_2O_3$ contents. The Flexural strength showed the value of 458.9 MPa for composites added with 4 wt% $Al_2O_3+Y_2O_3$ additives at room temperatures. Owing to crack deflection and crack bridging, the fracture toughness showed 6.2, 6.0 and 6.6 MPa.m1/2 for composites added with 4, 8 and 12 wt% Al2O3+Y2O3 additives respectively at room temperature. The resistance temperature coefficient showed the value of $3.6\times10^{-3},\; 2.9\times10^{-3}\; and\; 3.0\times10^{-3} /^{\circ}C$$^{\circ}C$ for composite added with 4, 8 and 12 wt% $Al_2O_3+Y_2O_3$additives respectively at room temperature. The electrical resistivity of the composites was all positive temperature coefficient resistance(PTCR) in the temperature range of $25^{\circ}C\; to\; 700^{\circ}$.

• Proceedings of the KIEE Conference
• /
• 2001.11a
• /
• pp.75-77
• /
• 2001

The mechanical and electrical properties of the pressureless annealed SiC-$TiB_2$ electro conductive ceramic composites were investigated as functions of the transition metal of $TiB_2$. The result of phase analysis for the SiC-$TiB_2$ composites by XRD revealed $\alpha$-SiC(6H). $TiB_2$, and YAG($Al_5Y_3O_{12}$) crystal phase. The relative density showed the lowest 84.8% for the SiC-$TiB_2$ composites added with 39vol.%$TiB_2$. Owing to crack deflection, crack bridging and YAG of fracture toughness mechanism, the fracture toughness showed the highest value of $7.8\;MPa{\cdot}m^{1/2}$ for composites added with 39vol.%$TiB_2$ under a pressureless annealing at room temperature. The electrical resistivity of the SiC-27vol.%$TiB_2$ composites was negative temperature coefficient resistance(NTCR), and the electrical resistivity of the besides SiC-27vol.%$TiB_2$ composites was all positive temperature coefficient resistance(PTCR) in the temperature range of $25^{\circ}C$ to $700^{\circ}C$.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.51 no.4
• /
• pp.141-146
• /
• 2002

The mechanical and electrical properties of the pressureless sintered SiC-TiB$_2$electroconductive ceramic composites were investigated as functions of the transition metal of TiB$_2$. The result of phase analysis for the SiC-TiB$_2$ composites by XRD revealed $\alpha$-SiC(6H), TiB$_2$, and YAG(Al$_{5}$Y$_3$O$_{12}$) crystal phases. The relative density showed the lowest 84.8% for the SiC-TiB$_2$composites added with 39vol.%TiB$_2$. Owing to crack deflection, crack bridging and YAG of fracture toughness mechanism, the fracture toughness showed the highest value of 7.8 MPa.m$^{1}$2/ for composites added with 39vol.%TiB$_2$under a pressureless annealing at room temperature. The electrical resistivity of the SiC-27vol.%TiB$_2$ composites was negative temperature coefficient resistance(NTCR), and the electrical resistivity of the besides SiC-27vol.%TiB$_2$composites was all positive temperature coefficient resistance(PCTR) in the temperature range of $25^{\circ}C$ to $700^{\circ}C$.EX>.