• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1252_1253
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• 2009

The composites were fabricated by adding 0, 15, 20, 25[vol.%] Zirconium Diboride(hereafter, $ZrB_2$) powders as a second phase to Silicon Carbide(hereafter, SiC) matrix. The physical, mechanical and electrical properties of electroconductive SiC ceramic composites by spark plasma sintering(hereafter, SPS) were examined. Reactions between $\beta$-SiC and $ZrB_2$ were not observed in the XRD analysis The relative density of mono SiC, SiC+15[vol.%]$ZrB_2$, SiC+20[vol.%]$ZrB_2$ and SiC+25[vol.%]$ZrB_2$ composites are 90.97[%], 74.62[%], 77.99[%] and 72.61[%] respectively. The XRD phase analysis of the electroconductive SiC ceramic composites reveals high of SiC and $ZrB_2$ and low of ZrO2 phase. The electrical resistivity of mono SiC, SiC+15[vol.%]$ZrB_2$, SiC+20[vol.%]$ZrB_2$ and SiC+25[vol.%]$ZrB_2$ composites are $4.57{\times}10^{-1}$, $2.13{\times}10^{-1}$, $1.53{\times}10^{-1}$ and $6.37{\times}10^{-2}[{\Omega}{\cdot}cm]$ at room temperature, respectively. The electrical resistivity of mono SiC, SiC+15[vol.%]$ZrB_2$, SiC+20[vol.%]$ZrB_2$ and SiC+25[vol.%]$ZrB_2$ are Negative Temperature Coefficient Resistance(hereafter, NTCR) in temperature ranges from 25[$^{\circ}C$] to 100[$^{\circ}C$]. It is convinced that SiC+20[vol.%]$ZrB_2$ composite by SPS can be applied for heater above 1000[$^{\circ}C$].

• 한국세라믹학회지
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• 제31권6호
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• pp.660-670
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• 1994

Transparent, crack-free dried gel monoliths with a composition of LiZr1.5Si2P2O12.5 have been synthesized by the low temperature polymerization of the Sol-Gel technique using metal alkoxides as starting materials. After initial reaction (20~40 min), each metal alkoxide closely paralleled each other during the hydrolysis reactions. The safe drying conditions of gels with no creaks the control of the shrinkage rate. The gels converted into the glass by heat treatment at 75$0^{\circ}C$. FTIR data indicated that the gels were phase separated into silicarich and phosphate-rich regions with the lithium. XRD results showed the formation of crystalline LiH2PO4. The gels dried at 15$0^{\circ}C$ or fired at 75$0^{\circ}C$ contained the residual water. The high ionic conductivity at room temperature for these gels was attributed to the motion of protons.

• 한국세라믹학회지
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• 제46권4호
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• pp.397-404
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• 2009

Using rice husk ash as silica, the influence of the firing temperature and holding time on the color intensity of Pr-$ZrSiO_4$ pigments were investigated. The Pr-yellow pigments were calcined at 500, 700, 800, 900, 950, 1000, $1100^{\circ}C$ in a ceramic method. The synthesized pigments were characterized by DT-TG thermal analysis, X-ray diffraction, UV-Vis spectroscopy, and SEMEDAX analysis. The relationship between the zircon phase-formation growth and Pr-yellow color development was evaluated and the optimum firing conditions were determined. The color of the pigment samples was characterized on the grounds of the Commission Internationale de l'Eclairage (CIE) standard procedure (CIE $L^*a^*b^*$ measurement) after an application on the bisque ceramic tile.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.155-159
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• 2002

This paper has studied to obtain the grinding characteristics and optimal grinding conditions of ceramics in the grinding with diamond wheel by Taguchi method. Feed rate was most important factor to the surface roughness. In the case of 4{Si_3}{N_4}$ and ${A1_2}{O_3}$, surface roughness value were small at 3m/min of feed rate. In the case of $ZrO_2$. surface roughness value was small at 4m/min of feed rate. Surface roughness have much influenced by major load for the :ii3N4 and $ZrO_2$. On the other hand, ${A1_2}{O_3}$ have more influenced by grain shedding of brittle fracture phenomenon. The major factors affecting the surface roughness and the optimum grinding conditions were obtained with minimum experiment using Taguchi method.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.381-384
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• 2001

The $\beta$-SiC+ZrB$_2$ and $\beta$-SiC+TiB$_2$ceramic electroconductive composites were pressureless-sintered and annealed by adding l2wt% A1$_2$ $O_3$+Y$_2$ $O_3$(6 : 4wt%) powder as a function of sintering temperature. The relative density showed highest value of 84.92% of the theoretical density for SiC-TiB$_2$ at 190$0^{\circ}C$ sintering temperature. The phase analysis of the composites by XRD revealed of $\alpha$-SiC(6H), TiB$_2$, $Al_{5}$Y$_2$ $O_{12}$ and $\beta$-SiC(15R). Flexural strength showed the highest of 230 MPa for SiC-ZrB$_2$ composites sintered at 190$0^{\circ}C$. The vicker's hardness increased with increasing sintering temperature and showed the highest for SiC-ZrB$_2$ composites sintered at 190$0^{\circ}C$. Owing to YAG, the fracture toughness showed the highest of 6.50 MPa . m$^{1}$2/ for SiC-ZrB$_2$ composites at 190$0^{\circ}C$. The electrical resistivity was measured by the Rauw method from $25^{\circ}C$ to $700^{\circ}C$. The electrical resistivity of the composites showed the PTCR(Positive Temperature Coefficient Resistivity).).

• 한국재료학회지
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• 제18권7호
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• pp.352-356
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• 2008

Effect The effect of sintering additives ($SiO_2$, $Al_2O_3$, Clay) on the mechanical characteristics of sintered zircon was investigated. 1 vol% of additives in zircon powder was was sintered at $120{\sim}1500^{\circ}C$, the mechanical characteristics were measured, and microstructure analysis were was conducted. $Al_2O_3$ and clay additions increase the formation of monoclinic and tetragonal-$ZrO_2$ formation. An addition of SiO2 addition suppressed the formation of tetragonal-$ZrO_2$ formation., The A specimen sintered at $1400^{\circ}C$ showed the a density of $4.05\;g/cm^3$ and the a microhardness of 1120 HV, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1254_1255
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• 2009

The composites were fabricated by adding 30, 35, 40, 45[vol.%] Zirconium Diboride(hereafter, $ZrB_2$) powders as a second phase to Silicon Carbide(hereafter, SiC) matrix. The physical, mechanical and electrical properties of electroconductive SiC ceramic composites by Spark Plasma Sintering(hereafter, SPS) were examined. Reactions between $\beta$-SiC and $ZrB_2$ were not observed in the XRD analysis. The relative density of SiC+30[vol.%]$ZrB_2$, SiC+35[vol.%]$ZrB_2$, SiC+40[vol.%]$ZrB_2$ and SiC+45[vol.%]$ZrB_2$ composites are 88.64[%], 76.80[%], 79.09[%] and 88.12[%], respectively. The XRD phase analysis of the electroconductive SiC ceramic composites reveals high of SiC and $ZrB_2$ and low of $ZrO_2$ phase. The electrical resistivity of SiC+30[vol.%]$ZrB_2$, SiC+35[vol.%]$ZrB_2$, SiC+40[vol.%]$ZrB_2$ and SiC+45[vol.%]$ZrB_2$ composites are $6.74{\times}10^{-4}$, $4.56{\times}10^{-3}$, $1.92{\times}10^{-3}$ and $4.95{\times}10^{-3}[{\Omega}{\cdot}cm]$ at room temperature, respectively. The electrical resistivity of SiC+30[vol.%]$ZrB_2$, SiC+35[vol.%]$ZrB_2$, SiC+40[vol.%]$ZrB_2$ and SiC+45[vol.%]$ZrB_2$ are Positive Temperature Coefficient Resistance(hereafter, PTCR) in temperature ranges from 25[$^{\circ}C$] to 500[$^{\circ}C$]. It is convinced that SiC+40[vol.%]$ZrB_2$ composite by SPS can be applied for heater or electrode.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2000년도 추계총회,초청강연,특별강연,연구발표회
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• pp.153.1-153
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• 2000

• 한국세라믹학회지
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• 제34권7호
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• pp.685-692
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• 1997

Effects of sintering temperature and time on the phase formation, the characteristics of sintering and electrical behaviors of NASICON compounds with Na3Zr2Si2PO12 and Na3.2Zr1.3Si2.2P0.8O10.5 compositions synthesized by solid state reaction were investigated. Maximum relative densities of 96% and 91% were obtained for Na3Zr2Si2PO12 and Na3.2Zr1.3Si2.2P0.8O10.5 compounds, respectively. Complex impedance analysis in a frequency range below 4 MHz was performed to measure the ionic conductivity and migration barrier height of the compounds at RT-30$0^{\circ}C$. The maximum ionic conductivity and the minimum migration barrier height were 0.45 ohm-1cm-1 and 0.07 eV, respectively. The migration barrier height of the high temperature form (space group : R3c) is about 30-40% of that of the low temperature form (space group : C2/c) in two NASICON compounds. Ionic conductivity increases with increasing sinterability, and the presence of glass phase in Na3.2Zr1.3Si2.2P0.8O10.5 compounds lowers significantly ionic conductivity at temperatures above 14$0^{\circ}C$.

• JSTS:Journal of Semiconductor Technology and Science
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• 제17권2호
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• pp.245-251
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• 2017

Niobium doped zirconium oxide (Nb-Zr-O:NZO) thin films were fabricated on Si substrates by a sol-gel technique with an annealing temperatures of $500{\sim}1000^{\circ}C$ in air ($N_2:O_2=3:1$) for 20 minutes. It was found that the NZO film is based on tetragonal $ZrO_2$ polycrystalline structure with the Nb 5+ ion state and there is almost no diffusion of Nb or Zr to Si substrate. The relative dielectric constant for the NZO film with the Nb composition of 30 mol% and annealed at $800^{\circ}C$ was around 40. The root mean roughness was 1.02 nm. In addition, the leakage current of NZO films was as low as $10^{-6}A/cm^2$ at 4.4 V.