• Electrical & Electronic Materials
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• v.10 no.7
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• pp.674-681
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• 1997

Ternary compound ceramics, (1-y-x) BaTiO$_3$-y SrTiO$_3$-x MgTiO$_3$(0.00 x 0.20), were fabricated by the conventional ceramic process. The structural and dielectric properties of specimens were investigated while varying the composition and sintering temperature(1,200~1,45$0^{\circ}C$) in order to obtain the optimum condition of capacitor. As is well known, Curie temperature(T$_{c}$) of high dielectric-based ceramic(BaTiO$_3$) was shifted and temperature of capacitance was decreased in according to increase of solid solution with (Sr, Mg)TiO$_3$. As a result, a suitable condition of compound rate for capacitor was obtained such as the BSM-11(0.8BaTiO$_3$-0.1SrTiO$_3$-0.1MgTiO$_3$), and sintering temperature was sintered at 1,25$0^{\circ}C$ for two hours. In this case, dielectric constant<1,300, dielectric loss(tan$\delta$)<0.03, and the variation rate of capacitance had less than 3% in the range -10~7$0^{\circ}C$.>.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1990.10a
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• pp.31-35
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• 1990

In the ($Bi_{1-x}Pb_{x}$)$_2$$Sr_2$$Ca_2$$Cu_{3.6}$$O_{y}$ (x=0∼0.5) superconductors, DTA and XRD-pattern analyses were performed to obviousely define optimal calcining and sintering temperature. And, understanding behaviors of High-Tc phase with preparation condition of superconductors, that is, calcining and sintering temperature, sintering time, and variation of Pb contents, in order to make single phase of superconductor, microstructure and its composition were analyzed with SEM, XRD, and EDAX. continuously, the cause of phase transition was define with synthetically studying mutural relation between measured electrical resistivity and current density. Also, in order to design enhancement of critical current density, Jc required for realization, samples varied with pressing condition were made, and measured its, Jc.

• Journal of the Korean Ceramic Society
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• v.33 no.11
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• pp.1253-1259
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• 1996

In the fabrication of alumina-based multilayer ceramics sintering shrinkages with lamination conditions such as lamination pressure temperature and laminating with and without press die were compared. The sintering shrinkage was affected substantially by lamination pressure and temperature and in the case of laminatino without press die the lower laminated density and a large difference in shrinkage with direction were observed. These results can be explained by introducing a new factor which is the ratio of the changes of areas before and after lamination.

• Journal of the Korean Ceramic Society
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• v.27 no.4
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• pp.481-486
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• 1990

Microstructure of polycrystalline Lead Telluride was controlled by the change of sintering conditions. Three properties which determine the thermoelectric figure of merit of the material were measured in the temperature range of 300-650K in order to investigate the effect of each sintering condition on the thermoelectric efficiency. Based on the observed experimental results, defect structure is concluded to be more important than microstructure though both can be controlled by processing variables.

• Journal of the Korean Ceramic Society
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• v.27 no.2
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• pp.169-178
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• 1990

The sintering characteristics of ZrO2 were analyzed in terms of pore microstructure and kinetics of pore elimination. The pore structue of the ZrO2 sample prepared from colloid suspension was characterized by three distinct types of pores ; intradomain, interdomain, and intergglomerate pores. Sintering data at 1600$^{\circ}C$ showed that pores larger than a certain critical size(∼3$\mu\textrm{m}$) were difficult to remove, and this was analyzed in terms of the interagglomerate pore formed from the suspension under the condition of low kinetic stability, that is, the stability ratio smaller than its critical value. A theoretical equation for densification rate was derived and was applied to the densification rate of the ZrO2 polycrystalline body containging both the matrix(the 1st-generation) pores and the interagglomerate (the 2nd-generation) pores under the condition of slow grain growth.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.661-662
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• 2006

Development of recycling method at cemented carbide scraps was researched. Some properties of recycled cemented carbides were investigated. Recycled WC fine powder suffered the surface oxidation. Therefore it was necessary to be done by reduction treatment at 1073K-3.6ks under hydrogen atmosphere. When sintering condition at 1673K-3.6ks was treated under vacuum condition, it gained the deflective strength of about 90%, and gained hardness and sintering density about same value compared with commercial alloys. As a result, it was able to recycle only by 7 processes.

• Journal of the Korean Magnetics Society
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• v.13 no.1
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• pp.15-20
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• 2003

Diffusion speed of Cu metal fine particle is fast better than CuO, so it will promote grain growth in sintering. In this paper, the influence on substituting Cu fine particle for CuO of NiCuZn ferrite with basic composition (N $i_{0.204}$C $u_{0.204}$Z $n_{0.612}$ $O_{1.02}$)F $e_{1.98}$ $O_{2.98}$ has been investigated with varying Cu/CuO ratio. The perfect spinel structure of sintered specimen at 90$0^{\circ}C$ was confirmed by the analysis of XRD patterns. The best condition was obtained when the ratio of Cu/CuO was 60%, and the permeability was 1100 and Ms was 87 emu/g in this condition. Cu has influenced on grain growth in sintering, substituting Cu fine particle for CuO could lower sintering temperature over the 3$0^{\circ}C$. After sintering, substituting Cu performed as good as CuO.s CuO.s CuO.

• Journal of the Korean Ceramic Society
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• v.40 no.6
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• pp.566-571
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• 2003

Hydroxyapatite (HAp)/Polyacrylic Acid(PAA) homogeneous composites of four different composition ratio were preparation by co-precipitation process with synthetic HAp and PAA as a binder. HAP/PAA composites were molding by cold isostatic pressing and were sintering by various condition in air. Crystallinity and structure of sintered HAp/PAA composites were investigated by XRD and FT-IR. Also, the compressive strength and the fracture surface of sintered specimens were measured by UTM and SEM. HAp/PAA composites were showed phase transformation of partially ${\alpha}$, ${\beta}$-tricalcium phosphate at sintering condition of 1200$^{\circ}C$ and 3 h. The pore size and porosity of sintered body were showed the range of 0.2∼3.0 $\mu\textrm{m}$ and 0.49∼13.43%, respectively. The compressive strength of sintered specimens were appeared the range of 36.6∼58.2 MPa. From these results, the sintered HAp/PAA comosites can be accounted for the microporous HAp having a good compressive strength due to homogeneous pore morphology.

• The Korean Journal of Ceramics
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• v.1 no.1
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• pp.45-54
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• 1995

Four kinds of silicon nitride based ceramic materials have been hot pressed. Effect of the sintering additives on the phase transformation, microstructural development and mechanical properties was investigated. While sintering under the same condition a big difference among the microstructures of the specimens, they appeared alike if sintered to have a similiar $\alpha$-$\beta$ phase ratio. The specimen of the stoichiometric $\alpha$-$\beta$ sialon composition showed very limited amount of the intergranular glassy phase and a significant degree of the residual stress. It exhibited almost no strength degradation up to $1300^{\circ}C$, and the strength of the specimen degraded more as its composition deviated from the stoichiometry.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1994.03a
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• pp.149-158
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• 1994

Powder forged Connecting Rods have become attractive for use in automotive engines. The powder forging process offers beneficial material utilization as well as the minimization of finishing operations over that of conventionally forged rods. In the present work, the sintering behavior of Fe-2Cu-0.6C, optimum preform design and forgeability of various forging variables were investigated. Our data were generated using a newly proposed sub-scale con-rod developed specifically to simulate the powder forging process. We obtain optimum condition of sintering and powder forging process.