• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1418-1419
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• 2006

PZT(80/20) powder was prepared by a sol-gel method and PZT thick films were fabricated by the screen-printing method on the alumina substrates. The coating and drying procedure was repeated 4 times. And then the PZT(20/80) precursor solution was spin-coated on the multilayered thick films. A concentration of a coating solution was 0.5 mol/L and the number of coating was repeated from 0 to 6. The porosity of the thick films was decreased with increasing the number of coatings and the PZT thick films with 6-times coated showed the dense microstructure and thickness of about 60-65 ${\mu}m$. All PZT thick films showed the typical XRD patterns of a typical perovskite polycrystalline structure. The relative dielectric constant and the dielectric loss of the PZT-6 thick film were 275 and 3.5, respectively. And the PZT-6 film shows the remanent polarization of 22.1 $C/cm^2$ and coercive field of 13.7 kV/cm.

• Journal of Welding and Joining
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• v.18 no.6
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• pp.96-101
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• 2000

Sintered alumina ceramic substrate has been used for the insulating substrate for thick Hybrid IC owing to its cheapness and good insulating properties. Some of thick HIC's are important to eliminate the heat emitted from the parts that are mounted on the ceramic substrate. Sintered ceramic substrate can not transfer and emit the heat efficiently. It's been tried to do plasma spray coating of alumina ceramic on the metal substrates that have a good heat emission property. The most important properties to commercialize this ceramic coated metal substrate are surface roughness and deposition efficiency. In this study, plasma spray coating parameters are optimized to minimize the surface roughness and to maximize the deposition efficiency using Taguchi experimental method. By this optimization, the deposition efficiency was greatly improved from 35% at the frist time to 75% finally.

• Progress in Superconductivity and Cryogenics
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• v.10 no.1
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• pp.6-9
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• 2008

We have investigated the MOD process successfully for the fabrication of the YBCO thick film on the $LaAlO_3$(001) single crystalline substrate. The cracking problem in YBCO thick film, a serious problem in the conventional TFA-MOD method, could be overcome with a careful control of precursor materials. Thus coating solution was prepared for the YBCO thick film by using fluorine-free precursor material. The precursor solutions were coated on the LAO(001) single crystalline substrate using the dip coating method, calcined at the temperature up to $500^{\circ}C$, and fired at various high temperatures for 2 h in a reduced oxygen atmosphere. Optimally processed YBCO thick film exhibited high critical current($I_c$) over 200 A/cm-width at 77K in self-field.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.12
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• pp.1092-1098
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• 2006

The influence of the concentration of precursor solution and the number of solution coatings on the densification of the $Pb(Zr_xTi_{1-x})O_3$ (PZT) thick films was studied. PZT powder and PZT precursor solution were prepared by3 sol-gel method and PZT thick films were fabricated by the screen-printing method on the alumina substrates. The composition of powder and precursor solution were PZT(70/30) and PZT(30/70), respectively. The PZT precursor solution was spin-coated on the PZT thick films. A concentration of a coating solution was 0.5 to 2.0 mol/L[M] and the number of coating was repeated from 0 to 6. The XRD patterns of all PZT thick films shelved typical perovskite polycrystalline structure. The porosity of the thick films was decreased with increasing the number of coatings and 6-time coated films with 1.5 M showed the dense microstructure and thickness of about $60{\mu}m$. The relative dielectric constant of the PZT thick film was increased with increasing the number of solution coatings and the thick films with 1.5 M, 6-time coated showed the 698. The remanent polarization the 1.5 M and 6-time coated PZT thick films was $38.3{\mu}C/cm^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.260-261
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• 2005

The heterolayered thick/thin structure consisting of $Pb(Zr_{0.52}Ti_{0.48})O_3$ and $BaTiO_3(BT)$ were fabricated by a sol-gel process. PZT powders, prepared by the sol-gel method, were mixed with an organic vehicle and the PZT thick films were fabricated by the screen printing techniques on alumina substrate with Pt electrodes. The microstructural and dielectric characteristics of the stacked heterolayered PZT/BT/PZT films were investigated by varying the number of coating $BaTiO_3$ layers. The existence of a $BaTiO_3$ layer between the PZT thick films of the tri-layer $Pb(Zr_xTi_{1-x})O_3/BaTiO_3/Pb(Zr_xTi_{1-x})O_3$thick/thin/thick film can greatly improve the leakage current properties of the PZT thick films. The average thickness of a PZT(5248)/$BaTiO_3$ heterolayered thick/thin film was 25$\mu$m. The relative dielectric constant and dielectric loss of the PZT(5248)/$BaTiO_3$-3 heterolayered thin film coated three times were 1087 and 1.00% at 1[MHz].

• Journal of Powder Materials
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• v.12 no.2 s.49
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• pp.106-111
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• 2005

The effect of post-heat treatment on the coating characteristics and the fatigue strength of the gas flame thermally sprayed Stellite alloy coatings on $0.35\%$ carbon steel were investigated. The fatigue fracture surfaces of the heat treated samples were observed using SEM (Scanning Electron Microscopy). For as-sprayed samples, there was considerable scattering in the fatigue life due to the presence of the pores in the coating. After the post-heat treatment to improve the microstructural characteristics of the coating layer, the fatigue strength of the specimens was greatly improved, increasing with increasing the coating thickness. For the specimens with the 0.3mm and 0.5mm thick coating, the fatigue cracks originated in the substrate region just below the interface. On the contrary, for the specimens with the 1.0mm thick coating, they nucleated at the pore within the coating, and the fatigue strength was 2.6 times higher than that of the substrate due to the high fatigue resistance of the coating.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.7
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• pp.667-672
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• 2006

Ferroelectric $Pb(Zr_{0.52}Ti_{0.48})O_3$ (PZT(52/48)) thick films were fabricated by the screen-Printing method on the alumina substrates, and $PbTiO_3$ (PT) Precursor solution, which prepared by sol-gel method, was spin-coated on the PZT(52/48) thick films to obtain a densification. Its structural and electrical properties of the PZT(52/48) thick films with the treatment of PT precursor solution coating were investigated. The particle size of the thick films was increased with increasing the number of coatings and the thickness of the PZT-6 (6: number of coatings) films was about $60{\mu}m$. The relative dielectric constant increased and the dielectric loss decreased with increasing the number of PT sol coatings. The relative dielectric constant and dielectric loss of the PZT-6 thick film were 475 and 2 %, respectively. The remanent polarization, coercive field and breakdown strength of the PZT-6 film were $32.6{\mu}C/cm^2$, 15 kV/cm and 60 kV/cm, respectively.

• Proceedings of the KIEE Conference
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• 2008.05a
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• pp.169-170
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• 2008

The heterolayered PZT/PT thick films were fabricated by two different methods - thick films of the PZT by screen printing method on alumina substrates electrodes with Pt, thin films of $PbTiO_3$ by the spin coating method on the PZT thick films and once more thick films of the PZT by the screen printing method on the $BaTiO_3$ layer The structural and the dielectric properties were investigated for effect of various stacking sequence of sol-gel prepared $PbTiO_3$ coating solution at interface of the PZT thick films. The insertion of $PbTiO_3$ interlayer yielded the PZT thick films with homogeneous and dense grain structure with the number of $PbTiO_3$ layers. The leakage current density of the PZT/$PbTiO_3-1$ film is less that $4.41{\times}10^{-9}\;A/cm^2$ at 5 V.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.123-124
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• 2006

The sandwiched PZT/$BaTiO_3$/PZT thick films were fabricated by two different methods thick films of the PZT by screen printing method on alumina substrateselectrodes with Pt, thin films of $BaTiO_3$ by the spin-coating method on the PZT thick films and once more thick films of the PZT by the screen printing method on the $BaTiO_3$ layer. The structural and the dielectric properties were investigated for effect of various stacking sequence of sol-gel prepared $BaTiO_3$ coating solution at interface of the PZT thick films, The insertion of BaTi03 interlayer yielded the PZT thick films with homogeneous and dense grain structure with the number of $BaTiO_3$ layers. The leakage current density of the $PZT/BaTiO_3-1$ film is less that $4.41{\times}10^{-9}A/cm^2$ at 5 V.

• Journal of the Korean Professional Engineers Association
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• v.21 no.1
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• pp.5-12
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• 1988

The purpose of this paper is to investigate on the optimum coating thickness layer of TiC-Al$_2$O$_3$ coated cemented carbide tool. Chemical Vapor Deposition (CVD) of a thick film of TiC-A1$_2$O$_3$ on a cemented carbide produces an intermediate layer, $1.5mutextrm{m}$, 4.5${\mu}{\textrm}{m}$, 7.5${\mu}{\textrm}{m}$ 10.5${\mu}{\textrm}{m}$, 4 kind of TiC between the substrate and the $1.5mutextrm{m}$ constant thick A1$_2$O$_3$ coating. Experiments were carried out with the test relationship between coating thickness and shear angle, surface roughness, cutting force, microphotograph of crater wear, flank wear, tool life. From the experimental results, it was found that the optimum coating thickness of TiC-A1$_2$O$_3$ is 6${\mu}{\textrm}{m}$. Although the coating thickness layer 9${\mu}{\textrm}{m}$. 12${\mu}{\textrm}{m}$ have a much loger tool wear than an 3${\mu}{\textrm}{m}$, 6${\mu}{\textrm}{m}$ coating tool in cutting condition feed 0.05mm/rev, and the condition of feed 0.2mm/rev, 0.3mm/rev has upon in the shot time phenomenon of chipping.