• 한국세라믹학회지
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• 제49권5호
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• pp.417-422
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• 2012

Copper nano particles have been considered as the materials for conductive ink due to its good thermal, electrical conductivity and low cost. However, copper nanoparticles oxidize easily, decreasing dispersion stability and electrical conductivity. Therefore, it is important to develop a method to minimize oxidation of copper nano particles to improve its dispersion stability property in copper nano ink. In this study, copper nano particles were coated with 1-Octanethiol VSAM(Vaporized Self Assembled Multilayers) to prevent oxidation and coated copper powders were dispersed in conductive ink successfully by studying its relationship of different chain length of solvents to 1-Octanethiol coating layer to fabricate nano ink. Various alcohol solvents, such as 1-Hexanol, 1-Octanol, and 1-Decanol were used. The coating layer was observed using FESEM and TEM. Furthermore, dispersion of copper nano particles in nano inks, was characterized using Turbiscan analyzer, viscometer, and contact angle measurement tool.

• Journal of Ceramic Processing Research
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• 제18권11호
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• pp.810-814
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• 2017

Proton exchange membrane fuel cells (PEMFCs) are some of the most efficient electrochemical energy sources for transportation applications because of their clean, green, and high efficiency characteristics. The optimization of catalyst layer morphology is considered a feasible approach to achieve high performance of PEMFC membrane electrode assembly (MEA). In this work, we studied the effect of the solvent on the catalyst layer of PEMFC MEAs fabricated using the electrostatic spray deposition method. The catalyst ink comprised of Pt/C, a Nafion ionomer, and a solvent. Two types of solvent were used: isopropyl alcohol (IPA) and dimethylformamide (DMF). Compared with the catalyst layer prepared using IPA-based ink, the catalyst layer prepared with DMF-based ink had a dense structure because the DMF dispersed the Pt/C-Nafion agglomerates smaller and more homogeneously. The size distribution of the agglomerates in catalyst ink was confirmed through Dynamic Light Scattering (DLS) and the microstructure of the catalyst layer was compared using field emission scanning electron microscopy (FE-SEM). In addition, the electrochemical investigation was performed to evaluate the solvent effect on the fuel cell performance. The catalyst layer prepared with DMF-based ink significantly enhanced the cell performance (1.2 A cm-2 at 0.5 V) compared with that fabricated using IPA-based ink (0.5 A cm-2 at 0.5 V) due to the better dispersion and uniform agglomeration on the catalyst layer.

• 한국전기전자재료학회논문지
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• 제27권12호
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• pp.866-870
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• 2014

In solid oxide fuel cell system, yttria-stabilized zirconia is generally adopted as the electrolyte, which has high strength and superior oxygen ion conductivity, and the air electrode and the fuel electrode are attached to this. Recently, new structure of 'layered planar SOFC module' was suggested to solve the reliability problem due to the high temperature stability of a sealing agent and a binding material. In this study to materialize the air electrode in a layered planar SOFC module, the LSM ink was coated to form homogeneous electrode in the channel after the ink preparation. As the porosity control agent, PMMA or active carbon powder was adopted with use of a commercial dispersant in ethanol. The optimal amounts of both the porosity control agents and the dispersant were determined. Four (4) vol% of the dispersant for the LSM-PMMA case and 15 vol% for LSM-carbon powder showed the lowest viscosities respectively to indicate the best dispersed states of the slurries. With PMMA and carbon powder, sintered LSM ink shows the relatively homogeneous distributions of pores and with increases of the agents, the porosities increased in both cases. From this, it can be thought that the amount of the PMMA or carbon powder could be used to control the porosity of the LSM ink.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2003년도 춘계총회 및 연구발표회 초록집
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• pp.82.1-82
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• 2003

• 한국세라믹학회지
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• 제56권4호
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• pp.354-359
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• 2019

Information security films that can ensure personal privacy by reducing the viewing angle of display screens were fabricated by microlouver patterning and a ZnO nano-ink filling process. Optical simulation results demonstrated that all the microlouver films showed good security performances. Security performances were evaluated as calculated relative luminance ratios compared between the side and front. Based on the simulation results, microlouver films were fabricated by UV imprint lithography and nano-ink bar coating. However, distortion of the microlouver pattern occurred with the use of high-viscosity nano-inks such as ZrO₂ and TiO₂, and the CuO-filled microlouver film suffered from very low optical transmittance. Accordingly, the effects of ZnO filling height on security performance were intensively investigated through simulation and experimental measurements. The fabricated microlouver film with a 75-㎛-high ZnO filling exhibited a good relative luminance ratio of 0.75 at a 60° side angle and a transmittance of 44% at a wavelength of 550 nm.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.80-80
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• 2009

$BaTiO_3$ has high permittivity so that has been applied to dielectric and insulator materials in 3D system-level package integration. In order to achieve excellent performance of device, the $BaTiO_3$ layer should be highly dense. In this study, $BaTiO_3$ thick films were prepared by the inkjet printing method using 4 vol.% $BaTiO_3$ colloidal inks and cured at $28^{\circ}C$ for 5 h after infiltration of polymer resin for non-sintered process using 3 vol.% cyanate ester emulsion ink. From the obtained results. packing density was determined to be improved by overlapping rabbit ears which were generated by coffee ring effect. We also calculated the packing densities of the films and correlated these packing densities to the measured permittivity of the films.

• 한국세라믹학회지
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• 제54권3호
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• pp.243-248
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• 2017

Pd-doped $SnO_2$ thick film with a pure tetragonal phase was prepared on patterned Pt electrodes by an ink dropping method. Nanostructured $SnO_2$ powder with a diameter of 10 nm was obtained by a modified hydrazine method. Then the ink solution was fabricated by mixing water, glycerol, bicine and the Pd-doped $SnO_2$ powder. When the Pd doping concentration was increased, the grain size of the Pd-doped $SnO_2$ thick film became smaller. However, an agglomerated and extruded surface morphology was observed for the films with Pd addition over 4 wt%. The orthorhombic phase disappeared even at a low Pd doping concentration and a PdO peak was obtained for a high Pd doping concentration. The crack-free Pd-doped $SnO_2$ thick films were able to successfully fill the $30{\mu}m$ gap of the patterned Pt electrodes by the optimized ink dropping method. The prepared 3 wt% Pd-doped $SnO_2$ thick films showed monoxide gas responses ($R_{air}/R_{CO}$) of 4.0 and 35.6 for 100 and 5000 ppm, respectively.

• 한국생산제조학회지
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• 제25권4호
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• pp.258-265
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• 2016

Digital printing has been used in various industrial areas, including semiconductor manufacturing and textile printing. However, implications on ceramic textile have not been well established so far. Printing high-viscosity materials requires an understanding of their behavior. An inorganic high viscous material with a viscosity range of 20-30 cps is analyzed using a viscometer and through X-ray diffraction. In this study, a digital printer is designed and assembled using a high-viscosity material with software for PC control, resulting in reduced processing at a fast area velocity of $20m^2/hr$. The present study demonstrated that the printer is capable of controlling the shape of the drop mass to smear ink smoothly onto the ceramic surface under an economic budget. In addition, to avoid any difficulty in color management, the ceramic printer is equipped with an independent color management system designed to cope with images on a highly viscous material.

• 한국세라믹학회지
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• 제41권10호
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• pp.788-791
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• 2004

입자크기가 수 nm인 고농도 은 나노 졸을 이용하여 잉크젯 기법으로 은 미세라인을 형성하고자 하였다. 고분자전해질을 사용하여 합성한 $10wt\%$ 농도의 은 나노 졸의 입자크기는 10nm 이하였으며, 은 나노 졸을 이용한 미세 라인의 인쇄특성은 은 나노 졸의 접촉각에 매우 깊은 관계를 갖고 있었다. 순수한 ITO 기판에서 은 나노 졸은 높은 접촉각을 나타내었으며, dot 형상이 나타났다. 그러나 100ppm의 Polyethylenimine(PEI)을 코팅한 ITO 기판은 젖음성이 크게 개선되었으며, 잉크젯 기법을 이용하여 $60\~100{\mu}m$의 선폭을 갖는 은 나노 졸의 미세라인 형성이 가능함을 확인할 수 있었다.

• 한국결정성장학회지
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• 제24권4호
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• pp.169-175
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• 2014

최근 각광받고 있는 디지털 프린팅을 이용한 디자인 기법은 세밀한 표현과 다양한 이미지 구현이 가능하고, 원료의 낭비가 적어 효율성이 높은 장점을 가지고 있다. 디지털 프린팅 공정에서는 cyan, magenta, yellow, black이 기본적인 디지털 4원색으로 사용되며, 도자제품에 적용되는 세라믹 안료의 경우 $1000^{\circ}C$ 이상의 고온 소성이 가능하도록 우수한 열적, 유약 안정성과 발색 특성이 요구된다. 본 연구에서는 고상합성법을 이용하여 $CaO-SnO_2-Cr_2O_3-SiO_2$ 조성의 pink-red 고온발색 무기안료를 합성하였다. $Ca(Sn,Cr)SiO_5$ 세라믹 안료의 합성 조건에 따른 물성을 XRD, SEM, PSA, FT-IR를 이용하여 분석하였고, Cr 치환량 변화가 $Ca(Sn,Cr)SiO_5$ 무기 안료의 발색 거동에 미치는 영향을 Uv-vis.와 CIE 표색계 값($L^*a^*b^*$)을 기준으로 한 색도측정을 통해 관찰하였다.