• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.630-630
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• 2013

Recently, atomically smooth hexagonal boron nitride(h-BN) known as a white graphene has drawn great attention since the discovery of graphene. h-BN is a III-V compound and has a honeycomb structure very similar to graphene with smaller lattice mismatch. Because of strong covalent sp2bonds like graphene, h-BN provides a high thermal conductivity and mechanical strength as well as chemical stability of h-BN superior to graphene. While graphene has a high electrical conductivity, h-BN has a highly dielectric property as an insulator with optical band gap up to 6eV. Similar to the graphene, h-BN can be applied to a variety of field, such as gate dielectric layers/substrate, ultraviolet emitter, transparent membrane, and protective coatings. However, up until recently, obtaining and controlling good quality monolayer h-BN layers have been too difficult and challenging. In this work, we investigate the controlled synthesis of h-BN layers according to the growth condition, time, temperature, and gas partial pressure. h-BN is obtained by using chemical vapor deposition on Cu foil with ammonia borane (BH3NH3) as a source for h-BN. Scanning Transmission Electron Microscopy (STEM, JEOL-JEM-ARM200F) is used for imaging and structural analysis of h-BN layer. Sample's surface morphology is characterized by Field emission scanning electron microscopy (SEM, JEOL JSM-7100F). h-BN is analyzed by Raman spectroscopy (HORIBA, ARAMIS) and its topographic variations by Atomic force microscopy (AFM, Park Systems XE-100).

• 멤브레인
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• 제27권1호
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• pp.92-103
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• 2017

본 연구에서는 리튬이온전지용 친수화된 세퍼레이터의 전기화학적 성능에 대한 연구를 진행하였다. 리튬이온전지용 분리막으로 사용되는 폴리올레핀 소재는 소수성이고, 카보네이트 계열의 유기용매를 사용하는 전해액은 친수성을 가진다. 따라서 리튬이온전지는 수계전해액을 사용하기 때문에 폴리올레핀계 분리막에 다양한 친수성 고분자를 도입하여 친수화 처리하였다. 코팅된 세퍼레이터의 변화를 평가하기 위해, 표면 관찰, 코팅시간에 따른 친수화도, 다공성, 젖음성에 대한 특성평가를 수행하였다. 최종적으로 리튬이온이 코팅된 세퍼레이터의 저항과., 이온전도도를 측정하여 리튬이온전지 성능평가를 진행하였다. PMVE로 코팅한 세퍼레이터의 친수화 정도가 우수하며, 세퍼레이터의 기공이 잘 유지되어 우수한 이온전도도를 나타냄으로써 이차전지 배터리에 적용을 위한 잠재성을 가짐을 확인하였다.

• 대한기계학회논문집A
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• 제33권7호
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• pp.652-657
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• 2009

Strength characteristics of $Si_3N_4$ composite ceramics has been studied as functions of heat-treatment temperature and additive $SiO_2$. $SiO_2$ colloidal could significantly increase the bending strength. Crack healing temperature decreased 300 K by additive $TiO_2$. Bending strength of specimen added $SiO_2$ is higher than that of non-added $SiO_2$. Moreover, bending strength of specimen with $SiO_2$ colloidal coating is much higher that of non-coated specimen. In in-situ observation, crack-healed specimen at 1,573 K shows phenomenon like a fog on the surface. By SPM, both crack-healed specimen, non-coating and coating of $SiO_2$ colloidal, at 1,273 K were healed completely but both of 1,573 K exist crack. This was made by evaporation of $SiO_2$ at high temperature. Crack-healing materials of $Si_3N_4$ composite ceramics is crystallized $Y_2Si_2O_7$, $Y_2Ti_2O_7$ and $SiO_2$. A large amount of Si and O, and little C were detected by EPMA. Si and O increase but C decreases according to heat treatment temperature. Specimens with additive $SiO_2$ were more detected Si and O than that of non-additive $SiO_2$. Specimen with $SiO_2$ colloidal coatings were much more detected O.

• Corrosion Science and Technology
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• 제6권5호
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• pp.219-226
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• 2007

Pre-construction primer (PCP), or shopprimer, have been applied to steel plates to control temporary corrosion during ship fabrication. For surface preparation at ship block stage, in common shipyard practices, welding beads, burnt and rusted areas shall be blasted or power tool cleaned and the contamination such as zinc salt shall be removed with blasting or power tool. Whereas, the sound film of PCP needs not to be removed or roughened as the paint having good compatibility with PCP is used for the first coat. In many cases, however, full blasting or sweep blasting on the sound PCP treated block assemblies was requested. There still has been argument about the legitimacy of this practice, thus, it is critical to evaluate the quality of the coating system applied on the sound PCP retained condition, comparing with the one applied on the full blasted or sweep blasted condition. In this study, two different epoxy systems for water ballast tank were applied on the surfaces with sound PCP condition, full blasted condition, and sweep blasted condition. Coating performances such as durability, anti-corrosion, cathodic disbondment resistance were evaluated. The test results clearly indicated that the sound film of PCP needed not to be removed or roughened as the paint having good compatibility with PCP based on inorganic zinc silicate.

• 한국결정성장학회지
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• 제31권5호
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• pp.212-217
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• 2021

Silica sol에 YAG 형광체를 첨가량별로 spin 코팅 후, 코팅막의 blue LED에서 백색광이 발현되는 정도와 표면 및 곡면 코팅용 binder로써, 적용가능성을 확인하였다. SEM, PSA를 통해YAG의 입자 크기는 D₅₀: 9~10 ㎛ 내외이며, XRD를 통해 YAG의 결정구조가 garnet(Y₃Al₅O₁₂), cubic인 것을 확인하였다. 코팅막은 crack이 없고 동시에 silica sol이YAG 형광체를 균질하게 도포된 형상을 보였으며, 첨가량 증가와 비례하게 코팅막 내에서 YAG 첨가량과 두께는 최대 40 ㎛까지 증가하는 추세를 보였다. 그리고 YAG 첨가량이 증가할수록 PL emission intensity 증가와 chromatic locus 곡선 끝 방향으로 색좌표 이동을 확인하였다. Soda-lime 유리기판 표면에 코팅 후, crack이 없으며 YAG 형광체가 균질하게 도포된 코팅성과 코팅막의 백색광 발현특성을 확인할 수 있었고 이는 직접적으로 LED에 다양한 형태의 형광 형상의 구현이 가능하다는 것을 의미한다.

• 반도체디스플레이기술학회지
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• 제18권2호
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• pp.6-10
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• 2019

In the presence of $\mu-tip$ for narrow stripe coating, there appears lateral capillary flow along the hydrophilic head lip because the $\mu-tip$ has some resistance to flow. It was known to be suppressed by increasing the contact angle of the head lip. In this paper, we have demonstrated by computational fluid dynamics(CFD) simulations that it can also be suppressed by the formation of micro-patterns on the shim and meniscus guide embedded into the slot-die head. To optimize the micro-patterned structure, we have performed simulations by varying the groove width, depth, and clearance. In the absence of micro-patterns, it is shown by experiment and simulation that the solution spreads to a distance of $1,300{\mu}m$ from the ${\mu}-tip$. In the presence of micro-patterns with the groove width and clearance of $50{\mu}m$, the distance the solution spreads is reduced to $260{\mu}m$. However, no further suppression in the capillary flow is observed with micro-patterns with the groove width of $40{\mu}m$ or less. It is also observed that the capillary flow is not affected by the groove depth if it is larger than $10{\mu}m$. We have shown that the distance the solution spreads can be reduced further to $204{\mu}m$ by coating a hydrophobic material (contact angle of $104^{\circ}$) on the surface of micro-patterns having the groove width and clearance of $50{\mu}m$.

• 한국정보통신학회논문지
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• 제23권9호
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• pp.1131-1138
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• 2019

부품 또는 제품들의 정전기 방지와 내마모성 및 내부식성 향상, 미각화 등 다양한 목적으로 코팅의 중요성이 증가되고 있다. 코팅막의 두께를 측정하는 방법으로 주로 프로브(probe)로 코팅면을 측정하는 접촉식 측정방식이 이용되는데, 코어의 투자율 변화에 의해 센서 출력 왜곡이나 부하 현상이 발생하여 정확도가 떨어지는 문제점이 있다. 본 논문에서는 비선형적인 특성에 의해 발생할 수 있는 문제점을 최적화된 회로설계와 두께측정 알고리즘을 적용하여 코팅막의 측정 오차를 줄이는 방법을 제안한다. 여러 코팅 샘플을 통한 실험 결과 ${\pm}2%$ 이내의 측정 정확도를 갖는 것을 확인할 수 있다.

• 한국건축시공학회지
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• 제21권6호
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• pp.519-527
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• 2021

본 연구에서는 기존의 전자기파 차폐 성능이 없는 콘크리트를 대상으로 아크 금속용사 공법을 적용하여 전자기파 차폐성능을 확보하고자 한다. 이를 위해 금속 코팅의 두께에 전기적 특성을 평가하기 위해서 8 종류의(Cu, CuAl, CuNi, CuZn, Al, Zn, ZnAl, AlMg) 금속들을 두께 100, 200 및 500㎛의 금속 코팅으로 제작하여 4pin-probe로 표면에서의 전기전도도를 측정하였고, KS C 0304에 의거하여 전자기파 차폐 성능 시험을 실시하였다. 금속 코팅 시험 결과를 토대로 전자기파 차폐를 위한 최적의 금속 코팅 두께 200㎛를 제안하였으며, 이를 300×300×100mm 콘크리트 시험체에 용사하여 전자기파 차폐 성능을 분석한 결과 목표 성능 1GHz에서 80dB의 전자기파 차폐 성능이 확보됨을 확인하였다. 하지만 부착 강도의 경우 최대 1.11MPa로 목표 성능 대비 74% 이하로 확인되어 추후 콘크리트 표면에 미세한 요철을 형성하여 부착 성능을 향상시키는 연구가 필요할 것으로 판단된다.

• Tribology and Lubricants
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• 제38권4호
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• pp.136-142
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• 2022

This paper investigates the enhanced wear performance of a CrAl coated accident tolerant fuel (ATF) cladding. In the wake of the Fukushima accident, extensive research on ATF with respect to improving the oxidation resistance of cladding materials is ongoing. Since coated Zr claddings can be applied without major changes to the criteria for reactor core design, many researchers are studying coatings for claddings. To improve the quality of the CrAl coating layer, optimization of the manufacturing process is imperative. This study employs arc ion plating to obtain improved CrAl coated claddings using CrAl binary alloy targets through an improved coating method. Surface roughness and adhesion are improved, and droplets are reduced. Furthermore, the coated layer has a dense and fine microstructure. In scratch tests, all the tested CrAl coated claddings exhibit a superior resistance compared to the Zr cladding. In a fretting wear test, the wear volume of the CrAl coated claddings is smaller compared to the Zr cladding. Furthermore, the coated cladding manufactured through the improved process exhibits better wear resistance than other CrAl coated claddings. Based on these results, we suggest that fine microstructure is attributed to a mechanically and microstructurally robust CrAl coating layer, which enhances wear resistance.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.339-339
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• 2002

In the RABiTS approach to coated conductor development, successful (both economic and technological) depends on the refinement and optimization of each of three important components: the metal tape substrate, the buffer layer(s), and the HTS layer. Here we will report on the ORNL approach and progress in each of these areas. - Most applications will require metal tapes with low magnetic hysteresis, mechanical strength, and excellent crystalline texture. Some of these requirements are competing. We report on progress in obtaining a good combination of these characteristics on metal alloys of Ni-Cr and Ni-W. - The deposition of appropriate buffer layers is a crucial step. Recently, base research has shown that the presence of a stable sulfur superstructure present on the metal surface is needed for the nucleation and epitaxial growth of vapor-deposited seed buffer layers such as YSZ, CeO$_2$ and SrTiO$_3$. We report on the details and control of this superstructure for nickel tapes, as well as recent results for Cu and Ni-13%Cr. - Processes for deposition of the HTS coating must economically provide large values of the figure-of-merit for conductors, current x length. At ORNL, we have devoted efforts to a precursor/post-annealing approach to YBCO coatings, for which the deposition and reaction steps are separate. We describe motivation for and progress toward developing this approach. - Finally, we address some issues for the implementation of coated conductors in real applications, including the need for texture control and electrical stabilization of the HTS coating.