We present the detection characteristics of nitrogen monoxide(NO) gas using p-type copper oxide(CuO) thin film gas sensors. The CuO thin films were fabricated on glass substrates by a sol-gel spin coating method using copper acetate hydrate and diethanolamine as precursors. Structural characterizations revealed that we prepared the pure CuO thin films having a monoclinic crystalline structure without any obvious formation of secondary phase. It was found from the NO gas sensin measurements that the p-type CuO thin film gas sensors exhibited a maximum sensitivity to NO gas in dry air at an operating temperature as low as 100 oC. Additionally, these CuO thin film gas sensors were found to show reversible and reliable electrical response to NO gas in a range of operating temperatures from 60 oC to 200 oC. It is supposed from these results that the ptype oxide semiconductor CuO thin film could have significant potential for use in future gas sensors and other oxide electronics applications using oxide p-n heterojunction structures.

목 적: 하드코팅과 광변색 코팅을 동시에 실시하여 제조한 광변색 렌즈에 대한 퇴색속도 중심으로 광학 적 특성을 조사하여 비교하고자 하였다. 방 법: Tetraethyl orthosilicate와 3-glycidoxypropyltrimethoxysilane로 조성된 하드코팅 액에 적, 황, 청색의 광변색 물질을 각각 혼합하고, 플라스틱 안경렌즈 표면에 플로우 코팅 후 열경화하였다. 코팅된 광변색 렌즈의 표면 물성과 광학적 특성을 평가하였다. 결 과: 광변색 코팅 렌즈는 우수한 부착력과 무코팅 렌즈보다 강한 표면 경도로 하드코팅의 특성을 보였 다. 광변색 코팅 렌즈의 최대흡광도(λmax)는 적색, 황색, 청색 렌즈에서 각각 499, 418, 606 nm이었으며, 이를 기준으로 반감기에 의한 퇴색속도는 청, 적, 황색의 변색 렌즈 순으로 각각 204, 416, 670 sec이었다. 코팅 렌즈의 퇴색속도는 spironaphthoxazine계인 청색이 naphthopyran계인 적색과 황색보다 빨랐고, 동일 계열에서도 폐환상태의 열적 안전성이 클수록 빠르게 평가되었다. 결 론: 광변색 코팅 렌즈의 퇴색속도는 열적으로 안정한 상태로 가역하려는 광변색 물질의 특성에 따라 달라진다. 따라서 광변색 코팅에서 코팅 성분보다 광변색 물질이 갖는 고유의 퇴색속도를 우선적으로 고려 하여야 할 것이다.

The effect of heat treatment environment on the microstructure and properties of tantalum coating layer manufactured by kinetic spraying was examined. Heat treatments are conducted for one hour at 800oC, 900oC, and 1000oC in two different environments of vacuum and Ar gas. Evaluation of microstructure and physical properties are conducted. High density α- tantalum single phase coating layer with a porosity of 0.04% and hardness of 550 Hv can be obtained. As heat treatment temperature increases, porosity identically decreases regardless of heat treatment environment (vacuum and Ar gas). Hardness of heat treated coating layer especially in Ar gas environment deceases from 550 Hv to 490 Hv with increasing heat treatment temperature. That in vacuum environment deceases from 550 Hv to 530 Hv. The boundary between particles became vague as heat treatment temperature increases. Oxygen distribution of tantalum coating layer is minute after heat treatment in vacuum environment than Ar gas environment.

A microencapsulated cinnamon oil (CO)-coated film was developed using a pilot-plant scale film coating system. CO microencapsulated with polyvinyl alcohol was incorporated with a printing ink and the ink mixture was applied to the surface of a polypropylene (PP) film as an ink coating using a gravure printing press at a speed of 20-200 m/min. The tensile strength, percentage elongation at break, elastic modulus, and water vapor permeability of the PP films with and without coating with the microcapsules were not significantly different (p > 0.05), which indicates that the coating did not alter those properties of the films. Microencapsulation effectively prevented the volatilization of CO in the films. The microencapsulated system may be extended to other food-packaging films for which the same ink-printing platform is used. The results from this study imply that the oil-microencapsulated films could be potentially produced by a modern film manufacturing system.

Anti-reflection coating films have used to increase the transmittance of displays and enhance the efficiency of solar cells. Hydrophobic anti-reflection coating films were fabricated on a glass substrate by sol-gel method. To fabricate an anti-reflection film with a high transmittance, poly ethylene glycol (PEG) was added to tetraethyl orthosilicate (TEOS) solution. The content of PEG was changed from 1 to 4 wt% in order to control the morphology, thickness, and refractive index of the SiO2 thin films. The reflectance and transmittance of both sides of the coated thin film fabricated with PEG 4 wt% solution were 0.3% and 99.4% at 500 nm wavelength. The refractive index and thickness of the thin film were n = 1.29 and d = 105 nm. Fluoro alkyl silane (FAS) was used for hydrophobic treatment on the surface of the anti-reflection thin film. The contact angle was increased from 13.2˚ to 113.7˚ after hydrophobic treatment.

고분자 필름의 표면에 친수성의 증가시키는 것은 그 자기 세정 및/또는 방담 특성을 가지게 하는데 중요한 접근 방법이다. 일반적으로 친수성 표면은 비이온 계면활성제를 코팅하거나 표면에너지를 증가시킴으로써 제조할 수 있다. 본 연구에서는 가격이 저렴하고 톨루엔 용제에 잘 용해될 뿐 만아니라 커플링제와 반응할 수 잇는 하이드록시기를 가지고 있는 Tween, Span 및 PEG-PPG 블록공중합체를 선택하여 실험을 수행하였다. 배합 조건에 따라 PET 필름 표면의 친수도에 큰 영향을 미침을 확인하였다. 그러나, PET 필름의 표면상에 단순히 이들 계면활성제의 도입은 수세 후에는 높은 내구성을 보여주지 않았다. 내구성을 높이기 위해 에폭시 및 이소시아네이트와 같은 두 종류의 커플링제를 사용하였다. 코팅액에 6 중량 %isophrone 디이소시아네이트 (IPDI)를 함유한 코팅액으로 코팅된 PET 필름 표면의 물에 대한 접촉각은 8.7˚까지 낮아졌으며, 이는 매우 높은 친수성에 대한 간접적인 증거이다. 또한, 코팅된 PET 필름의 광 (파장 500 nm) 투과율 값은 높은 투명 특성을 유지하면서 87%에서 85%로 약간 감소하였다. 이 PET 필름은 자기 세정 특성이 필요한 필름산업에 적합한 소제로 사용될 수 있다.

다중벽 탄소나노튜브(MWCNT)는 전기적, 기계적 성질이 매우 우수한 소재이나, MWCNT를 복합 체로 응용하는 과정에서 MWCNT의 분산이 어려워 복합체의 제조에 제한을 받고 있다. 본 연구에서는 MWCNT의 표면을 산화시켜 -OH기를 표면에 도입하고, 표면에 음전하를 증가시켜 불소 고분자(PTFE) 도막에서 MWCNT의 분산을 증대시켰다. 그리고, MWCNT의 효과적인 분산으로 PTFE 복합체 도막의 경도와 소수성이 증가되고, 전기 정도성을 부여하여 표면의 기능성이 증대됨을 보여주었다.

PURPOSES: The objective of this study is to evaluate the tack-coating material’s properties using the bitumen bond strength(BBS) test and damping test as function of changed curing times. In this study, bonding strength tests were performed according to the curing time of tack coating materials. METHODS : In order to investigate bonding characteristic of tack coating materials, the Pneumatic Adhesion tensile Testing Instrument(PATTI) device is used to measure the bond strength between the tack coating materials and aggregate substrate based on the AASHTO TP-91. Also, damping test as in situ test was used to determine an appropriate traffic openting time for construction vehicle. Four different tack-coating materials were used in this study. The BBS tests were performed a one hour curing and testing temperatures of 5℃, 15℃, and 25℃. Damping test was conducted at 30min, 60min, 90min, and 120 min of curing times with temperatures of 20℃ and 30℃. RESULTS and CONCLUSIONS : The BBS test results show various bond strength as function of tack coat materials. At the same testing condition, A tack coat material shows almost two times higher than D tack coat materials although both materials are satisfied the criteria of material’s physical properties. Also, Dampting test results shows similar trend with BBS test result. The damping test result was significantly changed as function of tack coat materials. Based on this study, the tack coating material’s curing time is very important. Therefore, both curing time and the bond strength’s characteristic has to be considered in standard specification.

To elucidate the effects of a pretreatment process on the uniformity of Ag electroless plating on Cu flakes, pretreatment time was mainly considered with a mixed solution of 0.15 M ammonium hydroxide and 0.0375 M ammonium sulphate. Optical inspection of Ag-coated Cu flakes determined that the optimal pretreatment time is 120 s. Repetition of the sequence in which Ag plating was done immediately after the pretreatment of 120 s clearly enhanced the plating uniformity. Scanning electron microscopy revealed that holes were formed irregularly on some Cu flakes during the period from the asdropping of an Ag precursor solution to 5 min. The hole formation was judged to be due to continuous removal of Cu on the local surfaces by the repetitive formation and elimination of Cu2O or Cu(OH)2 layers. However, the increase of the amount of Ag coating suppressed the hole creation and increasingly enhanced the antioxidant property.

Sesame is a major cooking oil crop in Korea. One of the primary problems in sesame cultivation is low healthy stand establishment due to the occurrence of seedling rot and damping-off resulting from a complex of soil-borne pathogens in the field. To address the problem, the bioformulation of Pseudomonas fluorescens M45 was prepared in powder form using clay and vermiculite, and was evaluated for its effect on biological control of soil-borne pathogens in sesame cultivation. In the petri dish trial, the emergence rate was overall good (> 92%) regardless of seeds being pelleted and/or M45-treated. In both pot and field trials containing disease-conducive soils, seed-pelleting substantially reduced emergence rate, whereas seed-pelleting with M45 significantly improved the emergence rate (> 26%). The emergence rate of sesame seeds treated with the strain M45 was greater than 30% regardless of seed pelletization. We also found that M45r colonized in the roots at the density of 1.6×105 cfu/g. With aid of the bioformulation, however, root colonization of the strain was significantly increased to 4.0×106 cfu/g. The powder formulation with strain M45 enhanced the rate of healthy stand establishment in disease-conducive soil. Therefore, bioformulation with strain M45 is a promising method to overcome problems associated with the successive cultivation of sesame.

The coating of solid lubricant on the part of fixed or orbiting scroll wrap in a scroll compressor can not only reduce friction loss, noise & vibration and time cost for surface finishing but also improve efficiency and performance of the compressor. In this study, we found the most appropriate combination of the solid lubricant by carrying out many measurements and tests such as coefficient of friction, surface structure, the coating thickness and surface roughness for the various cases. We have come to conclusion that the most appropriate solid lubricant can be obtained by adding WS2 3% to Base(SM 3901) without any solvent and filler.

본 연구에서는 종결정 코팅층이 NaA 제올라이트 분리막 형성에 미치는 영향에 대하여 고찰하였다. NaA 제올라이트 분리막은 평균입경 100 nm 종결정을 다공성 α-알루미나 표면에 진공여과 코팅하고 100˚C에서 24시간 수열처리하여 합성되었다. 이때 지지체 표면에 분포된 종결정 양을 조절한 후 형성된 NaA 제올라이트 분리층의 두께와 결정입 크기 등 미세구조에 미치는 영향에 대하여 고찰하였다. 종결정 코팅 양은 지지체를 통과한 종결정 수용액의 여과 양을 조절하여 제어하였다. 종결정을 단일층으로 코팅한 후 합성하였을 경우, 코팅 양이 증가함에 따라 분리층 단면에서의 두께와 균일도는 증가하였으며, 표면에서의 결정입 크기는 감소하면서 균일도는 증가하였다. 반면, 종결정을 다층으로 코팅한 후 합성하였을 경우, 균일한 분리층을 형성하였지만 단일층으로 코팅된 경우에 비하여 불균일하였으며 두꺼운 분리층이 형성되었다. 균일하고 초박형의 결함이 없는 제올라이트 분리층을 형성하기 위해서는 종결정을 균일하고 단일층으로 코팅하여야 함을 알 수 있었다. 본 연구로부터 종결정의 코팅 상태가 이차성장에 의한 NaA 제올라이트 분리층의 미세구조를 결정하는 중요한 인자임을 확인할 수 있었다.

This study is a basic research for repair material production which manufactured a Cu repair coating layer on the base material of a Cu plate using kinetic spray process. Furthermore, the manufactured material underwent an annealing heat treatment, and the changes of microstructure and macroscopic properties in the Cu repair coating layer and base material were examined. The powder feedstocks were sphere-shaped pure Cu powders with an average size of 27.7μm. The produced repair coating material featured 600μm thickness and 0.8% porosity, and it had an identical α-Cu single phase as the early powder. The produced Cu repair coating material and base material displayed extremely high adhesion characteristics that produced a boundary difficult to identify. Composition analysis confirmed that the impurities in the base material and repair coating material had no significant differences. Microstructure observation after a 500℃/1hr. heat treatment (vacuum condition) identified recovery, recrystallization and grain growth in the repair coating material and featured a more homogeneous microstructure. The hardness difference (δHv) between the repair coating material and base material significantly reduced from 87 to 34 after undergoing heat treatment.

본 연구에서는 축전식 탈이온 공정(capacitive deionization, CDI)의 성능을 개선하기 위해 poly(2,6-di-methyl-1,4-phenylene oxide) (PPO)를 기저물질로 이용하여 코팅이 가능한 음이온교환 이오노머(quaternized PPO, QPPO) 용액을 제조하였다. 제조된 QPPO는 상용 음이온교환막(AMX, Astom Corp., Japan) 대비 우수한 이온전도도 특성을 나타내었으며 전기화학적 특성 또한 동등 수준임을 확인할 수 있었다. 다공성 탄소 전극에 이오노머 용액을 코팅하여 CDI 성능평가를 수행하였으며 그 결과 약 94.9%의 높은 염 제거 효율을 나타내었다. 기존의 CDI와 상용 음이온교환막을 결합한 membraneCDI (MCDI), QPPO가 코팅된 전극을 사용한 coated CDI (CCDI)의 탈염 성능을 비교한 결과 QPPO의 높은 이온선택성 및낮은 이온 전달저항으로 CCDI가 기존의 CDI에 비해 52.1%, MCDI에 비해 18.3% 향상된 높은 염 제거 성능을 나타냄을 확인하였다.

본 연구에서는 소수성 PVDF막 표면에 중성 친수성 고분자인 Poly(vinyl alcohol) (PVA)를 코팅한 후 순수 투과도를 측정하고 대표적인 단백질 오염물질인 bovin serum albumin (BSA)에 대하여 파울링 실험을 수행하였다. BSA 용액 20ppm 조건에서 파울링 실험을 수행한 결과, 코팅 전 막에 비하여 순수 투과도는 감소하였지만 내오염성은 현저히 증가됨을 알 수 있었다. 코팅된 PVA의 분자량이 커질수록 순수 투과도는 감소하였으나, 내오염성이 증가하는 경향을 보였다. 또한, 코팅된 PVA의 농도가 높아질수록 순수 투과도는 감소하였고, 내오염성이 증가하였다. 이는 접촉각과 AFM 측정 결과와 관련하여 코팅 후 막 표면에 친수성의 증가와 거칠기가 감소했기 때문으로 여겨진다.

Metal foams have a cellular structure consisting of a solid metal containing a large volume fraction ofpores. In particular, open, penetrating pores are necessary for industrial applications such as in high temperature filtersand as a support for catalysts. In this study, Fe foam with above 90% porosity and 2 millimeter pore size was suc-cessfully fabricated by a slurry coating process and the pore properties were characterized. The Fe and Fe2O3 powdermixing ratios were controlled to produce Fe foams with different pore size and porosity. First, the slurry was preparedby uniform mixing with powders, distilled water and polyvinyl alcohol(PVA). After slurry coating on the polyure-thane(PU) foam, the sample was dried at 80℃. The PVA and PU foams were then removed by heating at 700℃ for 3hours. The debinded samples were subsequently sintered at 1250℃ with a holding time of 3 hours under hydrogenatmosphere. The three dimensional geometries of the obtained Fe foams with an open cell structure were investigatedusing X-ray micro CT(computed tomography) as well as the pore morphology, size and phase. The coated amount ofslurry on the PU foam were increased with Fe2O3 mixing powder ratio but the shrinkage and porosity of Fe foams weredecreased with Fe2O3 mixing powder ratio.

Thermal barrier coatings(TBCs) are being applied in many industrial fields such as thermal power generation, aviation and seasonal fields. ZrO2-Y2O3(8%) thermal spray coating powders are commercially used as thermal-barrier coating materials to protect against oxidation and corrosion of heat-resistant alloys at elevated temperatures. Currently, ZrO2-Y2O3(8%) thermal-spray powder is made using the industrial co-precipitation process, which is very complex and requires a lot of time. In this study, orthorhombic ZrO2 and Y2O3 powders were fabricated by mechanical mixing, which is more economical than the co-precipitation process. A tetragonal, yttria-stabilized zirconia(YSZ) coating-layer was produced by plasma spraying, using orthorhombic ZrO2-Y2O3(8%) powder. Our experimental results indicate that ZrO2-Y2O3(8%) mixed powder can be used economically in industry because it is no longer necessary to make this powder by liquid and gas-phase methods.

합성된 스테인레스 스틸에 대한 NATM(New Austria Tunnel Method) 수지의 기계적 특성은 SEM, FT-IR, 인장특성, 그리고 [NCO]/[OH]의 mole %, 입도분석에 의해 측정하였다. 친환경적인 NATM에 관한 관심이 고조됨에 따라 스테인레스 등의 금속에 코팅하는 무용제 도료를 합성하였다. 폴리올, IPDI, 충진제, 실리콘 계면활성제, 촉매 등이 함유된 기존 NATM수지보다 폴리올, MDI, 충진제, 실리콘 계면활성제, 촉매, 가교제가 함유되어 합성된 NATM 수지의 도료가 내구력과 강도가 양호하였다. 견고한 NATM 수지의 기계적 특성은 가교와 [NCO]/[OH]의 mole%가 증가함에 따라 강도가 증가하였다. 결론적으로 NATM의 가교된 미세조직는 스테인레스 스틸 같은 금속물질 코팅에 좋은 물질이다.

This study manufactured a CIG-based composite coating layer utilizing a new warm spray process, and amixed powder of Cu-20at.%Ga and Cu-20at.%In. In order to obtain the mixed powder with desired composition, theCu-20at.%Ga and Cu-20at.%In powders were mixed with a 7:1 ratio. The mixed powder had an average particle size of35.4 µm. Through the utilization of a warm spray process, a CIG-based composite coating layer of 180 µm thicknesscould be manufactured on a pure Al matrix. To analyze the microstructure and phase, the warm sprayed coating layerunderwent XRD, SEM/EDS and EMPA analyses. In addition, to improve the physical properties of the coating layer, anannealing heat treatment was conducted at temperatures of 200℃, 400℃ and 600℃ for 1 hour each. The microstructureanalysis identified α-Cu, Cu4In and Cu3Ga phases in the early mixed powder, while Cu4In disappeared, and additionalCu9In4 and Cu9Ga4 phases were identified in the warm sprayed coating layer. Porosity after annealing heat treatmentreduced from 0.75% (warm sprayed coating layer) to 0.6% (after 600℃/1 hr. heat treatment), and hardness reducedfrom 288 Hv to 190 Hv. No significant phase changes were found after annealing heat treatment.

내화성 및 내화학성이 우수한 현무암사의 표면에 회분식 방법에 의한 테프론 코팅 연구의 결과를 토대로 연속식 코팅 공정 인자를 도출하기 위한 연구를 수행하였다. 현무암사를 7,5 wt% 트리에톡시트리플루오로실란(TMTFPS)으로 연속적으로 전처리 한 후, 침투제로 0.25 wt% bis(2-ethylhexyl)sulfo succinate (DOS-Na)가 함유된 20 wt% 테프론 수분산액으로 딥 코팅한 후 2 m의 120 ℃ 건조 챔버에서 12 m/mim의 속도로 건조한 후 2 m의 380 ℃ 소성 챔버에서 40초간 소성하여 최종 3.4 gf/D의 인장 강도와 2.3 gf/D의 루프강도를 가지는 테프론이 코팅된 고내열 재봉사용 현무암사를 제조하였다.