• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.67-67
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• 2018

The 5xxx series aluminum alloys are recently used in not only marine system but also automotive area because of a low density material, good mechanical properties and better resistance to corrosion. However, Aluminum alloys are less resistant than the purest aluminum such as 1xxx aluminum alloy. Electrochemical anodization technique has attracted in the area of surface treatment because of a simple procedure, a low-cost efficiency than other techniques such as lithography and a large volume of productivity, and so on. Here, The relationship between the corrosion behavior and the thickness of aluminum anodic oxide have been studied. Prior to anodization, The 5052 aluminum sheets ($30{\times}20{\times}1mm$) were degreased by ultra-sonication in acetone and ethanol for 10 minutes and eletropolished in a mixture of perchloric acid and ethanol (1:4, volume ratio) under an applied potential of 20V for 60 seconds to obtain a regular surface. During anodization process, Aluminum alloy was used as a working electrode and a platinum was used as a counter electrode. The two electrodes were separated at a distance of 5cm. The applied voltage of anodization is conducted at 40V in a 0.3M oxalic acid solution at $0^{\circ}C$ with appropriate magnetic stirring. The surface morphology and the thickness of AAO films was observed with a Scanning Electron Microscopy (SEM). The corrosion behavior of all samples was evaluated by an open-circuit potential and potentio-dynamic polarization test in 3.5wt% NaCl solution. Thus, The corrosion resistance of 5052 aluminum alloy is improved by the formation of an anodized oxide film as function of increase anodization time which artificially develops on the metal surface. The detailed electrochemical behavior of aluminum 5052 alloy will be discussed in view of the surface structures modified by anodization conditions such as applied voltages, concentration of electrolyte, and temperature of electrolyte.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.461-461
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• 2013

Over the last decade, zinc oxide (ZnO) thin films have attracted considerable attention owing to large band gap of 3.37 eV and large exciton binding energy of 60 meV at room temperature [1-3]. Recent interest in ZnO related researches has been switched into the fabrication and characterization of low-dimensional nanostructures, such as nano-wires and nano-dots that can be applicable to manufacture the optoelectronic devices such as ultraviolet lasers, light-emitting-diodes and detectors. Since the optical properties of ZnO nano-structures might be distinct from those of bulk materials or thin films, the low-dimensional phenomena should be examined further. In order to utilize such advanced optoelectronic devices, one of the challenges is how to control the surface state related emissions that are drastically increased with increasing the density of the nano-structures and the surface-to-volume ratio. This paper reports the synthesis and characterization of self-assembled ZnO hexagonal nano-disks grown by radio-frequency magnetron sputtering. X-ray diffraction data and scanning electron microscopy data showed that ZnO hexagonal nano-disks were nucleated on top of the flat surfaces as the film thickness reached to 1.56 ${\mu}m$ and then the number of nano-disks increased with increasing the film thickness. The lateral size of hexagonal nano-disks was ~720 nm and height was ~74 nm. The strong photo luminescence spectra obtained at 10 K was also observed, which was assigned to a surface exciton emission at 3.3628 eV arising from the surface sites of hexagonal nano-disks.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권3호
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• pp.114-119
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• 2005

We investigated compatibilizing effects of electrical properties such as charge distributions and electrical breakdown in blends of low density polyethylene (LDPE) / polystyrene (PS) with poly [styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS), the triblock copolymer. The blends with $70\;wt\%$ of LDPE and $30\;wt\%$ of PS were prepared through a melt blending in a batch type kneader at a temperature of $220^{\circ}C$ when the SEBS content increased up to $10\;wt\%$. Scanning electron microscopy (SEM) was investigated for observation of morphology of LDPE / PS blends increasing SEBS contents. The morphological observation showed that addition of SEBS results in the domain size reduction of the dispersed PS phase and a better interfacial adhesion between LDPE and PS phases. Measurements of space charge distributions for blends was carried out with pulsed electroacoustic (PEA) method. It was possible to observe that the amount of charge storage in the LDPE / PS blends decreased wiか increasing of SEBS content. The location of SEBS at a domain interface enables charges to move from one phase to the other via domain interface and results in a indicative decrease in the amount of space charge for the LDPE / PS blends with SEBS. Electrical breakdown strength of these blends was observed. It was found that the maximum breakdown strength of the blend was 51.55 kV/mm. These results were better than 38.38 kV/mm of LDPE used electrical insulator for cables and were caused by crystalinity of blends. Because the crystalinity of blends were lower than LDPE, electrical breakdown strength of LDPE / PS blends is higher than that of LDPE. We evaluated the possibility of these blends for insulating material substituted LDPE.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.111-111
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• 2007

Further scaling the semiconductor devices down to low dozens of nanometer needs the extremely shallow depth in junction and the intentional counter-doping in the silicon gate. Conventional ion beam ion implantation has some disadvantages and limitations for the future applications. In order to solve them, therefore, plasma source ion implantation technique has been considered as a promising new method for the high throughputs at low energy and the fabrication of the ultra-shallow junctions. In this paper, we study about the effects of DC bias and base pressure as a process parameter. The diluted mixture gas (5% $PH_3/H_2$) was used as a precursor source and chamber is used for vacuum pressure conditions. After ion doping into the Si wafer(100), the samples were annealed via rapid thermal annealing, of which annealed temperature ranges above the $950^{\circ}C$. The junction depth, calculated at dose level of $1{\times}10^{18}/cm^3$, was measured by secondary ion mass spectroscopy(SIMS) and sheet resistance by contact and non-contact mode. Surface morphology of samples was analyzed by scanning electron microscopy. As a result, we could accomplish the process conditions better than in advance.

• 센서학회지
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• 제30권3호
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• pp.175-180
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• 2021

In this paper, methods for improving the sensitivity of gas sensors to NO₂ gas are presented. A gas sensor was fabricated based on an SnO₂ nanowire network using the vapor-phase-growth method. In the gas sensor, the Au electrode was replaced with a fluorinedoped tin oxide (FTO) electrode, to achieve high sensitivity at low temperatures and concentrations. The gas sensor with the FTO electrode was more sensitive to NO₂ gas than the sensor with the Au electrode: notably, both sensors were based on typical SnO₂ nanowire network. When the Au electrode was replaced by the FTO electrode, the sensitivity improved, as the contact resistance decreased and the surface-to-volume ratio increased. The morphological features of the fabricated gas sensor were characterized in detail via field-emission scanning electron microscopy and X-ray diffraction analysis.

• 공업화학
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• 제18권6호
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• pp.592-598
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• 2007

Temperature programmed desorption (TPD), XRD, SEM 및 FT-IR를 이용하여 코발트 프탈로시아닌 유도체의 황과 아민화합물에 대한 흡착효율을 조사하였다. 코발트 프탈로시아닌 유도체의 암모니아에 대한 TPD 측정결과, 산도가 낮은 온도($100{\sim}150^{\circ}C$)와 높은 온도($350{\sim}400^{\circ}C$)에서 두개의 탈착피크가 나타났다. 테트라카르복실 코발트프탈로시아닌(Co-TCPC)은 코발트 프탈로시아닌(Co-PC)보다 낮은 온도(물리적 흡착)에서 탈착피크가 약했지만 높은 온도(화학적 흡착)에서 강한 탈착피크가 나타났다. Co-TCPC와 Co-PC의 비표면적은 각각 37.5와 $18.4m^2/g$이었다. Co-TCPC와 Co-PC의 기공부피는 각각 0.17과 $0.10cm^3/g$이었다. 파과곡선으로부터 흡착용량을 계산하였더니 트리에틸 아민 가스 120 ppm의 평형농도에서 Co-TCPC의 흡착용량은 24.3 mmol/g, Co-PC의 흡착용량은 0.8 mmol/g로 나타났다. Co-TCPC와 Co-PC로 디메틸 술파이드 제거효율은 디메틸 술파이드 초기농도 225 ppm에서 각각 92와 18% 제거효율을 보였다. Co-TCPC와 Co-PC로 트리메틸아민 제거효율은 트리메틸아민 초기농도 118 ppm에서 각각 100.0%와 17.0% 제거효율을 보였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.563-566
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• 2000

The effect of CuO and CuO-B $i_2$ $O_3$ additives on microwave dielectric properties of (P $b_{0.45}$C $a_{0.55}$)[F $e_{0.5}$N $b_{0.5}$)$_{0.9}$S $n_{0.1}$] $O_3$were investigated to decrease the sintering temperature for usage of Low Temperature Co-firing Ceramics (LTCC). The (P $b_{0.45}$C $a_{0.55}$)[F $e_{0.5}$N $b_{0.5}$)$_{0.9}$S $n_{0.1}$] $O_3$ceramics was sintered at 11$65^{\circ}C$. In order to decrease the sintering temperature, CuO and Cuo-B $i_2$ $O_3$ were added in the (Pb,Ca)[(Fe,Nb)Sn] $O_3$ with CuO-B $i_2$ $O_3$. For the addition of 0.4 wt.% CuO, the sintered density and the dielectric constant of the ceramics were revealed the maximum values of the 6.06g/c $m^2$ and 83 respectively and temperature coefficient of resonance frequency ($\tau$$_{f}$) shifted to the positive value. As increasing B $i_2$ $O_3$to the (Pb,Ca)[(Fe,Nb)Sn] $O_3$ with CuO-B $i_2$ $O_3$with 0.2 wt.% CuO, the sintered density, the $\varepsilon$$_{r}$ and the Q was decreased, and $\tau$$_{f}$ was minimized at 0.2 wt.% CuO, and 0.2 wt.% B $i_2$ $O_3$. For this composition, dielectric properties were $\varepsilon$$_{r}$ of 81, Q. $f_{0}$ of 4400 GHz, and $\tau$$_{f}$ of 5 ppm/$^{\circ}C$ at sintering temperature of 100$0^{\circ}C$. the relationship between the microstructure and properties of ceramics was studied by X-ray diffraction(XRD), scanning electron microscopy(SEM).copy(SEM).oscopy(SEM).copy(SEM).EM).

• 마이크로전자및패키징학회지
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• 제11권4호
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• pp.55-59
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• 2004

본 논문은 광 활성도가 가장 좋은 아나타제(anatase)상의 광촉매 $TiO_2$분말을 상온에서 aerosol deposition 법을 사용하여 박막을 제조하였다. 이런 제조 방법은 aerosol 분말을 초음속으로 분사하여 기판에 증착시키는 방법으로, 저온에서 박막증착이 가능하여 thermal stress를 줄일 수 있고, 공정 단가를 낮출 수 있다는 장점이 있다. 박막 제조시 aerosol bath의 압력은 500 torr이고, chamber의 압력은 0.4 torr 였다. 이런 압력차는 $0.4 mm{\times}10 mm$의 크기의 노즐을 통해 $TiO_2$ 나노 분말을 초음속으로 가속하여 기판에 증착시켰다. 박막 제조를 위해 사용한 기판은 수질정화에 응용하기 위해 직경 50 mm인 원판 SUS mesh를 사용하였다. $TiO_2$ 분말의 고른 분포를 위해 $TiO_2$ 분말에 함유되어 있는 수분을 제거하고 이차 입자의 생성을 억제하기 위해서 알코올 bath 속에서 90분간 초음파 세척을 한 후 건조하였다. SUS mesh 위에 증착되어 있는 $TiO_2$ 박막의 입자크기를 알아보기 위해 주사 현미경(SEM)으로 분석하였으며, $1 {\mu}m$정도의 입자 크기를 관찰 할 수 있었다. X-ray diffraction (XRD) 분석 결과 aerosol deposition 후에도 분말의 anatase상은 그대로 유지되었으며, 이런 결과는 광촉매 작용을 이용한 수처리용 필터로 활용이 가능하다.

• Korean Chemical Engineering Research
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• 제60권1호
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• pp.1-6
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• 2022

최근 웨어러블 디바이스에 대한 수요가 증가하면서 유연 전극 소재 개발에 대한 다양한 연구들이 진행되고 있다. 특히, 헬스케어용 웨어러블 센서들은 체온이나 심장 박동, 혈당, 혈중 산소 농도 등 신체 정보들의 실시간·지속적인 모니터링과 정확한 진단, 검출이 가능해야 하기 때문에 고성능 유연 전극 소재의 개발이 무엇보다 중요하다. 본 연구에서는 탄소나노튜브 섬유(carbon nanotube fiber; CNT fiber) 기반의 유연 전극 소재의 성능을 개선시키기 위해 CNT fiber 위에 전기화학적 중합(electrochemical polymerization) 공정을 통해 polyaniline (PANI) layer를 합성하고, 이에 대한 전기화학적 특성 분석과 비효소적 글루코스(glucose) 검출 특성을 확인하였다. 제작된 PANI/CNT fiber 전극의 표면 분석은 주사전자 현미경(SEM)을 이용하여 진행되었으며, 전극의 전기화학적 특성 및 글루코스에 대한 센싱 성능은 시간대전류법(CA)과 순환전압 전류법(CV), 전기화학 임피던스법(EIS)을 이용하여 분석되었다. PANI/CNT fiber 전극의 전기화학적 특성은 bare CNT fiber 전극에 비해 작은 electron transfer resistance와 낮은 peak separation potential, 증가된 전극 면적을 나타내며, 이런 향상된 특성들 덕분에 글루코스 검출에 대한 센싱 성능이 개선되었다. 따라서, 본 연구를 기반으로 다양한 나노구조체를 도입하고 접목을 통해 고성능 CNT fiber 기반의 유연 전극 소재 개발이 가능할 것으로 기대된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.222-222
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• 2012

Metal oxide gas sensors based on semiconductor type have attracted a great deal of attention due to their low cost, flexible production and simple usability. However, most works have been focused on n-type oxides, while the characteristics of p-type oxide gas sensors have been barely studied. An investigation on p-type oxides is very important in that the use of them makes possible the novel sensors such as p-n diode and tandem devices. Monoclinic cupric oxide (CuO) is p-type semiconductor with narrow band gap (~1.2 eV). This is composed of abundant, nontoxic elements on earth, and thus low-cost, environment-friendly devices can be realized. However, gas sensing properties of neat CuO were rarely explored and the mechanism still remains unclear. In this work, the neat CuO layers with highly ordered mesoporous structures were prepared by a template-free, one-pot solution-based method using novel ink solutions, formulated with copper formate tetrahydrate, hexylamine and ethyl cellulose. The shear viscosity of the formulated solutions was 5.79 Pa s at a shear rate of 1 s-1. The solutions were coated on SiO2/Si substrates by spin-coating (ink) and calcined for 1 h at the temperature of $200{\sim}600^{\circ}C$ in air. The surface and cross-sectional morphologies of the formed CuO layers were observed by a focused ion beam scanning electron microscopy (FIB-SEM) and porosity was determined by image analysis using simple computer-programming. XRD analysis showed phase evolutions of the layers, depending on the calcination temperature, and thermal decompositions of the neat precursor and the formulated ink were investigated by TGA and DSC. As a result, the formation of the porous structures was attributed to the vaporization of ethyl cellulose contained in the solutions. Mesoporous CuO, formed with the ink solution, consisted of grains and pores with nano-meter size. All of them were strongly dependent on calcination temperature. Sensing properties toward H2 and C2H5OH gases were examined as a function of operating temperature. High and fast responses toward H2 and C2H5OH gases were discussed in terms of crystallinity, nonstoichiometry and morphological factors such as porosity, grain size and surface-to-volume ratio. To our knowledge, the responses toward H2 and C2H5OH gases of these CuO gas sensors are comparable to previously reported values.