• Journal of Energy Engineering
• /
• v.7 no.2
• /
• pp.180-186
• /
• 1998

In this study, the effect of shear rate on the viscosity variation is examined to understand the flow characteristics of the mixture of bentonite and water. The variation of film thickness according to mixing ratio and viscosity is measured to characterize the film formation. And, the separation of dried film is studied according to film thickness. Specific surface area affecting on adsorption capability is measured using BET method. The viscosity decreases and the film thickness increases as the mixing ratio increases. The separation characteristic of dried film is suitable within a range of 40 to 150 ${\mu}{\textrm}{m}$ in film thickness and 5 to 10% in mixing ratio.

• Journal of the Korean Ceramic Society
• /
• v.40 no.5
• /
• pp.501-505
• /
• 2003

SrZrO$_3$ resistive oxides on Ag tapes were prepared by the sol-gel and dip coating method to investigate the effect of PVP content and drying condition on microstructure of the films. Although the film thickness increased with the addition of PVP, the amount of PVP and heat treatment were not effective to reduction of formation of microcracks at the films. However, lower drying temperature and longer drying time were beneficial to control the microcracks of the SrZrO$_3$ films, indicating that the microcracking of the films was governed primarily by the drying condition.

• Journal of the Korean Ceramic Society
• /
• v.36 no.3
• /
• pp.307-318
• /
• 1999

동결건조법에 의한 저유전성 실리카 박막의 제조공정 개발 및 층간 절연물질로의 응용성이 연구되었다. 코팅용 폴리머 실리카 졸은 TEOS와 이소프로판올(iso-propanol:IPA)또는 터트부탄올(tert-butanol:TBA)을 용매로한 2단계 공정에 의하여 제조되었으며, 이들 졸을 p-Si(111)웨이퍼 상에 스핀코팅한 습윤겔 박막을 동결건조 하여 다공성 실리카 박막을 제조하였다. 균일한 박막 코팅층을 얻을 수 있는 실리카 졸의 최적 점도범위는 IPA와 TBA를 용매로 한 실리카 졸의 경우 각각 10~14 cP와 20~30cP 정도였으며 스핀속도는 2000 rpm 이상이었다. 결함이 없는 다공성 실리카 박막은 TBA(빙점 $25^{\circ}C$)를 동결용매로 하여-196$^{\circ}C$까지 급랭시킨 후 $0^{\circ}C$와 0.1 torr 까지 가열 감압한 상태에서 고상의 TBAFMF 모두 제거한 다음 20$0^{\circ}C$까지 열처리하여 제조되었다. 다공성 실리카 박막의 두께는 졸의 타입과 스핀코팅 속도에 의해 2500~15000$\AA$범위 내에서 제어가 가능하였으며 이들 막의 밀도와 유전상 수 값은 각각 0.9$\pm$0.3g/㎤(기공율 60$\pm$10%)과 2.4 정도였다.

• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.1128-1133
• /
• 2008

Drying process in the thin film layer of sludge with the thickness less than a few millimeters has been investigated using the simple one-dimensional model. Thin film drying is usually used to dry the viscous materials like sewage sludge. The thin film layer of sludge is dried on the metallic surface through which thermal energy is supplied to the layer during drying. In order to solve the equations, the mass transfer rate on the drying surface should be determined. The mass flux of evaporated water vapor on the surface is estimated with the formulation given in the literature. The effect of heating temperature, film thickness, and air velocity on drying has been examined to figure out the drying characteristics of the sludge layer.

• Applied Chemistry for Engineering
• /
• v.25 no.6
• /
• pp.598-601
• /
• 2014

The effects of process parameters for the formation of polypropylene film such as the polypropylene concentration in the solution, drying temperature for coating film, and variation of nano-silica content on the surface structure and property of polypropylene film have been studied. A super-hydrophobic polypropylene film with a maximum contact angle of $154^{\circ}$ was obtained at the condition of a polypropylene concentration of 30 mg/mL, a drying temperature of $30^{\circ}C$, a drying pressure of 93 mtorr for 90 min. The increase of a drying temperature reduced the contact angle by enhancing the surface smoothness of the film. The increase of nano-silica content in the composite film composed of polypropylene and silica changed the surface shape from microporous to microglobular, which led to increasing the contact angle and showed the super-hydrophobic surface property.

• Applied Chemistry for Engineering
• /
• v.33 no.4
• /
• pp.367-372
• /
• 2022

The effect of the addition of a polyvinylchloride (PVC) non-solvent to a PVC-tetrahydrofuran (THF) solution on the surface properties of the PVC thin film was analyzed. The non-solvents used were composed of alcohol-based and non-alcoholic ones. Surface morphologies of PVC thin films according to the addition of the non-solvent were compared. In addition, the hydrophobic properties relying on the surface characteristics were compared. The micro-bubbles generated in the preparation of PVC-THF solution affected the surface morphology of the thin film. In order to implement the normal surface physical properties of the coating thin film at the relatively high concentration of PVC-THF solution, the selection of appropriate drying method was required. When an alcohol-based non-solvent was added, a PVC thin film having a granular porous surface was obtained and exhibited super hydrophobic properties. The volume ratio of the PVC-THF solution to the non-solvent affects the surface shape of the coating thin film. The larger the amount of non-solvent was added, the more advantageous it was to form a super hydrophobic PVC thin film.

• Proceedings of the Optical Society of Korea Conference
• /
• 2006.07a
• /
• pp.457-458
• /
• 2006

졸겔공정을 이용하여 Ag나노입자가 형성된 석영유리계 유리박막을 제조하였다. Dip-coating 과 건조 및 소결처리를 거쳐 $60{\sim}275nm$ 두께의 박막을 제조하였고, TEM 분석 결과 $2{\sim}5nm$ 크기의 Ag나노 입자가 유리박막에 형성된 것을 확인하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2007.04a
• /
• pp.38-39
• /
• 2007

Chromium nitrids(Cr-N)박막은 경질박막재료이며 특히 PVD법을 제조한 CrN 박막은 다른 이원계 박막에 비해 높은 내마모성을 갖는다고 알려져 있다. 본 실험에서는 CrN박막에 Zr을 첨가하여 3원계의 CrZrN 박막을 합성하여 박막의 Zr 함량에 따른 표면경도 및 조도를 측정하고 Ball-on-disk type의 마모실험과 습도제어 하에서의 마모실험을 실시하였다. 박막의 Zr 함량이 증가함에 따라 박막의 표면경도가 증가하고 표면조도는 낮아지는 것을 알수 있었고, 그에 따라 마찰계수 값 또한 낮게 측정되었다. 습도제어하에서는 마찰계수 값은 비슷한 경향을 보였으나 습도가 매우 낮은 건조한 환경에서는 박막의 마찰계수 값이 높게 나타나는 경향을 보였다.

• Composites Research
• /
• v.32 no.6
• /
• pp.314-318
• /
• 2019

A simple and very flexible automatic dipping machine was constructed for producing functional multilayer films on wide substrates via the layer-by-layer (LbL) assembly technique. The proposed machine exhibits several features that allow a fully automated coating operation, such as various depositing recipes, control of the dipping depth and time, operating speed, and rinsing flow, air-assist drying nozzles, and an operation display. The machine uniformly dips a substrate into aqueous mixtures containing complementary (e.g., oppositely charged, capable of hydrogen bonding, or capable of covalent bonding) species. Between the dipping of each species, the sample is spray cleaned with deionized water and blow-dried with air. The dipping, rinsing, and drying areas and times are adjustable by a computer program. Graphene-based thin films up to ten-bilayers were prepared and characterized. This film exhibits the highly filled multilayer structures and low thermal resistance, indicating that the robotic dipping system is simple to produce functional thin film coatings with a variety of different layers.

• Korean Journal of Materials Research
• /
• v.9 no.11
• /
• pp.1069-1074
• /
• 1999

본 연구에서는 PbZr(sub)0.53Ti(sub)0.47O$_3$(PZT) 박막을 복수 도포함에 따른 박막내의 응력을 온도의 함수로 실시간(in situ) 측정하였으며, 응력발생의 원인에 박막의 건조, 열분해(pyrolysis), 치밀화 및 결정화 현상과 연관시켜 설명하였다. 도포직후 단층박막에 생성된 55MPa의 인장응력은 가열됨에 따라$ 300^{\circ}C$-$350^{\circ}C$에서 최대 145MPa로 증가하였으며, 박막내의 응력은 모든 온도구간에서 항상 인장응력을 나타내었더. 다층도포시 $650^{\circ}C$까지 열처리 주기를 완료한 층이 두꺼워질수록 새로 도포한 층의 영향은 점차 감소하였으며, 9층박막에 이르러서는 가열과 냉각에 따라 응력이 동일하게 변화하였다. 응력측정 결과 다층박막의 치밀화는 $350^{\circ}C$에서 시작되어 $520^{\circ}C$-$550^{\circ}C$ 부근에서 완료되는 것으로 나타났으며 치밀화가 시작하는 온도는 미세경도 측정결과와 일치하였다. $PbTiO_3$(PT)와 달리 PZT 다층박막은 Si 기판 위에서 perovskite로의 결정화가 일어나지 않았다.