http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
친수성과 소수성이 복합된 마이크로/나노 혼합 구조 표면에서의 수조비등 연구
조학래(Hak Rae Cho),김영현(Young Hyun Kim),장진규(Jin Gyu Jang),Narayan Pandurang Sapkal,박수청(Su Cheong Park),주형민(Hyeong Min Joo),유동인(Dong In Yu) 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.12
Surface roughness and wettability is important to enhance not only critical heat flux (CHF) but also boiling heat transfer coefficient (HTC). Generally hydrophilic micro/nano structures contribute on enhancing liquid supply to dry spot and delay CHF and hydrophobic surface contribute on promoting nucleation and enhancing HTC. Therefore, excellent pool boiling performance can be achieved by combining hydrophilic structures and hydrophobic structures. In this study, we fabricated hydrophilic micro pillar (MP) surface, biphilic micro pillar (BMP) surface, hydrophilic micro/nano pillar (MNP) surface and biphilic micro/nano pillar (BMNP) surface. To investigate the effect of surface roughness and heterogeneous wettability on critical heat flux phenomena, pool boiling experiments were conducted using fabricated surfaces and bare surface.
계층적 마이크로-나노 구조물 기반 PMMA 기판의 젖음특성 제어
박용민(Yong Min Park),서영호(Young Ho Seo),김병희(Byeong Hee Kim) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5
In this paper, we verified the influence of surface energy according to the gradually changed surface roughness through the implementation of hierarchical micro-nano structure texturing. In generally, it well known that surface roughness has a very important parameter for define the surface characteristics such as hydrophobic or superhydrophobic state and these surface conditions have defined as theoretical models of Cassie-Baxter or Wenzel. In order to fabrication of hierarchical micro-nano structures, we have performed silicon anisotropic wet etching and aluminum anodizing processes. We have designed four different surfaces of smooth, nano-structured, micro-structrued, and hierarchically micro-nano structrued surfaces to investigate the geometric effect on contact angle. Four types of surfaces were also chemically treated to reduce surface energy using silane (Trichlro-silane, Sigma-Aldrich Inc.). Contact angles were measured as 104±2℃, 112±2℃, 138±4℃, and, 159±2℃ after chemical treatment, respectively. In the case of micro-nanostructured surfaces that had super-hydrophobic feature.
이상민(Sang Min Lee),정임덕(Im Deok Jung),박치열(Chi Yeol Park),고종수(Jong Soo Ko) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Surface wettability on the micro nano multi-scale structures has been examined. To evaluate the influence of the nano structures on the contact angles, we fabricated two different kinds of nano structures: bump-type and tip-type nano structures. Bump-type and tip-type nano structures were fabricated by reactive ion etching (RIE) and deep reactive ion etching (DRIE) processes, respectively. For the hydrophobic coating, plasma polymerized fluorocarbon (PPFC) was finally deposited onto the fabricated structures. The fabricated micro nano multi-scale structures showed a very high contact angle, ca 170°.
하이드록시아파타이트 표면 나노 구조 성장에 의한 고분자 표면의 초소수성 개질
남윤한(Yoon Han Nam),조용상(Yong Sang Cho),서경덕(Kyoung Duck Seo) 대한기계학회 2020 大韓機械學會論文集B Vol.44 No.2
초소수성 표면은 자가 세정, 방빙 등의 특성을 가지며, 산업 여러 방면에 활용될 수 있어 많은 관심을 받고 있다. 그러나 초소수성 표면 구현을 위해 제안된 기존의 방법들은 복잡한 제작 공정 및 고가의 장비가 필요하다는 한계가 있다. 따라서 본 연구에서는 의사체액(SBF: Simulated Body Fluid)을 이용하여 하이드록시아파타이트 마이크로/나노 구조를 고분자 표면 위에 성장시키고 SAM(Self-Assembled Monolayer) 코팅을 함으로써 손쉽게 초소수성 표면을 제작하였다. 제작된 초소수성 표면의 접촉각은 163.3±2.7°로 측정되었다. 더 나아가 마스킹 테이프를 이용하여 초소수성 표면을 다양한 형상으로 선택적으로 패터닝 할 수 있음을 확인하였으며, 제작된 초소수성 표면의 자가 세정 특성을 보임을 검증하였다. Superhydrophobic surfaces have attracted research interest owing to their self-cleaning characteristics, antiicing properties, etc. However, conventional fabrication methods for these surfaces still require complex processes and special facilities. Therefore, in this study, we propose a facile and cost-effective fabrication method for superhydrophobic surfaces using simulated body fluid (SBF). A PMMA (poly (methyl methacrylate)) substrate with a hydroxyl group is initially immersed in the SBF. Hydroxyapatite with micro/nanostructure is then crystallized on the substrate. Finally, a self-assembled monolayer (SAM) coating is prepared to introduce superhydrophobicity. After the coating process, the contact angle of the fabricated substrate is measured as 163.3 ± 2.7°. We also demonstrate that hydroxyapatite with a micro/nanostructure can be patterned with various shapes by using masking tape. In addition, the self-cleaning effect of the fabricated surface is observed.
Two-step capillary force lithography for fabricating biomimetic, superhydrophobic surfaces
Hoon Eui Jeong(정훈의),Rhokyun Kwak(곽노균),Jae Kwan Kim(김재관),Kahp Y. Suh(서갑양) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Inhibition effects in UV radiation curing by oxygen were utilized for fabricating monolithic, micro/nanoscale hierarchical polymer structures via two-step UV-assisted capillary force lithography. It was found that the UV exposure time for the partial curing of microstructure was a crucial parameter; a shorter exposure time induced collapse of the underlying microstructure while a longer time gave rise to non-fluidity of the microstructure. The partial curing is attributed to inhibition of UV cross linking by trapped or permeated oxygen within mold cavities. Using this method, various dual-scale hierarchical structures were fabricated with minimum resolution to 50 nm over a large area (5×5 ㎠) in a fast and reproducible manner.
전기화학 에칭 공정을 이용한 스테인리스 스틸 메쉬의 방수 특성 연구
이찬(Chan Lee),김지민(Ji Min Kim),김형모(Hyungmo Kim) 한국트라이볼로지학회 2021 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.37 No.5
A straightforward, yet effective surface modification method of stainless steel mesh and its interesting anti-wetting characteristics are reported in this study. The stainless steel mesh is electrochemically etched, and the specimen has both micro and nano-scale structures on its surface. This process transforms the two types of mesh specimens known as the regular and dense specimens into hydrophobic specimens without applying any hydrophobic chemical coating process. The fundamental wettability of the modified mesh is analyzed through a dedicatedly designed experiment to investigate the waterproof characteristics, for instance, the penetration threshold. The waterproof characteristics are evaluated in a manner that the modified mesh resists as high as approximately 2.7 times the pressure compared with the bare mesh, i.e., the non-modified mesh. The results show that the penetration threshold depends primarily on the advancing contact angles, and the penetration stop behaviors are affected by the contact angle hysteresis on the surfaces. The findings further confirm that the inexpensive waterproof meshes created using the proposed straightforward electrochemical etching process are effective and can be adapted along with appropriate designs for various practical applications, such as underwater devices, passive valves, and transducers. In general, , additional chemical coatings are applied using hydrophobic materials on the surfaces for the applications that require water-repelling capabilities. Although these chemical coatings can often cause aging, the process proposed in this study is not only cost-effective, but also durable implying that it does not lose its waterproof properties over time.