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DDPO₄ 와 ODPO₄ SAM 코팅의 나노 응착 및 마찰 특성 연구
윤의성(Eui-Sung Yoon),양승호(Seung Ho Yang),공호성(Hosung Kong),Andrei Ya Grigoriev 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.35 No.-
Nano adhesion between SPM (scanning probe microscope) tips and DDPO₄ (dodecylphosphoric acid ester) and ODPO₄ (octadecylphosphoric acid ester) SAM (self-assembled monolayer) was experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM(atomic force microscope) and LFM(lateral force microscope) modes with the applied normal load. DDPO₄ and ODPO₄ SAM were formed on TiMe and TiOx surfaces. TiMe and TiOx were coated on the Si wafer by ion sputtering. Adhesion and friction of DDPO₄ and ODPO₄ SAM surfaces were compared with those of OTS (octadecyltrichlorosilane) SAM and DLC surfaces. DDPO₄ and ODPO₄ SAM converted the TiMe and TiOx surfaces to be hydrophobic. When the surface was hydrophobic, the adhesion and friction forces were found lower than those of bare surfaces. Work of adhesion was also discussed to explain how the surface was converted into hydrophobic. Results also showed that tribological characteristics of DDPO₄ and ODPO₄ SAM had good properties in the adhesion, friction, wetting angle and work of adhesion. DDPO₄ and ODPO₄ SAM could be one of the candidates for the bio-MEMS elements.
은 박막이 코팅된 표면에서 물질전이층의 형성 및 그 트라이볼로지적 역할에 관한 연구
양승호(Seung Ho Yang),공호성(Hosung Kong),윤의성(Eui-Sung Yoon),김대은(Dae Eun Kim) 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.35 No.-
The tribological role of mass transfer layer was studied with silver coatings under various ranges of load and sliding speed. Silver coating was performed with a functionally gradient coating method. Tests were performed in dry sliding conditions, using a ball-on-disk contact configuration, at the load of 0.0196-17.64 N and the sliding speed of 20-1,000 ㎜/s in ambient air. Optical microscope and EPMA analyses showed that contact surfaces were covered with the mass transfer layers of agglomerated wear particles depending upon the contact conditions, and they greatly influenced the tribological characteristics of the surfaces. However, the formation of mass transfer layer was suppressed as the sliding speed increased, and above a critical sliding speed, no mass transfer layer was able to form. For building up a general framework of tribological behavior of the coated silver films, all test data were summarized on a map whose axes are contact pressure and sliding speed.
표면형상이 젖음각과 마이크로/나노 트라이볼로지 특성에 미치는 영향
윤의성(Eui-Sung Yoon),오현진(Hyun-Jin Oh),양승호(Seung Ho Yang),공호성(Hosung Kong) 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.35 No.-
Effect of surface topography on the water wetting nature and micro/nano tribological characteristics of Si-wafer and PTFE was experimentally studied. The ion beam treatment was performed with a hollow cathode ion gun in different argon ion dose conditions in a vacuum chamber to change the surface topography. Micro/nano tribological characteristics, water wetting angles and roughness were measured with a micro tribo tester, SPM (scanning prove microscope), contact anglemeter and profilometer, respectively. Results showed that surface roughness increased with the argon ion dose. The water wetting angle of the ion beam treated samples also increased with the ion dose. Results also showed that micro-adhesion and micro-friction depend on the wetting characteristics of the PTFE samples. However, nano-tribological characteristics showed little dependence on the wetting angles. The water wetting characteristics of modified PTFE samples were discussed in terms of the surface topographic characteristics.
Tribochemical interactions of Si-doped DLC film against steel in sliding contact
Duc-Cuong Pham,Eui-Sung Yoon(윤의성),Ho-Sung Kong(공호성),Hyo-Sok Ahn(안효석) 한국트라이볼로지학회 2006 한국트라이볼로지학회 학술대회 Vol.2006 No.6
This study concerns the effects of tribochemical interactions at the interface between Si-DLC (silicon-doped diamond-like carbon) film and steel ball in sliding contact on tribological properties of the film. The Si-DLC film was deposited on DLC/Si substrate using radio frequency plasma-assisted chemical vapor deposition (r.f. PACVD) with different Si concentration. Friction tests against steel ball using a reciprocating type wear tester were performed in ambient environment. X-Ray photoelectron spectroscopy (XPS) and auger electron spectroscopy (AES) were used to study the chemical characteristics and elemental composition of the film and mating balls after tests. As results, a dark-gray transfer film consists of carbon, oxygen and silicon elements were observed on worn surface of steel ball with different thickness. The oxidation of Si-DLC surface and steel ball was also identified at particular regions of contact area. On the contrary, the transfer film could not be found on surface of the ball slid against pure DLC coating. This demonstrates that chemical reactions were occurred at contact area of Si-DLC and steel ball during sliding. While friction test of DLC film versus steel ball exhibited high friction coefficient (~0.06), the Si-DLC in its turn showed very low friction (~0.022) with the presence of tribofilm on mating ball surface. However, Si-DLC film possesses poor wear resistance in comparison with the pure DLC. We suggest that the tribochemical process strongly affected to tribological properties of the Si-DLC film in sliding against steel.
졸-겔 공정에 의한 유기변성 하이브리드 세라믹 물질의 미세 마찰마모 특성
한흥구(Hung-Gu Han),공호성(Hosung Kong),윤의성(Eui-Sung Yoon),양승호(Seung-Ho Yang) 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.35 No.-
In order to enhance the thermal stability of binder materials of bonded type solid lubricants, several combinations of metal-alkoxide based sol-gel materials such as methyltrimethoxysilane(MTMOS), titaniumisopropoxide(Ti(Opr<SUP>i</SUP>)₄), zirconiumisopropoxide(Zr(Obu<SUP>i</SUP>)₄) and aluminumbutoxide(Al(Obu<SUP>t</SUP>)₄) were chemically modified by epoxy-, acrylic- and fluoro-silane compounds, respectively, in this work. Friction and wear characteristics of these hybrid ceramic materials were tested with a micro tribo-tester where a reciprocating steel ball slid on a test material, and the tribological property was also evaluated with respect to both heat-curing temperature and the time. Test results generally showed that hybrid ceramic materials modified by epoxy-silane compounds had a low friction compared to others. And the higher heat-curing temperature and the longer heat treatment time resulted in the higher friction and the lower wear. IR spectroscopic analyses revealed that it was caused mainly by the increased metal oxide content in hybrid ceramics when the heat-curing temperature was over 320℃.