• Macromolecular Research
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• 제8권4호
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• pp.179-185
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• 2000

Generally vascular grafts with a relatively large inner diameter (> 5 mm) have been successfully employed for replacement in the human body. However, the use of small diameter grafts is limited, because these grafts rapidly occlude due to the thrombosis. The ideal blood-contacting surface of a prosthesis would be an endothelial cell (EC) lining, because the confluent monolayer of healthy ECs that culture natural blood vessels represents the ideal nonthrombogenic surface. For vascular graft application, the stable EC adhesion on surface under How conditions is very important. In this study, the adhesive strength of ECs attached on polymer surfaces coated with collagen type IV (Col IV), fibronectin (Fn), laminin (Ln), and treated with corona was investigated onto polyurethane (PU) films. The EC-attached PU surfaces were mounted on parallel-plate flow chambers in a How system prepared for cell adhesiveness test. Three different shear stresses (100, 150, and 200 dyne/㎠) were applied to the How chambers and each shear stress was maintained for 120 min to investigate the effect of shear stress and surface treatment condition on the EC adhesion strength. It was observed that the EC adhesion strength on the surface-modified PU films was in the order of Ln≡Fn > Col IV > corona 》 control. More than 70% of the adhered cells were remained on surface-modified PU surface after applying the shear stress,200 dyne/㎠ for 2 hrs, whereas the cells were completely detached on the control PU surface within 10 min after applying the same shear stress. It seems that the type of adsorbed proteins and hydrophilicitv onto the PU surfaces play very important roles for cell adhesion strength.

• 대한치과보철학회지
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• 제25권1호
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• pp.317-325
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• 1987

A study on the shear bonding strength between dental alloy and porcelain according to various kidns of sputtered metallic thin films was established by Ingtron universal testing machine, and the change of the elemental weight % at the surface of dental alloy was studied by E.D.S. The kind of metallic thin films were Al, Ni, In, Cr. Ti and Sn with $0.3{\mu}m$ thickness. The dental alloys were Verabond made by Aalba Dent. Co. and Degudent H manufactured by Degussa Co. The control groups were Verabond and Degudent H. The obtained results were as follows; 1. The shear bonding strength of Al plated sample was the strongest of all. 2. The shear bonding strength of Ni plated sample was stronger than that of Degudent H, Sn plated samples. 3. The shear bonding strength of Verabond was weaker than that of Al, Ni, In, Cr, plated samples. 4. After degassing, it is more weight % of Ni at the alloy surface of the Ni sputtered specimen than the Sn sputtered sample.

• 한국표면공학회지
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• 제39권1호
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• pp.1-8
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• 2006

In this study, effect of sputtering after plasma nitriding and before PVD coating on the microstucture, microhardness, surface roughness and the adhesion strength of CrN thin films were investigated. Experimental results showed that this sputtering process not only removed surface compound layer which formed during a plasma nitriding process but also induced an alteration of the surface of plasma nitrided substrate in terms of microhardness distribution and surface roughness, which in turn affected the adhesion strength of PVD coatings. After sputtering, microhardness distribution showed general decrease and the surface roughness became increased slightly. The critical shear stress measured from the scratch test on the CrN coatings showed an approximately twice increase in the binding strength through the sputtering prior to the coating and this could be attributed to a complete removal of compound layer from the plasma nitrided surface and to an increase in the surface roughness after sputtering.

• 한국표면공학회지
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• 제39권6호
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• pp.268-275
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• 2006

In this study, effect of sputtering on the plasma-nitriding substrate and before PVD coating on the microstucture, microhardness, surface roughness and the adhesion strength of CrZrN thin films were investigated. Experimental results showed that this sputtering process not only removed surface compound layer which formed during a plasma nitriding process but also induced an alteration of the surface of plasma nitrided substrate in terms of microhardness distribution, surface roughness. This in turn affected the adhesion strength of PVD coatings. After sputtering, microhardness distribution showed general decrease and the surface roughness became increased slightly. The critical shear stress measured from the scratch test on the CrZrN coatings showed an approximately 1.4 times increase in the adhesion strength through the sputtering prior to the coating and this could be attributed to a complete removal of compound layer from the plasma nitrided surface and to an increase in the surface roughness after sputtering.

• 한국표면공학회지
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• 제33권5호
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• pp.319-328
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• 2000

Silver is known to have such characteristics as low shear strength, good transfer-film forming tendency, and good corrosion resistance. Silver thin films have been prepared by ion plating of physical vapour deposition (PVD) using both argon gas pressure and bias voltage of processing condition. After the silver films were prepared, the properties in them were examined by gas pressure and bias voltage of substrate. Their morphology and crystal orientation were investigated by scanning electron microscopy (SEM) and X-ray diffractor. The properties of film were, also, studied to relate with morphology, X-ray diffraction pattern, and friction coefficient at vacuum ambient. The friction coefficient was stabilized remarkably on deposited films with increasing argon pressure for deposition. Also, the effect of increasing of the bias voltage for deposition resulted in lower friction coefficient and stability in $1.7$\times$10^{-4}$ torr. On the contrary, behavior of friction coefficient was stabilized on deposited films with decreasing the bias voltage in $1.7$\times$10^{-5}$ torr for deposition.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.49-50
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• 2002

Rapid advancements in analytical instrumentations and techniques in the last several decades offer an unprecedented opportunity to analyze the complex chemistry and probe the surfaces for chemical evidence. Recent developments in nanotechnology provide further ability to examine phenomena and mechanisms at the nanometer level. As a result of these advances, our understanding of the complex lubrication system has improved significantly. This paper will attempt to provide a molecular basis of how lubricant and additives function in lubrication.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 추계학술발표대회
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• pp.25.1-25.1
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• 2011

Over the past few decades, metallic nanoparticles (NPs) have been of great interest due to their unique mesoscopic properties which distinguish them from those of bulk metals; such as lowered melting points, greater versatility that allows for more ease of processability, and tunable optical and mechanical properties. Due to these unique properties, potential opportunities are seen for applications that incorporate nanomaterials into optical and electronic devices. Specifically, the development of metallic NPs has gained significant interest within the electronics field and technological community as a whole. In this study, gold (Au) pads for surface finish in electronic package were developed by inkjet printing of Au NPs. The microstructures of inkjet-printed Au film were investigated by various thermal treatment conditions. The film showed the grain growth as well as bonding between NPs. The film became denser with pore elimination when NPs were sintered under gas flows of $N_2$-bubbled through formic acid ($FA/N_2$) and $N_2$, which resulted in improvement of electrical conductance. The resistivity of film was 4.79 ${\mu}{\Omega}$-cm, about twice of bulk value. From organic anlayses of FTIR, Raman spectroscopy, and TGA, the amount of organic residue in the film was 0.43% which meant considerable removal of the solvent or organic capping molecules. The solder ball shear test was adopted for solderability and shear strength value was 820 gf (1 gf=9.81 mN) on average. This shear strength is good enough to substitute the inkjet-printed Au nanoparticulate film for electroplating in electronic package.

• Journal of the Korean Wood Science and Technology
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• 제45권5호
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• pp.559-571
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• 2017

본 연구에서는 열가소성수지 필름의 사용량과 적층방향에 따른 합판의 접착성능을 알아보고자 하였다. 사용된 표판과 이판은 열대산 활엽수 잡목(Mixed light hardwood) 단판과 심판은 라디에타파인(Pinus radiata D. Don) 단판을 사용하였다. 필름은 폴리프로필렌(Polypropylene, PP) 필름과 폴리에틸렌(Polyethylene, PE) 필름을 사용하였다. 먼저 PP와 PE 필름의 특성을 알아보기 위하여 열분석과 인장강도를 조사하였다. 그 결과, PP 필름과 PE 필름의 용융온도는 $163.4^{\circ}C$, $109.7^{\circ}C$였으며, 결정화온도는 $98.9^{\circ}C$, $93.6^{\circ}C$로 나타났다. 각 필름별 인장강도와 신장률은 길이방향보다 폭방향이 더 큰 것으로 나타났다. 필름의 특성을 고려하여, 필름 사용량에 대한 시험은 단판 상에 목표두께별로 필름을 적층하는 방법으로 실시하였다. 그리고 필름의 적층방향에 따른 시험은 단판의 목리방향을 기준으로 필름의 길이방향과 폭방향을 구분하여 각각 적층한 후 합판을 제조하였다. 각각 제조된 합판으로 접착성능을 시험한 결과, 준내수 인장 전단 접착력은 PP 필름의 두께가 0.05 mm 이상, PE 필름은 0.10 mm 이상일 때 KS기준을 만족하였다. 내수 인장 전단 접착력은 PP 필름 두께가 0.20 mm일 때 KS기준을 상회하였다. 필름의 적층방향별 접착성능 시험에서, 단판의 목리방향과 필름의 폭방향으로 적층했던 합판은 필름의 길이방향으로 적층했던 합판보다 더 우수한 결과를 보였다. 현미경으로 관찰된 합판의 표면과 접착층에서 열가소성수지가 단판 내부와 할렬부위로 침투하여 기계적 결합을 이룬 것으로 확인되었다.

• 비파괴검사학회지
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• 제32권4호
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• pp.393-400
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• 2012

최근 나노 박막은 MEMS/NEMS, 광학 코팅, 반도체 산업 등 다양한 분야에서 사용이 되고 있다. 박막은 마모, 침식, 부식, 고온 산화를 방지하기 위한 목적으로 사용될 뿐 아니라 특성화된 자기, 유전적 특성을 만들기 위한 목적으로 사용된다. 많은 연구자들이 이러한 박막 구조의 특성(밀도, 입자 크기, 탄성 특성, 필름/기지 계면의 특성)을 평가하기 위하여 많은 연구를 진행하고 있다. 이들 중에 박막과 기지 사이의 접합 특성을 평가하는 것이 많은 연구자들의 주 관심사가 되어 왔다. 본 연구에서는 나노 박막의 접합 특성을 평가하기 위하여 각기 다른 접합 특성을 가지는 폴리머 박막 시험편을 제작하였다. 제작된 시험편의 접합 특성을 측정하기 위하여 초음파현미경의 V(z) 곡선법을 이용하여 표면파의 속도를 측정하였다. 또한 계면을 포함하는 시험편의 표면을 전파하는 표면파의 속도와 접합력의 상관관계를 확인하기 위해 나노 스크래치 시험을 적용하였다. 그 결과 초음파현미경을 이용하여 측정된 표면파의 속도와 나노스크래치 시험을 이용한 임계하중이 일치하는 경향성을 나타내었다. 결론적으로 초음파현미경의 V(z) 곡선법은 나노 스케일 박막 계면에서의 접합 상태를 평가할 수 있는 기법으로 그 가능성을 나타내었다.