• 한국정밀공학회지
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• 제32권7호
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• pp.603-609
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• 2015

Railway vehicles driven by wheels obtain force required for propulsion and braking by adhesive force between wheels and rails, this adhesive force is determined by multiplying adhesion coefficient of the friction surface by the applied axle load. Because the adhesion coefficient has a peak at certain slip velocity, it is important to determine the maximum values of the friction coefficient on the contact area. But this adhesive phenomenon is not clearly examined or analyzed. Thus we have developed new test procedure using the scaled adhesion test-bench for analyzing of the adhesion coefficient between wheel and rail. This adhesion test equipment is an experimental device that contacts mutually with twin disc which are equivalent to wheels and rails of railway vehicles.

• 한국표면공학회지
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• 제42권4호
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• pp.173-178
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• 2009

DLC film was synthesized on plastic injection mold(SKD11, $30\;mm\;{\times}\;19\;mm\;{\times}\;0.5\;mm$) and Si(100) wafer for 2 h at $130^{\circ}C$ under 6 mTorr using hybrid method of rf sputtering and ion source. The obtained film was analysed by Raman spectroscopy, AFM, TEM, Nano indenter and scratch tester, etc. The film was defined as an amorphous phase. In the Raman spectrum, broad peak of $sp^2$-bonded carbon attributed to graphite at $1550\;cm^{-1}$ were observed, and the ratio of ID($sp^3$ diamond intensity)/IG($sp^2$ graphite intensity) was approximately 0.54. The adhesion of DLC film was more than 80 N with scratch tester when $0.2\;{\mu}m$ thickness Cr was coated as interlayer. The micro-hardness was distributed at 35~37 GPa. The friction coefficient was 0.02~0.07, and surface roughness(Ra) was 0.34~1.64 nm. The lifetime of DLC coated plastic injection mold using as a connector part in computer was more than 2 times of non-coated mold.

• 감성과학
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• 제14권2호
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• pp.191-196
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• 2011

노즐시험기로 측정되는 직물의 당김 힘은 직물이 갖는 포괄적인 촉감을 나타낸다. 노즐시험기는 기존 KES 시스템보다 저가이며, 측정에 있어서 절차가 간단하고 빠르다. 본 연구에서는 노즐시험기로 측정되는 직물의 촉감을 정량적으로 평가하기 위해 마찰법칙을 기초로 하여 반 실험적 촉감 방정식을 개발하였다. 모델 식에서 고려된 변수들은 직물의 마찰계수, 그리고 직물의 굽힘 길이와 전단 신도에 의해 결정되는 직물의 3차원적 변형 특성을 나타내는 드레이프 계수이다. 12 종류의 서로 다른 물성의 면과 폴리에스터 직물들을 사용하여 실험 측정한 촉감 값과 모델 방정식으로부터 예측한 촉감 값들을 비교 분석하였다. 높은 마찰계수, 높은 굽힘 길이, 그리고 낮은 전단 신도를 갖는 직물일수록 높은 촉감 마찰력, 즉 낮은 촉감 성능을 보여주었다. 실험 측정한 촉감 값과 모델 식으로부터 계산한 값들 사이 잘 일치하였으며, 이와 같은 결과는 모델 식을 사용하여 직물의 고유 물성들로써 촉감의 객관적인 예측이 가능함과 더불어 촉감 성능의 향상을 위한 직물설계에 있어서도 유용한 정보를 제공할 수 있음을 보여준다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.173-174
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• 2002

To study the effects of mating materials on the tribological properties of DLC films. we used a ball-on-plate reciprocating friction tester in dry air and mating materials of martensite stainless steel (hardened, annealed SUS440C), austenite stainless steels (SUS304), and bearing steel (hardened, annealed SUJ2). At a light load of 0.6 N, the friction coefficient always exceeded ${\mu}>0.3$. Tribological properties of DLC film were still excellent above 0.6 N, except in sliding against annealed SUJ2. Analysis using micro-laser Raman spectroscopy showed that the difference between annealed SUJ2 and others materials appears mainly due to structural change in film.

• 한국전기전자재료학회논문지
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• 제19권7호
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• pp.631-635
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• 2006

The properties of metal interlayered DLC films between the Si substrate and the DLC films were studied. DC magnetron sputtering method has been used to deposit intermediate layers of metals. And RF-PECVD method has been employed to synthesize DLC onto substrates of the silicon and metal layers. After we used metal Inter-layers, such as chromium, nickel, titanium and we studied tribological properties of the DLC films. The thickness of films were observed by field emission scanning electron microscope (FE-SEM). Also the surface morphology of the films were observed by an atomic force microscope (AFM). The crystallographic properties of the films were analyzed with X-ray diffraction (XRD), the friction coefficients were investigated by AFM in friction force microscope (FFM) mode. Tribological performances of the films were estimated by nano-indenter, stress tester measurement.

• The Korean Journal of Ceramics
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• 제3권2호
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• pp.96-100
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• 1997

Hydrogenated amorphous carbon films were deposited on silicon substrates by using an RF PECVD. The hydrogen/methane ratio was varied from 50% to 88% to study the effect of hytdrogen in the film on the tribological properties. The friction and wear behaviors of the deposited films were investigated by ball-on-disk type wear tester. FT-IR spectra were used to characterize the structure of the films. Tribological properties of carbon films were correlated with their structure such as ratio of "polymer-like" stretching type and that of sp2 bonding. The result showed that the annealing caused a decrease in the amount of wear of contacted $Si_3N_4$ balls and a increase in the coefficient of friction. Possible explanation for annealing effect was discussed by the hydrogen desorption.esorption.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.241-244
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• 2004

In this paper wear ratio, hardness and microstructure were experimented for study of friction wear characteristic of automotive disk brake considering running distance. In this work.4 specimens were employed for test of the friction&wear tester as a function running distance. Despite the fact that brakes must operate under a variety of environmental conditions. most research has worked in laboratory with ideal condition.

• 한국기계가공학회지
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• 제6권4호
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• pp.15-21
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• 2007

The effect of manufacturing parameters on friction characteristics of motorcycle break system was studied using a disk-on-pad type friction tester. Such parameters conditions have an effect on the frictional factor such as number of ventilated disk hole, applied load, sliding speed, and sliding distance. However, it is difficult to know the mutual relation of these factors. In this study, the friction characteristics using design of experiment containing 4 elements were investigated for an optimal condition for the best motorcycle break system employing regression analysis method. From this study, the result was shown that the applied load in frictional factors was the most important, next to sliding speed, number of ventilated disk hole.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.124-130
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• 1998

The wear characteristics and wear mechanisms of dental composite resins were investigated. Composite resins such as Metalii, Silux Plus, Heliomolar and Palfique Estelite were selected as specimens and contents of filler in specimens in order to analyze the effect of Prepolymerized Particle Fillers in friction and wear characteristics. Ball on flat wear tester was used for a wear test. Friction and wear tests are carried out at room temperature. The friction coefficient of Metafil was quite high relatively, and the wear resistance of Silux Plus and Palfique Estelite was better than that of Metafil and Hellomolar at the same experimental condition. The main wear mechanism is plastic flow and abrasive wear by crack propagation.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.17-24
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• 1998

Plasma-sprayed coatings were obtained by spray-dried $Cr_2O_3$ powder with and without Mo addition. A reciprocal type tribo-tester was employed to examine friction and wear behavior of the specimens at room temperature. The composition and the worn surface of coated specimens were observed by XRD and SEM. The results showed that friction Coefficient of the Mo added specimens were lower than one of $Cr_2O_3$ specimen. But $Cr_2O_3$ specimen had a lower wear loss. Protecting layer were observed at the worn surface of coated specimens with Mo addition.