• Tribology and Lubricants
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• 제38권5호
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• pp.222-226
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• 2022

Between diaphragms made of stainless steel (SUS), which is the main component of a hydrogen gas compressor, micro-slip occurs owing to repeated bending, resulting in scratches on the surface. The surface scratch of the compressor part is a problem with airtightness, which reduces the efficiency of the compressor; in severe cases, damage is a possibility. In this study, the changes in friction and wear characteristics due to the surface polishing of SUS and carbon-based solid lubricant films (graphene and CNT) were analyzed. Bare SUS, polished SUS, graphene film, and CNT film specimens were prepared. The surface roughness of the SUS was significantly reduced by surface polishing but increased by carbon-based solid lubricating films. In contrast, the friction coefficient maintained a similar value after surface polishing but was significantly reduced by the carbon-based solid lubricant films. In particular, the graphene film exhibited the lowest initial friction coefficient, while the CNT film exhibited the lowest overall average friction coefficient. Regarding the wear rate, polished SUS exhibited the lowest value, but the surface condition of the wear track showed that the carbon-based solid lubricating films were relatively less damaged. Although the wear rate measured was largely attributed to the solid lubricating film peeling off, the SUS surface under the film was considered protected.

• 한국추진공학회지
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• 제17권5호
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• pp.95-100
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• 2013

동적 기밀구조에 사용되는 고체윤활재의 선택에 있어 중요 설계 변수들은 기밀성, 내마멸성, 윤활막의 형성 등이 있다. 본 연구에서 그라파이트의 고체유할 특성에 영향을 미치는 영향인자들이 분석되었고 다양한 시험 조건들에 대하여 발생하는 마모거동이 왕복동 마모시험으로부터 얻은 결과들과 비교되었다. 또한 윤활 막들의 생성에 대한 최적조건들이 그라파이트 소재의 특성들을 평가하기 위하여 조사되었다. 마멸입자의 생성, 윤활 막의 생성, 윤활 막의 소멸의 과정을 반복하는 과정이 마모 깊이의 변화와 통하여 마모 메커니즘을 평가하였다. 따라서 그라파이트 씰의 윤활막은 마모된 표면위에 마모 입자들의 응착에 의해 발생한 윤활막이 발생되었고 이는 마모특성에 매우 유용하였다.

• Tribology and Lubricants
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• 제22권1호
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• pp.33-39
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• 2006

During the high speed train operation in the conventional line, it was found to have extremely severe flange wear, due to the curvy routes. This paper looks at the actions that have been taken to bring the wear to an acceptable level. In particular, it have been presented for flange wear variation depending on curve radius, cant, transition curve length by using numerical method. And the impacts on the flange wear by the application of stick type solid lubricant are also presented.

• Tribology and Lubricants
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• 제14권2호
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• pp.35-41
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• 1998

The $WS_2$ solid lubricant synthesized through the vapour phase transport method was coated on the commercial bearing steel (SUJ 2) substrate, and the tribological behaviour of the lubricant was investigated using a ball-on-disk type tester. The $WS_2$ powder was spray-coated at room temperature using compressed air, and the change of friction coefficient was examined in various conditions, i.e., specimen configuration, atmosphere (air and nitrogen), applied load and rotating speed. $WS_2$ coated ball and disk showed the optimum friction coefficient of 0.07 and wear life of 45,000 cycles in the nitrogen atmosphere under 0.3 kgf and 100 rpm, whereas relatively high coefficient of 0.13 and reduced wear life of 4,000 cycles were observed in air atmosphere. The effect of rotating speed on the friction coefficient was not observed both in nitrogen and in air atmospheres. This confirmed that the spray-coated $WS_2$ solid lubricant was effective in reducing the friction coefficient and improving wear life in nitrogen atmosphere, and the oxygen and moisture existing in air could seriously deteriorate the lubrication effect of $WS_2$ coating layer.

• Tribology and Lubricants
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• 제34권6호
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• pp.254-261
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• 2018

In order to reduce resistance torque and energy loss, minimizing friction between race surface and rolling elements of a bearing is necessary. Recently, to reduce friction in bearing element, solid lubricant coating for the bearing raceway surface has been receiving much attention. Considering the operating conditions of real bearings, verifying the effect of solid lubricant coatings under extreme conditions of high load that is more than 1 GPa is necessary. In this study, we evaluated the friction and wear characteristics of SUJ2 bearing steels deposited by carbon-based coatings (Si-DLC, ta-C), $MoS_2$ and graphite. In case of $MoS_2$ and graphite coatings, different surface treatments were applied to the coatings to verify the effect of surface treatment. A pin-on-disc type tribotester was used to evaluate the tribological characteristics of the coatings. It was possible to quantitatively estimate the friction and wear characteristics of solid lubricant under dry and lubrication conditions. The carbon-based coatings improved the friction and wear properties of SUJ2 bearing steels under the high load condition, but $MoS_2$ and graphite coatings were not suitable for high load conditions due to its low hardness. Different friction and wear behaviors were found for different substrate surface treatment method. Also, it was confirmed that solid lubricant coatings had a more positive effect than just applying the lubricant for improving the tribological characteristics.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1997년도 제26회 추계학술대회
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• pp.110-116
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• 1997

The tribological behaviour of WS$_2$ solid lubricant was investigated using a ball-on-disk type tester. The WS$_2$ powder was spray-coated at room temperature and the effects of specimen configuration, atmosphere, applied load and rotating spccd on the friction coefficient was examined. WS$_2$ coated ball and disk showed the lowest friction coefficient of 0.05 in the nitrogen atmosphere under 0.3 kgf and 100 rpm, whereas relatively high coefficient of 0.1 - 0.15 was observed in air atmosphere. This confirmed that the spray-coated WS$_2$ solid lubricant was effective in reducing the friction coefficient and improving wear life in nitrogen atmosphere.

• Journal of Welding and Joining
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• 제21권2호
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• pp.27-34
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• 2003

• 한국추진공학회지
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• 제17권3호
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• pp.15-20
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• 2013

Graphite는 고온/고압의 가스가 추진기관 내의 구동장치에 유입되지 않게 기밀 소재로 사용되며, 마모 과정에서 윤활막을 형성하여 구조물 안에서 윤활과 기밀을 돕는다. 본 연구는 기밀 소재로 사용되는 Graphite의 고온 마모 시험을 통해 고온 마모 특성을 평가하였다. 고밀도 Graphite (HK-6)에 대하여 실제 작동환경에 기초 한 온도, 미끄럼 속도, 접촉 하중 조건에 따른 마모 특성을 평가 및 고찰하였다. 마모 표면 관찰을 통해 마모 메카니즘을 파악하고 고온 마모 특성을 통하여 최적화된 작동 환경 조건에 대하여 제안 하였다. 결과적으로, 상온에서 보다 고온 환경에서 윤활막 형성에 유리 하여 마찰 계수가 비교적 낮게 나타나는 것을 알 수 있다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.415-420
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• 2005

Korea High Speed Railway of which wheels have been excessively worn during the trial operation prior to opening was additionally applied with solid lubricant besides the existing oil lubricant in order to overcome such excessive wear. Therefore, it was shown that wear status has been improved in the test by which railway system including vehicles and tracks was stabilized during a year's commercial operation, comparing to that with excessive wear in the trial operation prior to opening to the public. In this connection, wheel's wear per mileage was analyzed, based on vehicles in service in order to make out the wheel's wear at present, from which the useful data relating to wheel maintenance could be obtained.

• Tribology and Lubricants
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• 제35권3호
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• pp.183-189
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• 2019

The driver seat of an automobile is in direct contact with the driver and provides the driver with a safe and comfortable ride. The seat consists of a frame, a rail, and many recliners. In recent years, strength and operating force measurement testing of the recliner have become vital for designing car seats. However, performance evaluation requires expensive testing equipment, numerous seat products, and considerable time. Therefore, the trend is to reduce experimentation through interpretation. This study examines the lubrication of solid lubricant for automotive seat recliners and confirms the friction and wear performance. In this study, the lubrication behavior of solid lubricants for car seat recliners is investigated to ascertain the friction and wear performance and to provide accurate values for the strength analysis. The friction material consists of a pin and a plate made from steel, which is widely used in recliners. The friction and wear under lubrication conditions are measured by a reciprocating friction wear tester. The friction coefficient is obtained according to the load and speed. Based on the obtained results, it is possible to achieve a reduction in the error of the test value and the analysis by providing the friction coefficient and wear of the lubricant. The results can be applied to the analysis of automobile seat design.