• Journal of Advanced Marine Engineering and Technology
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• 제32권4호
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• pp.514-521
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• 2008

Many research works for improving a boundary lubrication performance have been executed by using solid lubricants, and been tried to apply an engine lubrication. However those general lubricants have not been applied on engines due to the extreme conditions such as very high temperature and pressure during combustion process in a cylinder. In this study a lubricant containing copper alloy nano-powder is applied on a diesel engine driven by an electric motor. Torques and shaft vibrations are measured, then an engine friction loss and rotating stability are assessed. The results show that the frequency of the vibration is about the same as that of a general lubricant, but the amplitudes in the both X and Y direction are reduced as well as the friction loss is reduced.

• 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 2002년도 proceedings of the second asia international conference on tribology
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• pp.7-8
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• 2002

It is a time to introduce a concept of lubrication to space systems. Minimum amount of lubricant should be supplied to a contact interface instead of preparing too much lubricant on surfaces of the earth. In situ controllable lubrication method is wanted to overcome unexpected tribo-troubles in space. Tribo-coating, which forms a thin solid film in nm-scale by vacuum deposition during friction, is a promising lubrication method for space.

• 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.

• 한국표면공학회지
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• 제56권1호
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• pp.1-11
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• 2023

Lubricant-impregnated nanoporous surfaces (LIS), which is created by impregnating water-immiscible oil into nanoporous surface structure, have been explored considering wide range of application fields. Due to the lubricant impregnated in nanoporous structure, the surface shows extreme de-wetting with a high mobility of water droplets, so that various functionalities can be realized. The lubricant layer inhibits the contact of corrosive media to porous structure as well as metal substrate, thus the surface improves the corrosion resistance. The water on the surface freeze without any contact to solid porous structure, showing a low ice adhesion for de-icing an anti-icing. The extremely high mobility of water droplets on lubricant-impregnated porous surfaces also contributes the enhancement of condensation heat transfer as well as water harvesting from fog and moisture. Moreover, the bacteria adhesion on metal surface forming biofilms causing serious hygiene issues can be inhibited on the lubricantimpregnated surfaces. Despite of such superior functionalities, the lubricant-impregnated porous surface has a limitation of lubricant depletion by external flow of fluids. Therefore, extensive efforts to improve the durability of lubricant-impregnated surface are required for practical applications.

• 한국세라믹학회지
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• 제32권6호
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• pp.643-652
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• 1995

Si-SiC-graphite composites were developed by incorporating solid lubricant graphite into Si-SiC, in the light of improving tribological properties of Si-SiC ceramics. Si-SiC-graphite composites were fabricated by infilterating silicon melt into the mixture of α-SiC, carbon black and graphite powder at 1750℃ under 3 Torr. The particle size of graphite was in the range of 150 to 500㎛, and the loading content of graphite was 0, 20, 25, 30, 35 vol% in the mixture of α-SiC and carbon black. The mechanical and tribological properties of this composites were studied. The density, hardness, flexural strength, compressive strength and Young's modulus were decreased with increasing of graphite content. An additiion of solid-lubricant graphite up to 30 vol% has improved tribological properties of Si-SiC ceramics without considerable degradation of mechanical properties.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2000년도 추계학술대회 논문집(Proceeding of the KOSME 2000 Autumn Annual Meeting)
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• pp.61-67
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• 2000

Many research works for improving a boundary lubrication performance have been executed by using solid lubricants, and been tried to apply an engine lubrication. However those general lubricants like MoS$_2$ or PTFE have not been applied on engines due to the extreme conditions such as very high temperature and pressure by combustion process in a cylinder. A copper nickel alloy fine particle has been introduced and studied. In this Paper the lubricant using the alloy Particles is applied on a marine diesel engine and assessed by the engine performance test The results showed the increase of cylinder pressure related strongly to the engine efficiency as well as the improving the engine lubrication performance.

• Tribology and Lubricants
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• 제35권2호
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• pp.87-93
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• 2019

This work aims to develop a dry lubricant for oilless bush, especially a solid lubricant, thereby creating a coating method with improved properties of anti-friction and load-carrying capacity without oil lubrication. In this work, spherical-shaped powders of thermosetting resin such as polyimide (PI) are mixed with a binder matrix obtained by mixing a fluorocarbon compound resin such as Polytetrafluoroethylene (PTFE) or Ethylene tetra fluoro ethylene (ETFE) with itself or with a non-fluorocarbon thermoplastic resin such as Polyether ether ketone (PEEK). And these dry lubricant mixtures are thickly coated (200-300 mm in the thickness) on the inner surface of the bush by using a wet-typed air-spray deposition method. It was found that the load-carrying capacity of the solid lubricant for excavator bush (60 mm in diameter) that operates under a high load condition (at 40 MPa) is greatly improved owing to the spherical-shaped powders of thermosetting resin. In addition, the coefficient of friction at the sliding surface is also reduced less than 0.1. Thick coating also lowers the contact stress at the edge of a bush that results in better tribological performances. The result suggests that the lubrication performance and durability life of the bush can be remarkably improved even without lubrication (oil or grease).

• 소성∙가공
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• 제15권6호
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• pp.453-458
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• 2006

While the die casting has been mainly used to manufacture the magnesium alloy parts, the press forming is considered as an alternative to the die casting for saving the manufacturing cost and improving the structural strength of the magnesium alloy parts. Because the magnesium alloy has low formability at room temperature, forming at elevated temperatures is a necessary condition to obtain the required material flow for press forming. However, the elevated temperature forming does not always guarantee the sufficient formability under the dry friction condition because the surface damage such as scratch or wear may accelerate the material failure. In the present study, the solid-type lubricants such as PTFE, graphite and $MoS_2$ were tested for the square cup warm deep drawing using the magnesium alloy AZ31 sheet. The formability improvement by using the lubricant was examined by comparing the maximum deep drawing depth using the PTFE against no lubricant. The formability difference for the different lubricant was also examined based on the maximum deep drawing depth.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제27회 춘계학술대회
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• pp.173-179
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• 1998

The processing conditions for the synthesis of platelet WS$_2$ lubricant powder through the solid-gas reaction were optimized. The tungsten and sulfur powders were sealed in a vacuum of 10$^{-6}$ torr, prior to heat-treating at 850$\circ$C for 8 days. The react~on product showed the well-developed platelet WS$_2$ powder with an average size of 3.8 $\mu$m. The synthesized WS$_2$ powder was coated on the commercial deep grooved ball bearing (No. 6203) to examine the effects of WS$_2$ coating layer on the noise and endurance of the ball bearing. The level of noise obtained from WS$_2$ coated-ball bearing was higher (56 dB) than the value occurred in the case of greece (37 dB). The life-time of the ball-bearing assembled after coating WS$_2$ powder increased 50 times compared to the non-coated bali-bearing.