• 청정기술
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• 제12권3호
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• pp.113-127
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• 2006

폐윤활유는 세멘트 킬른과 화력발전소의 직접 연료로 사용하여 에너지원으로 재활용하거나 정제 과정을 거쳐 연료유 또는 재생 윤활기유로 재활용 되고 있다. 우리나라는 주로 이온처리 공정을 활용하여 폐윤활유를 저급 연료유로 재활용하고 있고 2003년도 예치금제에서 생산자 책임재활용제도를 도입하여 폐윤활유의 재활용을 촉진하고 있다. 그러나 지난 5년간 재활용율은 70% 이내로 정체되고 있고 아직까지 선진국에서 추구하고 있는 재생 윤활기유로의 재활용기술 개발연구도 전혀 없는 실정이다. 이에 비하여 일부 선진 국가에서는 근래에 폐윤활유의 열분해 생성유 중의 타르 및 악취의 발생을 대폭 감소시키고 색도를 향상시켜 고급연료유를 생산하는 안정화 기술과 폐윤활유로부터 고급 재생 윤활기유를 생산하는 새로운 공정을 개발하여 상용화하였다. 또한 호주, 이태리, 독일, 미국 등 몇몇 국가에서는 폐윤활유를 재생윤활기유로 재활용하였을 경우 훨씬 많은 보조금을 지급하거나 국가나 지방 정부에서 재생 윤활유를 우선적으로 구매하도록 하고 소비자로 하여금 재생 윤활유를 사용하도록 권장하는 정책을 채택하고 있다. 이렇게 선진국에서는 점차적으로 고갈되는 석유자원의 절약과 환경오염을 저감시키는 폐윤활유를 윤활기유로 재활용하는 정책을 채택하고 있어 우리나라에서도 지속가능한 개발을 위한 새로운 윤활유 재활용정책을 수립하여야할 시점에 있다고 판단된다.

• Journal of Mechanical Science and Technology
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• 제17권9호
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• pp.1276-1286
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• 2003

The performance of porous bearing under different lubricants and lubricating conditions was experimentally investigated in this study. In order to carry out the experiments, a new test rig was designed to determine the tribological properties of based sintered bronze journal bearings that were manufactured by powder metallurgy (P/M) techniques. To determine the effects of lubricating conditions with and without oil supplement (OS) on the tribological characteristics of these bearings under static loading and periodic loadings, some experiments were carried out using different lubricants. In the tests, pure base oil (SAE 20W50), two fully formulated commercial engine oils (SAE20W50) and lubricating oils with commercial additive concentration ratio of 3％ were used. The worn surfaces of test bearings were examined using optical microscopy. Experimental results showed that the change in friction coefficient was more stable and in smaller magnitude under static loading than that of periodic loading. In addition, the friction coefficient and the wear rate conducted with base oil resulted in higher values than those of fully formulated oils with and without OS lubricating conditions. The experimental results obtained in this study indicated that the correct selection of lubricant and suitable running conditions were very important on the tribological characteristics of porous bearings.

• Tribology and Lubricants
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• 제17권2호
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• pp.146-152
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• 2001

Environmentally adapted synthetic base oils of polyalkylene glycols (PAGs) and polyol esters (POEs) show a high polarity because of their functional groups containing oxygen atom. The lubricating performance of these polar base oils was investigated by using a four-ball tribometer under boundary lubrication condition. Four polyalkylene glycols and five polyol ester base oils were used as sample base oils of high polarity. A mineral oil (MO) and alkylnaphthalene (AN) were used as low polarity base oils. Tricrecylphosphate (TCP) was added to all the base oils, in the range of 10 mmol/L-2000 mmol/L, as an antiwear additive. All the TCP-for-mutated base oils showed optimum concentration characteristics for minimizing wear. The order of optimum concentration of all the base oils was in a good accordance with the order of relative stability of TCP in base oils. The interaction model on solvation between additive and different polar base oils can expect the stability order of TCP. Thus, the model on solvation can explain well the order of optimum concentration of all the base oils, by using the effect of polarity (dielectric constant, $\varepsilon$) and molecular size (molecular weight, MW) of them on stability of TCP in polar base oils. Finally, a good correlation of the optimum concentration for all the base oils was obtained when it was arranged as a function of C∝(M $W_{Base Oil}$/M $W_{TCP}$)$^{-2}$.71/.($\varepsilon$$_{Base Oil}$)$^{3.38}$ by these two parameters.s..

• Tribology and Lubricants
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• 제34권4호
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• pp.160-167
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• 2018

Vegetable oils can contribute to the goal of energy independence and security owing to their naturally renewable resources. One of the representative vegetable oils is biodiesel, which is being used in domestic and European markets as a blended fuel with automotive diesel. Vegetable oils are promising candidates as base fluids to replace petroleum lubricants because of their excellent lubricity and biodegradability. We prepared biodiesel with a purity of 99.9% via the esterification of waste cooking oil. Blended biodiesel and Petro-lube base oil were mixed to produce five types of mixed lubricating oil. We analyzed the various characteristics of the blended biodiesel with Petro-lube base oil for different blending ratios. The lubricity of the vegetable lubricant improves as the content of biodiesel increases. In addition, since zinc dialkyldithiophosphates (ZnDTPs) are widely used as multifunctional additives in petroleum-based lubricants, we optimized the blending ratio for lubricity, oxidation stability, and shear stability by adding ZnDTP as a performance additive to improve the biodiesel properties, such as oxidation stability and hydrolysis. The optimized lubricants improve by approximately 25% in lubricity and by 20 times in oxidation stability and shear stability after the addition of ZnDTP.

• Tribology and Lubricants
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• 제17권3호
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• pp.171-178
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• 2001

In order to elucidate the lubricating mechanism of polyolester base oils [POEs], the wear characteristics of 27 kinds of polyolester base oils including mixed POEs were investigated. Their wear results were discussed in terms of the effect of molecular structure on wear performance and compared with those of mineral oil. In addition, the adsorption ability of POEs to reduced iron and their hydrolysis rates were measured and the effect of their molecular structures on the adsorptivity and hydrolysis rate of POEs was discussed, respectively. Finally, the lubricating mechanism anlyzed from these results of wear characteristics, adsorptivity and hydrolysis rate was proposed. That is to say, POEs are firstly adsorbed to friction surface and decomposed by hydrolysis or thermal degradation. Fatty acids obtained by degradation of POEs form adsorption film on friction surface. The larger become cohesive ability among fatty acid molecules in the adsorption film, the better gets the wear performance of POEs.

• 한국응용과학기술학회지
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• 제30권4호
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• pp.715-725
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• 2013

바이오디젤은 세계 화석연료의 흐름을 변화시킬 수 있는 환경 친화적 대체물질로 관심의 대상이 되고 있으며 대체연료 외에도 다양한 분야에서 수많은 응용 연구가 진행되고 있다. 최근에는 원유의 정제로부터 얻어진 석유제품을 대체하려는 다양한 움직임이 활발하게 진행되고 있다. 그 중 윤활기유로서의 식물성 오일은 급속도로 발전된 석유산업으로 인해 상용화 되지 못했던 오일로 관심의 대상이 되고 있으며 자연친화적 생분해성과 무독성, 윤활유로서의 낮은 휘발성과 우수한 계면윤활 등 대체 오일로써 충분한 가능성을 지니고 있다. 하지만 우수한 윤활 및 마모성능에도 불구하고 윤활연구에 넓게 활용되지 못했던 이유 중에는 지방산메틸에스테르가 갖는 열악한 산화안정성(oxidation stability) 및 열화안정도(thermal stability) 때문으로 보고되고 있다. 따라서 바이오디젤을 윤활기유 내 일정비율로 혼합하여 윤활성능 및 산화안정성의 변화를 확인하였으며 사구식 내마모 성능시험 후 발생되는 산화 및 열화현상을 알아보았다. 또한 산화에 따른 혼합 오일의 윤활특성 변화를 분석하였으며 이러한 결과를 바탕으로 윤활유 또는 윤활 향상제로서의 가능성을 살펴보았다.

• Tribology and Lubricants
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• 제32권3호
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• pp.82-87
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• 2016

We performed an experimental research on lubricant oil in dual fuel medium-speed engines. It is important to select the appropriate lubricant oil because it could significantly affect engine lifetime and performance. We generally recommend the selection of the lubricant oil according to the fuel grades as contents in the project guide. However, it is a considerable challenge for shipyards to implement this concept because of the lack of space to install the complicated lubricating oil system for dual fuel engines. Therefore, we determine the adaptability of one-common lubricant oil for HiMSEN dual fuel engine through this experimental research. To check abnormality in gas mode operation and durability of engine components when a lubricating oil with high BN (base number) is used, overhaul inspections and lubricant oil analysis are carried out two times, and four times, respectively, during an operation of approximately 300 h. We investigated the variations in kinematic viscosity, base number, element quantity, pentane insoluble and sulfated ash in lubricant oil analysis. Moreover, we also investigated whether the deposit formation or wear occurred in various bearings, injectors, exhaust valves, intake valves, piston rings and so on through the overhaul inspections. There are no problems in the lubricant analysis and the overhaul inspections. Through the experimental research, we confirm that one-common lubricant oil should be selected according to the higher sulfur content of fuel oil in dual fuel engines.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제29회 춘계학술대회
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• pp.189-194
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• 1999

The antiwear performance of several organic phosphates ,such as tricrecylphosphate(TCP), tributylphosphate(TBP), diphenylhydrogenphosphate(DPHP) ,dissolved in polyol ester based oils is studied. These organic phosphates are well known for antiwear additive for lubricating oil that produce reacted surface protective film. These antiwear additives can drastically reduce wear with their concentration increasing, because the amount of additive adsorbed on metal sur(ace increases. But in the higher concentration region, the wear is increased by excessive and corrosive reaction of the metal surface with these additives. That is to say, there is an optimum concentration for minimum wear. The optimum concentration was different with the kinds of base oils and additives. Different polyolesters showed different optimum concentrations of the additive. The order of optimum concentration among the polyolesters was different with different phosphates. The order of the optimum concentration is shown that the effect of the concentration of additives on the antiwear performance. It can be explained by the interaction between additives and base oils using the solubility parameter.

• Tribology and Lubricants
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• 제14권4호
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• pp.79-87
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• 1998

Morphological analysis of wear particles in the lubricating oil is a very effective and versatile means of lubricant analysis for machine condition monitoring and fault diagnosis. The prospects for determining quantitative information about wear particle morphology have been considerably enhanced by recent developments reported in the application of image processing and analysis techniques. This study was undertaken to investigate the influence of oiliness agent and extreme pressure agent on the shape of wear particles. The wear test was performed under different experimental conditions with stearic acid, dibenzyl disulfide(DBDS) and tricresol phosphate(TCP) in paraffinic base oil. Wear particles characteristics were described using four shape parameters, namely 50% volumetric diameter, aspect, roundness and reflectivity. The results showed that the four shape parameters of wear particles depend on a kind of the additives. This analysis of wear debris with computer image processing techniques is sufficient to distinguish some types of wear debris. The wear volume of three kinds of the specimens are affected by the additives with boundary films.

• 한국생산제조학회지
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• 제9권6호
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• pp.127-132
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• 2000

Morphological analysis of wear particles is one of useful methods for machine condition monitoring because it is well reflected in machine driving state. This paper was undertaken to apply to the condition monitoring of hydraulic piston motor. The lubricating wear test was performed under different experimental conditions using the wear test device and wear specimens of the pin on disk type was rubbed in paraffinic base oil by three kinds of lubricating materials, varying applied load, sliding distance. The four shape parameters(50% volumetric diameter, aspect, roundness and reflectivity) are used for morphological analysis of wear particles. The results showed that the four shape parameters of wear particles depend on a kind of the lubricating materials. It was capable of calculating presumed wear volume for three kinds of materials on driving time to foresee as damage condition of lubricating materials.