• 폴리머
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• 제38권4호
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• pp.496-501
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• 2014

폴리알파올레핀은 낮은 유동점, 높은 점도지수와 같은 물리화학적 특성이 기존의 광유보다 우수한 합성윤활유이다. 본 논문은 퍼옥사이드계 개시제를 이용하여 올레핀을 사용하지 않고 이소파라핀 분자간의 알킬레이션 반응을 통한 합성 윤활유 제조에 관한 새로운 경로를 제시한다. 평균 탄소수가 i-$C_{16}$, i-$C_{18}$, 그리고 i-$C_{23}$인 세가지 장쇄 이소파라핀의 알킬레이션과 i-$C_{18}$과 2-pentene의 알킬레이션을 di-tert butyl peroxide 라디칼 개시제를 사용하여 여러가지 반응조건에서 수행하여 단독 알킬레이션 반응 경로를 확인하였다. 세가지 유분으로 제조된 알킬레이트를 합성 윤활유로의 적용 가능성을 알아보기 위하여 동점도, 점도지수, 및 유동점을 조사하였다. i-$C_{16}$ 및 i-$C_{18}$ 유분으로 제조된 단독 알킬레이트는 극초고점도지수(>140)와 낮은 유동점(< $-30^{\circ}C$)을 보였다.

• Tribology and Lubricants
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• 제28권6호
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• pp.315-320
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• 2012

For proper functioning, general machines usually need lubricant oil as a cooling, cleaning, and sealing agent at points of mechanical contact. The quality of lubricant oil can deteriorate during operation owing to various causes such as high temperature, combustion products and extraneous impurities. In this study, a heavy load stopped during operation, and the oil was analyzed to check whether any impurities were added. Extraction using acetonitrile followed by reaction with BSTFA(bistrimethylsilyl trifluoroacetamide) showed that, trimethylsilylated ethylene glycol was present in the lubricant oil. To quantify the ethylene glycol in the oil, deuterium-substituted ethylene glycol, which acted as an internal standard, was added to the sample and then extracted with the solvent. Next, the extract was reacted with the derivatizing agent(BSTFA) and then analyzed with GC/MS. The detection limit of this method was found to be $0.5{\mu}g/g$ and the recovery of oil containing $20,000{\mu}g/g$ of ethylene glycol was measured to be 94.8%. A damaged O-ring and eroded cylinder liner were found during the overhaul, which implied the leakage of coolant containing ethylene glycol into the lubricating system. The erosion of the cylinder liner was assumed to be due to cavitation of the coolant in the cooling system.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2004년도 춘계학술대회
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• pp.311-314
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• 2004

바이오디젤 (지방산 메틸에스테르)을 기반으로 하여 생산된 합성윤활유 베이스에 대한 독성을 분석 평가하였다. OECD 207의 방법에 의거하여 인공토양(artifical soil)에서 300$\~$600 mg의 지렁이를 선별하였다. 0.01, 0.1, 1, 10, 100과 1,000 mg/kg의 각 농도별로 선별된 지렁이를 10마리씩 넣고 수분 $31\~37\%$, 온도 $20{\pm}2^{\circ}C$와 PH 6.0 $\pm$ 0.5를 조절하여 14일간 지렁이의 반수치사농도(lethal concentration when $50\%$ of the population were killed, $LC_{50}$)를 측정하였다. 합성윤활유의 측정 된 반수치사농도($LC_{50}$)는 1,555 mg/kg로 측정되었으며, 유의 확률이 < 0.02로서 유의수준 $5\%$에서 유의함을 알 수 있었다.

• 폴리머
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• 제29권5호
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• pp.475-480
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• 2005

폴리(에틸렌 나프탈레이트)(PEN)의 가공 특성 향상을 위하여 윤활제 첨가와 폴리(에틸렌 테레프탈레이트)(PET)와의 블렌딩에 의한 상호에스테르 교환반응 유발에 따른 용융 점도 변화에 대하여 고찰하여 보았다. PEN에 윤활제로 calcium stearate(CaST)를 첨가한 결과, 점도를 낮출 수 있었으나 $2wt\%$ 이상의 CaST첨가는 PEN의 열분해를 촉진하여 기계적 물성이 현저히 감소됨을 확인하였다. PEN에 PET를 $10wt\%$ 첨가하여 상호에스테르 교환반응을 유발시킨 PEN/PET블렌드는 PEN보다 낮은 점도를 가지며 이에 $1wt\%$의 CaST윤활제를 같이 첨가하면 CaST가 윤활제 역할을 하는 동시에 상호에스테르 교환반응 촉진제로 작용하여 추가적인 점도 감소가 일어남을 확인하였다.

• 소성∙가공
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• 제21권1호
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• pp.13-18
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• 2012

During warm forging, materials are formed in the temperature range of $300^{\circ}C\sim900^{\circ}C$. In this temperature range, the friction between the forging die and the material is very high and has a negative effect on the forming process causing severe die wear and possible defects in the component because of stick-slip. Thus, lubrication characteristics are a very important factor for productivity during warm forging. In this paper, ring compression experiments were conducted to estimate the friction factor between the die and the materials as the main factor in characterizing the lubricant. Also, ring tests using normal graphite power as a lubricant coating system were compared with tests using nano graphite powder. The results confirm that the nano graphite is superior to the normal graphite in view of its lubricating effect. In addition, the friction factor (m) was estimated with respect to the amount of the nano graphite content in the lubricant. With 10 % nano graphite the friction factor had the lowest value as compared to other amounts. It can be concluded that the amount of the nano graphite in the coating system can be optimized to obtain the best lubrication condition between the die and the material using ring test experiments.

• 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.

• Tribology and Lubricants
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• 제36권6호
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• pp.365-370
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• 2020

Recently, additive manufacturing (AM) technology has been applied to various industries such as automotive, aviation, medical, and electronics. Most prior studies are limited to the mechanical properties of printed materials, and few studies are being conducted on their tribological characteristics. However, the friction and wear characteristics of the material should be studied in order to utilize the components manufactured using AM technology as mechanical parts. In this study, the friction and wear characteristics of acrylonitrile-butadiene-styrene (ABS)-like resin printed with stereo lithography apparatus (SLA) 3D printing are evaluated according to the viscosity of silicon oil lubricant using a ball-on-disk experiment. Lubricants with a viscosity of 500, 1000, and 2000 cSt are prepared for the experiment. If silicon oil lubricants are used during the ball-on-disk test, the coefficient of friction (COF) and wear rates are significantly reduced, and the higher the viscosity of the lubricant, the lower will be the COF and wear rates. It is also verified that the temperature of the specimen owing to friction also decreases according to the viscosity of the lubricant. This is because of the silicon oil film thickness, and the higher the viscosity of the lubricant, the thicker will be the oil film. More studies on the tribological characteristics of 3D printing materials and suitable lubricants will be required to use 3D printed parts as mechanical elements.

• KSTLE International Journal
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• 제2권2호
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• pp.150-153
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• 2001

The effects of humidity on friction performance of automotive brake materials were studied using a pad-on-disk type friction tester. Three different friction materials based on a simple formulation were investigated by changing the solid lubricant graphite, MoS$_2$, and Sb$_2$S$_3$. Friction materials without solid lubricants were also examined to study the effect of other ingredients in the matrix on humidity. The friction material containing graphite was strongly affected by the humidity showing lower friction coefficient at high humidity level than other conditions. On the other hand, the friction material containing MoS$_2$exhibited higher friction coefficient at initial stage under high humidity level. The friction material without solid lubricant or with Sb$_2$S$_3$ was not affected by humidity conditions. However, the friction material containing barite showed strong speed dependence.

• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.2044-2050
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• 2013

A series of poly(glycerol-succinic acid) dithiocarbamate and 1,3,4-thiadiazole dendrimers, which have potential as anti-wear oil additives, were synthesized. Their anti-wear properties in three different oils (100N, DB-51, and soybean) were evaluated using a four-ball wear tester. The results indicated that thiocarbamate dendrimers have moderate anti-wear properties in DB-51 oil, and 1,3,4-thiadiazole dendrimers exhibited good anti-wear properties in 100N and DB-51 oils. However, dithiocarbamate and 1,3,4-thiadiazole dendrimers were not effective anti-wear additives in soybean oil.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.244-247
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• 2001

Lubricanting characteristics in the warm forging have influence on forgeability of products. but Research on deformation characteristic of warm forging on the lubricant and lubricating method lack. This paper deform a bevel gear by warm forging and evaluate deformation loads and quality of products by each lubricants and lubricating method using oil-based lubricants(Soy, Oildag) and water-based lubricants(Deltaforge $\#31$, Renite S-26-X, Deltaglaze $\#151$). In conclusion, the less a deformation load by lubricants the more improvement a quality of product in manufacture of a bevel gear and water-based lubricants in the warm forging reduce a deformation load and improve a quality of products. Especially, Deltaforge $\31$ have excellent characteristic in the warm forging.