• Tribology and Lubricants
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• 제3권2호
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• pp.44-49
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• 1987

Molecular alignment has been postulated as influencing non-Newtonian behavior of liquid lubricants containing various additives. Four blended lubricants, two synthetic and two mineral were analyzed by FTIR spectroscopy. All of the lubricants exhibited polarization changes in their infrared emission spectra at 60$\circ$C under shear. For this work a special mockup journal bearing was constructed to seperate load and shear effects. At a temperature of 100$\circ$C polarization by shear was always reduced, presumably by Browninn motion. This work should be useful in pointing to the shear-sensitive factors. The presence of of a VI improving additive is manifested by the independence of the infrared emissivity with temperature at several wavelengths; a lubricant without a VI improver generally shows a decrease of emissivity at higher temperature.

• KSTLE International Journal
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• 제3권1호
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• pp.26-29
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• 2002

The International Lubricant Standardization and Approval Committee (ILSAC) GF-3 passenger car engine oil specification has been introduced commercially in July 2001. The new specification oil provides superior performance in terms of fuel economy, control of high temperature deposits, and oil consumption. These enhanced performances of GF-3 engine oil need high quality base oil as well as a better additive system. In this paper, the effect of base oil on various performances of ILSAC GF-3 engine oil was investigated. From the GF-3 sequence engine tests, Group III base oil shows better performance in fuel economy retention, oxidation and varnish control than combination of group III and group II or group III and group 1.

• 한국분말재료학회지
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• 제18권5호
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• pp.417-422
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• 2011

Hydrophobic nanodiamond (ND) were dispersed in engine oil (Helix Oil, Shell co.) as an additives to improve tribology properties. In this study, nanodiamond prepared by an explosive method was used. Tribology properties of both pure Helix oil and engine oil containing ND additive were evaluated. The rotating disks were made of Gray Cast Iron (240 Hv) and SKD11 (710 Hv). Surface topographies of the disks' wear tracks and friction coefficient were compared. The results show that nanodiamond-dispersed lubricants are capable of reducing these metals' wear loss. The friction coefficient is strongly affected to the hardness of wear track.

• 공업화학
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• 제28권4호
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• pp.460-466
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• 2017

극지방은 혹한의 날씨로 인해 일반 석유제품을 사용할 경우, 석유제품 내 왁스 성분 등이 고체상으로 석출되어 원활한 연료공급 등에 문제발생을 일으킬 수 있다. 따라서 극지방에서 사용하는 석유제품은 혹한의 온도에 적합하게 생산, 판매되고 있지만 해외로부터 공급받고 있어, 수급의 어려움이 존재한다. 본 연구에서는 기존 남극유를 대체할 수 있는 석유제품을 검토하기 위해 기존 연료에 대한 연료적 특성을 분석한 뒤, 저온특성이 우수한 항공유에 윤활성 향상제를 일정농도 첨가하여, 남극유 대체연료로서 연료적 특성을 분석하였다. 분석결과, 윤활성 향상제인 R621A제품의 윤활성이 가장 우수하였으며, 윤활성 향상제 첨가량이 증가할수록 윤활성이 증가하였지만, 1000 mg/L만 첨가하여도 충분한 윤활성 향상효과를 보였다. 따라서 항공유에 윤활성 향상제를 첨가한 대체연료는 극지방의 혹한 기온에서 사용하여도 큰 문제가 없을 것으로 판단된다.

• Tribology and Lubricants
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• 제35권6호
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• pp.343-349
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• 2019

According to a report in 2011, hexagonal boron nitride demonstrated good solubility in pure water, even without surfactants or organic functionalization. Hexagonal boron nitride nanosheets are an effective lubricant additive, and their solubility in pure water has motivated lubrication engineers to utilize aqueous solutions containing these nanosheets as water-based lubricants. In this study, we measure the width and height of the hexagonal boron nitride nanosheets dispersed in pure water by using the Zetasizer and atomic force microscopy. Without surfactants or functionalization, aqueous solutions containing 0.10, 0.07, 0.05, and 0.01 wt% of hexagonal boron nitride nanosheets are synthesized via sonication-assisted hydrolysis. The Zetasizer provides only a one-dimensional size of approximately 410 nm, regardless of the concentration of the solution. Thus, it does not allow the estimation of the shape of the nanosheet. To acquire the three-dimensional size of the nanosheets, atomic force microscopy is employed. The aqueous solutions containing 0.10, 0.07, 0.05, and 0.01 wt% of the hexagonal boron nitride nanosheets show average values of 740, 450, 700, and 610 nm in width, and 37, 26, 33, and 32 nm in thickness, respectively. No significant trend is observed between the concentration of the solution and size of the nanosheets. Therefore, when preparing a water-based lubricant, it may be appropriate to adjust conditions such as ultrasonication time rather than the concentration.

• 대한화학회지
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• 제19권1호
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• pp.43-49
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• 1975

소량의 요오드 화합물이 윤활류에 함유될 때 금속표면사이의 마찰을 감소시키고 내마모성을 향상시키는데 이는 금속표면에 박층상구조의 이요오드화물이 형성되기 때문이라고 한다. 그러나 금속표면에서의 화학반응성, 마모와 극압실험 및 hot wire method에 의한 결과에 의하면 윤활기구는 이 요오드화물의 박층상 구조가 아니고 다른 기구에 의한 것임을 알았다. 유기 요오드화합물중에서 특히 N-iodopyridinium dichlorodate는 double charge transfer complex로써 다른 methyl iodide계의 화합물 보다 금속표면 사이의 마찰을 더욱 감소시키고 윤활기구는 interhalogen의 화학반응에 의한 것임을 알았다.

• Nuclear Engineering and Technology
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• 제34권4호
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• pp.323-330
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• 2002

Various types of compounds were tested with the aspects of decomposition and formation of residue in a $CO_2$ or 7H$_2$+93$N_2$ atmosphere. The evaporation temperature range of each compound was determined from thermogravimetric curve. Decomposition of dicarbon amide, stearic acid, acrowax and zinc stearate was studied by thermogravimetry in $CO_2$ or in 7H$_2$+93$N_2$ atmosphere. All compounds were decomposed in $CO_2$ atmosphere at lower than 40$0^{\circ}C$, but the residue, ZnO remained for zinc stearate. ZnO did not decompose in $CO_2$ atmosphere up to 130$0^{\circ}C$, but reduced into Zn metal and disappeared in the temperature range of $600^{\circ}C$ to 120$0^{\circ}C$ in 7H$_2$+93$N_2$ atmosphere. The effect of residue, which trapped in closed pores of sintered pellet, on the thermal stability was studied using the resintering test at 1$700^{\circ}C$ in 7H$_2$+93$N_2$ atmosphere. In the case of oxidative sintered pellet with admixing zinc stearate, the cavity formation accompanied with a density drop after resintering is due to the pressure of the Zn gases trapped in the isolated pores.

• 한국기계가공학회지
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• 제20권12호
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• pp.16-23
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• 2021

Pin-to-disc wear testing experiments were conducted to investigate the wear characteristics of commercial oil (5W-40) with nano-diamond particles. The upper specimen was a SUJ-2 high-carbon chromium steel ball with a diameter of 4 mm, and the lower specimen was made of the Al-6061 alloy. The applied load was 5 N, and the sliding speed was 0.25 m/s. The wear tests were conducted at a sliding distance of 500 m. The friction coefficients and wear rates of the Al-6061 specimens were tested using commercial oil with different nano-diamond concentrations ranging from 0 to 0.02 wt.%. The addition of nano-diamond particles to commercial oil reduced both the wear rate and coefficient of friction of the Al-6061 alloy. The use of nano-diamond particles as a solid additive in oil lubricants was found to improve the tribological behavior of the Al-6061 alloy. For the Al-6061 alloy, the optimal concentration was found to be 0.005 wt.% in view of the friction coefficient and wear rate. Further investigation is needed to determine the optimal concentration of nano-diamond particles for various loadings, sliding speeds, oil temperatures, and sliding distances.

• 에너지공학
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• 제26권3호
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• pp.131-136
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• 2017

자동차 엔진오일은 엔진 시동 시 가장 중요한 윤활제이다. 최근 자동차 회사 와 윤활유 제조업체들은 교환주기를 연장하기 위해 첨가제를 사용하여 오일의 품질을 상당히 개선하고 있다. 대부분의 고객은 자동차 제작사의 정품오일을 사용하거나 전문가의 추천을 받아 사용한다. 본 논문을 통해 소비자가 고효율 윤활유를 선택하는 또 다른 기준점을 제안한다. 본 논문은 7개월 동안 실제 자동차의 운전 조건을 고려하여 오일의 6가지 화합물을 조사 비교 분석하였다. 물리적, 화학적 관점에서 실험을 수행했다. 현장에서 다양한 실험을 통해 광유와 합성유 화합물은 산화, 점도, 유동성 및 TBN에서 크게 구분된다. 이들은 엔진 부품 피스톤, 베어링 등의 마모에 영향을 준다. 다양한 오일을 비교하였을 때 인화점, 산화 안정성에서 합성유의 성능이 좋고 오염 물질인 Fe와 Al 화합물의 변화가 적은 것으로 나타났다. 오일의 첨가제는 광유와 합성유에서 청정분산제 Ca가 확연한 차이를 나타냈다. 극압제 Zn과 윤활 향상제 P는 유사하였다.

• 한국식품과학회지
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• 제45권5호
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• pp.545-549
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• 2013

본 연구에서는 GC-FID를 이용하여 식품첨가물공전에 사용량이 정해져 있는 빵류, 캡슐류, 건조과실류 채소류 및 과실류 채소류 중 유동파라핀의 함량을 측정하였다. 시료에서 n-hexane으로 유동파라핀을 추출하고 $KMnO_4$ 산화반응을 통해 추출물 중 불포화탄화수소의 극성을 증대시킨 다음 aluminium oxide를 충진한 SPE 카트리지로 정제하여 GC-FID로 측정하였다. 검출한계와 정량한계는 각각 10 mg/kg과 20 mg/kg으로 개별 n-alkane으로 정량하는 방법이 아닌 넓은 봉우리로 나타나는 유동파라핀의 면적의 합으로 정량하는 문헌들(15,17)의 값과 유사하게 나타났다. 유동파라핀은 빵류, 건조과실류 채소류 및 캡슐류에서 이형제 등으로 사용되고 있으나 최종 완제품에서 사용기준 이하로 검출되었고, 과실류 채소류에서 모두 불검출로 나타남에 따라 안전한 수준으로 관리되고 있음을 알 수 있었다.