• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.149-155
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• 2001

New semi-fluorinated polyol esters were synthesized by condensation reaction of polyols (NPG and TMP) and carboxylic acids such as 2-ethylhexanoic acid, stearic acid and perfluorooctanoic acid. The structures of polyol esters were confirmed by FT-IR and H-NMR etc. And, the fluorinated polyol esters were insoluble in several oils, however, the semi-fluorinated polyol esters were soluble in several oils depended on the structure of polyol esters. The physical properties such as 4-ball wear property and extreme-pressure (EP) properties were characterized by measuring wear scar diameter through ASTM D2266 and by determining the load-carrying through ASTM D2783 method, respectively. As the results, wear scar diameters of oils in which the semi-fluorinated polyol esters were added were not changed compared to those of not added oils. While extreme-pressure properties remarkably Increased with fluorine contents of the esters depended on the structure of acid moiety and polyol moiety. Also, the extreme-pressure property of semi-fluorinated NPG polyol ester in gasoline engine oil was better than that of commercial Teflon coating additive.

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.405-412
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• 2018

Three types of bis[3-(dialkyloxylphosphorothionyl) thio-2-methylpropanyloxy]alkane (BAPA) drived from alkane diol were synthesized. The principal chain of each BAPA had a different carbon number, i.e., 6, 9, and 11. The three types of synthesized BAPA were compared to zinc dialkyl dithiophosphates (ZDDPs) in terms of abrasion resistance. A four-ball test was conducted to evaluate the anti-abrasion performance of the synthesized BAPA according to the length of the principal carbon chain. Each product was added to an additive at a concentration of 1% of the base oil weight, and the wear scar diameter (WSD) was measured as 0.472, 0.459, and 0.480 mm, respectively. Among the BAPA compounds, dialkyl dithiophosphoric acid (DDP), which is the side chain of bis[methacryloyloxy] nonane (BMOO9), was synthesized by varying the carbon number, i.e., 4, 8, and 12, and subsequently the 4-ball test was carried out. The WSD was determined as 0.537, 0.459, and 0.531 mm, respectively. As a result, it was found that when a side chain is short, a thin film is formed. In contrast, a long side chain hindered the formation of a film, and hence the best result was achieved when the carbon number was 8. As for the ZDDPs, the WSD was determined to be 0.563 mm, when measured under the same conditions. The measurements confirm that the synthesized BAPA compounds are superior to the ZDDPs as abrasion resistance additives.

• Tribology and Lubricants
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• v.16 no.5
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• pp.332-340
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• 2000

The reduction of sulfur content in the diesel fuel has caused the poor lubricity of diesel fuel in the distributor type injection pumps of diesel engines that use the diesel for lubrication of their moving parts. To investigate the reason for poor lubricity of low sulfur diesel fuels, the wear scar diameters by HFRR (High Frequency Reciprocating Rig) were measured on the diesel fuels from Korean markets and the results were compared with their physical and chemical properties. Also, the lubricity change and the improvement effects on lubricity additives for the ultra low sulfur diesel fuel, were made experimentally, that will be regulated to a maximum of 0.005 wt% from about 2005 were evaluated. As a result, a good correlation was found between the wear scar diameter and the polyaromatic compound which includes heterocyclic compound in the diesel fuel. It was also found that the content of polyaromatic compound including heterocyclic compound was affected by the amount of desulfurization treatment fraction. And the lubricity additives with ester base were more effective than that with acid base on the ultra low sulfur diesel fuel. Therefore, it is suggested that the factors affecting the lubricity stated above should be taken into account to improve the lubricity property of the diesel fuel in the refining process.

• Tribology and Lubricants
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• v.31 no.5
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• pp.195-204
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• 2015

Several researches are focused on improving the value of fine chemicals based on biomass resources due to environmental and other concerns associated with the use of petroleum-based products. Therefore, the synthesis and application of estolides derived from plant-based waste oil materials and their application as lubricants and as processing oil for butyl rubber products have been studied. Four kinds of estolide were prepared with conversions of 71~92% over 24h using various vegetable oils, as determined by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy. FT-IR spectroscopy determines the esterification of estolides using 2-ethylhexyl alcohol. The estolides have iodine values of 35~90, α-ester/α-acid ratios of 0.45~0.55, and total acid number of 114~134 mg KOH g^–1. Four ball wear tests show that the wear scar diameters (WSDs) of estolides as base oil significantly decreased to 0.328~0.494 mm, compared to WSDs of 0.735 and 0.810 mm of WSD for 150N and Yubase 6, respectively, as general base oil. Thus, the estolides have better wear resistance and satisfying design objectives for the engineering of a variety of lubricant base oils.

• Corrosion Science and Technology
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• v.5 no.2
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• pp.52-61
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• 2006

Recently, much of the current development in surface modification engineering are focused on multilayered coatings. Multilayered coatings have the potential to improve the tribological properties. Four different multilayered coatings were deposited on AISI D2 steel. The prepared samples are designed as $WC-Ti_{0.6}Al_{0.4}N$, $WC-Ti_{0.53}Al_{0.47}N$, $WC-Ti_{0.5}Al_{0.5}N$ and $WC-Ti_{0.43}Al_{0.57}N$. The multilayered coatings were investigated with respect to coating surface and cross-sectional morphology, roughness, adhesion, hardness, porosity and tribological behavior. Especially, wear tests of four multilayered coatings were performed by using a ball-on-disc configuration with a linear sliding speed of 0.017 m/sec, 5.38 N load. The tests were carried out at room temperature in air by employing AISI 52100 steel ball ($H_R=66$) having a diameter of 10 mm. The surface morphology, and topography of the wear scars of samples and balls have been determined by using scanning electron spectroscopy (SEM). Results have showed an improved wear resistance of the $WC-Ti_{1-x}Al_xN$ coatings with increasing of Al concentration. $WC-Ti_{0.43}Al_{0.57}N$ coating with the lower surface roughness and porosity with good adhesion enhanced wear resistance.

• Applied Chemistry for Engineering
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• v.23 no.4
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• pp.421-427
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• 2012

To improve the lubricity of ultra low sulfur diesel, vegetable oil-based alkanol amide derivatives were prepared and their lubricity properties were studied. To synthesize the alkanol amides, we conducted the amidation reaction of diethaolamine High Frequency Reciprocating Rig (HFRR) and the fatty acid methyl esters, obtained by the continuous transesterification of methanol and several vegetable oil, such as soybean oil, palm oil and coconut oil. The synthesized amides were soluble in ultra low sulfur diesel in the concentration range of ca. 1 wt%; the lubricating properties of ultra low sulfur diesel containing 120 ppm of amides were measured using an HFRR method. It was found that the wear scar diameter in the pure ultra low sulfur diesel decreased significantly from 581 ${\mu}m$ to 305~323 ${\mu}m$ upon the addition of the amides, indicating that lubricating properties of the diesel were improved. On the other hand, the types of vegetable oils did not affect the wear scar diameters, implying that lubricating properties of the diesel did not depend strongly on the structures of alkyl groups of alkanol amide derivatives. When we measured the lubricating properties of the one type of diesels containing various amounts of alkanol amide, we observed that the wear scar diameter decreased drastically with increasing the amide concentration, meaning that the lubricity improved with the amide concentration.

• Tribology and Lubricants
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• v.26 no.5
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• pp.272-276
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• 2010

Aminated oilve oil derivative as the new organic disperse phases of the water soluble metal working fluid has been synthesized and tribological properties of the aqueous solutions composed of aminated olive oil derivative investigated using Four Ball Wear Tester and Falex EP Tester. The formulated aqueous solutions showed higher antiwear and extreme pressure properties and also lower friction coefficient. On the basis of the the results, water soluble aminated oilve oil derivative showed excellent tribological properties due to the polarizability of oleic acid derivative composed of majority part in oilve oil.

• Tribology and Lubricants
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• v.30 no.5
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• pp.256-264
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• 2014

Enhancing the value of fine chemicals based on biomass resources is an important objective for addressing environmental and other concerns such as demand for renewable or green products, as well as from the political perspective to reduce dependence on fossil feedstock associated with the use of petroleum-based products. Based on these considerations, we studied the synthesis of estolide using waste plant-based oil materials and their application as lubricants and pour point depressants. Five estolides were prepared by varying molar ratio of palmitic acid (PA) to oleic acid (OA) using a reaction time of 48 h. The estolides were characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR). The isolated yields were in the range of 57-78 % and purity was 93-97%, showing iodine values of 18.2-37.8, total acid numbers (TANs) of 75.6-94.2 mg KOH/g and estolide numbers (ENs) of 1.2-1.8. Increasing the ratio of OA to PA in the synthesis decreased the kinematic viscosity and clouding point of the estolides. Four ball wear test of the estolides as a base oil demonstrated that the wear scar diameter (WSD) of the estolides was significantly lower (0.320-0.495 mm) than the WSD of general base oils such as 150N and Yubase (0.735 and 0.810 mm, respectively), indicating better wear resistance of the estolides. However, the lubricant property was found to be independent of the amount of OA in the estolides. These new materials are prospective candidates for application as a lubricant base oil.

• Tribology and Lubricants
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• v.20 no.6
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• pp.306-313
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• 2004

Many of the current development in surface modification engineering are focused on multilayered coatings, which have the potential to improve the tribological properties. Four different multilayered coatings were deposited on AISI D2 steel in this study. The prepared samples are designed as $WC-Ti_{0.6}Al_{0.4}N,\;WC-Ti_{0.53}Al_{0.47}N,\;WC-Ti_{0.5}Al_{0.5}N\;and\;WC-Ti_{0.43}Al_{0.57}N$. The multilayered coatings were investigated with respect to coating surface and cross-sectional morphology, roughness, adhesion, hardness, porosity and tribological behaviors. Especially, wear tests of four multilayered coatings were performed by using a ball-on-disc configuration with a linear sliding speed of 0.017 m/sec and a normal load of 5.38 N load. The tests were carried out at room temperature in air by employing AISI 52100 steel ball $(H_R\;=\;66) $ having a diameter of 10 mm. The surface morphology, and topography of the wear scars of samples and balls have been determined by using scanning electron spectroscopy (SEM). Also, wear mechanism was determined by using SEM coupled with energy-dispersive spectroscopy (EDS). Results have showed an improved wear resistance of the $WC-Ti_{1-x}Al_xN$coatings with increasing of Al (aluminum) concentration.

• Tribology and Lubricants
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• v.30 no.6
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• pp.323-329
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• 2014

The friction-reducing properties of lubricants containing ionic liquids based on ammonium dithiocarbamate are studied. The ionic liquids are produced through the following two steps: the synthesis of sodium alkyl dithiocarbamates via the substitution reaction of dialkylamine and carbon disulfide and their subsequent conversion into ammonium dithiocarbamate-based ionic liquids through an ion-exchange reaction with a quaternary alkyl ammonium halide salt. The structures of the ionic liquids are characterized by NMR spectroscopy and Fourier transform infrared spectroscopy. The isolated yields of the ionic liquids, which are viscous and pale yellow, are approximately 92%. The Brookfield viscosities and pour points of the ionic liquids are determined. Further, their wear resistances are measured through the four-ball wear test and the Schwingung Reibung Ver-schleiss (oscillation, friction, wear) test. The wear scar diameter of the lubricants containing 1 wt of the quaternary alkyl ammonium dithiocarbamate-based ionic liquids (0.475-0.631 mm) is significantly lower than that of the base oil (0.825 mm), proving that the ammonium dithiocarbamate-based ionic liquids have good friction-reducing characteristics. However, these friction-reducing characteristics fade significantly after long-term storage, owing to the degradation of the ionic liquids.