著者

中村 健太 村木 正芳 中津 賢治

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.66, no.3, pp.220-228, 2021-03-15 (Released:2021-03-15)

参考文献数

14

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Influence of alkyl group of primary zinc dialkyldithiophosphate (ZDDP) on the friction and wear properties was studied using two different kinds of ZDDPs under the boundary lubrication condition with a pin-on-disk type tribotester. A coefficient of friction (COF) was determined under the following three operating conditions: the constant condition, the step-load condition and the variable-speed condition. COF of linear-alkyl ZDDP showed lower value than that of branched-alkyl ZDDP under all these conditions. Nano-friction force of the tribofilm obtained in the constant condition test was measured by means of an atomic force microscope. Meanwhile, nano-friction force ratio of the branched type to the linear type was almost same as COF ratio. It was suggested that macro-scale frictional behaviour was governed by nano-scale mutual interaction of tribofilms. On the other hand, the wear scar diameter decreased with increasing ZDDP concentration. From the energy dispersive X-ray spectroscopy analysis, the wear scar diameter was inversely correlated with phosphorus concentration on the worn surface. These results suggested that COF depended on mechanical properties of top layer of tribofilm while wear resistance depended on the thickness of base layer of tribofilm containing polyphosphate.

著者

小野寺 康 佐藤 魁星 渡部 誠也 佐々木 信也

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.66, no.5, pp.363-371, 2021-05-15 (Released:2021-05-15)

参考文献数

16

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Friction reduction by engine oil under low and high temperature conditions is required because of the increasing number of hybrid vehicles where oil temperature is low. Friction modifier (FM) technology to realize it are required. Friction performance of molybdenum dithiocarbamate (MoDTC) used with adsorption type FMs was investigated, which showed different results depending on types of adsorption type FMs: glycerol monooleate (GMO) inhibited friction reduction while polymer FM (PFM) did not. To understand the cause of the difference, the effect of reaction film formation by Zinc dithiophosphate (ZnDTP), which is crucial for the friction reduction by MoDTC, on adsorption type FMs was investigated. GMO inhibited the reaction film formation by ZnDTP, while PFM did not fully, observed with mini-traction machine spacer layer imaging (MTM-SLIM) and EPMA analysis. The cause was studied by their adsorption performance examined by quartz crystal microbalance (QCM). GMO showed higher adsorption density, while PFM showed lower compared to that of ZnDTP. The result indicated that GMO competitively adsorbed on the surface, inhibiting the reaction film formation by ZnDTP while polymer FM did not. Adsorption performance under co-existence of PFM and ZnDTP indicated that ZnDTP is capable to adsorb on the surface under the existence of PFM. The study indicated that the key to achieve low friction is to use PFM which does not fully inhibit ZnDTP reaction film formation.

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.59, no.3, pp.176, 2014-03-15 (Released:2018-05-03)

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トライボロジスト 58巻11号 798-803 ●和文表題 誤)トライボロジー現象化で生じるアコースティックエミッション 正)トライボロジー現象下で生じるアコースティックエミッション

著者

長谷 亜蘭

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.58, no.11, pp.798-803, 2013-11-15 (Released:2018-05-08)

参考文献数

24

著者

角銅 洋実 高田 仁志 平山 朋子

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

pp.20-00012, (Released:2021-02-25)

参考文献数

20

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Ball bearings on the main shaft of rocket engine turbopumps which supply cryogenic propellants to the main combustion chamber are critical elements of the entire propulsion system of a rocket. A self-lubricating ball bearing with a retainer made of glass-cloth-polytetrafluoroethylene (PTFE) laminate has been used in turbopumps developed in Japan. In the operation of the turbopump, the bearing heat generation is possible to cause sudden temperature rises of bearing elements which finally result in bearing seizure. Therefore, it is important to predict the accurate bearing heat generation under various operating conditions. In this research, the bearing heat generation operated in cryogenic hydrogen was experimentally investigated under the various operating conditions where the rotational speed and the bearing coolant condition were changed. In addition, the bearing heat generation was compared with that theoretically predicted on a numerical model of mechanical losses. It was finally clarified that the bearing heat generation is influenced dominantly by the friction loss on balls and the drag loss on an inner race.

著者

鷲家 真吾 森 務 酒井 良明

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.60, no.8, pp.527-533, 2015-08-15 (Released:2017-04-03)

参考文献数

9

著者

南 一郎

出版者

日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.57, no.4, pp.246-248, 2012-01-01

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"トライボロジーはカオスだ"と開き直ってしまうと研究は進歩しない.複雑な現象を筋道立てて説明するために摩擦面に介在する物質の同定を試みる.今や潤滑剤やコーティングのトライボロジー特性を評価・解析するために表面の化学分析(以後"表面分析"と略す)は必須のツールとなっている.しかし表面分析は"打出の小槌"でも"アラジンの魔法のランプ"でもない.高価な測定料を払うのだから相応の価値のある解析結果を導きたい.そのためには分析の原理やテクニックよりも分析試料の素性を知ることに焦点を当てると良い.このような観点から本稿では摩擦面の分析戦略を練るための情報源を精選して紹介する.

著者

木之下 博 政安 亮祐 藤井 正浩

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.58, no.11, pp.832-840, 2013-11-15 (Released:2018-05-08)

参考文献数

22

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Sandfish (Scincus scincus), which is kind of reptile living in desert, can move in sand like swimming. It is thought that since sandfish has a low friction scales, it is able to do that. However, the mechanism of the low friction property of the scales is not yet known. In this study, a micro structure of sandfish’s scales was investigated, and their tribological properties under μN loads were measured. Cuticle-like structure, which is observed on human hairs, appeared on the scales. Detected elements on the scales were O, C, N, and S. Ca and Si, which are elements of hard shells and bones, were not detected. A contact angle of sandfish’s scale was around 90º, and polytetrafluoroethylene (PTFE) and polyimide (PI) had contact angles of approximately 110º and 60º, respectively. However, an adhesion force of sandfish’s scales was lower than those of PTFE and PI. With the exception of a few frictional conditions, a friction force of sandfish’s scales was lower than those of PTFE and PI, which would result from the low adhesion force of sandfish’s scales.

著者

齊藤 利幸

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.65, no.2, pp.105-112, 2020

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<p>In this commentary, we will introduce the tribology technology related to the cultural properties of Aichi prefecture. First of all, with regard to intangible cultural properties, we focus on the Aichi parade floats and describe the technical features. Also on abundant industrial heritage, we describe machine tools and railway technology. In addition, we introduce the war legacy which keeps the remnant of war damage, and look back on the history of tribology. By looking at these cultural properties, you can feel familiar with the technologies that form the basis of today's tribology.</p>

著者

橋村 真治 伊藤 隼人 小松 恭一 大津 健史

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.61, no.12, pp.882-892, 2016-12-15 (Released:2016-12-15)

参考文献数

14

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It is well known that a main cause of tightening error on the torque control method is changes of the frictional coefficients in thread surfaces and bearing surfaces in bolt tightening. It has been shown in the previous study that the frictional coefficients depend on surface roughness of contact surface, lubrication conditions and bolt configuration errors. The frictional coefficients can be changed by the bolt configuration errors such as a bend of bolt shank and inclination of bolt bearing surface, if large wear and seizure do not occur on the lubricated surfaces.In this study, an influence of the squareness error of bolt bearing surface on the tightening accuracy has been investigated. Results clearly showed that the squareness error of bearing surface causes variations of torque coefficients and the clamping force error. It was shown by FEM analysis that the variation of torque coefficient between bearing surfaces is caused by change of an apparent frictional coefficient. Tightening accuracy also depended on the squareness error of bearing surface.

著者

村上 理 長谷部 寿郎 山田 敏明 前田 芳宏

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.58, no.7, pp.467-472, 2013-07-15 (Released:2018-12-04)

参考文献数

9

著者

大久保 光 角 太朗 田中 典義 佐々木 信也

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

pp.19-00004, (Released:2019-10-02)

参考文献数

10

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Mechanisms of the synergistic effects of MoDTC and organic polymer friction modifier (OPFM) on tribological properties was investigated by using X-ray photoelectron spectroscopy (XPS), quartz-crystal microbalance with dissipation (QCM-D) and frequency modulated atomic force microscopy (FM-AFM). The OPFM used in this study was poly-lauryl-acrylate with OH group: poly-lauryl-acrylate-hydroxyethyl-acrylate (PLA/HEA). Friction tests were conducted at steel/steel tribopairs lubricated with poly-alpha olefin (PAO) and PAO with PLA/HEA, MoDTC and PLA/HEA-MoDTC. From the friction test results, PAO +MoDTC+PLA/HEA exhibited lower friction compared to the other solutions. From all our results, the synergistic low frictional effects can be derived from the formation of MoS2 and the high viscous and thick additive adsorbates on the sliding surface.

著者

辻野 義雄

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.60, no.8, pp.518-526, 2015-08-15 (Released:2017-04-03)

参考文献数

25

著者

佐藤 真理子 田村 照子

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.58, no.1, pp.10-16, 2013-01-15 (Released:2019-01-30)

参考文献数

11

被引用文献数

1

著者

村木 正芳 中村 健太 鈴木 真 瀬上 高博 山本 賢二

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.59, no.8, pp.507-514, 2014-08-15 (Released:2018-02-23)

参考文献数

11

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Tribological performances of the oils containing polylaurylacrylates with and without hydroxyethyl group were studied under elastohydrodynamic lubrication (EHL), partial EHL and the boundary lubrication conditions. The base oil was polyalphaolefin and the viscosity of polymer solutions and the concentration of polymer was adjusted at the same level. Under the partial elastohydrodynamic contacts using a ball-on-disk type tribometer, polylaurylacrylatehydroxyethylacrylate (PLA/HEA) showed a greater oil film thickness while lower traction coefficient at low rolling speeds than polylaurylacrylate (PLA). This can be interpreted that adsorption of hydroxyethyl group of PLA/HEA reduced traction under the partial EHL condition. Under the boundary lubrication conditions using a pin-on-disk type tribometer, PLA/HEA exhibited the flat friction-velocity relation while PLA showed a large negative gradient of friction-velocity relation. Finally, PLA/HEA was superior to PLA in terms of the antiwear properties with a reciprocating friction tester. It is inferred that these better performances of PLA/HEA under the boundary lubrication conditions were brought about by formation of a tribofilm based on reaction of hydroxyethyl group and the sliding surface.

著者

木之下 博 政安 亮祐 藤井 正浩

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.59, no.9, pp.577-585, 2014-09-15 (Released:2018-02-23)

参考文献数

12

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It is thought that sandfish skink, living in desert, has scales that have low friction and high wear resistance properties. In previous study, we investigated the tribological properties of sandfish's scales under micro newton loads. It is found that the scales have low adhesion forces, which would lead to the low friction property. In this study, a tribological property of sandfish's scales was investigated under milli newton loads (of 3, 5, 10 mN) to investigate wear resistance property mainly. Tribological tests were also carried out using polytetrafluoroethylene (PTFE) and polyimide (PI) for comparison with the scales. Using a SUJ2 ball with a diameter of 1 mm, wear of sandfish scale was not occurred or much lower than those of PTFE and PI. When wear was not happened for sandfish's scale in the relative low contact pressure, a friction coefficient of the sandfish's scale was lower than those of PI and PTFE. When a tungsten probe with an apex diameter of 5 μm was used in which contact pressure was huge with compare to that using the SUJ2 ball, wears on all samples were observed. In the relative high contact pressure, the friction coefficient of sandfish's scale was higher than that of PI. Under the milli newton loads, the microstructure of the sandfish's scale did not affect its tribological property.

著者

石崎 啓太 中野 冠

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

pp.18-00002, (Released:2018-06-21)

参考文献数

43

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This paper presents a study of the environmental performance impact of a comprehensive set of conventional viscosity lubricants and latest low viscosity lubricants, considering the use for average fuel economy passenger vehicle (118.1 g-CO2/km in 2016). The vehicle is assumed to be equipped with either automatic transmission (AT) or contentiously variable transmission (CVT) with a lifetime mileage of 150 000 km. Engine oil, transmission fluid as well as oil filter were identified as requiring servicing (replacement) in use phase. It was found that the analyzed engine oil, AT fluid and CVT fluid with different formulations show almost identical CO2 emissions per weight from the lubricants production, and the contribution of the oil filters and the transmission fluids to CO2 emissions in maintenance phase accounts for over 20%. The latest low viscosity lubricants improve vehicle fuel economy by up to 4.0% compared to conventional viscosity lubricants. As a consequence, latest lubricants have the potential to save the vehicle life cycle CO2 emissions by up to 630 kg-CO2 even when subtracting the produced CO2 emissions in maintenance phase, with comparison of conventional viscosity lubricants.

著者

大津 健史 西田 一樹

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.61, no.2, pp.127-136, 2016-02-15 (Released:2016-05-23)

参考文献数

27

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This paper describes that the behavior of growth of cavitation formed in the journal bearing and the effect of cavity growth on the bearing performance. The journal bearing test apparatus in which the bearing was made of transparent acrylic plastic was used, and cavitation in lubrication film was observed by the fluorescent method in this study. Results show that the cavity is formed by the bubble occurred at the edge of bearing, and the angle of start and end position of cavity depends on applied weight. The cavity grows with time at a constant load of 45 N because the cavity coalesces with small cavities occurred at the edge of bearing, and the eccentricity ratio and the attitude angle are also changed during the time of growth. It is also shown by a numerical analysis that the cavity growth is related with the oil flow generated by the negative pressure at the outlet of the cavity.