Tribological behaviors of three novel imidazoline-type thiadiazole derivatives as multifunctional lubricant additives in biodegradable lithium grease

Three novel imidazoline-type thiadiazole derivatives are prepared and used as antiwear and extreme-pressure additives in biodegradable lithium grease, and their tribological performances are evaluated using a four-ball tester. Tribological tests show that all derivatives are effective in reducing wear, especially at lower additive concentrations. Oleic acid-imidazoline-type thiadiazole derivative is a preferred additive to reduce wear. For the friction-reducing property of base grease, improvements after using these derivatives are not remarkable. On the other hand, these derivatives are also effective extreme-pressure additives. In order to understand the friction process further, chemical composition of tribofilms under antiwear/extreme-pressure regime is analyzed by X-ray absorption near edge structure spectroscopy, and thermal films are also considered for comparison. Thermal films formed by these imidazoline-type thiadiazole derivatives consist of adsorbed organic sulfide and ferrous sulfide. Sulfur presents several chemical valences in the antiwear regime, and tribofilms generated by stearic acid and lauric acid-imidazoline-type thiadiazole derivatives at 1.0 wt% are composed of ferrous disulfide, ferrous sulfide and ferrous sulfate. The appearance of disulfide suggests that the interfacial temperature between the upper ball and three lower balls under antiwear conditions is considerably low. Composition of extreme-pressure films generated by oleic acid and lauric acid-imidazoline-type thiadiazole derivatives is only ferrous sulfide, and the extreme-pressure film for stearic acid imidazoline-type thiadiazole derivative is a mixture of ferrous sulfide, ferrous sulfate, and adsorbed organic sulfide.

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Tribological Characteristics of Three Novel Imidazoline-Type Thiadiazole Derivatives in Colza Oil and Synthetic Diester

Journal of Tribology ◽

10.1115/1.4006925 ◽

2012 ◽

Vol 134 (3) ◽

Cited By ~ 2

Author(s):

Lin Shui ◽

Yi Zhou ◽

Guoru Zhang ◽

Huan Chen ◽

Yidong Zhao

Keyword(s):

Ferrous Sulfate ◽

Lubricant Additives ◽

Metallic Surface ◽

Organic Sulfide ◽

Tribological Behaviors ◽

Ferrous Sulfide ◽

Thiadiazole Derivative ◽

Thiadiazole Derivatives ◽

Main Component ◽

Thermal Films

Owing to the requests of exploring environment-friendly and multifunctional lubricant additives, three novel imidazoline-type thiadiazole derivatives are prepared and used as lubricant additives in two biodegradable base stocks, colza oil and synthetic diester, respectively, and their tribological performance is tested using the four-ball tester. For further understanding of their tribological behaviors, x-ray absorption near edge structure (XANES) spectroscopy is adopted to analyze the thermal films and tribofilms generated from these additives in two base stocks. Tribological tests show that all these thiadiazole derivatives are effective in reducing wear in synthetic diester, and derivative SIB (stearic acid-imidazoline-type thiadiazole derivative) is better than derivative OIB (oleic acid-imidazoline-type thiadiazole derivative) and derivative DIB (lauric acid-imidazoline-type thiadiazole derivative) in reducing friction at high additive concentrations. But these derivatives almost fail in improving the tribological characteristic of colza oil. According to XANES spectra, thermal films formed in two base stocks are mainly composed of ferrous sulfate and adsorbed organic sulfide. These derivatives are also easily oxidized into high-valent sulfate in colza oil during the rubbing process, and ferrous sulfate is the main component of these tribofilms. But in synthetic diester, tribofilms are mainly composed of ferrous sulfide, and it is notable that the tribofilm generated by derivative SIB at 1.0 wt. % is composed of ferrous sulfide and ferrous disulfide. Under extreme-pressure conditions, these derivatives easily react with the metallic surface to generate ferrous sulfide in colza oil. But in synthetic diester, adsorbed organic sulfide is the main component of those films. The base stock has a great impact on the compositions of these reaction films, so the tribological behaviors of these derivatives are different in two base stocks.

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Tribological behaviors of some novel dimercaptothiadiazole derivatives containing hydroxyl as multifunctional lubricant additives in biodegradable lithium grease

Industrial Lubrication and Tribology ◽

10.1108/ilt-08-2011-0065 ◽

2014 ◽

Vol 66 (1) ◽

pp. 51-61 ◽

Cited By ~ 1

Author(s):

Huan Chen ◽

Junhui Jiang ◽

Tianhui Ren ◽

Lei Zheng ◽

Yidong Zhao

Keyword(s):

Lubricant Additives ◽

Short Chain ◽

Lithium Grease ◽

Edge Structure ◽

Content Type ◽

Organic Sulfide ◽

Ferrous Sulfide ◽

Heterocyclic Derivatives ◽

Main Component ◽

Thermal Films

Purpose – In order to meet the requests of exploring environmental-friendly and multifunctional lubricant additives, some novel dimercaptothiadiazole derivatives containing hydroxyl are prepared and used as antiwear (AW) and extreme-pressure (EP) additives in biodegradable lithium grease. The paper aims to discuss these issues. Design/methodology/approach – The tribological performances of the grease samples containing these derivatives are evaluated by using a four-ball tester. X-ray absorption near edge structure (XANES) spectroscopy is used to analyze the chemistry of tribofilms under AW/EP regime, and thermal films are also considered for comparison. Findings – The tribological tests show that these derivatives are all effective in reducing wear, especially at lower additive concentrations, but they are basically failed in reducing friction. They are also helpful in improving the EP characteristic of the base grease. The thermal films generated by these derivatives are composed of adsorbed organic sulfide and ferrous sulfate, though for short-chain derivatives, organic sulfide is the only component at 5.0 wt.%. Ferrous sulfide is the main component of the tribofilms formed by these derivatives at various additive concentrations. But for short-chain derivatives, these tribofilms consist of ferrous sulfide and ferrous disulfide at 5.0 wt.%, and the appearance of disulfide suggests that the interfacial temperature between the upper ball and three lower balls under these conditions is considerably low. The EP films generated by short-chain derivatives are all composed of organic sulfide and ferrous sulfide, while for long-chain derivatives, ferrous sulfide is the main component. Originality/value – These low-toxic and oil-soluble dimercaptothiadiazole derivatives are effective in improving the tribological characteristic of the biodegradable lithium grease, and these heterocyclic derivatives may be good substitutes for some harmful traditional additives.

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Comparison Between the Action of Nano-Oxides and Conventional EP Additives in Boundary Lubrication

Lubricants ◽

10.3390/lubricants8050054 ◽

2020 ◽

Vol 8 (5) ◽

pp. 54

Author(s):

Valdicleide Silva Mello ◽

Marinalva Ferreira Trajano ◽

Ana Emilia Diniz Silva Guedes ◽

Salete Martins Alves

Keyword(s):

Friction Coefficient ◽

Boundary Lubrication ◽

Friction And Wear ◽

Film Formation ◽

Environmental Issues ◽

Protective Film ◽

Extreme Pressure ◽

Extreme Pressure Additives ◽

Environmental Requirements ◽

Lubrication Conditions

Additives are essential in lubricant development, improving their performance by the formation of a protective film, thus reducing friction and wear. Some such additives are extreme pressure additives. However, due to environmental issues, their use has been questioned because their composition includes sulfur, chlorine, and phosphorus. Nanoparticles have been demonstrated to be a suitable substitute for those additives. This paper aims to make a comparison of the tribological performance of conventional EP additives and oxides nanoparticles (copper and zinc) under boundary lubrication conditions. The additives (nanoparticles, ZDDP, and sulfur) were added to mineral and synthetic oils. The lubricant tribological properties were analyzed in the tribometer HFRR (high frequency reciprocating rig), and during the test, the friction coefficient and percentual of film formation were measured. The wear was analyzed by scanning electron microscopy. The results showed that the conventional EP additives have a good performance owing to their anti-wear and small friction coefficient in both lubricant bases. The oxides nanoparticles, when used as additives, can reduce the friction more effectively than conventional additives, and displayed similar behavior to the extreme pressure additives. Thus, the oxide nanoparticles are more environmentally suitable, and they can replace EP additives adapting the lubricant to current environmental requirements.

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