No abstract

Currently, vegetable oils have been studied as biolubricants in order to reach new environmental standards. Besides being non-renewable, mineral oils from petroleum bring consequences to the environment due to its low biodegradability. Thus, the aim of this work is to develop a biolubricant and to add oxide nanoparticles (ZnO and CuO) in order to improve abrasion resistance and friction. This product must be biodegradable and has better performance under boundary lubrication. The methodology consisted of the synthesis of biolubricants using vegetable oils (soybean and sunflower) by epoxidation reaction. The tribological performance was evaluated by HFRR (High Frequency Reciprocating Rig). The developed biolubricants showed good tribological properties besides being more adapted to the environment. Also, it was possible to verify that biolubricants without additives are slightly more tribologically effective than lubricants with additives.

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.

We investigate the chemical, physical and tribological properties of nanolubricants consisting of epoxidized sunflower oil with Cu nanoparticles as additive, the latter produced by magnetron sputtering at distinct current levels in the deposition, to improve the development of nanolubricants by enhancing the nanoparticles dispersion. The nanolubricants are here characterized by Fourier Transform Infrared spectroscopy, zeta potential, UV-vis absorbance spectroscopy, small angle X-ray scattering and scanning electron microscopy. After all, the tribological properties of the bionanolubricants are investigated using a high frequency reciprocating ring equipment, scanning electron microscopy, and energy dispersive spectroscopy. Our results place the nanolubricants produced using the magnetron sputtering technique has excellent nanoparticle dispersion, as well as good tribological performance.

The future lubricants must be more environmentally adapted, with a higher level of performance lower total life cycle, cost than currently used lubricants. Environmental friendly, the biodegradable alternatives are available for a large variety of mineral oil based lubricants. Vegetable oils are the major source of these base fluids, although they have lower thermal and oxidation stability and even worse low-temperature behavior than mineral oil. These physical and chemical properties can be improved by chemical modification. The aim of this study was to evaluate physicochemical properties and film formation from modified vegetable oils. The vegetable oil was chemically modified by epoxidation reaction with acetic and formic acid using sunflower oils. Viscosity, iodine value, density, acidity value and thermal stability were determined for epoxidized oils. The film formation was analyzed using a HFRR tribometer. The results showed that epoxidized vegetable oils had excellent properties to be used as lubricant, and their tribological performance is higher than mineral oil.