In this paper, it is shown that specifi c ionic liquids have great potential to be used as additives for tribological applications. The results promise a high load carrying capacity; especially for the cation 3-Octhylthiazolium and long term stability up to temperatures of 120°C is given. However, only extreme pressures/ anti-wear properties are examined in detail with the selected test method. Friction modifi er (FM) effectiveness cannot easily be demonstrated, because of the good performance of the selected base stock. Nevertheless, ionic liquids in general did not change the FM characteristic of the base oil in a negative way. A promising potential for ionic liquids to replace a majority of additives in tribological systems is given. Methods used are Schwing-Reib-Verschleiß test according to DIN ASTM D 5706, and Four Ball Tests according to DIN 51360. Mechanisms related to additives in lubricants are investigated by X-ray photoelectron spectroscopy.
When looking in detail at analyses of the tribological load-carrying capacity of lubricants, it becomes apparent that an exclusive evaluation of the development of the coefficient of friction cannot provide any sufficient criteria for determining the occurrence of adhesive failure. This is due on the one hand to the increasing complexity of lubricant formulae, and on the other hand to the increasing power capacity of modern drive and control concepts in the construction of tribometers. For this reason, it is urgently needed to examine the adhesive processes and their detection in more detail with the help of appropriate tribological values and criteria. The evolution of the friction can be coupled with the stroke, contact resistance, and other parameters. Besides, from new criteria for adhesive failure, which were compiled by the workgroup for the relevant ISO, DIN, and ASTM standards, this contribution discusses the inclusion of additional parameters. The SRV® test system—where SRV stands for the German acronym for oscillation, friction, and wear—is one that was developed to analyze adhesive failure from many measurements alongside the coefficient of friction. Testing with the SRV® system is done via step tests with standardized procedures and parameters, which are in accordance with ASTM test methods. The system continuously monitors electrical resistance, zero stroke position signals, temperature, and other measurements, and can derive further parameters that also help to identify adhesive failure and other adhesive events. These dimensionally reduced parameters can provide new insight on the mechanism of the adhesive behavior. This paper aims to discuss how the interpretation of these step tests beyond the development of coefficient of friction can lead to new knowledge and insight in tribological research, and explores the applicability of Stribeck’s theory to the oscillatory and reciprocating motion utilized in the SRV® tribometer.
Several methods have been studied as alternatives for water desinfection. Among them, the use of metals such as silver, mainly in its nanostructured form have gained great attention. This work aimed to synthesize silver nanoparticles using the aminoethyl-aminopropyl-trimethoxysilane (APTMS) as stabilizer and coupling agente to incorporate these nanostructures onto the surface of microcrystalline celulose particles. Among the different amounts of APTMS tested, the concentration of 10.8 mmol.L-1 resulted in a higher concentration of silver nanoparticles with smaller dispersion of sizes, and better colloidal stability along the time. In this way, such functionalized natural particles could be used as an antibacterial filter filling capable to disinfected water. The developed product presented excellent antibacterial properties, eliminating 100% of the bacteria in only 15 minutes for the tests with 5 and 10 ppm of NpAg.
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