In order to investigate the influence of a single tribo system on the ageing of lubricants, a so-called Tribo-Oxidationtest has been designed at IFAS. It consists of a disc on disc tribometer integrated into the pressure vessel of an oxidation test according to ASTM D 2112. The coefficient of friction µ of different friction partners is discussed in this paper. The attempts are done with biological esters which are synthesized in a collaborative research centre. Due to biological aspects they contain no additives. It has been shown that there is an influence of oil ageing on friction coefficient but also a big influence of viscosity on friction coefficient.

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Within the subproject A3 "Ageing behavior of environmentally friendly fluids" new fluids are analysed to determine their ageing behavior using laboratory and test rig methods. The experimental results of a modified rotary-bomb-test show the efficency of the chemical modifications of ester liquids conducted by subproject A1 concerning the fluid ageing. These results are confirmed by test rig experiments. Interdependencies between the experimental parameters are investigated by means of correlation analysis. The exertion of the method of neural networks in order to simulate the influence of temperature and fatty acid distribution on the ageing behavior is shown. The simulation results confirm this method as a useful tool in the development of lubricants in order to work timeand costefficently.

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