In situ study of multialkylated cyclopentane and perfluoropolyalkyl ether chemistry in concentrated contacts using ultraviolet Raman spectroscopy

In situ analysis of lubricated, concentrated contacts can be performed using ultraviolet Raman spectroscopy. An ultraviolet Raman spectrometer has been constructed and interfaced to a ball-on-flat tribology apparatus. Two lubricants have been studied under various loads with and without pure sliding: (1) a mixture of perfluoropolyalkyl ethers (Krytox 143AC), and (2) a mixture of high molecular weight multialkylated cyclopentanes (2001A). Results show that without sliding, Krytox and 2001A remain stable under the various loads used. When sliding was applied, both Krytox and 2001A undergo chemical decomposition to amorphous carbon (friction polymer). An analysis of the Raman spectra shows a structural difference between the amorphous carbon produced from Krytox and that produced from 2001A. Results also demonstrate the importance of in situ analysis since the composition at the contact center during and after sliding are different.