Lubricating oil degradation analysis due to temperature through Raman spectroscopy

摘要

Lubricating oils are essential in vehicles motors, and there are currently three variations in oil types: mineral, semisynthetic and synthetic. This work aimed to evaluate the degradation of these three types, by heating them in the laboratory between 120 to 150 °C for 48h, and subsequently evaluating their change in the composition through Raman spectroscopy. It was possible to observe compounds in common between the mineral and semi-synthetic oils in the peaks at 1002, 1380 and 1621 cm~(-1), and between the semi-synthetic and synthetic in the peak at 892 cm~(-1). In the evaluation of samples after heating, trough principal component analysis (PCA) technique, it was observed a decrease in the intensity of some peaks, suggesting molecular breakdown, as well as an increase in the intensity of other peaks suggesting formation of amorphous carbon. It was found a high correlation through heating time and peak intensity, by adjusting 2nd order polynomial curves, R2 ranging from 0.96 to 0.99.