Raman spectroscopy used in the analysis of degradation of automotive lubricating oils caused by temperature Andressa Cristina de Mattos Bezerra, Landulfo Silveira Jr., Marcos Tadeu Tavares Pacheco, Nelize Maria de Almeida Coelho, Dorotéa Vilanova Garcia

Abstract

To ensure the safety and proper functioning of motor vehicles, it is necessary to be up to date. Aiming the correct operation of the engine, maintaining the integrity of the moving parts and optimizing its performance, it is required to use lubricating oils with specifications appropriate to each type of engine. The wide variety of brands, types and specifications of oils has widened the range of consumer options because some brands and types meet or even exceed manufacturers' specifications. Due to the time of use of the automobile, the lubricating oil loses its lubricity and protection properties, and its exchange is necessary, and this change is often based on factors such as color and viscosity, or even at the recommendation of the automobile manufacturer. In order to evaluate the degradation of the oil as a function of the temperature to which it is subjected, the work had as objective to carry out a preliminary evaluation of the degradation of two types of lubricants, synthetic and semi-synthetic of the same brand, using Raman spectroscopy with excitation in 830 nm. The results showed that it was possible to identify differences in the intensities of Raman peaks at 1300 and 1440 cm^-1, attributed to methylene torsion vibration (-CH₂-) and CH₂/CH₃ deformation, respectively, after 16 hours of heating at the mean temperature of 125,4 ° C for the first 8 hours and 127,5 ° C for the following hours.