Monitoring of engine oil aging by diffusion and low-field nuclear magnetic resonance relaxation

Abstract

Time domain, also named lowfield nuclear magnetic resonance is used to monitor oil degradation by measuring relaxation and diffusion. As quality control of oils is indispensable to optimize oil change intervals while simultaneously preventing machinery damage, the technique was applied to detect the degradation state of engine oils as time domain nuclear magnetic resonance is known as a well suited tool to measure quality control parameters for example in food industry. Correlations with commonly applied oil analytics like viscosity measurements and inductively coupled plasma optical emission spectrometry allow to interpret relaxation and diffusion data in detail and finally to deepen the understanding of oil aging processes. Additionally, the measurement temperature was varied to achieve the maximum sensitivity towards oil aging. Low field NMR is not only realized in form of table top instruments, but also in form of field cycling and single sided NMR devices. Fast field cycling as well as single-sided NMR were also explored to study oil aging and to provide valuable insight. The latter device was used to obtain information about translational diffusion and transverse relaxation of oils simultaneously.