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Dedicated NMR sensor to analyze relaxation and diffusion in liquids and its application to characterize lubricants
Author(s) -
Rudszuck Thomas,
Zick Klaus,
Groß Dieter,
Nirschl Hermann,
Guthausen Gisela
Publication year - 2021
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.5155
Subject(s) - chemistry , magnet , relaxation (psychology) , diffusion , nuclear magnetic resonance , analytical chemistry (journal) , sensitivity (control systems) , pulsed field gradient , magnetic field , chemical physics , chromatography , mechanical engineering , thermodynamics , physics , molecule , organic chemistry , electronic engineering , psychology , social psychology , quantum mechanics , engineering
A dedicated nuclear magnetic resonance (NMR) sensor was designed for the analysis of liquids. The magnets are arranged in a V shape, creating a spatially dependent magnetic field in the gap. Measurements of samples with diverse diameters are possible underdefined magnetic field gradients at a given position. The magnet thus combines properties of single sided NMR with high static magnetic field gradients and classical time domain (TD) devices with lower to almost zero gradients. The sensor can easily be adapted to the requirements of the considered investigation; probes can be customized. On the example of lubricants and their aging, the added value and applicability of this sensor in quality control are highlighted in this publication. Relaxation and diffusion were measured by Carr–Purcell–Meiboom–Gill (CPMG) while varying the echo time τ e and quantified via numerical modeling. Especially, relaxation shows a high sensitivity towards aging of lubricants such as particulate abrasion and changes in molecular dynamics induced, for example, by additive depletion. The applicability of this NMR sensor in quality control is demonstrated on the example of engine and transmission oils as well as of lubrication greases.