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.

中文翻译：

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用于分析液体中弛豫和扩散的专用 NMR 传感器及其在表征润滑剂方面的应用

专用的核磁共振 (NMR) 传感器专为液体分析而设计。磁体呈 V 形排列，在间隙中产生空间相关的磁场。在给定位置测量具有不同直径的样品可能存在欠定义的磁场梯度。因此，该磁体将单侧 NMR 的特性与高静磁场梯度和经典时域 (TD) 设备的特性相结合，具有低到几乎为零的梯度。传感器可以很容易地适应所考虑的调查的要求；探头可定制。在润滑剂及其老化的示例中，本出版物重点介绍了该传感器在质量控制中的附加值和适用性。通过 Carr-Purcell-Meiboom-Gill (CPMG) 测量松弛和扩散，同时改变回波时间τ _e并通过数值建模量化。特别是，松弛对润滑剂老化表现出高度敏感性，例如颗粒磨损和由添加剂消耗引起的分子动力学变化。该 NMR 传感器在质量控制中的适用性在发动机油和变速箱油以及润滑脂的示例中得到了证明。