机油中痕量磨损金属元素的间接烧蚀LIBS探测研究

The Detection of Trace Wear Elements in Engine Oil Using Indirect Ablation-Laser Induced Breakdown Spectroscopy

机油在发动机的运转过程中具有非常重要的作用。发动机的运转,会使机油的成分和元素含量发生变化,导致机油变质,进而加剧发动机的磨损,探寻一种快速有效的机油性能检测手段,则是防止发生事故的重要前提。间接烧蚀激光诱导击穿光谱技术(IA-LIBS)是针对机油样品提出的一种全新检测方法,其核心是基于金属基底产生的高温等离子体间接烧蚀样品,在保持了LIBS基本特点的基础上,提高了样品检测灵敏度和稳定性。在前期研究基础上,以机油中Mg、Fe和Ni为目标元素,分析了不同类型机油中的基体效应对其定量分析结果的影响,表明不同油种之间的基体效应对目标元素的定标曲线影响甚小,可忽略;同时建立了目标分析元素的综合定标曲线,拟合线性系数达到了0.99以上。通过对现场机油中添加的已知浓度的目标元素的检测,IA-LIBS分析结果与实际值吻合较好,准确度均低于5%。该研究完善了IA-LIBS的方法研究,为以后评价机油的性能提供了依据,对于诊断发动机的磨损状况具有重要的科学意义。

Engine oil plays an important role in the engine operation.Elements composition and concentration in engine oil will be changed as the engine operates,which can lead to the deterioration of engine oil, and the engine thereby will be worse.A rapid and effective detection approach for oil performance,therefore,is proposed to prevent further deterioration.Indirect ablation laser induced breakdown spectroscopy（IA-LIBS）is a new technology introduced specially for oil samples,which focuses on the indirect ablation of oil samples by metallic plasma with high temperature,improving the detection sensitivity and stability.In this paper,the matrix effect on calibration curves of analytical elements（Mg,Fe and Ni）in different oils was investigated.The results show that the matrix effect is quite small and reasonably negligible.A universal calibration curve can be established for analytical metals in different types of oil, and the linear fitting coefficients are all superior to 0.99.We used the universal calibration curves to determine the concentrations of Mg,Fe and Ni in mixed oils.The IA-LIBS results show a good agreement between the measured and known values.The IA-LIBS is further improved and can promote the detection of engine oil performance,which has important scientific significance for the diagnosis of engine wear.