【摘要】 为改善激光诱导击穿光谱技术对润滑油中金属元素的检测效果，避免激光诱导击穿光谱技术应用于润滑油检测时的等离子体淬灭、油液飞溅以及光谱强度低等问题，采用蜂蜡作为基质，将润滑油样品由液相转化为固相，对润滑油中的Mg元素和Ca元素进行了定量分析。首先，提出了采用蜂蜡制备润滑油检测样品的方案。其次，对脉冲激光能量、采集延时以及激光聚焦位置等实验参数进行了优化。将激光能量从30 mJ调整到120 mJ,每次增加10 mJ,分析了激光能量对谱线强度和信背比的影响，结果表明，当激光能量为90 mJ时，实验结果最佳；选择不同的采集延迟，每次改变0.5μs,对比采集延迟从1μs到5μs的实验结果，结果显示，当采集延迟为2.5μs时，可以得到最佳实验结果；对比分析激光聚焦位置对光谱信号的影响，将激光聚焦位置从样品表面上方1 mm调整到样品表面下方5 mm处，每次移动0.5 mm,得出当激光聚焦位置位于为样品表面下方2 mm时，目标元素的光谱信号强度和信背比最佳。然后，选取了Mg（Ⅱ）279.552 8 nm和Ca（Ⅱ）393.366 nm作为Mg元素和Ca元素的分析谱线，在最佳实验条件下，对7个不同浓度蜂蜡制样的润滑油样品进行了光谱采集，建立了Mg元素和Ca元素的定标曲线，Mg元素定标曲线的线性相关系数达到0.996 1, Ca元素定标曲线的线性相关系数达到0.995 8,计算得出Mg元素和Ca元素的检测限分别为4.08和6.11μg·g^-1。最后，基于建立的定标曲线，对4个不同浓度润滑油样品中的Mg元素和Ca元素的浓度进行了检测，得出Mg元素的加标回收率范围为92.67%～106.15%, Ca元素的加标回收率范围为95.88%～108.57%。研究结果表明，利用蜂蜡作为基质制备样品检测润滑油中的金属元素，解决了激光诱导击穿光谱技术用于润滑油检测时的光谱强度低和油液飞溅等问题，实现了润滑油中金属元素μg·g^-1量级的检测，提出的方法对激光诱导击穿光谱技术检测润滑油中的金属元素具有重要的科学意义。更多还原

【Abstract】 To improve the detection effect of laser-induced breakdown spectroscopy on the metal elements in lubricating oil and avoid the problems of plasma quenching, oil splashing, and low spectral intensity when laser-induced breakdown spectroscopy is applied to the detection of lubricating oil, beeswax was used as the matrix to convert the lubricating oil sample from the liquid phase to the solid phase. The Mg element and Ca element in the lubricating oil were quantitatively analyzed. Firstly, a scheme was proposed to prepare lubricating oil test samples using beeswax. Secondly, the experimental parameters such as pulsed laser energy, acquisition delay, and laser focus position were optimized. The laser energy was adjusted from 30 to 120 mJ. Each time, it was increased by 10 mJ, and the effect of laser energy on the spectral line intensity and signal-to-back ratio was compared and analyzed. The results showed that the experimental results were the best when the laser energy was 90 mJ. The best experimental results can be obtained with an acquisition delay of 2.5 μs, choosing different acquisition delays, varying by 0.5 μs each time, and comparing the experimental results with acquisition delays ranging from 1 to 5 μs. The influence of the laser focus position on the spectral signal was compared and analyzed, and the laser focus position was adjusted from 0.5 mm above the sample surface to 5 mm below the sample surface. By moving 1 mm each time, it was concluded that when the laser focus position was 2 mm below the sample surface, the target element’s spectral signal intensity and signal-to-background ratio were the best. Then, Mg（Ⅱ） 279.552 8 nm and Ca（Ⅱ） 393.366 nm were selected as the analytical lines of Mg and Ca. Under the best experimental conditions, seven lubricating oil samples prepared with different concentrations of beeswax were spectra collected, and the calibration curves of Mg and Ca were established. The linear correlation coefficient of the calibration curve of Mg and Ca reached 0.996 1 and 0.995 8, and the detection limits of Mg and Ca were 4.08 and 6.11 μg·g^-1. Finally, based on the established calibration curves, the concentrations of Mg and Ca in four other lubricant samples with different concentrations were detected, and the recoveries of Mg and Ca were 92.67%～106.15%. The recoveries of Ca were 95.88%～108.57%. The results show that the use of beeswax as a matrix to prepare samples for the detection of metal elements in lubricating oil solves the problems of low spectral intensity and oil splashing when laser-induced breakdown spectroscopy is used for lubricating oil detection and realizes the detection of metal elements in lubricating oil on the order of μg·g^-1.The proposed method is of great scientific significance for detecting metal elements in lubricating oil by laser-induced breakdown spectroscopy.更多还原