激光诱导击穿光谱定量化标定谱线自动选择方法

选择合适的特征谱线是以内标法对激光诱导击穿光谱进行定量化分析的前提,需要科研工作者精心分析和比较,往往耗费大量精力和时间,而且还不能保证结果最优。基于遗传算法为内标法提出了一种从原始光谱中自动选择分析线和参考线的方法,使用该方法从低合金钢样的LIBS光谱中为锰(Mn)、镍(Ni)、铬(Cr)、硅(Si)和铁(Fe)元素分别选择了用于内标法定量分析的分析线和参考线。优选得到的最优谱线为,Mn的分析线和相应的参考元素Fe的参考线分别是403.306 8和368.745 7 nm,Si的分析线和相应的参考元素Fe的参考线分别是288.157 7和427.176 1 nm,Cr的分析线和相应的参考元素Fe的参考线分别是286.510 0和272.753 9 nm,Ni的分析线和相应的参考元素Fe的参考线分别是352.453 6和358.698 5 nm。最后基于优选得到的谱线以内标法对这些元素分别进行了定量分析,结果证明,使用这种谱线选择方法能够自动从原始光谱中找到最优特征谱线,使内标法定量分析得到最好的结果。     

激光诱导击穿光谱微区分析的研究应用进展

激光诱导击穿光谱微区分析通常是指利用紧聚焦激光束在微米尺度范围对样品表面进行分析的技术。相比于常规激光诱导击穿光谱分析,微区分析可以在更小范围、更少样品的情况下提供更加被分析样品丰富的形态、结构、含量信息,因而应用领域广泛。本文介绍了激光诱导击穿光谱微区分析在激光源选择以及光路系统结构方面的应用状况,综述了其在金属、半导体、动植物等领域的应用研究进展,讨论了目前存在的问题,对发展前景和发展方向进行了展望。     

利用激光诱导击穿光谱对铝合金成分进行多元素同时定量分析

利用激光诱导击穿光谱定量分析了铝合金中多种元素的成分。采用Nd∶YAG脉冲激光器,在空气环境下烧蚀铝合金固体样品获得等离子体。利用多通道光栅光谱仪和CCD检测器对200～980 nm波长范围的光谱进行同时检测。研究了检测时延、激光脉冲能量、元素深度分布对光谱强度的影响,考虑这些因素之后对实验参数进行了优化。在优化的实验参数下对国家标准铝合金样品中的八种元素Si,Fe,Cu,Mn,Mg,Zn,Sn及Ni进行了定标,并利用定标曲线对一种铝合金样品进行了定量分析。实验结果表明,测量结果的相对标准偏差(RSD)最大为5.89%,相对误差在-20.99%～15%范围内,说明对铝合金样品成分进行定量分析,激光诱导击穿光谱是一种有效的光谱分析工具,但是分析结果的准确度仍需要提高。     

基于LIBS技术在线监测熔融铝水中的元素成分

在辽宁忠旺集团有限公司的熔铸厂,利用自主研制的LIBS液态金属成分在线分析仪对熔融铝水的成分进行了在线监测.研究了通入探杆中氩气的最佳流量以及探测深度与氩气波动的规律,发现氩气流量为1~1.4L/min时,光谱强度最强,探测深度位于氩气压力波动范围在±300Pa,并且压力波动有规律时的位置,各元素浓度稳定性好;利用实验室分析得到的固样数据对设备进行了标定,长时间测试得到的在线监测结果为:Si、Fe、Cu、Mn、Cr的重复精度都小于2%;浓度在0.1%~1%之间的Si、Fe、Mg的测量偏差都小于0.01%,浓度低于0.1%的Cu、Mn、Cr的测量偏差都小于0.001%;探杆多次升降浓度测量的稳定性小于3%.LIBS液态金属成分分析仪的测量重复精度、测量偏差以及多次升降测量的稳定性都能满足工业现场要求,完全可以实现实时、在线监测熔融铝水的成分.     

In situ analysis of magnesium alloy using a standoff and double-pulse laser-induced breakdown spectroscopy system

To monitor the components of molten magnesium alloy during the smelting process in real time and online, we designed a standoff double-pulse laser-induced breakdown spectroscopy (LIBS) analysis system that can perform focusing, collecting and imaging of long-range samples. First, we tested the system on solid standard magnesium alloy samples in the laboratory to establish a basis for the online monitoring of the components of molten magnesium alloy in the future. The experimental results show that the diameters of the focus spots are approximately 1 mm at a range of 3 m, the ablation depth of the double-pulse mode is much deeper than that of the single-pulse mode, the optimum interpulse delay of the double pulse is inconsistent at different ranges, and the spectral intensity decays rapidly as the range increases. In addition, the enhancement effect of the double pulse at 1.89 m is greater than that at 2.97 m, the maximum enhancement is 7.1-fold for the Y(I)550.35-nm line at 1.89 m, and the calibration results at 1.89 m are better than those at 2.97 m. At 1.89 m, the determination coefficients (R²) of the calibration curves are approximately 99% for Y, Pr, and Zr; the relative standard deviations (RSDs) are less than 10% for Y, Pr, and Zr; the root mean square errors (RMSEs) are less than 0.037% for Pr and Zr; the limits of detection (LODs) are less than 1000 ppm for Y, Pr, and Zr; and the LODs of Y, Pr, and Zr at 2.97 m are higher than those at 1.89 m. Additionally, we tested the system on molten magnesium alloy in a magnesium alloy plant. The calibration results of the liquid magnesium alloy are not as favorable as those of the sampling solid magnesium alloys. In particular, the RSDs of the liquid magnesium alloy are approximately 20% for Pr and La. However, with future improvements in the experimental conditions, the developed system is promising for the in situ analysis of molten magnesium alloy.