Department of Chemistry, Mokpo National University, Muan-gun, Korea.
Plasma Spectroscopy Analysis Center, Mokpo National University, Muan-gun, Korea.
Appl Spectrosc. 2023 Apr;77(4):371-381. doi: 10.1177/00037028231154615. Epub 2023 Feb 1.
A simple cost-effective laser-induced breakdown spectroscopy (LIBS) instrument was used for quantification of major elements in several nickel alloys and also sorting them. A compact low-power diode-pumped solid-state laser and a miniature low-resolution spectrometer were assembled for the LIBS instrument. Material properties of the nickel alloys depend mainly on the composition of the major elements, Ni, Cr, and Fe, ranging from a few to ∼60 wt%. The emission peaks at 547.7 nm, 520.4 nm, and 438.1 nm for Ni, Cr, and Fe, respectively, were chosen for this analysis. The analytical performance was found to be enough for the quantification of Ni, Cr, and Fe in the nickel alloys. Limits of detection and accuracy were estimated to be a few weight percent (wt%) and measurement precisions were less than 10% in terms of relative standard deviation. The calibration performance of this intensity-based method was compared with that of the "ratio method" which is used in conventional optical emission spectroscopy analyses. The comparison indicates that the intensity-based method is more appropriate with the low-performance LIBS instrument that detects emission peaks of only a few major elements. Also, multivariate modeling of the six different nickel alloy samples based on the emission peak intensities of Ni, Cr, and Fe was performed using -nearest neighbors (KNN) and linear discriminant analysis (LDA). The KNN and ordinary LDA models showed 95.0% and 98.3% classification correctness for the separate test data set, respectively. To improve classification performance further, the two-step LDA model was trained. In this approach, the two closest sample classes responsible for the decrease in the classification correctness were separately modeled in the second step to exploit their difference effectively. The two-step LDA model showed 100% correctness in classifying the test objects. Our results indicate that such a low-performance LIBS instrument can be effectively utilized for quantitative analysis of the major elements in the nickel alloys and their rapid identification or sorting in combination with an appropriate multivariate modeling algorithm.
一种简单且经济高效的激光诱导击穿光谱（LIBS）仪器被用于定量分析几种镍合金中的主要元素，并对其进行分类。该 LIBS 仪器由紧凑型低功率二极管泵浦固态激光器和微型低分辨率光谱仪组成。镍合金的材料特性主要取决于主要元素 Ni、Cr 和 Fe 的组成，其含量范围从几到 ∼60wt%。分别选择了 547.7nm、520.4nm 和 438.1nm 处的发射峰用于此分析。结果表明，该分析方法足以定量分析镍合金中的 Ni、Cr 和 Fe。检测限和精度估计为几个重量百分比（wt%），相对标准偏差的测量精度小于 10%。将这种基于强度的方法的校准性能与传统光谱发射分析中使用的“比值法”进行了比较。比较表明，对于仅检测少数几个主要元素发射峰的低性能 LIBS 仪器，基于强度的方法更为合适。还基于 Ni、Cr 和 Fe 的发射峰强度，对六个不同镍合金样品进行了多元建模，使用了最近邻（KNN）和线性判别分析（LDA）。KNN 和普通 LDA 模型分别对单独的测试数据集显示了 95.0%和 98.3%的分类正确性。为了进一步提高分类性能，训练了两步 LDA 模型。在这种方法中，在第二步中分别对负责分类正确性降低的两个最接近的样本类进行建模，以有效地利用它们之间的差异。两步 LDA 模型对测试对象的分类正确率达到了 100%。我们的结果表明，这种低性能的 LIBS 仪器可以有效地用于定量分析镍合金中的主要元素，并结合适当的多元建模算法，对其进行快速识别或分类。
