激光诱导击穿光谱技术识别航空合金牌号

激光诱导击穿光谱(LIBS)作为一种多元素、高灵敏、非接触式的光谱分析技术,已经被广泛用于钢铁、铝合金等金属材料的定量与定性分析。为将LIBS技术用于航空合金牌号的高准确率识别,对6种不同牌号的航空合金进行了实验测量与分析。实验使用1064nm的Nd∶YAG固体激光器作为激发源,采集了每种合金的100组光谱,每组光谱为100次激光脉冲的平均结果。将得到的航空合金光谱按7∶3的比例划分为训练集和测试集,分别利用全光谱数据和特征谱线数据建立偏最小二乘判别分析(PLS-DA)模型进行航空合金LIBS识别。两种模型得到训练集和测试集的识别正确率均为100%。研究结果表明,LIBS技术与化学计量学结合可以快速准确识别航空合金牌号,且基于特征谱线数据的PLS-DA模型在较少数据输入的情况下可取得与全光谱数据模型相同的结果。实验可为进一步开展航空合金LIBS现场检测工作提供方法参考。     

基于光轴正交的高分辨率激光探针仪实验研究

针对激光探针分辨率低、精度差的问题,提出了一种高分辨率和高精度的激光探针系统。采用光轴正交的双反射镜和大数值孔径聚焦物镜,实现了集成同轴监测和同轴光谱采集系统的激光探针仪,在同轴监测系统作用下,同轴光谱采集系统的微区对准精度达±9μm;基于铝金属样品,实验研究了激光输入能量与分辨率的关系曲线,且在激光输入能量为1.45μJ时,在铝金属表面获得的极限分辨率为2.66μm,并能够采集到有效强度的光谱信号。     

Ash reduction strategies in corn stover facilitated by anatomical and size fractionation

There is growing interest internationally to produce fuels from renewable biomass resources. Inorganic components of biomass feedstocks, referred to collectively as ash, damage equipment and decrease yields in thermal conversion processes, and decrease feedstock value for biochemical conversion processes. Decreasing the ash content of feedstocks improves conversion efficiency and lowers process costs. Because physiological ash is unevenly distributed in the plant, mechanical processes can be used to separate fractions of the plant based on ash content. This study focuses on the ash separation that can be achieved by separating corn stover by particle size and anatomical fraction. Baled corn stover was hand-separated into anatomical fractions, ground to <19.1 mm, and size separated using six sieves ranging from 9.5 to 0.150 mm. Size fractions were analyzed for total ash content and ash composition. Particle size distributions observed for the anatomical fractions varied considerably. Cob particles were primarily 2.0 mm or greater, while most of the sheath and husk particles were 2.0 mm and smaller. Particles of leaves greater than 0.6 mm contained the greatest amount of total ash, ranging from approximately 8 to 13% dry weight of the total original material, while the fractions with particles smaller than 0.6 mm contained less than 2% of the total ash of the original material. Based on the overall ash content and the elemental ash, specific anatomical and size fractions can be separated to optimize the feedstocks being delivered to biofuels conversion processes and minimize the need for more expensive ash reduction treatments.     

激光诱导击穿光谱技术对铁矿石中磷硫碳的快速定量表征

激光诱导击穿光谱(LIBS)技术分析P、S、C元素时,分析波长一般在165~200nm之间,为真空紫外线光谱区,定量分析存在一定难度。根据铁矿石样品特性和分析元素的特点,采用LIBS技术对压片处理(压力为20t、恒压时间10s)的铁矿石标准物质中P、S、C元素进行了定量表征。最终选定样品室环境为抽真空充氩气(Ar)、样品室真空度为50Pa、激发的剥蚀条件为20个预剥蚀、30个剥蚀,并绘制了P、S、C元素定量表征的校准曲线,线性相关系数分别为0.998、0.997、0.998,由此建立了基于LIBS技术的铁矿石成分定量表征方法。采用实验建立的表征方法对铁矿石标准物质中P、S、C进行了定量分析,标准物质GSB03-2023-2006中P、S的测试结果,标准物质GSB03-2855-2012中P、S、C的测试结果分别与认定值相符。结果表明,LIBS技术可以对铁矿石中P、S、C元素实现快速的定量表征。     

智能化技术在铁矿品质检验应用及其发展

随着人工智能在各个领域的日益普及,在冶金行业生产的各个环节,智能化技术应用也日益广泛和深入。近20年来,在铁矿品质控制方面,应用技术从数理统计开始到化学计量学,再发展到人工智能,相关从业专家一直努力向新技术要效率,不断将人工智能最新发展的技术应用于铁矿采矿、配矿、运输、质量验收、炉料准备及炼铁过程品控、自动化生产、在线检测等,使得铁矿品质控制紧跟现代科学技术潮流。文章介绍智能化技术的发展及其在我国铁矿品质检验的应用、发展和趋向。共引用论文65篇。     

Utilization of laser‐assisted analytical methods for monitoring of lead and nutrition elements distribution in fresh and dried Capsicum annuum l. leaves

Laser induced breakdown spectroscopy (LIBS) and laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) have been applied for high‐resolution mapping of accumulation and distribution of heavy metal (lead) and nutrition elements (potassium, manganese) in leaves of Capsicum annuum L. samples. Lead was added in a form of Pb(NO₃)₂ at concentration up to 10 mmol L^?1 into the vessels that contained tap water and where the 2‐months old Capsicum annuum L. plants were grown another seven days. Two dimensional maps of the elements are presented for both laser‐assisted analytical methods. Elemental mapping performed on fresh (frozen) and dried Capsicum annuum L. leaves are compared. Microsc. Res. Tech., 2011. © 2010 Wiley‐Liss, Inc.     

LAMQS analysis applied to ancient Egyptian bronze coins

Some Egyptian bronze coins, dated VI-VII sec A.D. are analyzed through different physical techniques in order to compare their composition and morphology and to identify their origin and the type of manufacture. The investigations have been performed by using micro-invasive analysis, such as Laser Ablation and Mass Quadrupole Spectrometry (LAMQS), X-ray Fluorescence (XRF), Laser Induced Breakdown Spectroscopy (LIBS), Electronic (SEM) and Optical Microscopy, Surface Profile Analysis (SPA) and density measurements. Results indicate that the coins have a similar bulk composition but significant differences have been evidenced due to different constituents of the patina, bulk alloy composition, isotopic ratios, density and surface morphology. The results are in agreement with the archaeological expectations, indicating that the coins have been produced in two different Egypt sites: Alexandria and Antinoupolis. A group of fake coins produced in Alexandria in the same historical period is also identified.     

Application of laser-induced breakdown spectroscopy for characterization of material deposits and tritium retention in fusion devices

Laser-induced breakdown spectroscopy (LIBS) is discussed as a possible method to characterize the composition, tritium retention and amount of material deposits on the first wall of fusion devices. The principle of the technique is the ablation of the co-deposited layer by a laser pulse with P (power density) ≥ 0.5 GW/cm² and the spectroscopic analysis of the light emitted by the laser induced plasma. The typical spatial extension of the laser plasma plume is in the order of 1 cm with typical plasma parameters of n_e ≈ 3 × 10²² m^?3 and T_e ≈ 1–2 eV averaged over the plasma lifetime which is below 1 μs. In this study “ITER-Like” mixed deposits with a thickness of about 2 μm and consisting of a mixture of W/Al/C and D on bulk tungsten substrates have been analyzed by LIBS to measure the composition and hydrogen isotopes content at different laser energies, ranging from about 2 J/cm² (0.3 GW/cm²) to about 17 J/cm² (2.4 GW/cm²) for 7 ns laser pulses. It is found that the laser energies above about 7 J/cm² (1 GW/cm²) are needed to achieve the full removal of the deposit layer and identify a clear interface between the deposit and the bulk tungsten substrate by applying 15–20 laser pulses while hydrogen isotopes decrease strongly after the first laser pulse. Under these conditions, the evolution of the spectral line intensities of W/Al/C/hydrogen can be used to evaluate the layer composition.     

Characterization of a Series of Nitrogen‐Rich Molecules using Laser Induced Breakdown Spectroscopy

A series of nitrogen‐rich molecules, such as 5‐aminotetrazolium nitrate (HAT‐NO₃) and hydrazinebistetrazole (HBT), bis(2,2,2‐trinitroethyl)‐hydrazodicarboxylate (BTHC), cyclotrimethylene trinitramine (RDX), trinitrotoluene (TNT), melamine, sucrose, and L ‐glutamine were studied using laser‐induced breakdown spectroscopy (LIBS). The atomic emission intensities and intensity ratios of the constituent elements from the LIBS spectrum were shown to correlate with the mole fractions and stoichiometries of the molecules. In addition, the amount of oxygen present in the molecule influenced the emission intensities of molecular fragments such as C₂. Finally, we used principal components analysis to analyze the data from the LIBS spectra and separate the different organic molecules based on the atomic emission intensities and ratios.     

激光诱导击穿光谱对水系沉积物的分类及铬元素测定的研究

基于激光诱导击穿光谱技术对水系沉积物中铬元素进行快速定量检测为目的,利用激光诱导击穿光谱仪对标样和样品进行了分析,建立了标样中铬元素浓度与其激光诱导击穿光谱强度间的定标曲线,线性相关系数达到0.992,得到了样品中的铬含量。同时利用主成分分析方法对样品进行了分析,结果表明LIBS技术可用于水系沉积物的分类和鉴定的研究。