利用自行搭建的LIBS装置对原铝中硅铁含量进行了分析测试, 测试前对原铝试样进行了微观形貌分析, 研究发现原铝中硅元素除有个别区域聚团现象外, 其分布相对较为均匀; 铁元素多以团状汇聚形态出现, 且无明显的分布规律。 实验分别考察了激光脉冲能量对激光诱导原铝等离子体光谱的影响, 发现随着激光脉冲能量的增大, 硅、 铁元素信噪比先增加后减小, 硅、 铁谱线信噪比最大值均出现在160 mJ处, 实验选取的激光脉冲能量为160 mJ。 在上述较为合理的实验条件下, 以内标法为基础, 分别采用两种标样(纯铝标样与自选标样)建立了定标模型; 结果表明: 相比于纯铝标准试样, 采用自选试样建立的定标模型不够理想, 且数据的离散程度较大, 铁元素直线拟合优度仅为0.921 3, 相对标准偏差也较大。 采用纯铝标样时, 在试样不旋转的情况下, 硅、 铁元素定标曲线拟合优度分别为0.961 1与0.974 1, 相对标准偏差分别为8.85%与9.43%, 且误差棒显示误差随定标试样的硅、 铁含量升高而增大。 当试样台保持转速50 r·min-1条件下进行实验, 发现硅、 铁元素定标曲线的拟合优度分别为0.978 5与0.988, 相对标准偏差分别为3.78%与3.4%, 相比于试样平台固定情况下的定标结果, 拟合优度明显改善, 相对标准偏差也有所降低, 定标模型明显优于自选试样建立的模型。 使用两种定标模型对25个测试样进行了分析测试, 比较了两种测试结果的相对误差, 纯铝定标试样由于含量梯度较大, 跨度较宽, 采用该标样建立的定标模型对低铁原铝试样测试适应性相对较差, 而自选试样建立的定标模型虽然不够理想, 但针对低铁原铝试样的测试适应性相对较好。 对激光诱导原铝产生的等离子体进行了诊断, 通过镁元素几条离子谱线的玻耳兹曼图, 计算出了等离子体温度约为9 163.63 K, 利用镁元素一条谱线的Stark展宽估算出等离子体电子密度为1.69ⅹ1017 cm-3, 验证了激光诱导原铝等离子体处于局部热力学平衡状态的假设是成立的。

The content of silicon and iron in primary aluminum were detected by self-built LIBS device. The micro-morphology analysis of the primary aluminum sample was carried out before the experiment, It was found the distribution of silicon element is relatively uniform in the primary aluminum except little silicon has agglomerated in partial areas, the iron elements mostly appeared in agglomerated form, and there was no obvious distribution rule. The effects of laser energy on plasma spectrum characteristics were investigated in the paper. It was found that the signal-to-noise ratio of silicon and iron analytical lines increased firstly and then decreased with the increasing of laser energy, when the laser energy reached 160mJ, the signal-to-noise ratio was maximized, so the laser energy 160 mJ is the more reasonable experimental condition. The calibration model was established based on the CC method using two standard samples (pure aluminum standard samples and self-selected standard samples) under the above reasonable experimental conditions. The results showed that the calibration curve established by the self-selected sample was not ideal compared with the calibration curve established by standard samples, and there were large errors in the results, The fit goodness of the iron element calibration model is only 0.821 3, and the relative standard deviation is also large. When the pure aluminum standard samples were used, under the condition of fixed sample, the fit goodness of the calibration curves for silicon and iron elements was 0.961 1 and 0.974 1, respectively, and the relative standard deviations were 8.85% and 9.43%, respectively. Errors expressed by error bars increased with the increasing of silicon and iron contents in the pure aluminum standard samples. Under the condition of rotating sample pool, the fit goodness of the calibration curves for silicon and iron was 0.978 5 and 0.988, respectively, and the relative standard deviations were 3.78% and 3.4%, respectively. The calibration results showed that the fit goodness was significantly improved and the relative standard deviation was also reduced compared with fixed sample pool condition. The calibration model was significantly better than the model established by the self-selected samples. The 25 samples were detected using two different calibration models by LIBS, the relative errors for the results obtained from different models were compared, and the content of pure aluminum samples has a larger concentration gradient and a wider distribution, so the models obtained from pure aluminum samples have relatively poor adaptability to low-iron primary aluminum samples, while the calibration model established by the self-selected samples is not ideal, but the measurement adaptability for low-iron primary aluminum samples is relatively good. The plasma generated by laser-induced primary aluminum was diagnosed. The plasma temperature was calculated to be approximately 34 100.14 K from the Boltzmann diagram of several magnesium ion lines, The plasma electron density was estimated to be 1.69×1017 cm-3 by the Stark broadening of a line of magnesium, which confirms that the assumption that the plasma obtained from laser induced raw aluminium is in a local thermodynamic equilibrium state is valid.