Balzer Herbert, Hoehne Manuela, Noll Reinhard, Sturm Volker
Fraunhofer-Institut für Lasertechnik, Steinbachstrasse 15, 52074, Aachen, Germany.
Anal Bioanal Chem. 2006 May;385(2):225-33. doi: 10.1007/s00216-006-0347-z. Epub 2006 Mar 29.
In this study a new approach to the online monitoring of the Al depth profile of hot-dip galvanised sheet steel is presented, based on laser-induced breakdown spectroscopy (LIBS). The coating composition is measured by irradiating the traversing sheet steel with a series of single laser bursts, each at a different sheet steel position. An ablation depth in the same range as the coating thickness (about 10 microm) is achieved by applying a Nd:YAG laser at 1064 nm in collinear double-pulse and triple-pulse mode. The ablation depth is controlled by adjusting the burst energy with an external electro-optical attenuator. A fingerprint of the depth profile is gained by measuring the LIBS signals from zinc, aluminium and iron as a function of the burst energy, and by post-processing the data obtained. Up to three depths can be sampled simultaneously with a single laser burst by measuring the LIBS signals after each pulse within the laser burst. A concept for continuously monitoring the Al depth profile during the galvanising process is presented and applied to different hot-dip galvanised coatings. The method was tested on rotating sheet steel disks moving at a speed of up to 1 m/s. The potential and limitations of the new method are discussed.
本研究提出了一种基于激光诱导击穿光谱法（LIBS）在线监测热镀锌薄钢板铝深度分布的新方法。通过用一系列单个激光脉冲照射移动的薄钢板来测量涂层成分，每个脉冲位于薄钢板的不同位置。通过在共线双脉冲和三脉冲模式下应用波长为1064nm的Nd:YAG激光，可实现与涂层厚度相同范围（约10微米）的烧蚀深度。通过使用外部电光衰减器调节脉冲能量来控制烧蚀深度。通过测量锌、铝和铁的LIBS信号作为脉冲能量的函数，并对获得的数据进行后处理，得到深度分布的指纹图谱。通过测量激光脉冲内每个脉冲后的LIBS信号，单个激光脉冲可同时对多达三个深度进行采样。提出了一种在镀锌过程中连续监测铝深度分布的概念，并将其应用于不同的热镀锌涂层。该方法在以高达1m/s速度移动的旋转薄钢板圆盘上进行了测试。讨论了新方法的潜力和局限性。
