基于远程LIBS技术的镍基高温合金成分分析方法的研究

基于自行设计搭建的远程激光诱导击穿光谱(LIBS)系统,完成了远程LIBS的聚焦特性分析,并对远程LIBS技术应用于镍基高温合金成分分析的实验方法进行了研究.该LIBS系统具备激光发射光路和信号采集光路同轴且独立变焦的特点,通过自动聚焦,可实现1～10 m的远程分析.研究表明:受激光聚焦焦深的影响,等离子体光信号可探测...

Quantitative Analysis of Nickel-Based Superalloys Based on a Remote LIBS System

Based on the self-designed remote laser-induced breakdown spectroscopy (LIBS) system, the focusing characteristics of remote LIBS were analyzed, and the experimental method of quantitative analysis of nickel-base superalloy by remote LIBS was studied. In this LIBS system, the laser focusing and the plasma optical signal acquisition optical paths are coaxial and independently focused. Through automatic focusing, the remote analysis of 1~10 m can be achieved. The results show that affected by the depth of focus, the detectable range of plasma optical signal increases with the increase of working distance. That is, the requirement of the LIBS system for focusing accuracy decreases. At the same time, the decrease of power density caused by the increase of ablation spot size and the decrease of signal acquisition solid angle make the spectral line intensity attenuate in inverse proportion to the fourth power as the working distance increases. In this paper, the standard curves of Ni, Cr, Nb, Mo, Ti and Al in GH4169 nickel-based superalloy were established using the standard curve method without internal standard with internal standard. The goodness of fit of the standard curve with internal standard (0.999 7, 0.999 4, 0.999 87, 0.999 1, 0.998 1 and 0.999 7) was significantly better than that of the standard curve without internal standard (0.953 2, 0.876 6, 0.897 4, 0.914 5, 0.938 4 and 0.991 6). Finally, LIBS and XRF were compared. For major elements Ni, Cr, Nb and Mo, the relative standard deviations of the two methods were 1.75%~3.90% and 0.10%~0.52%, and the relative errors were 0.48%~0.92% and 0.64%~2.25%, respectively; for trace elements Ti and al, the relative standard deviations of the two methods were 5.58%, 5.86% and 2.39%, 5.64%, the relative error is 2.75%, 3.14% and 4.68%, 2.39% respectively. Due to the instability of plasma, the precision of the remote LIBS method is slightly lower than that of the XRF method. However, LIBS method can effectively reduce the measurement error through repeated measurements, which indicates that LIBS technology is feasible for remote on-line analysis of nickel-based superalloys.