Online laser induced breakdown spectrometry for metal particle powder flow analysis during additive manufacturing
Analysis of metal powder flow during additive manufacturing process was carried out by laser induced breakdown spectrometry (LIBS). Coaxial laser cladding is an additive manufacturing technology (laser direct metal deposition) based on part build-up process with metal powder melting by powerful continuous wave laser. A compact and lightweight LIBS probe has been designed to equip the laser cladding setup. Metal powder jet ablation by LIBS probe was carried out to protect probe’s optics and to use non-gated spectrometer. The poor LIBS measurements reproducibility was observed for metal powder jet ablation compared to that for solid metal target. Two different procedures for calibration curve construction (“spectra counting” and "spectra averaging”) were compared in terms of root mean square error of cross-validation (RMSECV) and curve linearity (R2). The better analytical capabilities of online LIBS analysis for tungsten and nickel were achieved with “spectra averaging” approach.