Synthetic Samples Preparation to Identify Al_2O_3 Particles in Steel by Laser Ablation ICP Mass Spectrometry

摘要

The analytical technique based on laser ablation of the sample followed by Argon plasma excitation and mass spectrometry detection (LA-ICP-MS), was used to identify Al_2O_3 inclusions size and distribution on surface in iron samples. The main aim of the work is to evaluate different approaches for synthetic iron matrix samples preparation. Samples were made in four formats, from pure Fe powder (<25 μm) and Aluminum oxide with different ranges of particle size up to 100 μm: 1) metal samples, by melting in an induction furnace; 2) compressed pellets, by pressing at 50 ton cm~(-2); 3) sintered compact samples, by sintering (1 050℃) and rolling (950℃) the compressed pellets; 4) beads (glass samples), by alkaline melting with lithium metaborate and sodium carbonate. The study includes the optimization of operating parameters; the evaluation of differences in ablation yield, by comparing the Fe signal intensities; and, the identification of Al_2O_3 particles in heterogeneous zones, by monitoring the Al time resolved signals. The optimized laser operating parameters were: laser pulse energy of 2.5 mJ pulse_(-1), repetition rate of 10 Hz, and scanning speed of 3 μms_(-1). A good correlation between Al intensity peaks and mean size of particles was found for all types of produced samples, allowing estimate the size and the distribution of the Al_2O_3 particles in the sample surface.