Elemental Mapping of Silicone Rubber Composites by Laser-induced Breakdown Spectroscopy (LIBS)

Elemental mapping of 2D and 3D surface distributions of inorganic filler in silicone rubber composites were obtained to analyze the information on the types and locations of the agglomerates. The elemental mapping of surface distribution in the samples were plotted by selecting the characteristic line strength of the elements, such as C, O, Al, Na, K, etc. Compared with the distribution of O and the accumulation of Al, the location of ATH filler and Al
2
O
3
particles can be characterized by the spectral line intensity distribution of Al. The identification of the agglomerates was confirmed with SEM/EDS. In addition, the surface distribution of Na is similar to K, which reflect the locations of contamination on the surface of the sample. This indicates that the 2D element mapping by LIBS can characterize the distribution of insulator contamination. On the basis of the strong linear relationship between the number of laser pulse bombardment and the depth of ablation, The 3D spatial information was obtained by continuously accumulating the intensity distribution of a single bombardment. The content and locations of Al abruptly decay and eventually stabilize with the increase of the depth of ablation. Finally, before and after ablation of the morphology were compared by the SEM/EDS. The lower the content of ATH filler, the more ablated the bottom of the ablation pit. LIBS has a great advantage in scanning speed and scanning area comparing to EDS/SEM. The obtained elemental images provide a valuable basis for further interpretation.