Fibre-reinforced geopolymer composites micro-nanochemistry by SEM-EDS simulations

The focus of the present study is on fibre-reinforced geopolymer composites, whose optimization and application necessarily need a detailed chemical characterization at the micro-nanoscale. In this regard, many geopolymer composites presenting micro and nanometric architectures pose a challenge for scanning electron microscopy with energy dispersive X-ray microanalysis (SEM-EDS) quantification, because of several potential sources of errors. For this reason, the present work reports a SEM-EDS Monte Carlo approach to carefully investigate the complex physical phenomena related to the cited quantification errors. The model used for this theoretical analysis is a simplified fibre-reinforced geopolymer with basalt-derived glass fibres immersed in a potassium-poly(sialatesiloxo) matrix. The simulated SEM-EDS spectra showed a strong influence on the measured X-ray intensity of (i) the sample nano-to-micro architecture, (ii) the electron beam probing energy and (iii) the electron probe-sample-EDS detector relative position. The results showed that, compared to a bulk material, the X-ray intensity for a nano-micrometric sized specimen may give rise to potential underestimation and/or overestimation of the elemental composition of the sample. The proposed Monte Carlo approach indicated the optimal instrumental setup depending on the sample and on the specific SEM-EDS equipment here considered.