A spectromicroscopy study of the corrosion of polymer coated steel

Soft X‐ray spectromicroscopy studies of pitting corrosion of reinforcing steel bar

“…The extent of corrosion detected by analysis of the Fe L 3 -edge μ-XANES spectra from the two areas can be further confirmed by comparing these results to the Fe XRF maps (Figure 2D,E). Figure 2D indicates a higher Fe fluorescent intensity than that in Figure 2E when comparing the spots from the uncorroded regions (spots [15][16][17][18][19][20]. Comparing the Fe XRF maps from the heavily corroded regions from Areas 1 and 2 (spots 1-5) shows the difficulty in using just these XRF maps to determine which area is more corroded because both regions have similar Fe fluorescent counts (~1500 counts).…”

“…The reason why the spectra from spots 1 to 4 in Area 2 have a higher Fe (III) contribution may be due to exposure to O 2 (g) during the corrosion test or The comparison of the fitted TEY and PFY Fe L 3 -edge μ-XANES spectra from Area 1 and Area 2 demonstrates that Area 1 was less corroded than Area 2 due to the higher ratio of iron metal to iron oxides (Fe (II/III) + Fe (III)) detected in the spectra from Area 1. For example, from the TEY LCF fitting results, the ratio of rebar to Fe (II/ III) from the spots located in the uncorroded region (spots [15][16][17][18][19][20] in Area 1 was between 0.96 and 1.27 (Table S1), while this ratio ranged from 0.25 to 0.75 (Table S3) for spots from Area 2 corresponding to the uncorroded regions (spots [15][16][17][18][19][20]. For the PFY fitting results from spots 15 to 20, the rebar to iron oxides ratio in Area 1 was either 19.00 or 24.00 (Table S2), while this ratio decreased to 13.29 to 19.00 (Table S4) when the spectra from Area 2 were studied, which is consistent when compared with the analysis of the TEY μ-XANES spectra.…”

“…12 Although X-ray microprobe has been previously applied in many research areas including geosciences, 13 biosciences, 14 and material science, 15 most microprobe images were either generated using hard X-rays or in transmission mode when using soft X-rays (ie, scanning transmission X-ray microscopy; STXM). [16][17][18][19][20][21][22] The authors have previously demonstrated the application of hard X-ray XRF microprobe to the study of the corrosion of materials. [16][17][18] However, the soft X-ray-based methodology discussed herein possesses the advantages of faster XRF map collection times and the ability to probe multiple depths of a sample with the trade-off being the need to remove the polymer film prior to analysis.…”

“…[16][17][18][19][20][21][22] The authors have previously demonstrated the application of hard X-ray XRF microprobe to the study of the corrosion of materials. [16][17][18] However, the soft X-ray-based methodology discussed herein possesses the advantages of faster XRF map collection times and the ability to probe multiple depths of a sample with the trade-off being the need to remove the polymer film prior to analysis. The objective of the present study was to demonstrate how the combination of soft X-ray XRF microprobe and μ-XANES can be used to map the corrosion products on corroded rebar surfaces and to identify the corrosion products at various depths by collection of TEY and PFY μ-XANES spectra.…”

A spectromicroscopy study of the corrosion of fusion‐bonded epoxy–coated rebar

“…The analysis of steel rebar corrosion through a polymer film using X‐ray spectromicroscopy has been demonstrated by Situm et al and Barlow et al The methodology utilized was a combination of X‐ray fluorescence (XRF) mapping using multiple excitation energies and Fe K‐edge X‐ray absorption near edge spectroscopy using a micrometer sized X‐ray beam (μ‐XANES) . The excitation energy of 7115 eV was used for XRF mapping because of the difference in absorption cross‐sections between unoxidized/bare Fe metal and oxidized Fe found in corrosion products . This difference in absorption cross‐sections allows for the detection of regions containing high Fe metal concentrations (low corrosion product concentration) or regions containing low Fe metal concentrations (high corrosion product concentration) .…”