A case study: Identification of interfacial phases in coated steel via simultaneous STEM EDS, EELS, and ELNES with STEMPack/EDS and GIF Tridiem system

The sample investigated was a section of steel pipe with a multi-layer wear- and corrosion-resistant coating developed by Dr. Deepak Upadhyaya of Sub-One Technology (sub-one.com). An important physical parameter of this coating is its adhesion to the underlying steel. To achieve an understanding of the coating adhesion it was important to learn the nature of the phases that form at the steel-coating interface. The targeted spectrum image area was sampled as an array of 160 x 40 points with 2.7 nm spacing, thus yielding 6400 pairs of EELS and EDS spectra (one pair at each sample point). The acquisition time per pixel was 0.5 s. The EELS acquisition was configured to capture the energy-loss range from 50 to 1050 eV with collection angle of about 17 mR and convergence angle 10 mR, while the EDS acquisition was set up to cover X-ray energies from 0.2 to 20 keV. A scan through the resultant data set, integrated laterally over 90 sample points parallel to the interface is shown in thus movie.