Figure 4. The arrow indicates a Ni rich particle in the SEM image (a), which was identified by the EDS mapping (b).
Figure 5 is a representative optical image demonstrating the formation of ferrite and perlite microstructure of the steel substrate and the coating thickness irregularity. Alumina was identified by EDS analysis adhered to the substrate due to the blasting, and it appears as the dark grey phase on the optical microscopy. There is no good resolution of coating splats in optical microscopy.