A field emission scanning electron microscope (FE-SEM) (Hitachi, S-4800) was used to observe the
microstructure of the coatings. A topology and surface roughness of the coatings was analyzed by
laser microscopy (KEYENCE, VK-X200 series). The average surface roughness was evaluated by scanning
the coating area of 70 x 70 mm2 in non-contact mode (average of five different measurements was
reported). X-ray photoelectron spectroscopy (XPS) was utilized to evaluate the surface chemistry of
the coatings.