(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
Figure 3: SEM micrographs of cross sections of titanium-based coatings and histogram plot of the pore size distribution: ((a), (b), and (c)) barrel length 300 mm; ((d), (e), and (f)) barrel length 400 mm; ((g), (h), and (i)) barrel length 500 mm (SEM, backscattered electron mode).