Figure 8.
SEM micrographs of silica coatings with different morphologies. (a) SiO2 coating on the surface of stainless steel: Note the surface appears smooth at low magnification, while a good distribution of visible particles of silica is observable at high magnification. (b) SiO2 coating on the surface of a titanium alloy substrate after an expansion test: Note it is difficult to see at low magnification, while at high magnification there are visible silica particles. In addition, an interesting property of this coating is its flexibility. (c) A cracked SiO2 coating on steel. (d) SiO2 coating with bubbles on the surface of the steel.