Anodes, sandblasted

With the aim to enhance the apparent current density of Ni cathodes, several surface treatments have been proposed to increase the surface area. The simplest procedure, and therefore the one of routine, consists in sandblasting the surface. The Tafel line turns out to be shifted towards higher currents without changes in its slope [137], Sandblasting is a common operation also prior to proceeding to the further activation of cathodes (or anodes) [259]. The aim is to provide a support of larger surface area and to ensure better adhesion of the overlayer. 

Figure 5 - Surface Grain Structure of a Cast Pb-Ca-Ag Sandblasted Anode (magnification 160x)...

The surface condition of the test sample is a critical variable in all hydrogen uptake tests. Studies have shown that abraded or sandblasted surfaces absorb hydrogen more readily than as-pickled surfaces [/]. Thickening of the surface oxide film by anodizing or thermal oxidation further retards absorption. The actual surface finish anticipated in service should be evaluated. 

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