densities of 25 to 90 mA/cm 2. Hence, pure zinc can be safely
used as an anode in these two electrolytes up to 90 mA/cm 2.
The data presented in Table 6 also indicate that the alloy
Zn + 0.01 wt.% Mg + 0.01 wt.% Pb has anode efficiency values
of 98.7 and 93.3% at a current density of 120 mA/cm 2,
and 98 and 96.6% at a current density of 25 mA/cm = in the
electrolytes C and D, respectively. It is therefore concluded
that the alloy can be used safely as an anode between 25 and
120 mA/cm 2 in the above two electrolytes (C and D), with
anode efficiency values that vary between 93 and 98%.
On the basis of anodic polarization studies, the maximum
anode current density is found to be 207 mA/cm 2. On the
basis of the long-term anode efficiency experiment, however,
120 to 150 mA/cm 2 is found to be a useful range. In fact the
lower limit, namely 120 mA/cm 2, is a better value with a
maximum sustainable anodic current at an anode efficiency
> 95%; the cutoff closed circuit potential for the anode is
- I.OV.
Zinc and its alloy, namely, Zn + 0.01 wt.% Mg + 0.01 wt.%
Pb, can be successfully used as anodes in four types of electrolytes.
All the systems are satisfactory from the point of
view of low corrosion rates, moderate anodic polarization
and high negative OCP values.