I conducted an experiment mainly in artificial sea-water, in order to investigate whether lead alloy can be used as an anode for cathodic protection. Using “saturated calomel electrode, ” I tested passing natural electrode potential, anode potentials, current and amount of corrosion, respectively.
The followings are the results:
1) As to the corrosion losses concerned, Pb-Ag anode has proved to be highly superior to lead alloy added with As, Sb, Cu, In and Te.
2) For the purpose to improve Pb-Ag anode, the addition of elements such as As, Cu, In and Te are proved to be entirely useless.
3) Pb-Ag-Sb anode is quite effective.
4) In an early stage of electrolysis, Pb alloy anode is corroded mostly.
5) β-PbO₂ is the main composition of the film formed on the surface in the sea-water.
6) Ag and Sn are essential to form a stable film in the early stage of electrolysis.
7) Velocity of forming PbO₂ is the most important factor in attaining corrosion resistance. However, as one can judge from the potentialhour diagram, it is quite unstable and complicated.

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Comparision test of cathodic protection on coiled tube type intercoolers immersed in high resistivity fresh water was done by applying, (1) galvoline anodes, (2) impressed current system using steel bar anodes, (3) zinc rich paint coating, (4) combined system of (2) and (3), and the last system was found to be the best.

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