Abstract
Some effective inhibitors against chemical (or natural) corrosion phenomenon, not induced by the underground stray current were investigated. Terrible corrosion is often seen on the cables dipped in the water of manhole. Therefore, the corrosion inhibitions of such reagents added into manhole water as ammonium-sulfate, sodium-sulfate, sodium silicate, sodium-hexame-taphosphate, α-picoline and aliphatic-amine were examined. For the purpose of accelerating the corrosion rate of lead, electrolysis and galvanic action by the contact of other metal or material were applied, and the corrosion potentials of the test pieces were measured in the same water.
1) The best effective corrosion inhibition was observed in the cases of addition of ammonium-sulfate or sodium-sulfate. Other reagents above mentioned were less effective, because they could not resist the local corrosion such as “pitting”, although they seemed to reduce total weight loss of the test piece.
2) The corrosion inhibition of ammonium-sulfate was found in the cathodic as well as anodic corrosion.
3) The contact of more electronegative metal or nonconducting material as glass on the corroded surface was usefull for the auxiliary test to evaluate effectiveness of inhibitors. This method of corrosion test seems to be useful practcally.
