Weathering test on protective coatings has been arried out for two years (since April, 1960) at the even sites as mentioned in the 1st report.
The rust-inhibitive pigments examined were: red ead, lead suboxide, lead cyanamide, calcium plumbate, basic lead chromate, metallic lead, zinc chromate, zinc oxide, zinc powder, aluminum powder and iron oxide.
The results showed that steel specimens coated with paints containing red lead, lead suboxide, basic lead chromate and zinc chromate are protected more effectively than those coated with the paint prepared from lead cyanamide, zinc oxide, zinc powder and iron oxide.
The most severe attack was observed in the seashore (Omaezaki) and subtropical districts (Makurazaki).

View full abstract

High molecular-weight mercaptan cannot be used as a corrosion inhibitor of Cu like amine in liquid media.
Ineffective adsorbability at lower temperature depends on defficiency of donating ability of an unshared electron-pair of S-atom of mercaptan. The defficiency can be made up by elevating temperature. Without the aid of being affected by the elevation of the temperature, suitable amounts of strong electron-donating substances, such as alcohol, ether, acid, ester, and amine, can enhance the adsorption of mercaptan. As those substances can, by hydrogen-bonding, draw H₂O which is strongly adsorbed on Cu-surface even if dried, the spot where adsorbed H₂O is forced to depart is refilled with mercaptan. S-atom in mercaptan donates its electrons to the metal by displacing H₂O, schematically illustrated as follows:
M: metal, R: H or alkyl radical
Mercaptan acts as corrosion inhibitors when collaborated with electron-donating substances, such as alcohol, ether, acid, ester, and amine.

View full abstract