Corrosion Inhibitors for Metals in Naval Environments

Macrocyclic compounds, phthalocyanines, were studied as corrosion inhibitors for metals because of their ability to interact with the surface, their stability, and their rigid planarity. A synthetic approach was used to tailor-make a system to achieve best corrosion inhibition. The steps involved consisted of 1 Synthesis of two types of water-soluble phthalocyanines - tetrasulfonated and tetraamino quarterized metallo-phthalocyanines. When tested in 1 Sodium Chloride at pH2, they were not very effective inhibitors, 2 Synthesis of polymeric phthalocyanines as corrosion inhibiting coatings - polymerization by decarboxylation of chloroiron III tetracarboxyphthalocyanine and reacting the acid chloride to attach 6 to 12 carbon alkyl chain. This showed corrosion inhibition efficiency of up to 88. The effect of central metal ion into the phthalocyanine ring was most effective with long alkyl chanin ZnII material. The inhibition with the above system was limited to steels only and could not be effective on aluminum alloys. However, when aluminum surface was pre-treated with aminosilanes. The binding of the phthalocyanine improved significantly. Keywords Impedance analysis Electrochemistry Corrosion resistant alloys Sea water corrosion.