Comparison of the corrosion inhibition efficiencies of the ATMP-molybdate system and the ATMPmolybdate-Zn2+system

Abstract

The formulation consisting of 50ppm ATM and 300ppm MoO4 2– had only 32 per cent efficiency in inhibiting the corrosion of mild steel immersed in a neutral aqueous environment containing 60ppm C1–, whereas the ATMP (50ppm) – MoO4 2– (300ppm) – Zn2+ (50ppm) system had 96 per cent inhibition efficiency. The lower inhibition efficiency in the former case was due to the dissolution of the protective film formed on the metal surface, and getting precipitated in the bulk of the solution; this system controlled the anodic reaction only. The latter system controlled both the anodic and cathodic reactions; the dissolution of the protective film formed on the metal surface was reduced to a greater extent.