Use of dicyclohexylamine nitrite in inhibition of coupled zinc and steel

Abstract The effect of dicyclohexylamine nitrite (DCHN), a volatile corrosion inhibitor, on the corrosion behaviour of steel, zinc, and coupled steel and zinc was studied. Corrosion rates were determined using mass loss methods as well as potentiodynamic polarisation and ac impedance measurements. Potentiodynamic polarisation studies show that DCHN acts as an anodic inhibitor in the corrosion of mild steel. However, for zinc, DCHN acts to accelerate corrosion. This is attributed to surface chelation between DCHN and zinc, resulting in the formation of a soluble complex. Zero resistance ammetry was used to investigate the dissolution behaviour of a galvanic couple between steel and zinc in the presence of DCHN; in such as situation, the inhibitor effectiveness depends mainly on its concentration.