Fatty acids as inhibitors of copper corrosion in chloride solutions

The inhibiting effect of straight chain mono- and di-carboxyilic acids and n-lauroylsarcosine on copper corrosion in 0.01 and 0.1 M NaCl solutions was studied. Tests were performed in the presence of 10-2 M concentration of inhibitors at pH 5.7 and 8.0, at 25 °C. Polarisation resistances were measured during 24 hours. Corrosion rate of Cu in the different solutions was determined by weight losses in 20 day tests. Anodic and cathodic polarisation curves were recorded after 24 hour immersion of electrodes in the solutions. The results showed that decanoic, undecanoic, sebacic acids and n-lauroylsarcosine at 10-2 M concentration were efficient inhibitors of copper corrosion in 24 hour tests in 0.01 and 0.1 M NaCl solutions at pH 5.7 and 8.0. By increasing the time length of tests, the inhibiting effect decreased or changed in stimulating effect. In 20 day tests only n-lauroysarcosine at pH 5.7 and undecanoic acid at pH 8.0 maintained their high inhibiting efficiency.