THE INHIBITION OF COPPER CORROSION IN 0.1 M NACL UNDER HEAT-EXCHANGE CONDITIONS

The inhibiting effects of 5-methylbenzotriazole, 5-chlorobenzotriazole , 5-n-hexylbenzotriazole, 2,4-dimercaptopyrimidine and 2-amino-5-merca ptothiadiazole at 0.1 and 0.5 mM concentrations on the copper corrosio n in 0.1 M NaCl solutions under heat exchange conditions (Delta T = 60 degrees C) are examined. The inhibiting efficiency of the different a dditives is evaluated from anodic and cathodic polarization curves and from the polarization resistance values after 2 h. The variation of t he corrosion rate of copper with time is followed through the measurem ent of the polarization resistance values for a period of 100 h. The i nfluence of the inhibitors is evaluated by the changes of the polariza tion resistance values with time. All the tested inhibitors at 0.5 mM concentration show high inhibiting efficiency. Only at 0.1 mM concentr ation, an appreciable decrease of the inhibiting efficiency of the thi adiazole derivative is observed. The examined compounds can afford pro tection to an already corroded copper surface, blocking or at least re ducing significantly the corrosion process. In all experimental condit ions investigated 5-n-hexylbenzotriazole provides the best inhibition efficiency.