CORROSION INHIBITION OF COPPER BY 2-MERCAPTOBENZOTHIAZOLE AND BENZOTRIAZOLE IN LOW-CONDUCTIVITY SOLUTIONS

Corrosion inhibition of copper in a low-conductivity medium (< 10 muS cm-1) containing benzotriazole (BTA) and/or 2-mercatobenzothiazole (MB T) was studied by using the AC impedance technique, Auger electron spe ctroscopy and corrosion tests. As the MBT concentration increased, the corrosion rate of copper abruptly rose to a peak, rapidly fell, and t hen finally decreased steadily. The maximum corrosion rate appeared at a MBT concentration of about 0.5 ppm. However, a concentration of mor e than 1.5 ppm MBT could effectively inhibit copper corrosion. The res ults from AC impedance measurements agreed with those from corrosion t ests. The film resistance could be observed only when the MBT concentr ation was in excess of 1.5 ppm. A combination of BTA and MBT proved to be more effective than either compound used alone.