Inhibitory protection of copper in acetic acid solutions

The kinetics of copper corrosion and the effect of convection on this process were studied in freely aerated acetic acid solutions. The copper corrosion rate in this medium does not depend significantly on the duration of contact between copper and the corrosive medium (1-20 days) and H3CCOOH concentration (0.25-4 M). There are no fundamental differences in the corrosivity of this medium toward copper upon transition from static to dynamic experimental conditions. The corrosivity of H3CCOOH solutions toward metallic copper is enhanced in the presence of the corrosion product, Cu(II) acetate. This effect is especially pronounced if metallic copper contacts a dynamic corrosive medium. A triazole derivative, IFKhAN-92, is recommended for copper protection in freely aerated H3CCOOH solutions. The efficiency of this compound does not depend considerably on the duration of contact between the metal and the corrosive medium, H3CCOOH content, and hydrodynamic characteristics of the solution. An important feature of the IFKhAN-92 inhibitor is that its protective ability toward metallic copper is preserved even if Cu(II) acetate is accumulated in the corrosive medium, which is true not only in static but also in dynamic media. The dependence of the copper corrosion rate on the convective factor in freely aerated 2 M H3CCOOH + 0.05 M Cu(H3CCOO)2, both in the absence and in the presence of the corrosion inhibitor, is formally described by the equation k=a+b. n(1/2), where a and b are empirical parameters and n is the rotation frequency of the magnetic stirrer. The addition of IFKhAN-92 decreases the parameters a and b in this equation.