INFLUENCE OF TEMPERATURE ON DISSOLUTION AND PASSIVATION OF COPPER IN CARBONATE-BICARBONATE BUFFERS

The influence of temperature on dissolution and passivation of copper in solutions containing carbonate (CO32-)-bicarbonate (HCO3-) ions at pH 8.9 to 10.5 was studied in the range from 5 degrees C to 65 degrees C. The strongest effect of temperature on corrosion behavior of coppe r was in the potential regions corresponding to electroformation of cu pric oxide (CuO) and cupric hydroxide (Cu[OH](2)) species as well as b asic copper carbonates (CuCO3). Effects of hydrodynamic conditions and electrolyte composition on base metal electrodissolution and prepassi ve layer dissolution processes were considered. The low activation ene rgy obtained for electroformation of CuO and Cu(OH)(5) layers In still solutions was compatible with a poorly structured thin passive layer, with the copper electrodissolution process taking place through a pre passive layer. Solution stirring and high temperature were shown to im prove protective characteristics of the passivating layer.