Crevice Corrosion of K60 in Dry Desertification Saline Soil Original Research Article

Corrosion products of K60 crevice samples which were buried in Ordos area were analyzed by scanning electron microscopy and X-ray diffraction. The result showed that, the corrosion potential decreased differently in the crevice and a maximum negative existed at the bottom side; with pH value reduced, the dissolved oxygen was nearly exhausted in the crevice. When the opening side of the coupons was coupled with each other, the crevice corrosion in the crevice might be accelerated and the pH value gradually reduced; however, the oxygen was not completely exhausted. The unbalanced current density between anode and cathode was the main cause of blocked self-catalysis effect in the crevice, and was also the main cause of corrosion of alloys. Lumpy corrosion happened on the surface of metal, and rusty layer was composed of Fe3O4, Fe2O3, FeO, FeOOH and FeS which distributed in the opening of crevice. There were the reddish-brown corrosion products and white matter which distributed in the form of filiform and spotted in the center part of crevice. The analysis showed that the white matter might include oxide of Fe and NaHCO3.