Surface characterisation and crevice corrosion behaviour of nickel-based alloys in the paper industry

Recycled water in the paper industry acts as a stronger electrolyte as its concentration and temperature are quite high. The lower pH that exists in t hese solutions enhances the corrosion and the high concentration of solids leads to leaching of metal ions from surface. Crevice corrosion is a form o f localised attack, which can quickly induce metal perforation even with hi gh grade stainless steels like 316L when the protective chromium oxide film is damaged. A specially designed crevice cell assembly uas used to study t he electrochemical aspects of nickel-based alloys with the commonly used 31 6L SS. The mounted specimen with its crevice was anodically polarised in a white water medium, which is normally encountered in the paper machine sect ion. The nickel-based alloys show remarkable crevice corrosion resistance. X-ray photoelectron spectroscopy studies revealed that the enhanced corrosi on resistance of these alloys is due to the contributing nature of the indi vidual elements Cr, Ni and Mo and their presence in the form of various oxi dised species on the passive films.