Studies on the effect of Zn ions on the corrosion behavior of iron-base alloys relevant to desalination and power plant conditions

摘要

The corrosion behavior of mild steel and AISI 304L SS in the presence of dissolved Zn ions under different experimental conditions have been investigated. Experimental conditions include: variation in aqueous medium, Zn ions concentration, pH, dissolved oxygen, and flow condition. The variation in corrosion rate in the presence of varying concentrations of Zn ions was determined using weight loss technique and spectrophotometric analysis of iron ions entered into the test solutions after completion of immersion. The pH of the test solutions was also monitored during the entire period of immersion. The Zn ions present in the test solutions after completion of immersion were estimated using atomic absorption spectro-photometer (AAS). Open circuit potential (OCP) measurements and potentiodynamic polarization (PDP) measurements were carried out to find out the role of Zn ions on the corrosion behavior of mild steel and SS 304L. The surface morphology of steel before and after immersion in aqueous solution containing Zn ions was also examined using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). The influence of Zn ions on the corrosion behavior of mild steel is quite pronounced and show interesting trends whereas SS 304L is unaffected both in distilled water or artificial seawater.