The main purpose of this study was to investigate the effect of chloride on the atmospheric corrosion of cast iron in an atmosphere with sulphur‐bearing pollutants.
Periodic wet‐dry tests, surface tension tests, electrochemical impedance (EIS) measurements, stereoscopic microscopy, scanning electron microscopy and energy dispersive atomic X‐ray analysis were used to investigate the corrosion processes and products. Weight loss measurements, electrochemical theory, as well as ion adsorption theory and penetration theory were used to explain the corrosion process.
The experimental results demonstrated that weight loss measurement approximately obeyed the relationship: ΔW=AtB. With addition of NaCl, the value of A decreased, whereas B increased. It is worth noting that NaCl acted as an inhibitor in the HSO3− bearing pollutant during the initial corrosion stage. However, as corrosion continued, the penetration effect of chloride and the different characteristics of the corrosion products tended to dominate the corrosion process, which led to changes of the corrosion rate. Both the EIS measurements and surface tension tests agreed well with the results of weight loss measurements.
The initial corrosion stage showed good agreement with associated surface activity. The paper explains the effect of chloride on the atmospheric corrosion of cast iron in sulphur bearing pollutants from a new viewpoint.
