EFFECT OF CHLORIDE ON THE ATMOSPHERIC CORROSION OF SIMULATED ARTIFACT IRON IN NO3− BEARING POLLUTANT ENVIRONMENT

The effect of chloride in nitrogen-bearing pollutant on the atmospheric corrosion of cast iron was investigated by using periodic wet-dry test, electrochemical experiment and surface tension test. Scanning electron microscopy (SEM) with energy disperse atomic X-ray (EDAX) was used to identify the corrosion processes and products. The results of the weight loss measurement showed that the whole corrosion kinetics can be approximately described by: ΔW=AtB. With the addition of NaCl, B increases. The result presented that Cl− accelerated the corrosion rate obviously during the whole corrosion process. The initial corrosion process was investigated from the viewpoint of surface tension. At the initial corrosion period, the corrosion rate was proportion to the adsorption of anions contained the solutions. And as corrosion went on, the penetration effect of anions and different characteristics of the corrosion products began to dominant the corrosion process, which led to the accelerated effect.