Abstract
Internal corrosion of exhaust systems has annoyed the automotive industries for many years. Currently, a diverse range of the severity of the internal corrosion depending on the regions has been recognized. The aim of this study is to understand the causes of the extraordinary corrosion issue inside the muffler in a certain region. In order to know whether the aggressiveness of the condensates varies depending on the regions, the condensates were collected from the test car in two different regions. The analysis of the recovered condensate using an anion exchange ion chromatography showed the evident difference in the concentration of the chloride and sulfate. In addition, the analysis of the fuels showed that a high sulfate concentration in the condensate is most likely derived from the fuel that contains a high concentration of sulfur. The corroded mufflers from the region whose condensate contains higher concentration of chloride and sulfate suffered from the significantly higher number of pits and many large size of the pits. The potentiostatic electrochemical analysis indicates that the presence of sulfate in the condensates results in the formation of the large pits. The present work suggested the high relevance of sulfate to the severe corrosion issue in a certain region..
