The effect of HCl and SO2 on gas phase corrosion of boiler steels

Satu Tuurna, Sroda Szymon, Liisa Heikinheimo

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

    2 Citations (Scopus)


    The high temperature corrosion kinetics and mechanism of different steel types, typically used in boiler applications, were investigated. Materials were exposed in simulated moist air atmosphere (8%O2 + 15%H2O) with 200 ppm SO2 and 2000 ppm HCl addition at temperatures of 500 and 600°C. The measured mass mass change for different exposure times up to 360 h shows that in the conditions used the oxidation rate of studied samples obeys parabolic rate law. Corrosion products, growing on tested materials, were analysed by SEM/EDS and XRD techniques. The obtained results indicated a significant influence of gas composition and temperature on the morphology and growth rate of the corrosion product. The presence of chlorine in simulated combustion atmosphere accelerates the oxidation process. In general, the oxidation layers formed in moist air with HCl addition are more prone to spallation, exhibits large porosity and several cracks. The observed morphology and composition of the oxide scales suggest that in this case the corrosion mechanism could be described as active oxidation process. Active oxidation assumes that the oxide scale contains physical defects through which the gas phase chlorine and oxygen can diffuse to reach the scale/metal interface. Then the iron is chlorinated, and volatile or condensed FeCl2 can form. In contrast, in the most of the studied cases the presence of sulphur seems to slow down the corrosion rate. The growing scales are more dense and adherent to the base metal. The sulphides, which were formed mainly at metal/scale interface, may play the significant role in ion transport through the scale
    Original languageEnglish
    Title of host publicationBALTICA VI - Life management and maintenance for power plants. Vol. 1
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    ISBN (Electronic)951-38-6292-5
    ISBN (Print)951-38-6291-7
    Publication statusPublished - 2004
    MoE publication typeB3 Non-refereed article in conference proceedings
    EventBALTICA VI - Life Management and Maintenance for Power Plants - Helsinki-Stockholm, Finland
    Duration: 8 Jun 200410 Jun 2004

    Publication series

    SeriesVTT Symposium


    ConferenceBALTICA VI - Life Management and Maintenance for Power Plants


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