51316-7822-Electrochemical Characterization of Ni and Fe-Based Alloys in Simulated Biomass Environments

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Product Number: 51316-7822-SG

ISBN: 7822 2016 CP

Author: Vilupanur Ravi

Publication Date: 2016

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Biomass is a renewable fuel source that is a promising alternative to fossil-fuel based power generation. It is derived from living organisms and encompasses a variety of fuels with different chemical compositions. Corrosive elements in biomass fuels such as chlorine sulfur and potassium are released as vapors in the flue gas during combustion. As they exit the boiler these vapors condense on metallic surfaces forming alkali-containing salt deposits e.g. potassium chloride and sulfate mixtures that result in excessive corrosion. This form of corrosion has been classified as “hot corrosion” i.e. attack by thin films of molten salts. The metallic component is degraded by the molten film salt leading to the loss of engineering function. Electrochemical techniques can be used to study the hot corrosion reaction mechanisms because the reaction mechanism involves the movement of electrons and ions.An electrochemical test setup containing a 3-electrode cell arrangement and capable of high temperature operation was built for this study. Commercial iron and nickel based alloy specimens were tested in molten KCl – K2SO4 eutectic salts at 710°C and under two different environments i.e. oxygen gas and a 1 vol% SO2 –air blend. A potentiostat was utilized to deploy DC electrochemical techniques in accordance with ASTM G59-97 standard and to record data. Additional testing was conducted with a blend of alkali chlorides and sulfates at 550°C to closely simulate the actual conditions in boiler components. Iron based alloys were the primary selection of materials for the latter.The morphology of attack was determined using optical and scanning electron microscopy coupled with energy dispersive spectroscopy (EDS). The results of these studies will be reported along with insights into the material response to the different environmental conditions.