Materials Science Forum, Vol.492-493, 305-310, 2005
Corrosion resistance of homogenous and FGM coatings
Homogeneous and FGM environmental barrier coatings (EBC) made of alumina - NiCr on the steel substrates by high-velocity oxygen fuel (HVOF) spraying technique were studied. At room temperature, these coatings were characterized by DC polarization measurements and by electrochemical impedance spectroscopy (EIS) after various exposure times in highly aggressive basic solutions. At high temperatures (400-750 degrees C) corrosion resistance was tested in respect to sulfide - sulfate - chloride - carbonate melts in air, which simulates environments in incinerators, kraft recovery boilers and turbines. After testing, the samples were examined by SEM and EDS and their corrosion resistance was compared.
Keywords:FGM coating;environmental barrier coatings;hot corrosion;HVOF;electrochemical impedance spectroscopy