Influence of KCl and HCl on a laser clad FeCrAl alloy: In-Situ SEM and controlled environment High temperature corrosion

This study investigated the effects of HCl and KCl on a laser-clad FeCrAl coating at 450 degrees C in an in-situ ESEM followed by a furnace exposure. In all in-situ TEM cross-sections, three major phases were identified: an iron rich oxide, an iron-chromium mixed oxide and an aluminium enriched layer. HCl allowed chlorine based corrosion to occur which suggests interaction from its gas phase. EDX of the regions around KCl crystals showed a decrease in chromium which is an indication of chlorine selectively removing chromium. Moreover, the mass gain in HCl with KCI was significantly lower than that observed in air with KCl.