Effect of Heavy Fuel Impurities on Hot Corrosion of Inconel 617

The use of heavy fuels containing impurities such as sulfur and vanadium can lead to the destruction of components gas turbine, exposed to combustion environments at high temperature, through hot corrosion. In this study, the effect of sulfur, vanadium, potassium, calcium and lead in heavy fuel oil on the hot corrosion behavior of Inconel 617 alloy were investigated. For this purpose, hot corrosion experiments were carried out in the presence of various corrosive compounds including 60%Na2SO4+ 40%V2O5, 2%K2SO4+ 58%Na2SO4+40%V2O5, 1% CaCl2+ 2% K2SO4+ 57%Na2SO4+40%V2O5 and 0.2% PbCl2+ 1% CaCl2+ 2% K2SO4+ 56.8%Na2SO4+40%V2O5 salts at two temperatures of 700 °C and 1000 °C for 8, 16, 24, 32 and 40 hours. The exposed samples were investigated with measurement of weight changes, SEM, EDS and XRD analysis. The results showed that the impurities of potassium, calcium and lead did not have any remarkable effect on the hot corrosion of inconel 617. It was also observed that the weight of the specimens increased with increasing hot corrosion time at testing temperature of 700 °C. However, a decrease in the weight of specimens was observed after 8 h hot corrosion at 1000 °C that was due to severe destruction of the surface. The cross-sectional images of the samples corroded at 700 °C indicated that there were two layers containing chromium oxide and salt compounds. Nevertheless, the cross-sectional analysis of samples corroded at 1000 °C indicated that there were porous and non-continuous oxide scales on the surface. X-ray diffraction analysis of corrosion products, formed on the corroded specimens at 1000 °C, showed the presence nickel oxide (NiO), chromium oxide (Cr2O3), nickel sulfide (NiS), chromium sulfate (Cr2(SO4)2), and sodium chromium oxide (Na2CrO4).