High temperature corrosion of gas turbine blade material in methane gas combustion environment with the injection of SO₂/NaCl

Interest in the integrated coal gasification combined cycle plant (IGCC) has increased because of its high efficiency and lowered environmental pollution. There are, however, some corrosive contaminants in the fuel gas such as sulfur, NaCl salt and other ash impurities that cannot be removed completely. They cause a high temperature corrosion attack and reduce service life of the gas turbine components. This study focuses on the high temperature corrosion behavior of Ni-base single crystal alloy CMSX-4, the CoNiCrAIY coating, the TBC coating and the IN738LC Ni-base alloy in a methane gas combustion environment with the injection of SO₂/NaCl at 730°C, 850°C, and 950° G Long-term experiments lasting up to 2700 hours were performed After these tests, surface deposits and reaction products were analyzed by X-ray diffraction (XRD), and cross sectional observation was performed by a scanning electron microscope (SEM) and an electron probe micro analyzer (EPMA). Results showed that sulfur and chlorine concentrated within the uncoated alloy of CMSX-4 and IN738LC, and the coatings exhibited good resistance to attacks by oxidation and sulfidation.