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Abstract
To meet environmental, legislative and commercial targets, gas turbines must operate with increasingly high gas temperatures and fuels with increased contaminant levels. A series of three burner rig tests have been used to evaluate the effects of fly ash, gas moisture and gas temperatures on alkali metal induced hot corrosion in the metal temperature range of 700 – 960°C on three uncoated materials (Haynes 230, IN939, and IN738LC) and one coated system (IN738LC/HVOF SV21). It has been found that the specific burner rig test conditions impact upon the severity of samples’ corrosion and oxidation, with samples exposed to impacting fly ash demonstrating reduced hot corrosion. However, type II hot corrosion (pitting) and type I hot corrosion (internal damage and sulfidation) have been observed under all test conditions. Generally IN939 was more resistant to hot corrosion over both high and low temperatures than IN738LC or Haynes 230. SV21-coatings on IN738LC provided improved resistance to both type I and II hot corrosion.