Steam oxidation resistant coatings for steam turbine components: a feasibility study

The principal objective of the COST Action 522 is to raise the operating temperatures of both gas and steam turbines in order to increase their efficiency to reduce fuel consumption and emissions. Concerning steam turbines, the operating temperature is expected to rise from 550DGC to 650DGC, and the use of oxidation resistant coatings is being considered for the first time in Europe. In this preliminary work, two deposition techniques have so far been explored: slurry paints and atmospheric plasma spray (APS). Commercially available materials, known to have good oxidation resistance, were selected for both deposition techniques: one aluminium slurry and three alloyed materials for thermal spray: AlFe, FeCrAl and Ni Al. The coatings were characterised by SEM-EDS and steam oxidation testing was carried out at 650DGC. The preliminary findings show that some of the studied coatings may offer adequate protection. (Substrate material: P92.)