Experience with metal/ceramic coating in stationary gas turbines

The uncooled rotating blades of the high pressure turbine (HPT) and of the low pressure turbine (LPT) of the peak load power gas turbine GT-100 are protected with electron-beam physically vapour deposited CoCrAlY coatings. Owing to low-temperature hot corrosion leakage, corrosion failure is observed. In order to improve the corrosion resistance, yttria stabilized zirconia (YSZ)/CoCrAlY coatings with a ceramic layer thickness of 50–70 μm have been developed. The maximum service life of blades with the YSZ/CoCrAlY coatings has exceeded 939 h with 253 starts. Study of the YSZ/CoCrAlY coated blades after different service periods (from 306 to 939 h) showed different conditions of the ceramic layer: without any kind of damage, with small local damage, and with large-area spalling.