Ceramic turbine components research and development. Part 2. evaluation of MCrAlY/ZrO/sub 2/ (Y/sub 2/O/sub 3/) thermal-barrier coatings exposed to simulated gas turbine environments. Final report

Technical Report · Fri Aug 01 04:00:00 EDT 1980

DOI:https://doi.org/10.2172/5085817· OSTI ID:5085817

Singhal, S. C.; Yee, S. Y.

The purpose of this study was to determine the resistance of two state-of-the-art duplex thermal barrier coating systems to utility turbine combustion gases. These coating systems are of interest because large electricity cost savings could be achieved if the coatings permit turbine operation with residual fuels at distillate-rated firing temperatures, and substantial savings in fuel and capital cost may be achieved through increased turbine inlet temperature. The coating systems evaluated consisted of a MCrAlY (M = Ni or Ni/Co) bond coat and ZrO/sub 2/ stabilized with 12 wt% Y/sub 2/O/sub 3/ overcoat, each deposited by plasma arc spray on Udimet-500 turbine alloy specimens. The corrosion testing was conducted in a pressurized turbine test passage at 2000/sup 0/F gas temperature using GT-2 diesel oil and that containing Na, V, P and S contaminants. Post-test analysis showed that the coatings performed well when exposed to clean GT-2 fuel and that containing 1 ppM Na or 5 ppM Pb; but in the presence of vanadium and/or phosphorous in the fuel, the ZrO/sub 2/ - 12 wt % Y/sub 2/O/sub 3/ coating deteriorated through severe cracking and eventual spalling. Various possible causes for the oxide coating degradation are discussed. This work shows that the thermal barrier coating concept is feasible for utility turbines, but coating development specifically for utility turbines burning residual fuels will be required.

• Research Organization: Westinghouse Electric Corp., Pittsburgh, PA (USA). Research and Development Center
• OSTI ID: 5085817
• Report Number(s): EPRI-AP-1539(Pt.2)
• Country of Publication: United States
• Language: English

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