Advanced protective coatings for gas turbine blading
The new gas turbines now being marketed are characterized by outputs and efficiencies which were unthinkable just a few years ago. A key factor for achieving efficiency is the highest possible turbine inlet temperature, currently approx. 1,400 C. In such a machine, it is the turbine blades which are subjected to the greatest thermal and mechanical stresses. They are also subjected to extreme chemical stress in the form of oxidation, which in the following is understood as the corrosive action due almost exclusively to the temperature of the turbine blade surface and (to a much lesser degree) the pressure and oxygen content of the hot gas. In many cases, this is compounded by hot corrosion, which results in accelerated oxidation due to impurities in the fuel and air. In terms of physics, this demanding challenge requires the use of cooling techniques which push the envelope of feasibility. In terms of materials engineering, an innovative multifaceted solution is called for. In more concrete terms, this means a combination of convection, impingement and film cooling of blades made of the strongest high-temperature alloy materials and coated with one or possibly multiple coatings. The base material ensures the blade's mechanical integrity while the coating(s) provide(s) protection against the oxidizing and corrosive attack, as well as the thermal stresses which cannot be sufficiently mitigated by cooling. The superiority of single crystal materials over polycrystalline or directionally solidified nickel-base superalloys is illustrated. The coating is a third-generation NiCoCrAIY VPS (vacuum plasma spray) coating. In the paper, the authors discuss the current status of coating developments for large, stationary gas turbines and present solutions for achieving important development objectives.
- Research Organization:
- Siemens Power Generation Group KWU, Ruhr (DE)
- OSTI ID:
- 20015037
- Resource Relation:
- Conference: 1998 International Joint Power Generation Conference, Baltimore, MD (US), 08/23/1998--08/26/1998; Other Information: Available as a 2 Volume set for $175.00; PBD: 1998; Related Information: In: Proceedings of the 1998 international joint power generation conference (PWR-Vol. 33). Volume 2: Power, by Legler, J. [ed.], 983 pages.
- Country of Publication:
- United States
- Language:
- English
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