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1116 |
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Tuesday, June 03, 2008, Auditorium 2 10:50 AM Gasturbines 2 Coatings for mobile and stationary turbines, protection against wear, high temperature corrosion and thermal stresses, clearance control coatings for a better efficiency |
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Technology advances in compressor and turbine abradables |
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Mitchell Dorfman* / Sulzer Metco (US) Inc., USA Scott Wilson/ Sulzer Innotec, Switzerland Dieter Sporer/ Sulzer Metco (Canada) Inc., Germany Paul Sheedy/ Sulzer Metco (US) Inc., USA |
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Abradable seals have been used in jet engines since the late 1960's. Today abradable seals are seeing applications in low pressure and high pressure sections of the compressor, as well as, the high pressure turbine module of jet engines. In addition, clearance control systems are gaining ever more attention in industrial gas turbines. One type of manufacturing approach for clearance control is thermal spraying. Thermal spraying is a relativey simple and cost effective means to apply abradable seals. These coatings work by minimizing gaps between rotating and stationary components by allowing the rotating parts to cut into the stationary ones. The types of coatings employed in the turbine are zirconia-based abradable material systems with polymer and, in some cases, hexagonal boron nitride additions. The coatings are designed to work at service temperatures of up to 1200 °C. Types of materials used in the low and high sections of the compressor are aluminum-silicon, nickel and MCrAlY-based systems. These compressors type systems typically have fugitive phases of polymer and/or solid lubricants such as hexagonal boron nitride, graphite or polymer. Operating temperature, depending on the material of choice and blade tip design, can be approximately 850°C. The objective of this paper is to review various types of commercial and experimental abradable systems and to assess their performance profiles. The paper will also review the benefits of gun and particle-temperature velocity sensor technology in improving the application robustness and cost savings compared to traditional equipment and processes. |