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Characterization of coating processes and coatings for steam turbine blades

Conference · · Mater. Compon. Fossil Energy Appl.; (United States)
OSTI ID:7048811
During boiler transients (start-up and cool-down cycles), the magnetite scales that form on the internal surfaces of the superheater and reheater tubes at elevated temperatures may spall and enter the steam flow. Such particles may then accumulate at various points in the steam circuit and eventually disrupt the flow of steam, or they may be entrained in the steam and eventually cause erosion of blades in the steam turbine. Coatings are being considered as one method to minimize this problem in the future. Boiler manufacturers have developed chromizing diffusion and chromate conversion coatings to reduce internal scale formation in boiler tubing. Service experience over three years indicates that boride diffusion coatings on high-pressure stationary nozzle vanes can double the vane life. Based on that experience, many high pressure nozzle vanes have been boride diffusion coated specifically to increase their erosion resistance. Ten different coatings were selected - based on available field and laboratory experience in various erosive applications - for evaluation for use on rotating and stationary blading. Of the ten coatings, six different processes were considered. These processes are discussed.
OSTI ID:
7048811
Conference Information:
Journal Name: Mater. Compon. Fossil Energy Appl.; (United States) Journal Volume: 63
Country of Publication:
United States
Language:
English