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Material and Coating Degradation

Hot section component materials and coatings degrade when they are exposed to service. The extent of degradation depends on both metal temperature and service time. In a cooled component, the material and coating degradation varies from location to location. The extent of in-service degradation increases with increasing metal temperature and/or service time. In-service material and coating degradation lowers mechanical properties, which lower the service life of components.
 

Base material and coating degradation of a Frame 6-GTD 111 DS blade after 25,800 hours of service.

These photographs show variations of coating degradation between two locations near the leading edge of a Frame 7FA blade. The coating at location 2 (left) is in good condition, while at location 1 (right), the coating is completely degraded after 20,000 hours of service.

Material Properties Evaluation

the service life of a gas turbine part is controlled by mechanical properties of the material. SwRI staff has experience in material property evaluation, conducting extensive testing of both new and service-run components to generate material properties for life assessment and to determine the extent of material degradation during service.

Degradation of material properties of a GTD 111 DS First Stage Blade after 49,000 hours of service

Nondestructive Evaluation

The Institute has performed nondestructive evaluation (NDE) condition assessment studies to identify the degradation mechanisms for several coatings and base materials and extensive NDE testing of new and service-exposed components. Knowledge of a component condition is required to make prudent run, repair, and replacement decisions.

Click image to enlarge		Click image to enlarge
GTD 111 blade with GT29 coating and 54,000 hours of service. Photo (left) shows coating degradation in grid area ranging from 0 to 100 percent. Eddy current data (right) of the same area shows that the eddy current signal increases in response to increasing degradation.

GTD 111 blade with GT29 coating and 54,000 hours of service. Photo (left) shows coating degradation in grid area ranging from 0 to 100 percent. Eddy current data (right) of the same area shows that the eddy current signal increases in response to increasing degradation.

SwRI can offer you a full range of capabilities and experience in gas turbine technology including becoming an extension of your engineering department. For more information about gas turbine condition assessment capabilities at SwRI or how you can contract with SwRI, please contact please contact Klaus Brun, Ph.D. at kbrun@swri.org or (210) 522-5449.

| Fluids Engineering Department | Mechanical & Materials Engineering Division | SwRI Home |

Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 11 technical divisions.

October 01, 2008