0
Research Papers: Gas Turbines: Manufacturing, Materials, and Metallurgy

Derivation of Temperature-Estimation Equation Based on Microstructural Changes in Coatings of In-Service Blades of Gas Turbines

[+] Author and Article Information
Mitsutoshi Okada, Tohru Hisamatsu, Terutaka Fujioka

Energy Engineering Research Laboratory, Central Research Institute of Electric Power Industry, Yokosuka, Kanagawa-ken 240-0196, Japan

J. Eng. Gas Turbines Power 133(2), 022101 (Oct 29, 2010) (6 pages) doi:10.1115/1.4001998 History: Received April 13, 2010; Revised April 26, 2010; Published October 29, 2010; Online October 29, 2010

A CoNiCrAlY-coated blade of an in-service gas turbine is analyzed, and a diffusion layer is formed along the boundary between the coating and the substrate due to the interdiffusion in the middle and tip of the blade. Such a layer is not observed in the vicinity of the blade root because of a comparatively low temperature during the operation. Coated specimens are prepared from the portions of the blade devoid of the diffusion layers, and the specimens are exposed to a high temperature in air. On the basis of the increase in the diffusion layer thickness, an equation for estimating the temperature of the blade is derived. An analysis of another in-service blade with a thermal barrier coating is carried out. The aluminum content decreases below the bond coat surface due to Al diffusion caused by the Al-oxide formation. This results in the formation of an Al-decreased layer (ADL) along the leading and trailing edges. The ADL is not observed at the center of the blade chord. The specimens are extracted from the portions of the blade that are devoid of ADL, and they are subjected to a high temperature in air. On the basis of the increase in the ADL thickness, a temperature-estimation equation is derived.

FIGURES IN THIS ARTICLE
<>
Copyright © 2011 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Morphologies of coating microstructures in the in-service CoNiCrAlY-coated blade (BDL signifies boundary diffusion layer)

Grahic Jump Location
Figure 2

Distribution of BDL thickness at 40% blade height of the CoNiCrAlY-coated blade

Grahic Jump Location
Figure 3

Relationship between BDL thickness at the trailing edge and the blade height

Grahic Jump Location
Figure 4

Morphologies of bond coat in the in-service TBC-blade

Grahic Jump Location
Figure 5

Distribution of ADL thickness in the in-service TBC-blade

Grahic Jump Location
Figure 6

Morphologies of microstructural change in the vicinity of the boundary between the coating and the substrate in the CoNiCrAlY-coated specimen at 1273 K

Grahic Jump Location
Figure 7

Distribution map of elements in the vicinity of the boundary between the CoNiCrAlY coating and the substrate

Grahic Jump Location
Figure 8

Relationship between BDL thickness and square root of test time

Grahic Jump Location
Figure 9

Arrhenius plot of the BDL growth rate constant

Grahic Jump Location
Figure 10

Morphologies of the bond coat in the TBC-specimen at 1273 K

Grahic Jump Location
Figure 11

Distribution map of elements in the vicinity of the boundary between the top coat and the bond coat

Grahic Jump Location
Figure 12

Relationship between the ADL thickness and square root of test time

Grahic Jump Location
Figure 13

Arrhenius plot of the ADL growth rate constant

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In