Examination of in-service coating degradation in gas turbine blades using a small punch testing method

Book · Tue Dec 31 04:00:00 EST 1996

OSTI ID:490755

Kameda, J; Bloomer, T E; Gold, C R ^[1]; Sugita, Y; Ito, M ^[2]; Sakurai, S ^[3]

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1. Iowa State Univ., Ames, IA (United States). Center for Advanced Technology Development
2. Chubu Electric Power Co., Inc., Nagoya (Japan). Electric Power R and D Center
3. Hitachi Ltd. (Japan). Mechanical Engineering Research Lab.

This paper describes examination of in-service coating degradation in land based gas turbine blades by means of a small punch testing (SP) method and scanning Auger microprobe (SAM). SP tests on coated specimens with unpolished surfaces indicated large variations of the mechanical properties because of the surface roughness and curvature in gas turbine blades. SP tests on polished specimens better characterized the mechanical degradation of blade coatings. The coated specimens greatly softened and the room temperature ductility of the coatings and substrates tended to decrease with increasing operation time. The ductile-brittle transition temperature of the coatings shifted to higher temperatures during the blade operation. From SAM analyses on fracture surfaces of unused and used blades, it has been shown that oxidation and sulfidation near the coating surface, which control the fracture properties, result from high temperature environmental attack.

• OSTI ID: 490755
• Report Number(s): CONF-960401--; ISBN 1-55899-337-1
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CHROMIUM ALLOYS
COBALT ALLOYS
COMPOSITE MATERIALS
DEFORMATION
EXPERIMENTAL DATA
GAS TURBINES
MECHANICAL PROPERTIES
MICROSTRUCTURE
NICKEL ALLOYS
OXIDATION
PROTECTIVE COATINGS
RENE 80
SULFIDATION
TURBINE BLADES
YTTRIUM ALLOYS