Environmental Barrier Coatings for the Energy Efficient Heat Engines Program

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This program aimed to develop a fundamental understanding of the microstructural, mechanical, and chemical properties of Ta{sub 2}O{sub 5}-based coatings for Si{sub 3}N{sub 4} (AS800) substrates and optimize such coatings for environmental barriers. The program consisted of three tasks: processing of Ta{sub 2}O{sub 5} coatings, phase and microstructural development, and life-limiting phenomena. Northwestern University formed a cross-functional team with Lehigh University, Honeywell Inc., and Oak Ridge National Laboratory. The major accomplishments are: (1) Conditions for the plasma spray of Ta{sub 2}O{sub 5} and its alloys were optimized to provide maximum density and thickness. (2) Adherent small particle plasma spray coatings ... continued below

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Faber, Katherine October 31, 2004.

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Description

This program aimed to develop a fundamental understanding of the microstructural, mechanical, and chemical properties of Ta{sub 2}O{sub 5}-based coatings for Si{sub 3}N{sub 4} (AS800) substrates and optimize such coatings for environmental barriers. The program consisted of three tasks: processing of Ta{sub 2}O{sub 5} coatings, phase and microstructural development, and life-limiting phenomena. Northwestern University formed a cross-functional team with Lehigh University, Honeywell Inc., and Oak Ridge National Laboratory. The major accomplishments are: (1) Conditions for the plasma spray of Ta{sub 2}O{sub 5} and its alloys were optimized to provide maximum density and thickness. (2) Adherent small particle plasma spray coatings of Ta{sub 2}O{sub 5} can be routinely prepared. (3) Ta{sub 2}O{sub 5} can be stabilized against its disruptive phase transformation to 1400 C by the addition of one or more oxides of Al, La, and/or Nb. (4) Residual stresses in the Ta{sub 2}O{sub 5} coatings were measured using X-rays and changed with thermal exposure. (5) Properly doped coatings are more resistant against thermal cycling than undoped coatings, and can be cycled many thousand times without spallation. (6) Water vapor testing in the ORNL Keiser Rig of adherent coatings showed that undoped Ta{sub 2}O{sub 5} is not an effective barrier at preventing chemical changes to the AS800. (7) Limited water vapor testing of doped and adherent coatings, which had successfully survived many thermal cycles, showed that in the water vapor environment, de-cohesion may occur.

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  • Report No.: None
  • Grant Number: FC26-01CH11086
  • DOI: 10.2172/940178 | External Link
  • Office of Scientific & Technical Information Report Number: 940178
  • Archival Resource Key: ark:/67531/metadc899088

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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  • October 31, 2004

Added to The UNT Digital Library

  • Sept. 27, 2016, 1:39 a.m.

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  • Nov. 23, 2016, 6:56 p.m.

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Faber, Katherine. Environmental Barrier Coatings for the Energy Efficient Heat Engines Program, report, October 31, 2004; United States. (digital.library.unt.edu/ark:/67531/metadc899088/: accessed October 24, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.