Arc-discharge system for nondestructive detection of flaws in thin ceramic coatings

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Description

The feasibility of nondestructively detecting small cracks or holes in plasma-sprayed ceramic coatings with an electric arc-discharge system was studied. We inspected ZrO/sub 2/ coatings 0.46 mm (0.018 in.) thick on Incoloy alloy 800 substrates. Cracks were artificially induced in controlled areas of the specimens by straining the substrates in tension. We designed and built a system to scan the specimen's surface at approximately 50 ..mu..m (0.002 in.) clearance with a sharp-pointed metal-tipped probe at high dc potential. The system measures the arc currents occurring at flaws, or plots a map of the scanned area showing points where the arc ... continued below

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Pages: 38

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Scott, G.W. & Davis, E.V. April 1, 1978.

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Description

The feasibility of nondestructively detecting small cracks or holes in plasma-sprayed ceramic coatings with an electric arc-discharge system was studied. We inspected ZrO/sub 2/ coatings 0.46 mm (0.018 in.) thick on Incoloy alloy 800 substrates. Cracks were artificially induced in controlled areas of the specimens by straining the substrates in tension. We designed and built a system to scan the specimen's surface at approximately 50 ..mu..m (0.002 in.) clearance with a sharp-pointed metal-tipped probe at high dc potential. The system measures the arc currents occurring at flaws, or plots a map of the scanned area showing points where the arc current exceeds a preset threshold. A theoretical model of the probe-specimen circuit shows constant dc potential to be the best choice for arc-discharge inspection of insulating coatings. Experimental observations and analysis of the data disclosed some potential for flaw description.

Physical Description

Pages: 38

Notes

Dep. NTIS, PC A03/MF A01.

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  • Report No.: ORNL/TM-6176
  • Grant Number: W-7405-ENG-26
  • DOI: 10.2172/5003808 | External Link
  • Office of Scientific & Technical Information Report Number: 5003808
  • Archival Resource Key: ark:/67531/metadc1061459

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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.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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Creation Date

  • April 1, 1978

Added to The UNT Digital Library

  • Jan. 22, 2018, 7:23 a.m.

Description Last Updated

  • Feb. 1, 2018, 6:04 p.m.

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Scott, G.W. & Davis, E.V. Arc-discharge system for nondestructive detection of flaws in thin ceramic coatings, report, April 1, 1978; Tennessee. (digital.library.unt.edu/ark:/67531/metadc1061459/: accessed July 21, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.