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Thermal Effects on a Low Cr Modification of PS304 Solid Lubricant CoatingPS304 is a high temperature composite solid lubricant coating composed of Ni-Cr, Cr2O3, BaF2-CaF2 and Ag. The effect of reducing chromium content on the formation of voids in the Ni-Cr particles after heat treatment in PS304 coating was investigated. Coatings were prepared with Ni-20Cr or Ni-10Cr powder and in various combinations with the other constituents of PS304 (i.e., chromia, silver and eutectic BaF2-CaF2 powders) and deposited on metal substrates by plasma spray. Specimens were exposed to 650 C for 24 hr or 1090 C for 15 hr and then examined for changes in thickness, coating microstructure and adhesion strength. Specimens with Ni-10Cr generally had less thickness increase than specimens with Ni-20Cr, but there was great variance in the data. Reduction of chromium concentration in Ni-Cr powder tended to reduce the appearance of voids in the Ni-Cr phase after heat exposure. The presence of BaF2-CaF2 resulted in a significant increase in coating adhesion strength after heat treatment, while coatings without BaF2-CaF2 had no significant change. Chemical composition analysis suggested that the void formation was due to oxidation of chromium in the Ni-Cr constituent.
Document ID
20040082398
Document Type
Technical Memorandum (TM)
Authors
Stanford, Malcolm K. (NASA Glenn Research Center Cleveland, OH, United States)
Yanke, Anne M. (Cleveland State Univ. Cleveland, OH, United States)
DellaCorte, Christopher (NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
September 7, 2013
Publication Date
June 1, 2004
Subject Category
Chemistry and Materials (General)
Report/Patent Number
E-114585
NASA/TM-2004-213111
Funding Number(s)
WBS: WBS 22-708-18-04
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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NameType 20040082398.pdf STI