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The role of NZP additions in plasma-sprayed YSZ: microstructure, thermal conductivity and phase stability effects

Trice, Rodney W. and Su, Y. Jennifer and Faber, K. T. and Wang, Hsin and Porter, Wally (1999) The role of NZP additions in plasma-sprayed YSZ: microstructure, thermal conductivity and phase stability effects. Materials Science and Engineering A, 272 (2). pp. 284-291. ISSN 0921-5093. https://resolver.caltech.edu/CaltechAUTHORS:20140908-181324609

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Abstract

A concept for lowering the thermal conductivity of plasma-sprayed yttria-stabilized zirconia (YSZ) was evaluated by adding a low thermal conductivity secondary phase. Ca_(0.5)Sr_(0.5)Zr_4P_6O_(24), a member of the zirconium phosphate or NZP family, was co-sprayed with YSZ using the recently patented small-particle plasma-spray process. The amount of NZP phase in the YSZ varied from 4 to 18 vol.%. Transmission electron microscopy revealed that the plasma-sprayed NZP existed as 30-50 nm size grains when sprayed with YSZ. Between 100 and 1200 degrees C, reductions in the thermal conductivity of NZP/VSZ composite coatings compared to YSZ-only coatings were traced to porosity effects. The NZP phase destabilized the t'-ZrO_2 phase of the YSZ, favoring the formation of t-ZrO_2, then m-ZrO_2, a phase with a high-thermal conductivity. Due to this phase change, a large hysteresis was observed in thermal conductivity during the initial heat-up and cool down cycles of the NZP containing samples.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/S0921-5093(99)00468-2DOIArticle
http://www.sciencedirect.com/science/article/pii/S0921509399004682PublisherArticle
ORCID:
AuthorORCID
Faber, K. T.0000-0001-6585-2536
Additional Information:Copyright © 1999 Elsevier. Received 14 April 1999; received in revised form 14 June 1999. The authors wish to thank Rick Marzec for fabrication of the coatings used in this study, Dr Chiou for assistance with the TEM, and Tom Easley and Luke Brewer for help in editing the final document. Also, Rama Nageswaran provided valuable insight into NZP. This work was supported by the U.S. Department of Energy, Federal Energy Technology Center, Cooperative Agreement No. DE-FC21-92MC29061, under subcontract 96-01-SR047. The thermal conductivity testing was supported by the U.S. DOE, Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Transportation Technologies, as part of the HTML User Program under contract DE-AC05-96OR22464, managed by Lockheed Martin Energy Research Corporation.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-FC21-92MC29061
Department of Energy (DOE)DE-AC05-96OR22464
Subject Keywords:Thermal barrier coatings; Zirconium phosphate; Yttria stabilized zirconia; Thermal conductivity
Issue or Number:2
Record Number:CaltechAUTHORS:20140908-181324609
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140908-181324609
Official Citation:Rodney W Trice, Y.Jennifer Su, K.T Faber, Hsin Wang, Wally Porter, The role of NZP additions in plasma-sprayed YSZ: microstructure, thermal conductivity and phase stability effects, Materials Science and Engineering: A, Volume 272, Issue 2, 30 November 1999, Pages 284-291, ISSN 0921-5093, http://dx.doi.org/10.1016/S0921-5093(99)00468-2. (http://www.sciencedirect.com/science/article/pii/S0921509399004682)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:49403
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:09 Sep 2014 20:28
Last Modified:03 Mar 2020 13:01

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