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Title: Examination of the platinum effect on the oxidation behavior ofnickel-aluminide coatings

Abstract

Oxidation resistant nickel-aluminide coatings are designed to develop a protective alumina scale during high temperature exposure. It is well established that platinum additions, typically about 6-8 at%, provide substantial improvements in oxidation resistance of such coatings, yet the nature of the platinum effect is still not fully understood. In this work, the oxidation behavior of two commercial NiAl and NiPtAl coatings deposited on the same Ni-base single crystal alloy CMSX-4 was analyzed. Cyclic and isothermal oxidation tests were conducted at 1150 C in air. Microstructure development and alumina/coating interface chemistry were studied as a function of oxidation time. Numerous voids developed at the Al{sub 2}O{sub 3}/NiAl interface, and sulfur was found to segregate at the void surfaces and at the contact interface, leading to spallation of the scale over the convex areas along ridges on the coating surface. The presence of platinum prevented sulfur segregation and void formation at the Al{sub 2}O{sub 3}/NiPtAl interface. As a result, the Al{sub 2}O{sub 3} scale on the NiPtAl coating remained adherent and virtually no spallation was observed even after prolonged cyclic oxidation.

Authors:
;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE Director. Office of Science. Basic EnergySciences
OSTI Identifier:
923207
Report Number(s):
LBNL-62479
R&D Project: 503001; BnR: KC0201020; TRN: US200804%%1027
DOE Contract Number:  
DE-AC02-05CH11231
Resource Type:
Conference
Resource Relation:
Conference: International Conference on MetallurgicalCoatings and Thin Films, San Diego, CA, April 23-27,2007
Country of Publication:
United States
Language:
English
Subject:
36; AIR; ALLOYS; CHEMISTRY; COATINGS; MICROSTRUCTURE; MONOCRYSTALS; OXIDATION; PLATINUM; PLATINUM ADDITIONS; SEGREGATION; SPALLATION; SULFUR; THIN FILMS

Citation Formats

Hou, Peggy Y., and Tolpygo, V.K. Examination of the platinum effect on the oxidation behavior ofnickel-aluminide coatings. United States: N. p., 2007. Web.
Hou, Peggy Y., & Tolpygo, V.K. Examination of the platinum effect on the oxidation behavior ofnickel-aluminide coatings. United States.
Hou, Peggy Y., and Tolpygo, V.K. Tue . "Examination of the platinum effect on the oxidation behavior ofnickel-aluminide coatings". United States. doi:. https://www.osti.gov/servlets/purl/923207.
@article{osti_923207,
title = {Examination of the platinum effect on the oxidation behavior ofnickel-aluminide coatings},
author = {Hou, Peggy Y. and Tolpygo, V.K.},
abstractNote = {Oxidation resistant nickel-aluminide coatings are designed to develop a protective alumina scale during high temperature exposure. It is well established that platinum additions, typically about 6-8 at%, provide substantial improvements in oxidation resistance of such coatings, yet the nature of the platinum effect is still not fully understood. In this work, the oxidation behavior of two commercial NiAl and NiPtAl coatings deposited on the same Ni-base single crystal alloy CMSX-4 was analyzed. Cyclic and isothermal oxidation tests were conducted at 1150 C in air. Microstructure development and alumina/coating interface chemistry were studied as a function of oxidation time. Numerous voids developed at the Al{sub 2}O{sub 3}/NiAl interface, and sulfur was found to segregate at the void surfaces and at the contact interface, leading to spallation of the scale over the convex areas along ridges on the coating surface. The presence of platinum prevented sulfur segregation and void formation at the Al{sub 2}O{sub 3}/NiPtAl interface. As a result, the Al{sub 2}O{sub 3} scale on the NiPtAl coating remained adherent and virtually no spallation was observed even after prolonged cyclic oxidation.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}

Conference:
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