Influence of sulfur, platinum, and hafnium on the oxidation behavior of CVD NiAl bond coatings

J. A. Haynes; B. A. Pint; K. L. More; Y. Zhang; I. G. Wright

doi:10.1023/A:1020525123056

Influence of sulfur, platinum, and hafnium on the oxidation behavior of CVD NiAl bond coatings

J. A. Haynes, B. A. Pint, K. L. More, Y. Zhang, I. G. Wright

Research output: Contribution to journal › Article › peer-review

192 Scopus citations

Abstract

The influences of S, Pt, and Hf on the oxidation behavior of chemical vapor deposition (CVD) NiAl bond coatings on high-S and low-S superalloys were investigated. Cyclic and isothermal-oxidation testing at 1150°C revealed that alumina-scale adherence to NiAl coatings was very sensitive to substrate S impurities. Scale spallation, as well as the growth of voids at the oxide-metal interface, increased as S increased. However, Pt-modified coatings were not sensitive to S, and did not form voids at the oxide-metal interface. Transmission-electron microscopy (TEM) revealed that alumina scales formed on (Ni, Pt) Al had Hf ions (from the superalloy) segregated to grain boundaries, whereas Hf was not detected in the alumina scale formed on NiAl coatings. Results suggested that the detrimental influence of S on scale adherence to NiAl is primarily related to void growth, which is eliminated or significantly reduced in Pt-modified coatings. A simple model relating void growth to excess vacancies and sulfur segregation is proposed.

Original language	English
Pages (from-to)	513-544
Number of pages	32
Journal	Oxidation of Metals
Volume	58
Issue number	5-6
DOIs	https://doi.org/10.1023/A:1020525123056
State	Published - Dec 2002

Keywords

Aluminide bond coating
Hafnium
Platinum
Sulfur
Voids

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title = "Influence of sulfur, platinum, and hafnium on the oxidation behavior of CVD NiAl bond coatings",

abstract = "The influences of S, Pt, and Hf on the oxidation behavior of chemical vapor deposition (CVD) NiAl bond coatings on high-S and low-S superalloys were investigated. Cyclic and isothermal-oxidation testing at 1150°C revealed that alumina-scale adherence to NiAl coatings was very sensitive to substrate S impurities. Scale spallation, as well as the growth of voids at the oxide-metal interface, increased as S increased. However, Pt-modified coatings were not sensitive to S, and did not form voids at the oxide-metal interface. Transmission-electron microscopy (TEM) revealed that alumina scales formed on (Ni, Pt) Al had Hf ions (from the superalloy) segregated to grain boundaries, whereas Hf was not detected in the alumina scale formed on NiAl coatings. Results suggested that the detrimental influence of S on scale adherence to NiAl is primarily related to void growth, which is eliminated or significantly reduced in Pt-modified coatings. A simple model relating void growth to excess vacancies and sulfur segregation is proposed.",

keywords = "Aluminide bond coating, Hafnium, Platinum, Sulfur, Voids",

author = "Haynes, {J. A.} and Pint, {B. A.} and More, {K. L.} and Y. Zhang and Wright, {I. G.}",

year = "2002",

month = dec,

doi = "10.1023/A:1020525123056",

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volume = "58",

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journal = "Oxidation of Metals",

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T1 - Influence of sulfur, platinum, and hafnium on the oxidation behavior of CVD NiAl bond coatings

AU - Haynes, J. A.

AU - Pint, B. A.

AU - More, K. L.

AU - Zhang, Y.

AU - Wright, I. G.

PY - 2002/12

Y1 - 2002/12

N2 - The influences of S, Pt, and Hf on the oxidation behavior of chemical vapor deposition (CVD) NiAl bond coatings on high-S and low-S superalloys were investigated. Cyclic and isothermal-oxidation testing at 1150°C revealed that alumina-scale adherence to NiAl coatings was very sensitive to substrate S impurities. Scale spallation, as well as the growth of voids at the oxide-metal interface, increased as S increased. However, Pt-modified coatings were not sensitive to S, and did not form voids at the oxide-metal interface. Transmission-electron microscopy (TEM) revealed that alumina scales formed on (Ni, Pt) Al had Hf ions (from the superalloy) segregated to grain boundaries, whereas Hf was not detected in the alumina scale formed on NiAl coatings. Results suggested that the detrimental influence of S on scale adherence to NiAl is primarily related to void growth, which is eliminated or significantly reduced in Pt-modified coatings. A simple model relating void growth to excess vacancies and sulfur segregation is proposed.

AB - The influences of S, Pt, and Hf on the oxidation behavior of chemical vapor deposition (CVD) NiAl bond coatings on high-S and low-S superalloys were investigated. Cyclic and isothermal-oxidation testing at 1150°C revealed that alumina-scale adherence to NiAl coatings was very sensitive to substrate S impurities. Scale spallation, as well as the growth of voids at the oxide-metal interface, increased as S increased. However, Pt-modified coatings were not sensitive to S, and did not form voids at the oxide-metal interface. Transmission-electron microscopy (TEM) revealed that alumina scales formed on (Ni, Pt) Al had Hf ions (from the superalloy) segregated to grain boundaries, whereas Hf was not detected in the alumina scale formed on NiAl coatings. Results suggested that the detrimental influence of S on scale adherence to NiAl is primarily related to void growth, which is eliminated or significantly reduced in Pt-modified coatings. A simple model relating void growth to excess vacancies and sulfur segregation is proposed.

KW - Aluminide bond coating

KW - Hafnium

KW - Platinum

KW - Sulfur

KW - Voids

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SP - 513

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JO - Oxidation of Metals

JF - Oxidation of Metals

IS - 5-6

ER -

Influence of sulfur, platinum, and hafnium on the oxidation behavior of CVD NiAl bond coatings

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Keywords

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