Characterization of the alumina scale formed on a commercial MCrAlYHfSi coating

K. A. Unocic; B. A. Pint

doi:10.1016/j.surfcoat.2010.08.111

Characterization of the alumina scale formed on a commercial MCrAlYHfSi coating

K. A. Unocic, B. A. Pint

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

57 Scopus citations

Abstract

A commercial NiCoCrAlYHfSi coating deposited on a Ni-base superalloy substrate was characterized before and after high temperature oxidation. The combination of Y, Hf and Si additions is reported to improve coating performance. Advanced characterization techniques including scanning-transmission electron microscopy were used to study the segregation behavior of Y and Hf ions to the alumina grain boundaries after 200h at 1050°C and 100 and 200h exposures at 1100°C. After both exposure times, two distinct oxide layers were observed. The outer transient layer included many Y- and Hf-rich oxide particles. The inner layer consisted of columnar α-Al₂O₃ grains normal to the surface of the coating. Segregation of Y and Hf ions was found on the alumina grain boundaries as has been observed in model alloys with similar compositions. Isothermal exposures for up to 200h at 1050° and 1100°C caused a minimal increase in surface roughness. However, 200 1-h cycles at 1100°C resulted in a more significant increase in surface roughness.

Original language	English
Pages (from-to)	1178-1182
Number of pages	5
Journal	Surface and Coatings Technology
Volume	205
Issue number	5
DOIs	https://doi.org/10.1016/j.surfcoat.2010.08.111
State	Published - Nov 25 2010

Keywords

Alumina
Bond coat
Hafnium
MCrAlY
Segregation
Yttrium

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10.1016/j.surfcoat.2010.08.111

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title = "Characterization of the alumina scale formed on a commercial MCrAlYHfSi coating",

abstract = "A commercial NiCoCrAlYHfSi coating deposited on a Ni-base superalloy substrate was characterized before and after high temperature oxidation. The combination of Y, Hf and Si additions is reported to improve coating performance. Advanced characterization techniques including scanning-transmission electron microscopy were used to study the segregation behavior of Y and Hf ions to the alumina grain boundaries after 200h at 1050°C and 100 and 200h exposures at 1100°C. After both exposure times, two distinct oxide layers were observed. The outer transient layer included many Y- and Hf-rich oxide particles. The inner layer consisted of columnar α-Al2O3 grains normal to the surface of the coating. Segregation of Y and Hf ions was found on the alumina grain boundaries as has been observed in model alloys with similar compositions. Isothermal exposures for up to 200h at 1050° and 1100°C caused a minimal increase in surface roughness. However, 200 1-h cycles at 1100°C resulted in a more significant increase in surface roughness.",

keywords = "Alumina, Bond coat, Hafnium, MCrAlY, Segregation, Yttrium",

author = "Unocic, {K. A.} and Pint, {B. A.}",

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doi = "10.1016/j.surfcoat.2010.08.111",

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AU - Unocic, K. A.

AU - Pint, B. A.

PY - 2010/11/25

Y1 - 2010/11/25

N2 - A commercial NiCoCrAlYHfSi coating deposited on a Ni-base superalloy substrate was characterized before and after high temperature oxidation. The combination of Y, Hf and Si additions is reported to improve coating performance. Advanced characterization techniques including scanning-transmission electron microscopy were used to study the segregation behavior of Y and Hf ions to the alumina grain boundaries after 200h at 1050°C and 100 and 200h exposures at 1100°C. After both exposure times, two distinct oxide layers were observed. The outer transient layer included many Y- and Hf-rich oxide particles. The inner layer consisted of columnar α-Al2O3 grains normal to the surface of the coating. Segregation of Y and Hf ions was found on the alumina grain boundaries as has been observed in model alloys with similar compositions. Isothermal exposures for up to 200h at 1050° and 1100°C caused a minimal increase in surface roughness. However, 200 1-h cycles at 1100°C resulted in a more significant increase in surface roughness.

AB - A commercial NiCoCrAlYHfSi coating deposited on a Ni-base superalloy substrate was characterized before and after high temperature oxidation. The combination of Y, Hf and Si additions is reported to improve coating performance. Advanced characterization techniques including scanning-transmission electron microscopy were used to study the segregation behavior of Y and Hf ions to the alumina grain boundaries after 200h at 1050°C and 100 and 200h exposures at 1100°C. After both exposure times, two distinct oxide layers were observed. The outer transient layer included many Y- and Hf-rich oxide particles. The inner layer consisted of columnar α-Al2O3 grains normal to the surface of the coating. Segregation of Y and Hf ions was found on the alumina grain boundaries as has been observed in model alloys with similar compositions. Isothermal exposures for up to 200h at 1050° and 1100°C caused a minimal increase in surface roughness. However, 200 1-h cycles at 1100°C resulted in a more significant increase in surface roughness.

KW - Alumina

KW - Bond coat

KW - Hafnium

KW - MCrAlY

KW - Segregation

KW - Yttrium

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DO - 10.1016/j.surfcoat.2010.08.111

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VL - 205

SP - 1178

EP - 1182

JO - Surface and Coatings Technology

JF - Surface and Coatings Technology

IS - 5

ER -

Characterization of the alumina scale formed on a commercial MCrAlYHfSi coating

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Keywords

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