Oxidation characteristics of gamma-TiAl-8Nb coated with a CrAlYN/CrN nanoscale multilayer coating
Oxidation characteristics of gamma-TiAl-8Nb coated with a CrAlYN/CrN nanoscale multilayer coating
The full exploitation of gamma-TiAl for high performance applications is currently hindered by its poor high temperature oxidation behaviour above 750 degrees C. To overcome this there is a need to develop coatings that protect against high temperature oxidation, bill do not adversely affect the mechanical properties. This work reports on the oxidation protection offered by a CrAlYN/CrN based multilayer coating deposited on gamma-TiAl-8Nb. Coated samples were subjected to quasi-isothermal oxidation in dry air at 850 degrees C for times Lip to 1030hrs. Excellent oxidation resistance was achieved with the coated samples exhibiting a four fold improvement compared to the uncoated intermetallic. Microstructural investigations revealed a mixed Cr/Al oxide scale at the surface of the coating after an exposure of 168hrs. However cracks in the coating, a result of thermal mismatch between the coating and substrate. led to oxidation of the substrate with the formation of an alumina rich oxide directly below the crack and the extensive growth of titania (rutile) at the surface. In addition, significant modification of the surface region of the substrate was observed with the formation of a thick polycrystalline TiN layer and a segregated (Ti)Al3Nb interface region between the TiN and the unaffected substrate.
9780873397209
315-322
Ross, I.M.
8cc6d91c-d3e6-4384-91dc-6558bd9449e1
Rainforth, W.M.
b9c1d1e5-ba6b-4856-8b62-03e38688358b
Zhou, Z.
ec4c2669-5686-45de-bf3f-acf80d0ed849
Walker, J.C.
b300eafd-5b0a-4cf5-86d2-735813b04c6f
Reinhard, C.
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Ehiasarian, A.P.
e516cffb-3efc-4808-a7ba-09de32ce5fb6
Hovsepian, P.E.
26dc9a32-7129-442c-b4f1-9310a9e597e7
Braun, R.
1ccd2501-556d-44e6-a421-d7bd42769253
Leyens, C.
4fede0f1-f010-4d62-b793-4ec5bb06f936
2008
Ross, I.M.
8cc6d91c-d3e6-4384-91dc-6558bd9449e1
Rainforth, W.M.
b9c1d1e5-ba6b-4856-8b62-03e38688358b
Zhou, Z.
ec4c2669-5686-45de-bf3f-acf80d0ed849
Walker, J.C.
b300eafd-5b0a-4cf5-86d2-735813b04c6f
Reinhard, C.
9d4e1fea-9578-4411-b2d0-a70d78934a9a
Ehiasarian, A.P.
e516cffb-3efc-4808-a7ba-09de32ce5fb6
Hovsepian, P.E.
26dc9a32-7129-442c-b4f1-9310a9e597e7
Braun, R.
1ccd2501-556d-44e6-a421-d7bd42769253
Leyens, C.
4fede0f1-f010-4d62-b793-4ec5bb06f936
Ross, I.M., Rainforth, W.M., Zhou, Z., Walker, J.C., Reinhard, C., Ehiasarian, A.P., Hovsepian, P.E., Braun, R. and Leyens, C.
(2008)
Oxidation characteristics of gamma-TiAl-8Nb coated with a CrAlYN/CrN nanoscale multilayer coating.
In,
Kim, Young-Won, Morris, David, Yang, Rui and Leyens, Christoph
(eds.)
Structural Aluminides for Elevated Temperatures Gamma Titanium and Other Metallic Aluminides.
(Structural Aluminides for Elevated Temperatures Symposium held at the TMS 2008 Annual Meeting and Exhibition)
Pennsylvania, US.
.
Record type:
Book Section
Abstract
The full exploitation of gamma-TiAl for high performance applications is currently hindered by its poor high temperature oxidation behaviour above 750 degrees C. To overcome this there is a need to develop coatings that protect against high temperature oxidation, bill do not adversely affect the mechanical properties. This work reports on the oxidation protection offered by a CrAlYN/CrN based multilayer coating deposited on gamma-TiAl-8Nb. Coated samples were subjected to quasi-isothermal oxidation in dry air at 850 degrees C for times Lip to 1030hrs. Excellent oxidation resistance was achieved with the coated samples exhibiting a four fold improvement compared to the uncoated intermetallic. Microstructural investigations revealed a mixed Cr/Al oxide scale at the surface of the coating after an exposure of 168hrs. However cracks in the coating, a result of thermal mismatch between the coating and substrate. led to oxidation of the substrate with the formation of an alumina rich oxide directly below the crack and the extensive growth of titania (rutile) at the surface. In addition, significant modification of the surface region of the substrate was observed with the formation of a thick polycrystalline TiN layer and a segregated (Ti)Al3Nb interface region between the TiN and the unaffected substrate.
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Published date: 2008
Organisations:
nCATS Group
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Local EPrints ID: 205459
URI: http://eprints.soton.ac.uk/id/eprint/205459
ISBN: 9780873397209
PURE UUID: 720db257-3239-4f3f-864c-1a56ddaee962
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Date deposited: 08 Dec 2011 10:25
Last modified: 10 Dec 2021 19:55
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Contributors
Author:
I.M. Ross
Author:
W.M. Rainforth
Author:
Z. Zhou
Author:
C. Reinhard
Author:
A.P. Ehiasarian
Author:
P.E. Hovsepian
Author:
R. Braun
Author:
C. Leyens
Editor:
Young-Won Kim
Editor:
David Morris
Editor:
Rui Yang
Editor:
Christoph Leyens
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