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Technology Overview
> Thermal Barrier Coatings
New class of refractory
layered perovskites to replace YSZ-based Thermal Barrier Coatings |
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Integrated approach to durable TBCs using
"naturally-occurring" nanolayered crystalline materials
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BaNd2Ti3O10 (BNT) offers excellent thermal
barrier and suitable physical and mechanical properties
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Exploitation of extensive crystalline
disorder to lower k and induce strain tolerance
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Uniform and highly dense coatings obtained
by Atmospheric Plasma Spray (APS)
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Thermal conductivity values as low as 0.5 W/mK
demonstrated at ~1573K for fully dense BNT
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CTE tailorable based on texture control
(~11.5 x 10-6/K - ~30% basal texture) to minimize residual stress
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Thermal, mechanical, and chemical stability
demonstrated for coated materials for over 100h at 1400°C
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Current project with US Army (SBIR Phase II)
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BNT belongs to a special class of highly anisotropic refractory layered
perovskites. The crystal structure contains easy-cleaving planes that
provide both lower thermal conductivity and required compliance. Measurement
of thermal conductivity on hot pressed BNT material shows lower k values
(especially at elevated T) compared to conventional e-beam PVD YSZ TBCs
(figure on right). Dense BNT coatings will provide desirable thermophysical
and mechanical properties and provide better oxidation protection and will
not be subject to sintering stresses that cause spallation. By controlling
the crystallographic texture, the CTE can be tailored to match the
substrate.
Technical Information
and Literature |
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Comparison of Thermal conductivity between YSZ (published data) and BNT
Plot Labels:
A:
Atmospheric Plasma Spray (APS) BNT (1.2 mm thick free-standing coating)
B:
fully dense BNT
C:
APS BNT on MCrAlY/Rene N5 laser heat flux tested at NASA for 20 hours at
temperature
D:
APS YSZ
E:
e-Beam PVD YSZ
F:
CoorsTek® fully dense YSZ
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The crystal structure of BNT contains
easy-cleaving planes that provide both lower thermal conductivity (blue
arrow) and required compliance (green arrow) for improved TBC performance.
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Room temperature impact test performed on BNT
coated copper demonstrating damage tolerance due to inherent low modulus and
compliant properties.
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Using ATFI’s proprietary synthetic process,
BNT powders with excellent flow characteristics have been used to deposit
dense coatings by APS on a variety of substrates with excellent adhesion and
thickness ranging from 15μm to over 1mm. Substrates include: copper, steel,
superalloy, MCrAlY, graphite, and alumina.
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Applied Thin Films, Inc.
