High thermal stability and resistance to oxidation at atmospheric conditions need to be critically proven to ensure a long lifetime of the receiver of concentrated solar power plants. In the present work, the titanium aluminum nitride tandem absorbers are showing one of the most promising selective coating solutions for solar receivers operating at high temperature. A series of samples were synthesized by vacuum plasma techniques in an industrial pilot-scale deposition machine. The structure consists in an Inconel 625 substrate with infrared reflective layer, followed by two TiAlN layers (tandem absorber) with refractive index gradation and covered with SiNCH, as an antireflective layer. A programmable electrical tubular furnace was used to apply cumulative aging tests on the samples under static ambient air at temperatures from 500°C to 690°C. One batch of samples was tested cumulatively in air at 500°C, for long-term representative aging, up to a total duration of 732 hours. Other samples were then submitted to cumulative accelerated aging in air at 630°C up to 264 hours, at 660°C up to 366 hours and at 690°C up to 156 hours. Spectral reflectance was systematically measured before and after aging. The results show that the optical properties did not change with aging, demonstrating long-term stability of optical properties at 500°C in air. EDS analysis revealed that the content in oxygen first increases then stabilizes over time (6 at.%), probably indicating the oxidation of the antireflective top layer SiNCH into SiO2 (as was also shown by previous XPS analysis), which then acts both as a barrier for further oxidation and as antireflective material. For higher temperatures, a maximum decrease of solar absorptance of -0.11 was observed. However, emittance also tended to decrease, limiting the decrease of the resulting heliothermal efficiency. In all cases, SEM imaging did not show any physical changes in surface morphology with aging. Overall, this type of selective coating shows both good optical performance and a very good resistance to aging at high temperature in air, rendering it very promising for CSP applications where the solar receiver is at or above 500°C, without the need to maintain it under vacuum.

1.
International Energy Agency (IEA)
,
Technology Roadmap: Solar Thermal electricity
,
2014
edition, pp.
26
27
.
2.
A.
Soum-Glaude
,
A.
Le Gal
,
M.
Bichotte
,
C.
Escape
and
L.
Dubost
,
Optical characterization of TiAlNx/TiAlNy/Al2O3 tandem solar selective absorber coatings
,
Solar Energy Mater. Solar Cells
170
,
254
262
(
2017
).
3.
L.
Rebouta
,
A.
Pitães
,
M.
Andritschky
,
P.
Capela
,
M.
Cerqueira
,
A.
Matilainen
, and
K.
Pischow
,
Optical characterization of TiAlN/TiAlON/SiO2 absorber for solar selective applications
.
Surf. Coat. Technol.
211
,
41
44
(
2012
).
4.
H.C.
Barshilia
,
S.
Nagarajan
,
K.S.
Rajam
,
D.V. Sridhara
Rao
, and
M.
Kuttanellore
,
Deposition and characterization of TiAlN/TiAlON/Si3N4 tandem absorbers prepared using reactive direct current magnetron sputtering
,
Thin Solid Films
516
,
6071
6078
(
2008
).
5.
M.
Bichotte
,
L.
Dubost
,
T.
Pouit
,
A.
Soum-Glaude
,
A.
Le Gal
,
H.
Glénat
, and
D.
Itskhokine
,
Arc deposited TiAlN selective absorber for high temperature CSP applications
,
AIP Conf. Proc.
1734
030006-1
9
(
2016
) (SolarPACES 2015).
6.
M.
Bichotte
,
T.
Kämpfe
,
W.
Iff
,
F.
Celle
,
S.
Reynaud
,
T.
Pouit
,
A.
Soum-Glaude
,
M.A.
Keilany
,
L.
Dubost
, and
Y.
Jourlin
,
2017
,
Diffractive gratings to improve TiAlN based spectrally selective solar absorbers
, (
SolarPACES 2017
).
7.
A.
Soum-Glaude
,
L.
Di Giacomo
,
S.
Quoizola
,
T.
Laurent
,
G.
Flamant
, “Selective Surfaces for Solar Thermal Energy Conversion in CSP: From Multilayers to Nanocomposites”, in
Nanotechnology for Energy Sustainability
, Edited by
B.
Raj
,
M.
Van de Voorde
and
Y.
Mahajan
(
Wiley-VCH Verlag GmbH
, ISBN 978-3-527-34014-9,
2017
), pp.
231
248
.
8.
Renewable Resource Data Center
, “
Standard Tables for Reference Solar Spectral Irradiance at Air Mass 1.5: Direct Normal and Hemispherical for a 37 Tilted Surface, ASTM G173-03.
Reference Spectra derived from SMARTS v. 2.9.2 (AM1.5)”.
9.
International Standard
,
ISO 22975-3, Solar energy-Collector components and materials-Part 3: Absorber surface durability
,
2014
.
10.
L.
An
,
S. Talat
Ali
,
T.
Søndergaard
,
J.
Nørgaard
,
Y.-C.
Tsao
, and
K.
Pedersen
,
Optimization of TiAlN/TiAlON/Si3N4 solar absorber coatings
,
Solar Energy
118
,
410
418
(
2015
).
11.
A.
Soum-Glaude
,
A.
Le Gal
,
M.
Bichotte
, and
L.
Dubost
,
Thermal stability and durability studies of tandem TiAlN high temperature solar selective coatings
,
SolarPACES 2016
,
Abu Dhabi, UAE
,
11–14 Oct 2016
.
12.
B.
Carlsson
,
K.
Möller
,
M.
Köhl
,
M.
Heck
,
S.
Brunold
,
U.
Frei
,
J. C.
Marechal
, and
G.
Jorgensen
,
The applicability of accelerated life testing for assessment of service life of solar thermal components
,
Solar Energy Mater. Solar Cells
84
,
255
274
(
2004
).
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