Broadband High Temperature Thermal Emitter/Absorber Designed by Adjoint Method

Author(s):  
Muhammed Kecebas ◽  
Kursat Sendur
Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1814
Author(s):  
Guozhi Hou ◽  
Qingyuan Wang ◽  
Yu Zhu ◽  
Zhangbo Lu ◽  
Jun Xu ◽  
...  

Thermal emitters with properties of wavelength-selective and narrowband have been highly sought after for a variety of potential applications due to their high energy efficiency in the mid-infrared spectral range. In this study, we theoretically and experimentally demonstrate the tunable narrowband thermal emitter based on fully planar Si-W-SiN/SiNO multilayer, which is realized by the excitation of Tamm plasmon polaritons between a W layer and a SiN/SiNO-distributed Bragg reflector. In conjunction with electromagnetic simulations by the FDTD method, the optimum structure design of the emitter is implemented by 2.5 periods of DBR structure, and the corresponding emitter exhibits the nearly perfect narrowband absorption performance at the resonance wavelength and suppressed absorption performance in long wave range. Additionally, the narrowband absorption peak is insensitive to polarization mode and has a considerable angular tolerance of incident light. Furthermore, the actual high-quality Si-W-SiN/SiNO emitters are fabricated through lithography-free methods including magnetron sputtering and PECVD technology. The experimental absorption spectra of optimized emitters are found to be in good agreement with the simulated absorption spectra, showing the tunable narrowband absorption with all peak values of over 95%. Remarkably, the fabricated Si-W-SiN/SiNO emitter presents excellent high-temperature stability for several heating/cooling cycles confirmed up to 1200 K in Ar ambient. This easy-to-fabricate and tunable narrowband refractory emitter paves the way for practical designs in various photonic and thermal applications, such as thermophotovoltaic and IR radiative heaters.


2020 ◽  
Vol 8 (8) ◽  
pp. 1900982 ◽  
Author(s):  
Zih‐Ying Yang ◽  
Satoshi Ishii ◽  
Anh Tung Doan ◽  
Satish Laxman Shinde ◽  
Thang Duy Dao ◽  
...  

CLEO: 2014 ◽  
2014 ◽  
Author(s):  
Jingjing Liu ◽  
Urcan Guler ◽  
Wei Li ◽  
Alexander V. Kildishev ◽  
Alexandra Boltasseva ◽  
...  

Author(s):  
M.S. Grewal ◽  
S.A. Sastri ◽  
N.J. Grant

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.


Author(s):  
B. J. Hockey

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.


Author(s):  
D. R. Clarke ◽  
G. Thomas

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.


Author(s):  
E. R. Kimmel ◽  
H. L. Anthony ◽  
W. Scheithauer

The strengthening effect at high temperature produced by a dispersed oxide phase in a metal matrix is seemingly dependent on at least two major contributors: oxide particle size and spatial distribution, and stability of the worked microstructure. These two are strongly interrelated. The stability of the microstructure is produced by polygonization of the worked structure forming low angle cell boundaries which become anchored by the dispersed oxide particles. The effect of the particles on strength is therefore twofold, in that they stabilize the worked microstructure and also hinder dislocation motion during loading.


Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization


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