Laser Processing of Thermal Sprayed Coatings for Thermoelectric Generators

2013 ◽  
Author(s):  
Mahder Tewolde ◽  
Di Liu ◽  
David J. Hwang ◽  
Jon P. Longtin
Keyword(s):  
Thermal Spray ◽  
Process Parameters ◽  
Laser Processing ◽  
Short Pulse ◽  
Low Cost ◽  
Laser Wavelength ◽  
Device Fabrication ◽  
Electrical Isolation ◽  
Adjacent Structures ◽  
Study Results

Recent research has shown that thermal spray has the potential to fabricate thermoelectric devices at low cost and high volumes. An integral aspect of the device fabrication is laser processing of the various thermal sprayed layers, which is used to form electrically isolated regions and minimize heat loss to adjacent structures. In this article, experimental results are presented for the laser patterning of thermal spray samples ranging from 50μm to 2mm in thickness. The optimization of process parameters is important for successful electrical isolation and high-quality features. In this study results are presented several short-pulse lasers (nanosecond and picosecond) in which laser power, laser wavelength, type of focusing lens, processing speed, repetition rate, and pressure and flow of purge gas were varied. The optimum laser parameters were those that minimize the heat affected zone and delamination due to thermal damage while providing maximum material removal. The resulting laser patterns were characterized using both optical and scanning electron (SEM) microscopy, and by verifying electrical isolation between patterned regions using contact resistance measurements. Cut quality attributes including kerf width and edge profile were also studied, and their dependence on process parameters reported.

POTENTIAL EVALUATION OF YELLOW COTTON (COCHLOSPERMUM REGIUM) PIGMENTS FOR DYE SENSITIZED SOLAR CELLS APPLICATION

2020 ◽  
pp. 16-21
Author(s):  
PHITCHAPHORN KHAMMEE ◽  
YUWALEE UNPAPROM ◽  
UBONWAN SUBHASAEN ◽  
RAMESHPRABU RAMARAJ
Keyword(s):  
Solar Cells ◽  
Low Cost ◽  
Dye Sensitized Solar Cells ◽  
Photoelectric Conversion Efficiency ◽  
Photoelectric Conversion ◽  
Plant Materials ◽  
Natural Pigments ◽  
Dye Sensitized ◽  
Study Results ◽  
Sensitized Solar Cells

Recently, dye-sensitized solar cells (DSSC) have concerned significant attention attributable to their material preparation process, architectural and environmental compatibility, also low cost and effective photoelectric conversion efficiency. Therefore, this study aimed to use potential plant materials for DSSC. This research presents the extraction of natural pigments from yellow cotton flowers (Cochlospermum regium). In addition, the natural pigments were revealed that outstanding advantages, including a wide absorption range (visible light), easy extraction method, safe, innocuous pigments, inexpensive, complete biodegradation and ecofriendly. Methanol was used as a solvent extraction for the yellow cotton flower. The chlorophylls and carotenoid pigments extractions were estimated by a UV-visible spectrometer. The chlorophyll-a, chlorophyll-b, and carotenoid yield were 0.719±0.061 µg/ml, 1.484±0.107 µg/ml and 7.743±0.141 µg/ml, respectively. Thus, this study results suggested that yellow cotton flowers containing reasonable amounts appealable in the DSSC production.

UKP-laserbasierte Herstellung von Netzen unterschiedlicher Transmissionsgrade/USP-laser based production of meshes of different transmission degrees

2020 ◽  
Vol 110 (11-12) ◽  
pp. 787-789
Author(s):  
Marcel Simons ◽  
Till Rusche ◽  
Tobias Valentino ◽  
Tim Radel ◽  
Frank Vollertsen
Keyword(s):  
High Precision ◽  
Processing Speed ◽  
Laser Processing ◽  
Short Pulse ◽  
High Quality ◽  
Mesh Width ◽  
Variable Transmission ◽  
Ultra Short Pulse ◽  
Mesh Structures

Die Ultrakurzpuls (UKP)-laserbasierte Bearbeitung erlaubt die Herstellung von Netzstrukturen mit verschiedenen Transmissionsgraden. Vorteile der UKP-laserbasierten Herstellung der Netze liegen vor allem in der hohen Präzision und Bearbeitungsgeschwindigkeit. Die UKP-Laserbearbeitung ermöglicht die Herstellung von Netzen aus Aluminium in hoher Qualität, bezogen auf die Stegbreitenabweichung von < 8 µm, mit variablen Transmissionsgraden. Ultra-short pulse (USP) laser based processing enables the production of mesh structures with different degrees of transmission. The advantages of USP-based production of mesh structures are mainly the high precision and processing speed. USP laser processing enables the production of meshes of aluminum in high quality, with respect to the mesh width deviation of < 8 µm with variable transmission degrees.

Chromium oxide dissolution in steels via short pulse laser processing

2013 ◽  
Vol 115 (4) ◽  
pp. 1469-1477 ◽  
Author(s):  
Evgeny Kharanzhevskiy ◽  
Sergey Reshetnikov
Keyword(s):  
Pulse Laser ◽  
Chromium Oxide ◽  
Laser Processing ◽  
Short Pulse ◽  
Oxide Dissolution ◽  
Short Pulse Laser

scholarly journals Tower Crane Location Optimization for Heavy Unit Lifting in High-Rise Modular Construction

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 121
Author(s):  
Hosang Hyun ◽  
Moonseo Park ◽  
Dowan Lee ◽  
Jeonghoon Lee
Keyword(s):  
Low Cost ◽  
Modular Construction ◽  
Algorithm Optimization ◽  
Location Selection ◽  
Project Completion ◽  
High Rise ◽  
Tower Crane ◽  
Proposed Model ◽  
Study Results ◽  
Crane Selection

Modular construction, which involves unit production in factories and on-site work, has benefits such as low cost, high quality, and short duration, resulting from the controlled factory environment utilized. An efficient tower crane lifting plan ensures successful high-rise modular project completion. For improved efficiency, the lifting plan should minimize the reaching distance of the tower crane, because this distance directly affects the tower crane capacity, which is directly related to crane operation cost. In situations where units are lifted from trailers, the trailer-to-tower crane distance can have a significant impact on the tower crane operation efficiency. However, optimization of this distance to improve efficiency has not been sufficiently considered. This research proposes a genetic algorithm optimization model that suggests optimized tower crane and trailer locations. The case study results show that through the proposed model, the project manager can reflect the optimal location selection and optimal tower crane selection options with minimal cost.

Characterization of Thermal Oxides of Laser Annealed Polysilicon

1981 ◽  
Vol 4 ◽  
Author(s):  
Rajiv R. Shah ◽  
Robert Mays ◽  
D. Lloyd Crosthwait
Keyword(s):  
Laser Processing ◽  
Single Crystal Silicon ◽  
Electrical Characterization ◽  
Device Fabrication ◽  
Breakdown Field ◽  
Guard Ring ◽  
Crystal Silicon ◽  
Process Sequence ◽  
Thermal Oxide

ABSTRACTWe report an investigation of the effects of laser processing on the thermal oxides of polysilicon. LPCVD polysilicon, 500 nm thick, deposited on 500 nm thermal oxide of single crystal silicon was laser processed at various stages in the process sequence for device fabrication. Effects of CW Ar+ and pulsed 1.06 and 0.53 μm laser processing were investigated. Laser annealed polysilicon was oxidized in a steam ambient. Using a second level of polysilicon, guard ring diode and capacitors were fabricated. Electrical characterization revealed an improvement in breakdown field strengths of these oxides without deleterious effects on any of the associated interfaces.

Influence of Rotary Friction Welding Parameters on Tensile Strength and Length of TMAZ of Dissimilar Welded Joints from 32G2 and 40KhN Steels

2021 ◽  
Vol 410 ◽  
pp. 299-305
Author(s):  
Artem S. Atamashkin ◽  
Elena Y. Priymak ◽  
Elena A. Kuzmina
Keyword(s):  
Tensile Strength ◽  
Base Metal ◽  
Process Parameters ◽  
Welded Joints ◽  
Friction Welding ◽  
Tensile Tests ◽  
Welding Parameters ◽  
Rotary Friction Welding ◽  
Study Results ◽  
Friction Pressure

In this work, pipe billets with a diameter of 73 mm and a wall thickness of 9 mm from steels 32G2 and 40KhN are friction welded with an aim to optimize the process parameters. The friction pressure, the forging pressure and the length of the fusion varied. After the implementation of various welding modes, tensile tests and metallographic studies were carried out. The optimal welding parameters have been established, which make it possible to obtain tensile strength at the level of the 32G2 base metal. The study results of the microstructure and SEM fractographs after the optimal welding mode are presented.

Laser-Induced Acoustic Waves for Measurement and Imaging

2000 ◽  
Author(s):  
Wen Li ◽  
Ronald A. Roy ◽  
Robin O. Cleveland ◽  
Lawrence J. Berg ◽  
Charles A. DiMarzio
Keyword(s):  
Acoustic Waves ◽  
Peak Power ◽  
Laser Light ◽  
Short Pulse ◽  
Laser Wavelength ◽  
Acoustic Imaging ◽  
Acoustic Energy ◽  
High Peak Power ◽  
First Case ◽  
Very High

Abstract A short pulse of laser light can act as a source of acoustic energy for acoustic imaging. Although there are a number of mechanisms by which the light pulse may generate sound, all require a pulse of high peak power density and short duration. In this work, we address examples where the material is highly absorbing at the laser wavelength, and the sound is generated near the surface. In these cases, there exist two different mechanisms which can convert the light to sound. The first is heating followed by expansion, and the second is generation of a plasma in the air above the surface. In the first case, sound generation occurs in the medium of interest and the energy efficiency can be very high, in the sense that no reflection losses occur. We present two applications from our own research.

scholarly journals Pulsed UV Laser Processing of Carbosilane and Silazane Polymers

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 372 ◽  
Author(s):  
Samuel Ligon ◽  
Gurdial Blugan ◽  
Jakob Kuebler
Keyword(s):  
Laser Beam ◽  
Laser Processing ◽  
Scanning Speed ◽  
Inert Atmosphere ◽  
Laser Wavelength ◽  
Uv Laser ◽  
Glass Substrates ◽  
Polymer Precursors ◽  
Laser Systems ◽  
Pre Treatment

Freestanding SiCNO ceramic pieces with sub-mm features were produced by laser crosslinking of carbosilane and silazane polymer precursors followed by pyrolysis in inert atmosphere. Three different pulsed UV laser systems were investigated, and the influence of laser wavelength, operating power and scanning speed were all found to be important. Different photoinitiators were tested for the two lasers operating at 355 nm, while for the 266 nm laser, crosslinking occurred also without photoinitiator. Pre-treatment of glass substrates with fluorinated silanes was found to ease the release of green bodies during solvent development. Polymer crosslinking was observed with all three of the laser systems, as were bubbles, surface charring and in some cases ablation. By focusing the laser beam several millimeters above the surface of the resin, selective polymer crosslinking was observed exclusively.

Image-Based Modeling for Assessing Thermal Conductivity of Thermal Spray Coatings at Ambient and High Temperature

2006 ◽  
Author(s):  
Y. Tan ◽  
A. Sharma ◽  
J. P. Longtin ◽  
S. Sampath ◽  
H. Wang
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Thermal Spray ◽  
Process Parameters ◽  
Thermal Spraying ◽  
Thermal Spray Coatings ◽  
Analysis Model ◽  
Element Analysis ◽  
Spray Coatings ◽  
Coating Microstructure

Thermal spray coatings are used extensively for protection of engineering components and structures in a variety of applications. Due to the nature of thermal spraying process, the coating thermal, mechanical, and electrical properties depend strongly on the coating microstructure, which consists of many individual splats, interfaces between the splats, defects and voids. The coating microstructure, in turn, is determined by the thermal spray process parameters. In order to relate coating process parameters to the final coating performance, then, it is desirable to relate coating microstructure to coating properties. In this work, thermal conductivity is used as the physical parameter of interest. Thermal conductivity of thermal spray coatings is studied by using an image analysis-based approach of typical coating cross sections. Three coating systems, yttria stabilized zirconia (YSZ), molybdenum, and Ni-5wt.%Al are explored in this work. For each material, thermal conductivity is simulated by using a microstructure image-based finite element analysis model. The model is then applied to high temperature conditions (up to 1200 °C) with a hot stage-equipped scanning electron microscope imaging technique to assess thermal conductivity at high temperatures. The coating thermal conductivity of metallic coatings is also experimentally measured by using a high-temperature laser flash technique.

scholarly journals Metal-Assisted Chemical Etching for Anisotropic Deep Trenching of GaN Array

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3179
Author(s):  
Qi Wang ◽  
Kehong Zhou ◽  
Shuai Zhao ◽  
Wen Yang ◽  
Hongsheng Zhang ◽  
...  
Keyword(s):  
Chemical Etching ◽  
Low Cost ◽  
Etching Rate ◽  
Surface Damage ◽  
Device Fabrication ◽  
Irreversible Damage ◽  
Catalytic Role ◽  
Metal Assisted Chemical Etching ◽  
Gan Etching

Realizing the anisotropic deep trenching of GaN without surface damage is essential for the fabrication of GaN-based devices. However, traditional dry etching technologies introduce irreversible damage to GaN and degrade the performance of the device. In this paper, we demonstrate a damage-free, rapid metal-assisted chemical etching (MacEtch) method and perform an anisotropic, deep trenching of a GaN array. Regular GaN microarrays are fabricated based on the proposed method, in which CuSO4 and HF are adopted as etchants while ultraviolet light and Ni/Ag mask are applied to catalyze the etching process of GaN, reaching an etching rate of 100 nm/min. We comprehensively explore the etching mechanism by adopting three different patterns, comparing a Ni/Ag mask with a SiN mask, and adjusting the etchant proportion. Under the catalytic role of Ni/Ag, the GaN etching rate nearby the metal mask is much faster than that of other parts, which contributes to the formation of deep trenches. Furthermore, an optimized etchant is studied to restrain the disorder accumulation of excessive Cu particles and guarantee a continuous etching result. Notably, our work presents a novel low-cost MacEtch method to achieve GaN deep etching at room temperature, which may promote the evolution of GaN-based device fabrication.

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