Material Properties of Laser-Welded Thin Silicon Foils

An extended monocrystalline silicon base foil offers a great opportunity to combine low-cost production with high efficiency silicon solar cells on a large scale. By overcoming the area restriction of ingot-based monocrystalline silicon wafer production, costs could be decreased to thin film solar cell range. The extended monocrystalline silicon base foil consists of several individual thin silicon wafers which are welded together. A comparison of three different approaches to weld 50 μm thin silicon foils is investigated here: (1) laser spot welding with low constant feed speed, (2) laser line welding, and (3) keyhole welding. Cross-sections are prepared and analyzed by electron backscatter diffraction (EBSD) to reveal changes in the crystal structure at the welding side after laser irradiation. The treatment leads to the appearance of new grains and boundaries. The induced internal stress, using the three different laser welding processes, was investigated by micro-Raman analysis. We conclude that the keyhole welding process is the most favorable to produce thin silicon foils.

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Design and Testing of a High-Efficiency Rapid Throughput Community-Scale Water Pasteurization System

Volume 2B: 43rd Design Automation Conference ◽

10.1115/detc2017-67830 ◽

2017 ◽

Cited By ~ 1

Author(s):

Nordica MacCarty ◽

Grace Burleson ◽

Nicholas Moses ◽

Tejas Mulky ◽

Joshua Johnson ◽

...

Keyword(s):

Drinking Water ◽

Business Models ◽

High Efficiency ◽

Performance Testing ◽

Field Testing ◽

Production Costs ◽

System Level ◽

Great Opportunity ◽

Emergency Situations ◽

Clean Drinking Water

Procurement of clean drinking water is one of the most important challenges facing 1 in 10 people in the world today. While there are many technologies available to disinfect water, there is still great opportunity for appropriate, sustainable technologies for low-resource or emergency situations. Pasteurizing water is an effective way to eliminate life-threatening pathogens such as bacteria, viruses, and protozoa, and requires a lower temperature (71° C) compared to traditional boiling (100° C). This research details the development and testing of a water pasteurization system that works with the 60 Liter InStove to produce upwards of 4,500 liters of safe drinking water per day at minimal cost to the users and the environment. This flow-through system uses a combination of a heating coil, thermostatic valve, fixed volume kill chamber, and heat exchanger for heat recovery immersed in a large pot of heated water. Initial performance testing revealed that the pasteurizer produced 6.7 liters of water per minute with an energy input of 9.1 grams of equivalent dry wood per liter (175 kJ/L) at steady-state operation accounting for startup time. Microbiological testing revealed that water initially inoculated with >100,000 bacteria/ml of E. coli had no colonies remaining after treatment, for a 99.999% reduction in contamination levels. Future work will include measurement and modeling of the flow and temperature profiles throughout the system to optimize its heat transfer performance and production costs, field testing, and user-centered system-level design that develops the end-to-end solution needed to acquire and deliver clean drinking water including maintenance, container disinfection, and development of business models to support local water production.

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Comparison of Electrically-Assisted and Conventional Friction Stir Welding Processes by Feed Force and Torque

Volume 1: Processing ◽

10.1115/msec2013-1192 ◽

2013 ◽

Cited By ~ 4

Author(s):

Hemanth Potluri ◽

Joshua J. Jones ◽

Laine Mears

Keyword(s):

Friction Stir Welding ◽

Large Scale ◽

Welding Process ◽

Electrical Current ◽

Ultra Sound ◽

Friction Stir ◽

Direct Electrical Current ◽

Electrically Assisted ◽

Feed Force ◽

Welding Processes

The process of friction stir welding involves high tool forces and requires robust machinery; the forces involved make tool wear a predominant problem. As a result, many alternatives have been proposed in decreasing tool forces such as laser assisted friction stir welding and ultra-sound assisted friction stir welding. However, these alternatives are not commercially successful on a large scale due to scalability and capital/maintenance costs. In an attempt to reduce forces in a cost-feasible manner, electrically-assisted friction stir welding (EAFSW) is studied in this work. EAFSW is a result of applying the concept of electrically-assisted manufacturing (i.e., passing high direct electrical current through a workpiece during processing) to the conventional friction stir welding process. The concept of EAFSW is a relatively new adaptation of conventional frictional stir welding, which is well established. The expected benefits are reduction in the feed force and torque, which allow for improved processing productivity as well as the possibility for deeper penetration of the weld.

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Numerical and Experimental Validation of Gas Metal Arc Welding on AISI 441 Ferritic Stainless Steel Through Mechanical and Microstructural Analysis

10.21203/rs.3.rs-1187414/v1 ◽

2022 ◽

Author(s):

SERAFINO CARUSO ◽

DOMENICO UMBRELLO

Keyword(s):

Grain Size ◽

Residual Stresses ◽

Arc Welding ◽

Gas Metal Arc Welding ◽

Microstructural Analysis ◽

Welding Process ◽

Production Costs ◽

Metal Arc Welding ◽

Residual Stresses And Strains ◽

Welding Processes

Abstract Residual stresses and strains, distortion, heat affected zone (HAZ), grain size changes and hardness variation during gas metal arc welding (GMAW), are fundamental aspects to study and control during welding processes. For this reason, numerical simulations of the welding processes represent the more frequently used tool to better analyse the several aspects characterizing this joining process with the aim to reduce lead time and production costs. In the present study an uncoupled 3D thermo-mechanical analysis was carried out by two commercial finite element method (FEM) software to model an experimental single bead GMAW of AISI 441 at different process set-up. The experimental HAZ and measured temperatures were used to calibrate the heat source of both the used numerical codes, then a validation procedure was done to test the robustness of the two developed analytical procedures. One software was used to predict the residual stresses and strains and the distortions of the welded components, while in the second software a user routine was implemented, including a physical based model and the Hall-Petch (H-P) equation, to predict grain size change and hardness evolution respectively. The results demonstrate that the predicted mechanical and microstructural aspects agree with those experimentally found showing the reliability of the two codes in predicting the thermal phenomena characterizing the HAZ during the analysed welding process.

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Development of a Recuperated Flameless Combustor for an Inverted Brayton Cycle Microturbine Used in Residential Micro-CHP

Volume 4B: Combustion, Fuels and Emissions ◽

10.1115/gt2017-65271 ◽

2017 ◽

Author(s):

Michel Delanaye ◽

Andrés Giraldo ◽

Rabia Nacereddine ◽

Mehdi Rouabah ◽

Valentina Fortunato ◽

...

Keyword(s):

Natural Gas ◽

Gas Turbine ◽

Large Scale ◽

High Efficiency ◽

Low Cost ◽

Primary Energy ◽

Brayton Cycle ◽

Cfd Modelling ◽

Great Opportunity ◽

Chp System

The paper presents recent work in the development of a clean and efficient natural gas combustor for a micro-CHP system based on a gas turbine for the residential sector. The large scale deployment of natural gas micro-CHP systems represents a great opportunity to contribute to a reduction of CO2 emissions by a substantial increase of the efficiency of primary energy source conversion. A micro-CHP system, well designed for a residential application, which means a power of 1kWe output and high efficiency (larger than 20%), may reduce annual household emissions up to factors close to 2.5. The micro-CHP system developed in this work uses a small gas turbine and an inverted Brayton cycle which advantageously allows the use of substantially larger turbomachinery components than a conventional pressurized Brayton cycle. The paper presents a new counterflow recuperator. Its design has been thoroughly studied by advanced 3D CFD to obtain compactness and high efficiency at low cost. A new flameless combustor has been developed in order to reduce to single digits the emissions of pollutants (NOx and CO) and obtain a highly efficient and stable combustion for various gases. The design methodology based on 3D CFD modelling is presented as well as experimental results demonstrating the performance of the recuperated flameless combustor for various operationg conditions.

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Improving productivity and quality in plastic and thin metallic plates manufacturing by using ultrasonic welding processes

Soldagem & Inspeção ◽

10.1590/s0104-92242009000400009 ◽

2009 ◽

Vol 14 (4) ◽

pp. 344-351

Author(s):

D. Dehelean ◽

O. Oanca

Keyword(s):

High Efficiency ◽

Process Development ◽

Welding Process ◽

Value Added ◽

Ultrasonic Welding ◽

Ultrasonic Process ◽

Welding Processes ◽

High Efficiency Welding ◽

Special Case

The paper presents an overview of the research done at the Romanian National R&D Institute for Welding and Material Testing ISIM Timisoara in the field of ultrasonic process development. It starts with a general presentation of the value added by the welding sector in Europe. There are presented figures representing the size of the welding sector in Romania. The need of development of new high efficiency welding processes is mentioned, ultrasonic welding being one of the special welding processes with exceptional application perspectives. Practical examples of industrial application of the ultrasonic welding process for joining plastic and metallic materials are presented. A special case study refers to the welding of new shape memory alloys. The use of the ultrasonic welding instead of an conventional welding process has lead in each presented case study to an increase of the efficiency of the welding process through higher productivity and saving of manpower, consumable, energy.

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Investigation on CO and Microparticles Concentrations Produced in MAG-M Welding Process

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.809-810.455 ◽

2015 ◽

Vol 809-810 ◽

pp. 455-460 ◽

Cited By ~ 2

Author(s):

Danuţ Mihailescu ◽

Marius Corneliu Gheonea ◽

Elena Scutelnicu

Keyword(s):

Metal Powder ◽

Welding Process ◽

Fusion Welding ◽

Feed Speed ◽

Shielding Gas ◽

Cored Wire ◽

Environment Quality ◽

Basic Flux ◽

Wire Feed Speed ◽

Welding Processes

It is well known that CO and microparticles generated during GMAW welding processes can affect the welder's health and the environment quality and should be avoided. The main goal of the research was to quantitatively assess the concentrations of CO and microparticules resulting through melted wire - shielding gas - welding pool interaction, specific to fusion welding process, in particular MAG-M (Metal Active Gas with Corgon shielding gas)) process. The concentrations of microparticles and emission of CO developed by several combinations of filler metal and shielding gas, such as ordinary solid wire, basic flux-cored wire, rutile flux-cored wire, metal powder cored wire, low fume metal powder cored wire and Corgon 18, as shielding gas mixture, have been monitored and investigated in detail. The experimental data, achieved for different wire feed speed values, were collected by using special devices as Multilyzer NG and MicroDust Pro and further processed, plotted and comparatively analysed. The analysis revealed that the low fume rutile flux-cored wire significantly developed lower concentrations of microparticles and CO, in comparison with the other types of wires used in MAG-M welding process, and a better protection of the environment would be achieved. Important conclusions related to the influence of the wire type on the concentrations of CO and microparticles produced during MAG-M welding process have been drawn and some recommendations useful for the producers of welded structures are provided at the end of the paper.

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Influence of Copper Interlayers on the Magnetic Pulse Welding Process between Aluminum and Steel

Metals ◽

10.3390/met11060868 ◽

2021 ◽

Vol 11 (6) ◽

pp. 868

Author(s):

Joerg Bellmann ◽

Kristina Roder ◽

Martina Zimmermann ◽

Eckhard Beyer ◽

Lothar Kroll ◽

...

Keyword(s):

Large Scale ◽

Intermetallic Phase ◽

Welding Process ◽

Fusion Welding ◽

Magnetic Pulse ◽

Scale Production ◽

Joint Formation ◽

Magnetic Pulse Welding ◽

Pulse Welding ◽

Welding Processes

Magnetic pulse welding (MPW) is a promising joining technology for the large-scale production of dissimilar metallic joints. Although the heat input is comparatively low, the temporary occurrence of high temperatures in the joining gap was found to play an important role during the joint formation. It is possible that the melting or even the boiling temperature of the involved materials will be exceeded, and fusion welding will occur. The purpose of this study is to investigate the influence of target materials with different thermal properties on the joint formation and weld seam characteristic. Therefore, MPW between steel targets and aluminum flyers was performed with and without copper coatings on steel. The lower melting temperature of copper compared to steel had no significant effect on the appearance of the mixed zones in the interface and the amount of molten target material or aluminum, respectively. Nevertheless, the comparison of the higher impact energies showed, that the copper interlayer can lead to a decrease in the weld length or a degradation of the weld quality due to an extended intermetallic phase formation or cracks. This result is important for the parameter adjustment of magnetic pulse welding processes.

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Large-Scale Welding Process Simulation by GPU Parallelized Computing

Welding Journal ◽

10.29391/2022.101.032 ◽

2021 ◽

Vol 100 (11) ◽

pp. 359-370

Author(s):

HUI HUANG ◽

◽

JIAN CHEN ◽

ZHILI FENG ◽

HUI-PING WANG ◽

...

Keyword(s):

Residual Stress ◽

Large Scale ◽

Welding Process ◽

Computational Design ◽

Nuclear Industry ◽

Welding Distortion ◽

Deformation Pattern ◽

Processing Unit ◽

Automotive Manufacturing ◽

Welding Processes

The computational design of industrially relevant welded structures is extremely time consuming due to coupled physics and high nonlinearity. Previously, most welding distortion and residual stress simulations have been limited to small coupons and reduced order (from three-dimensional [3D] to two-dimensional [2D]), or inherent strain approximations were used for large structures. In this current study, an explicit finite element code based on a graphics processing unit was utilized to perform 3D transient thermomechanical simulation of structural components during welding. Laser brazing of aluminum alloy panels as representative of automotive manufacturing scenarios was simulated to predict out-of-plane distortion under different clamping conditions. The predicted deformation pattern and magnitude were validated by laser scanning data of physical assemblies. In addition, the code was used to investigate residual stresses developed during multipass arc welding of a nuclear industry pressurizer surge nozzle and subsequent welding repair where a 3D simulation was necessary. Taking the experimental data as reference, the 3D model predicted better residual stress distribution than a typical 2D asymmetrical model. Stress evolution in welding repair was also presented and discussed in this study. The efficient numerical model made it feasible to use integrated computational welding engineering to simulate welding processes for large-scale structures.

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The Potential of Photoelectrochemical Carbon Sinks

10.26434/chemrxiv.6231140.v2 ◽

2018 ◽

Author(s):

Matthias May ◽

Kira Rehfeld

Keyword(s):

Global Warming ◽

High Temperature ◽

Greenhouse Gas ◽

Large Scale ◽

High Efficiency ◽

Carbon Sink ◽

Solar Fuels ◽

Negative Emissions ◽

Viable Approach ◽

Low Sensitivity

Greenhouse gas emissions must be cut to limit global warming to 1.5-2C above preindustrial levels. Yet the rate of decarbonisation is currently too low to achieve this. Policy-relevant scenarios therefore rely on the permanent removal of CO2 from the atmosphere. However, none of the envisaged technologies has demonstrated scalability to the decarbonization targets for the year 2050. In this analysis, we show that artificial photosynthesis for CO2 reduction may deliver an efficient large-scale carbon sink. This technology is mainly developed towards solar fuels and its potential for negative emissions has been largely overlooked. With high efficiency and low sensitivity to high temperature and illumination conditions, it could, if developed towards a mature technology, present a viable approach to fill the gap in the negative emissions budget.

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