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Separation of boron from silicon by steam-added electron beam melting
摘要： Removal of boron from silicon is a tough task by traditional directional solidification and vacuum refining techniques, due to its large and inappropriate segregation coefficient and low saturated vapor pressure. At high temperature boron react with oxygen to form volatile boron oxides which can be evaporated. So, the removal procedure of boron from silicon melt is investigated by incorporating a small amount of water vapor above the melted surface. The results show that boron is oxidized to mainly form BO and evaporated with 28% removal efficiency by average. It is considered that oxygen atoms experience a series of physical and chemical processes, such as a chemical reaction in the bulk of the melt, evaporation from the melt surface, transportation across the gas phase and ionization due the electron beam, which is conducive to the continuous removal of boron.
关键词： Electron beam melting,Photovoltaic,Boron removal,Oxygen self-circulating path,Solar-grade silicon
更新于2025-09-23 15:23:52
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Developing New Materials for Electron Beam Melting: Experiences and Challenges
摘要： Lack of industrially available materials for additive manufacturing (AM) of metallic materials along with the promises of materials with improved or unique properties provides a strong drive for developing new process/material combinations. As powder bed technologies for metallic materials are relatively new to the market, and to some extent are only maturing, developers of new process/material combinations have certain challenges to overcome. Firstly, basic knowledge on the behavior of materials (even those well established for other applications) under extreme conditions of melting/solidification with beam-based AM methods is far from being adequate. Secondly, manufacturing of the equipment is up to date driven by industrial application, thus optimization of the AM machines for small test batches of powders is still belongs to research and development projects. Also, majority of the powder manufacturers are primarily driven by the market development, and even they are well aware of the demands imposed by the powder bed AM machines, availability of small test batches of adequate powders may be problematic or at least quite costly for the R&D oriented users. Present paper describes the experiences in developing new materials for EBM A2 machine by Arcam EBM, modified for operating with powder batches of 100-200 ml and less. In particular it discusses achievements and challenges of working with powders from different materials with specifications far beyond the range suggested by machine manufacturer. Also it discusses the possibility of using blended rather than pre-alloyed powders for achieving both composite-like and alloyed materials in the same part by steering electron beam energy deposition strategy.
关键词： Electron Beam Melting,material development,composite materials,Additive Manufacturing,blended powders,in situ alloying
更新于2025-09-23 15:23:52
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Effects of laser shock peening on microstructure and fatigue behavior of Tia??6Ala??4V alloy fabricated via electron beam melting
摘要： Laser shock peening (LSP) is a post-treatment process that is widely used to modify the surface microstructure and mechanical properties of parts constructed by additive manufacturing (AM). In this study, the influence of LSP on the microstructure and fatigue behavior of Ti–6Al–4V alloy manufactured via electron beam melting (EBM), a popular method of AM, was investigated. The microstructure of the EBM sample consisted of the β phase (~6 vol%) and α lamellar phase. Grain refinement of the α phase occurred via both dislocation evolution and deformation twinning during LSP. A theoretical description of the microstructural evolution, particularly the distribution of deformation twins, was developed. The fatigue strength and micro-hardness of the EBM samples increased by approximately 17% and 11% after LSP treatment, respectively. The fatigue fracture morphologies at three defined damage stages (crack initiation, crack propagation, and instantaneous rupture) were examined for EBM samples before and after LSP. The dominant mechanism of fatigue strength enhancement by LSP was discussed. The effects of residual compressive stress assistant with adiabatic temperature increase and grain refinement of the α phase produced by LSP reduced the pre-existing crack size, suppressed crack initiation, and increased the required work for fatigue fracture.
关键词： Laser shock peening,Electron beam melting,Ti–6Al–4V titanium alloy,Fatigue behavior,Microstructural characterization
更新于2025-09-23 15:19:57
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Pilot capability evaluation of a feedback electronic imaging system prototype for in-process monitoring in electron beam additive manufacturing
摘要： Electron beam additive manufacturing (EBAM) is an additive manufacturing (AM) technique increasingly used by many industrial sectors, including medical and aerospace industries. The application of this technology is still, however, challenged by many technical barriers. One of the major issues is the lack of process monitoring and control system to monitor process repeatability and component quality reproducibility. Various techniques, mainly involving infrared (IR) and optical cameras, have been employed in previous attempts to study the quality of the EBAM process. However, all attempts lack the flexibility to zoom-in and focus on multiple regions of the processing area. In this paper, a digital electronic imaging system prototype and a piece of macroscopic process quality analysis software are presented. The prototype aims to provide flexibility in magnifications and the selection of fields of view (FOV). The software aims to monitor the EBAM process on a layer-by-layer basis. Digital electronic images were generated by detecting both secondary electrons (SE) and backscattered electrons (BSE) originating from interactions between the machine electron beam and the processing area using specially designed hardware. Prototype capability experiments, software verification and demonstration were conducted at room temperature on the top layer of an EBAM test build. Digital images of different magnifications and FOVs were generated. The upper range of the magnification achieved in the experiments was 95 and the demonstration verified the potential ability of the software to be applied in process monitoring. It is believed that the prototype and software have significant potential to be used for in-process EBAM monitoring in many manufacturing sectors. This study is thought to be the necessary precursor for future work which will establish whether the concept is suited to working under in-process EBAM operating conditions.
关键词： In-process monitoring,Electron beam melting,Electronic imaging,Metallic materials,Additive manufacturing,Quality control,Backscattered electrons,Secondary electrons
更新于2025-09-10 09:29:36
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Preparation of Si-SiOx nanoparticles from volatile residue produced by refining of silicon
摘要： Residual Si was produced on a furnace wall when upgraded metallurgical grade Si was re?ned by electron beam melting. It was then recycled to prepare Si-SiOx nanoparticles with an average size of 100 nm by planetary ball milling. The obtained Si-SiOx nanoparticles mainly consist of amorphous Si, crystalline Si and amorphous SiOx, which was con?rmed by XRD, FTIR, XPS and TEM. SiOx is mainly composed of SiO2 and SiO1.35. Distilled water used as a grinding aid not only enhances milling ef?ciency, but also plays a key role in obtaining SiOx. During re?ning of upgraded metallurgical grade Si, the deposition pattern of residual Si on furnace wall agrees with model of three-dimension growth. Growth of Si-SiOx nanoparticles is the mutual effect of distilled water and ball milling. Si-SiOx nanoparticles were doped into phenolic resin pyrolysis carbon as anode materials for lithium ion batteries, and 10% doping was observed to improve the speci?c capacity. After 500 cycles, speci?c capacity of delithiation remained around 550 mA h/g. It suggests the residual Si is a value-added by-product, and it can be recycled as anode materials for lithium ion batteries.
关键词： Residual Si,Si-carbon anode,Si-SiOx nanoparticles,Planetary ball milling,Electron beam melting
更新于2025-09-04 15:30:14