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https://www.readbyqxmd.com/read/29342074/characterization-of-an-additive-manufactured-tial-alloy-steel-joint-produced-by-electron-beam-welding
#1
Gloria Basile, Giorgio Baudana, Giulio Marchese, Massimo Lorusso, Mariangela Lombardi, Daniele Ugues, Paolo Fino, Sara Biamino
In this work, the characterization of the assembly of a steel shaft into a γ-TiAl part for turbocharger application, obtained using Electron Beam Welding (EBW) technology with a Ni-based filler, was carried out. The Ti-48Al-2Nb-0.7Cr-0.3Si (at %) alloy part was produced by Electron Beam Melting (EBM). This additive manufacturing technology allows the production of a lightweight part with complex shapes. The replacement of Nickel-based superalloys with TiAl alloys in turbocharger automotive applications will lead to an improvement of the engine performance and a substantial reduction in fuel consumption and emission...
January 17, 2018: Materials
https://www.readbyqxmd.com/read/29335485/electron-beam-melting-in-the-fabrication-of-three-dimensional-mesh-titanium-mandibular-prosthesis-scaffold
#2
Rongzeng Yan, Danmei Luo, Haitao Huang, Runxin Li, Niu Yu, Changkui Liu, Min Hu, Qiguo Rong
The study was designed to fulfill effective work-flow to fabricate three-dimensional mesh titanium scaffold for mandibular reconstruction. The 3D titanium mesh scaffold was designed based on a volunteer with whole mandible defect. (1) acquisition of the CT data; (2) design with computer aided design (CAD) and finite element analysis (FEA). The pore size and intervals with the best mechanic strength was also calculated using FEA. (3) fabrication of the scaffold using electron beam melting (EBM); (4) implantation surgery...
January 15, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29332500/microstructure-and-mechanical-properties-of-porous-titanium-structures-fabricated-by-electron-beam-melting-for-cranial-implants
#3
Khaja Moiduddin
The traditional methods of metallic bone implants are often dense and suffer from adverse reactions, biomechanical mismatch and lack of adequate space for new bone tissue to grow into the implant. The objective of this study is to evaluate the customized porous cranial implant with mechanical properties closer to that of bone and to improve the aesthetic outcome in cranial surgery with precision fitting for a better quality of life. Two custom cranial implants (bulk and porous) are digitally designed based on the Digital Imaging and Communications in Medicine files and fabricated using additive manufacturing...
January 1, 2018: Proceedings of the Institution of Mechanical Engineers. Part H, Journal of Engineering in Medicine
https://www.readbyqxmd.com/read/29285396/multi-environment-nanocalorimeter-with-electrical-contacts-for-use-in-the-scanning-electron-microscope
#4
Feng Yi, Ana Stevanovic, William A Osborn, A Kolmakov, David A LaVan
We have developed a versatile nanocalorimeter sensor which allows imaging and electrical measurements of samples under different gaseous environments using the scanning electron microscope (SEM) and can simultaneously measure the sample temperature and associated heat of reaction. This new sensor consists of four independent heating/sensing elements for nanocalorimetry and eight electrodes for electrical measurements, all mounted on a 50 nm thick, 250 μm × 250 μm suspended silicon nitride membrane. This membrane is highly electron transparent and mechanically robust enabling in situ SEM observation under realistic temperatures, environmental conditions and pressures up to one atmosphere...
November 2017: Materials Horizons
https://www.readbyqxmd.com/read/29215451/mandibular-reconstruction-using-a-customized-three-dimensional-titanium-implant-applied-on-the-lingual-surface-of-the-mandible
#5
You-Young Jo, Seong-Gon Kim, Min-Keun Kim, Sung-Ho Shin, Janghoon Ahn, Hyun Seok
A patient had a right mandibular defect due to resection of an ameloblastoma. Previously, the defect had been reconstructed by an iliac bone graft, and subsequently, a titanium mesh with xenograft was used. However, it was not successfully reconstructed. For the recovery of mandible continuity and rehabilitation of jaw movement, we manufactured a customized 3-dimensional titanium implant by computer-aided design and manufacturing and electron beam melting technology. This implant was designed to have a porous body structure and lingual plate...
December 6, 2017: Journal of Craniofacial Surgery
https://www.readbyqxmd.com/read/29170483/free-running-sn-precipitates-an-efficient-phase-separation-mechanism-for-metastable-ge1-xsnx-epilayers
#6
Heiko Groiss, Martin Glaser, Magdalena Schatzl, Moritz Brehm, Dagmar Gerthsen, Dietmar Roth, Peter Bauer, Friedrich Schäffler
The revival of interest in Ge1-xSnx alloys with x ≥ 10% is mainly owed to the recent demonstration of optical gain in this group-IV heterosystem. Yet, Ge and Sn are immiscible over about 98% of the composition range, which renders epilayers based on this material system inherently metastable. Here, we address the temperature stability of pseudomorphic Ge1-xSnx films grown by molecular beam epitaxy. Both the growth temperature dependence and the influence of post-growth annealing steps were investigated...
November 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29152535/time-zero-determination-for-fel-pump-probe-studies-based-on-ultrafast-melting-of-bismuth
#7
S W Epp, M Hada, Y Zhong, Y Kumagai, K Motomura, S Mizote, T Ono, S Owada, D Axford, S Bakhtiarzadeh, H Fukuzawa, Y Hayashi, T Katayama, A Marx, H M Müller-Werkmeister, R L Owen, D A Sherrell, K Tono, K Ueda, F Westermeier, R J D Miller
A common challenge for pump-probe studies of structural dynamics at X-ray free-electron lasers (XFELs) is the determination of time zero (T0)-the time an optical pulse (e.g., an optical laser) arrives coincidently with the probe pulse (e.g., a XFEL pulse) at the sample position. In some cases, T0 might be extracted from the structural dynamics of the sample's observed response itself, but generally, an independent robust method is required or would be superior to the inferred determination of T0. In this paper, we present how the structural dynamics in ultrafast melting of bismuth can be exploited for a quickly performed, reliable and accurate determination of T0 with a precision below 20 fs and an overall experimental accuracy of 50 fs to 150 fs (estimated)...
September 2017: Structural Dynamics (Melville, N.Y.)
https://www.readbyqxmd.com/read/29136309/comparison-of-fit-of-dentures-fabricated-by-traditional-techniques-versus-cad-cam-technology
#8
J Bryan McLaughlin, Van Ramos, Douglas P Dickinson
PURPOSE: To compare the shrinkage of denture bases fabricated by three methods: CAD/CAM, compression molding, and injection molding. The effect of arch form and palate depth was also tested. MATERIALS AND METHODS: Nine titanium casts, representing combinations of tapered, ovoid, and square arch forms and shallow, medium, and deep palate depths, were fabricated using electron beam melting (EBM) technology. For each base fabrication method, three poly(vinyl siloxane) impressions were made from each cast, 27 dentures for each method...
November 14, 2017: Journal of Prosthodontics: Official Journal of the American College of Prosthodontists
https://www.readbyqxmd.com/read/29134773/design-and-biological-functionality-of-a-novel-hybrid-ti-6al-4v-hydrogel-system-for-reconstruction-of-bone-defects
#9
Alok Kumar, K C Nune, R D K Misra
We have designed a unique injectable bioactive hydrogel comprising of alginate, gelatin, and nanocrystalline hydroxyapatite and loaded with osteoblasts, with the ability to infiltrate into three-dimensional Ti-6Al-4V scaffolds with interconnected porous architecture, fabricated by electron beam melting (EBM). A two-step crosslinking process using the EDC/NHS and CaCl2 was adopted and found to be effective in the fabrication of cell-loaded hydrogel/Ti-6Al-4V scaffold system. This hybrid Ti-6Al-4V scaffold/hydrogel system was designed for the reconstruction of bone defects, which are difficult to heal in the absence of suitable support materials...
November 14, 2017: Journal of Tissue Engineering and Regenerative Medicine
https://www.readbyqxmd.com/read/29111845/pre-clinical-evaluation-of-the-mechanical-properties-of-a-low-stiffness-cement-injectable-hip-stem
#10
Ibrahim Eldesouky, Ola Harrysson, Denis J Marcellin-Little, Harvey West, Hassan El-Hofy
In total hip arthroplasty (THA), the femoral stem can be fixed with or without bone cement. Cementless stem fixation is recommended for young and active patients as it eliminates the risk of loss of fixation at the bone-cement and cement-implant interfaces. Cementless fixation, however, suffers from a relatively high early revision rate. In the current research, a novel low-stiffness hip stem was designed, fabricated and tested. The stem design provided the option to inject biodegradable bone cement that could enhance initial stem stability...
November 7, 2017: Journal of Medical Engineering & Technology
https://www.readbyqxmd.com/read/29096063/halide-effects-on-the-sublimation-temperature-of-x-au-l-complexes-implications-for-their-use-as-precursors-in-vapor-phase-deposition-methods
#11
Will G Carden, Jakub Pedziwiatr, Khalil A Abboud, Lisa McElwee-White
Trends in volatility with changes in the halide ligand were established for gold(I) complexes of the type X-Au-L [X = Cl, Br, I; L = CN(t)Bu, CNMe, PMe3, P(NMe2)3, P(OCH2CF3)3] by determining the temperatures for the onset of sublimation (Tsub) at a fixed pressure. Within each series of isocyanide complexes, Tsub decreases with increasing atomic radius of the halide, making the iodide complex the most volatile. For the phosphine and phosphoramidate complexes, the chloride and bromide have similar Tsub values with the bromide slightly higher, but the iodide complex is again the most volatile of the three...
November 9, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29038806/kinetics-of-volatile-impurity-removal-from-silicon-by-electron-beam-melting-for-photovoltaic-applications
#12
Shuang Shi, Pengting Li, Jianxiong Meng, Dachuan Jiang, Yi Tan, H M Noor Ul Huda Khan Asghar
A full domain control model is established for impurity transportation in the liquid phase, gas-liquid interface and gas phase of silicon to analyze the dynamic mechanics of impurity removal. The results show that the overall mass transfer coefficient mainly depends on the temperature and the chamber pressure. Its value increases with the increase of temperature or the decrease of chamber pressure. Under the same melting condition, the order of the overall mass transfer coefficients for P, Al and Ca is kP > kAl > kCa, indicating that P is easier to remove by evaporation...
October 25, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28967051/additive-manufacturing-of-titanium-alloys-in-the-biomedical-field-processes-properties-and-applications
#13
Francesco Trevisan, Flaviana Calignano, Alberta Aversa, Giulio Marchese, Mariangela Lombardi, Sara Biamino, Daniele Ugues, Diego Manfredi
The mechanical properties and biocompatibility of titanium alloy medical devices and implants produced by additive manufacturing (AM) technologies - in particular, selective laser melting (SLM), electron beam melting (EBM) and laser metal deposition (LMD) - have been investigated by several researchers demonstrating how these innovative processes are able to fulfil medical requirements for clinical applications. This work reviews the advantages given by these technologies, which include the possibility to create porous complex structures to improve osseointegration and mechanical properties (best match with the modulus of elasticity of local bone), to lower processing costs, to produce custom-made implants according to the data for the patient acquired via computed tomography and to reduce waste...
September 25, 2017: Journal of Applied Biomaterials & Functional Materials
https://www.readbyqxmd.com/read/28937643/design-and-additive-manufacturing-of-3d-phononic-band-gap-structures-based-on-gradient-based-optimization
#14
Maximilian Wormser, Fabian Wein, Michael Stingl, Carolin Körner
We present a novel approach for gradient based maximization of phononic band gaps. The approach is a geometry projection method combining parametric shape optimization with density based topology optimization. By this approach, we obtain, in a two dimension setting, cellular structures exhibiting relative and normalized band gaps of more than 8 and 1.6, respectively. The controlling parameter is the minimal strut size, which also corresponds with the obtained stiffness of the structure. The resulting design principle is manually interpreted into a three dimensional structure from which cellular metal samples are fabricated by selective electron beam melting...
September 22, 2017: Materials
https://www.readbyqxmd.com/read/28937638/effects-of-processing-parameters-on-surface-roughness-of-additive-manufactured-ti-6al-4v-via-electron-beam-melting
#15
Pan Wang, Wai Jack Sin, Mui Ling Sharon Nai, Jun Wei
As one of the powder bed fusion additive manufacturing technologies, electron beam melting (EBM) is gaining more and more attention due to its near-net-shape production capacity with low residual stress and good mechanical properties. These characteristics also allow EBM built parts to be used as produced without post-processing. However, the as-built rough surface introduces a detrimental influence on the mechanical properties of metallic alloys. Thereafter, understanding the effects of processing parameters on the part's surface roughness, in turn, becomes critical...
September 22, 2017: Materials
https://www.readbyqxmd.com/read/28937633/predictive-simulation-of-process-windows-for-powder-bed-fusion-additive-manufacturing-influence-of-the-powder-bulk-density
#16
Alexander M Rausch, Vera E Küng, Christoph Pobel, Matthias Markl, Carolin Körner
The resulting properties of parts fabricated by powder bed fusion additive manufacturing processes are determined by their porosity, local composition, and microstructure. The objective of this work is to examine the influence of the stochastic powder bed on the process window for dense parts by means of numerical simulation. The investigations demonstrate the unique capability of simulating macroscopic domains in the range of millimeters with a mesoscopic approach, which resolves the powder bed and the hydrodynamics of the melt pool...
September 22, 2017: Materials
https://www.readbyqxmd.com/read/28933439/3d-printing-of-high-strength-aluminium-alloys
#17
John H Martin, Brennan D Yahata, Jacob M Hundley, Justin A Mayer, Tobias A Schaedler, Tresa M Pollock
Metal-based additive manufacturing, or three-dimensional (3D) printing, is a potentially disruptive technology across multiple industries, including the aerospace, biomedical and automotive industries. Building up metal components layer by layer increases design freedom and manufacturing flexibility, thereby enabling complex geometries, increased product customization and shorter time to market, while eliminating traditional economy-of-scale constraints. However, currently only a few alloys, the most relevant being AlSi10Mg, TiAl6V4, CoCr and Inconel 718, can be reliably printed; the vast majority of the more than 5,500 alloys in use today cannot be additively manufactured because the melting and solidification dynamics during the printing process lead to intolerable microstructures with large columnar grains and periodic cracks...
September 20, 2017: Nature
https://www.readbyqxmd.com/read/28886950/influence-of-thermo-mechanical-cycling-on-porcelain-bonding-to-cobalt-chromium-and-titanium-dental-alloys-fabricated-by-casting-milling-and-selective-laser-melting
#18
Maja Antanasova, Andraž Kocjan, Janez Kovač, Borut Žužek, Peter Jevnikar
PURPOSE: The aim has been to determine the effect of thermo-mechanical cycling on shear-bond-strength (SBS) of dental porcelain to Co-Cr and Ti-based alloys fabricated by casting, computer-numerical-controlled milling, and selective-laser-melting (SLM). METHODS: Seven groups (n=22/group) of metal cylinders were fabricated by casting (Co-Cr and commercially pure-cpTi), milling (Co-Cr, cpTi, Ti-6Al-4V) or by SLM (Co-Cr and Ti-6Al-4V) and abraded with airborne-particles...
September 5, 2017: Journal of Prosthodontic Research
https://www.readbyqxmd.com/read/28874795/tailoring-the-thermal-conductivity-of-the-powder-bed-in-electron-beam-melting-ebm-additive-manufacturing
#19
C J Smith, S Tammas-Williams, E Hernandez-Nava, I Todd
Metallic powder bed additive manufacturing is capable of producing complex, functional parts by repeatedly depositing thin layers of powder particles atop of each other whilst selectively melting the corresponding part cross-section into each layer. A weakness with this approach arises when melting overhanging features, which have no prior melted material directly beneath them. This is due to the lower thermal conductivity of the powder relative to solid material, which as a result leads to an accumulation of heat and thus distortion...
September 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28872620/electron-beam-welding-of-in792-ds-effects-of-pass-speed-and-pwht-on-microstructure-and-hardness
#20
Giuliano Angella, Giuseppe Barbieri, Riccardo Donnini, Roberto Montanari, Maria Richetta, Alessandra Varone
Electron Beam (EB) welding has been used to realize seams on 2 mm-thick plates of directionally solidified (DS) IN792 superalloy. The first part of this work evidenced the importance of pre-heating the workpiece to avoid the formation of long cracks in the seam. The comparison of different pre-heating temperatures (PHT) and pass speeds (v) allowed the identification of optimal process parameters, namely PHT = 300 °C and v = 2.5 m/min. The microstructural features of the melted zone (MZ); the heat affected zone (HAZ), and base material (BM) were investigated by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), electron back-scattered diffraction (EBSD), X-ray diffraction (XRD), and micro-hardness tests...
September 5, 2017: Materials
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