scholarly journals 3D Shape Analysis of Powder for Laser Beam Melting by Synchrotron X-ray CT

2019 ◽  
Vol 3 (1) ◽  
pp. 3 ◽  
Author(s):  
Tobias Thiede ◽  
Tatiana Mishurova ◽  
Sergei Evsevleev ◽  
Itziar Serrano-Munoz ◽  
Christian Gollwitzer ◽  
...  
Keyword(s):  
Particle Size ◽  
Laser Beam ◽  
Packing Density ◽  
Gas Atomization ◽  
Powder Bed ◽  
X Ray ◽  
Shape Distribution ◽  
Size And Shape ◽  
Laser Beam Melting

The quality of components made by laser beam melting (LBM) additive manufacturing is naturally influenced by the quality of the powder bed. A packing density <1 and porosity inside the powder particles lead to intrinsic voids in the powder bed. Since the packing density is determined by the particle size and shape distribution, the determination of these properties is of significant interest to assess the printing process. In this work, the size and shape distribution, the amount of the particle’s intrinsic porosity, as well as the packing density of micrometric powder used for LBM, have been investigated by means of synchrotron X-ray computed tomography (CT). Two different powder batches were investigated: Ti–6Al–4V produced by plasma atomization and stainless steel 316L produced by gas atomization. Plasma atomization particles were observed to be more spherical in terms of the mean anisotropy compared to particles produced by gas atomization. The two kinds of particles were comparable in size according to the equivalent diameter. The packing density was lower (i.e., the powder bed contained more voids in between particles) for the Ti–6Al–4V particles. The comparison of the tomographic results with laser diffraction, as another particle size measurement technique, proved to be in agreement.

Discrete Element Modeling of Scraping Process and Quantification of Powder Bed Quality for SLM

2020 ◽  
Author(s):  
Kuldeep Mandloi ◽  
Parth Amrapurkar ◽  
Harish P. Cherukuri
Keyword(s):  
Particle Size ◽  
Volume Fraction ◽  
Numerical Models ◽  
Discrete Element ◽  
Contact Model ◽  
Powder Particle Size ◽  
Particle Sizes ◽  
Powder Bed ◽  
Size And Shape

Abstract In selective laser melting (SLM) and selective laser sintering (SLS) additive manufacturing techniques, the powder spreading process plays a key role in the quality of the manufactured parts. Some of the important parameters that influence the quality of the powder bed are the powder particle size distribution, spreader-type (roller or blade), spreader speed, size and shape of the particles. In this work, we use the discrete element method to study the effect of these parameters on the quality of the powder bed. The interactions between the particles is modeled using Hertz-Mindlin contact model as well as Hertz-Mindlin with JKR contact model with the latter being used for studies of the effect of cohesiveness of particles on powder bed quality. The Dynamic Repose Angle (DRA) is used for validating the numerical models. Our studies differ from the previous studies in that we have introduced quantitative measures for powder bed quality in the form of Discretized Volume Fraction (DVF) and Particle Flow Rate (PFR) for the layering process. With the help of these quantities, we studied various factors that affect powder bed quality: cohesiveness of the particles, spreader shape, particle size and shape, and the distribution of particle sizes. Our results indicate that as DVF and PFR decrease and DRA increases, the potential for cavities and shifting defects increases due to increase in cohesiveness. Use of fixed particle size in the simulations leads to higher DRA than when a normal distribution of particle sizes is considered. Our results show that the roller geometry provides better bed quality as compared to the blade type geometry.

Improvement of Build Speed and Quality of H13 Tool Steel Processed by Laser-Beam Powder Bed Fusion with a High-Power Laser

2021 ◽  
Vol 68 (10) ◽  
pp. 415-421
Author(s):  
Takashi MIZOGUCHI ◽  
Takaya NAGAHAMA ◽  
Makoto TANO ◽  
Shigeru MATSUNAGA ◽  
Takayuki YOSHIMI ◽  
...  
Keyword(s):  
Laser Beam ◽  
Tool Steel ◽  
High Power ◽  
Powder Bed Fusion ◽  
High Power Laser ◽  
Power Laser ◽  
Powder Bed ◽  
H13 Tool Steel

scholarly journals Real-time synthesis and detection of plasmonic metal (Au, Ag) nanoparticles under monochromatic X-ray nano-tomography

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Amardeep Bharti ◽  
Keun Hwa Chae ◽  
Navdeep Goyal
Keyword(s):  
Particle Size ◽  
Real Time ◽  
Reduction Process ◽  
Localized Surface Plasmon ◽  
Plasmonic Nanostructures ◽  
X Rays ◽  
X Ray ◽  
The Real ◽  
Size And Shape

AbstractPlasmonic nanostructures are of immense interest of research due to its widespread applications in microelectronics, photonics, and biotechnology, because of its size and shape-dependent localized surface plasmon resonance response. The great efforts have been constructed by physicists, chemists, and material scientists to deliver optimized reaction protocol to tailor the size and shape of nanostructures. Real-time characterization emerges out as a versatile tool in perspective to the optimization of synthesis parameters. Moreover, in the past decades, radiation-induced reduction of metallic-salt to nanoparticles dominates over the conventional direct chemical reduction process which overcomes the production of secondary products and yields ultra-high quality and pure nanostructures. Here we show, the real-time/in-situ synthesis and detection of plasmonic (Au andAg) nanoparticles using single synchrotron monochromatic 6.7 keV X-rays based Nano-Tomography beamline. The real-time X-ray nano-tomography of plasmonic nanostructures has been first-time successfully achieved at such a low-energy that would be leading to the possibility of these experiments at laboratory-based sources. In-situ optical imaging confirms the radiolysis of water molecule resulting in the production of $$e_{aq}^-,\,OH^\bullet ,$$ e aq - , O H ∙ , and $$O_2^-$$ O 2 - under X-ray irradiation. The obtained particle-size and size-distribution by X-ray tomography are in good agreement to TEM results. The effect of different chemical environment media on the particle-size has also been studied. This work provides the protocol to precisely control the size of nanostructures and to synthesize the ultrahigh-purity grade monodisperse nanoparticles that would definitely enhance the phase-contrast in cancer bio-imaging and plasmonic photovoltaic application.

Characterization and Granulometric Correction Soil for the Production of Soil-Cement Blocks for Two Method, Particle Size and X-Ray Florescence to be Inserted in Phase Change Materials (PCMS)

2014 ◽  
Vol 798-799 ◽  
pp. 355-359 ◽  
Author(s):  
Valter Bezerra Dantas ◽  
U.U. Gomes ◽  
A.B. Vital ◽  
G.S. Marinho ◽  
Ariadne de Souza Silva
Keyword(s):  
Particle Size ◽  
Phase Change Materials ◽  
Clay Content ◽  
Particle Size Analysis ◽  
Liquid Limit ◽  
Size Analysis ◽  
X Ray ◽  
Soil Cement

This paper presents the results of tests for characterization of soil samples collected in Mossoró-RN, UFERSA-RN Campus (5 ° 12'34 .68 "South latitude, 37 ° 19 '5.74 "west longitude), for the purpose of producing soil-cement for the manufacture of pressed blocks. Objective of improving the quality of soil-cement, and provide conditions for the use of the soil making it ideal for the production of soil-cement block. Tests of compaction, particle size analysis, plastic limit, liquid limit and correct particle size, X-ray fluorescence and morphology by scanning electron microscopy (SEM). It was concluded that the soil needs correction particle size, due to the high clay content. The method combined grading, sieving, sedimentation and blooming X-ray as the fastest and most accurate in correcting soil particle size.

Mechanical Testing of Additive Manufactured Metal Parts

2015 ◽  
Vol 651-653 ◽  
pp. 713-718 ◽  
Author(s):  
Marion Merklein ◽  
Raoul Plettke ◽  
Daniel Junker ◽  
Adam Schaub ◽  
Bhrigu Ahuja
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Stainless Steel ◽  
Additive Manufacturing ◽  
Laser Beam ◽  
Round Robin Test ◽  
Metal Parts ◽  
Laser Beam Melting ◽  
Made In

The quality of additive manufactured parts however depends pretty much on the workers experience to control porosity, layer linkage and surface roughness. To analyze the robustness of the Laser Beam Melting (LBM) process a Round Robin test was made in which specimens from four institutes from different countries were tested and compared. For the tests each institute built a set of specimens out of stainless steel 1.4540. The aim of this work is to analyze the influence of the process parameters on the mechanical properties. The results show that there is a high potential for additive manufacturing but also a lot of further research is necessary to optimize this technology.

Quantifying Powder Losses and Analyzing Powder Conditions in order to Determine Material Efficiency in Laser Beam Melting

2016 ◽  
Vol 856 ◽  
pp. 231-237 ◽  
Author(s):  
Max Lutter-Günther ◽  
Alexander Hofmann ◽  
Christoph Hauck ◽  
Christian Seidel ◽  
Gunther Reinhart
Keyword(s):  
Laser Beam ◽  
Experimental Studies ◽  
Manufacturing Processes ◽  
Ecological Evaluation ◽  
Powder Bed ◽  
Material Efficiency ◽  
Laser Beam Melting ◽  
Measurement Results ◽  
Subtractive Manufacturing ◽  
End Use

Laser Beam Melting (LBM) is an additive manufacturing process, which is increasingly applied for the production of end use parts. One advantage of this powder bed fusion technology lies in the high material efficiency in comparison with subtractive manufacturing processes (i. e. milling, lathing). However, only few experimental studies have been conducted on the material efficiency of LBM. For the accurate evaluation of the LBM material efficiency, empirical values for powder losses are required. Furthermore, a lack of terminology for waste types and powder conditions in the context of LBM impedes communication and research on the topic. The presented paper aims to increase the understanding of material efficiency and powder conditions in Laser Beam Melting. A quantitative analysis of waste types is presented for different LBM application scenarios. This sets a basis for the ecological evaluation and comparison with conventional manufacturing processes. In order to achieve the aim, a terminology is introduced for waste types and powder conditions in the context of powder bed-based additive processes. Therefore, considerations regarding powder quality are taken into account. For the quantification of powder losses, the experimental setup and measurement results are described. Furthermore, loss types and their significance are analyzed and discussed.

scholarly journals Microstructure Evolution of FeNiCoCrAl1.3Mo0.5 High Entropy Alloy during Powder Preparation, Laser Powder Bed Fusion, and Microplasma Spraying

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7870
Author(s):  
Anton Semikolenov ◽  
Pavel Kuznetsov ◽  
Tatyana Bobkova ◽  
Svetlana Shalnova ◽  
Olga Klimova-Korsmik ◽  
...  
Keyword(s):  
Solid Solution ◽  
Phase Composition ◽  
Cast Alloy ◽  
High Entropy Alloy ◽  
Gas Atomization ◽  
Face Centered Cubic ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
X Ray

In the present study, powder of FeCoCrNiMo0.5Al1.3 HEA was manufactured by gas atomization process, and then used for laser powder bed fusion (L-PBF) and microplasma spraying (MPS) technologies. The processes of phase composition and microstructure transformation during above mentioned processes and subsequent heat treatment were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and differential thermal analysis (DTA) methods. It was found that gas atomization leads to a formation of dendrites of body centered cubic (BCC) supersaturated solid solution with insignificant Mo-rich segregations on the peripheries of the dendrites. Annealing leads to an increase of element segregations till to decomposition of the BCC solid solution and formation of σ-phase and B2 phase. Microstructure and phase composition of L-PBF sample are very similar to those of the powder. The MPS coating has a little fraction of face centered cubic (FCC) phase because of Al oxidation during spraying and formation of regions depleted in Al, in which FCC structure becomes more stable. Maximum hardness (950 HV) is achieved in the powder and L-PBF samples after annealing at 600 °C. Elastic modulus of the L-PBF sample, determined by nanoindentation, is 165 GPa, that is 12% lower than that of the cast alloy (186 GPa).

Influence of laser parameters and Ti content on the surface morphology of L-PBF fabricated Titania

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Abid Ullah ◽  
HengAn Wu ◽  
Asif Ur Rehman ◽  
YinBo Zhu ◽  
Tingting Liu ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Laser Beam ◽  
Surface Quality ◽  
Selective Oxidation ◽  
Laser Power ◽  
Scanning Speed ◽  
Content Type ◽  
Powder Bed ◽  
Laser Parameters

Purpose The purpose of this paper is to eliminate Part defects and enrich additive manufacturing of ceramics. Laser powder bed fusion (L-PBF) experiments were carried to investigate the effects of laser parameters and selective oxidation of Titanium (mixed with TiO2) on the microstructure, surface quality and melting state of Titania. The causes of several L-PBF parts defects were thoroughly analyzed. Design/methodology/approach Laser power and scanning speed were varied within a specific range (50–125 W and 170–200 mm/s, respectively). Furthermore, varying loads of Ti (1%, 3%, 5% and 15%) were mixed with TiO2, which was selectively oxidized with laser beam in the presence of oxygen environment. Findings Part defects such as cracks, pores and uneven grains growth were widely reduced in TiO2 L-PBF specimens. Increasing the laser power and decreasing the scanning speed shown significant improvements in the surface morphology of TiO2 ceramics. The amount of Ti material was fully melted and simultaneously changed into TiO2 by the application of the laser beam. The selective oxidation of Ti material also improved the melting condition, microstructure and surface quality of the specimens. Originality/value TiO2 ceramic specimens were produced through L-PBF process. Increasing the laser power and decreasing the scanning speed is an effective way to sufficiently melt the powders and reduce parts defects. Selective oxidation of Ti by a high power laser beam approach was used to improve the manufacturability of TiO2 specimens.

scholarly journals Computed X-ray Tomography of Powder Metallurgy Product for Rapid, Quantitative Size and Shape Distribution Analysis

2016 ◽  
Vol 22 (S3) ◽  
pp. 1756-1757
Author(s):  
Noah Budiansky ◽  
Daniel P. Dennies ◽  
Joel Forman ◽  
David Wong ◽  
Joe Tucker
Keyword(s):  
Powder Metallurgy ◽  
Distribution Analysis ◽  
X Ray ◽  
Shape Distribution ◽  
Size And Shape
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