bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection Of Presence Of Cracks In Green PM Parts By Means Of Vibration Spectroscopy
Authors: Tatarinov Alexey , Mironovs Viktors , Zemčenkovs Vjačeslavs , Kurtenoks Viktors
Published: November 2024

Although the diagnostics of cracks in sintered PM parts can be performed by resonant acoustic inspection, cracks detection in green parts still remains challenging. The problem persists due to the inapplicability of a mechanical impact to brittle green parts and a low mechanical Q-factor resulting in the absence of expressed natural resonances. Cross-correlation analysis applied to vibration spectra in healthy and damaged green PM gears obtained by laser Doppler vibrometry demonstrated minimal discrepancy between healthy parts and strong differences between healthy and cracked parts. To approach a vital industrial implementation, possibilities for an alternative simpler realization were explored. The compared testing modalities included pendulum test with a lightweight platform, contactless excitation by a pulsed electromagnetic action and frequency sweep with an electrodynamic actuator. All testing modalities along with laser vibrometry demonstrated differences in the vibration spectra between healthy and damaged green parts quantitatively assessed by cross-correlation and cross-coherence analysis.
Processing And Corrosion Behavior Of Metal Powder Blends In LPBF
Authors: Norda Michael , Köhler Marie Luise , Herzog Simone , Broeckmann Christoph , Petzoldt Frank
Published: November 2024

Laser Powder Bed Fusion (LPBF) has become an attractive alternative to conventional processing routes over the past years. While some alloys are already processed in series production, the overall amount of available materials is low. Due to the high price of specially atomized powders, material variation is often neglected. This work covers the blending, in-situ processing and testing of metal powder blends and the produced specimen. Different metal powders are blended to create a Super Duplex Steel. The powder blend quality is assessed by different methods. Heat treatments , corrosion tests and EDX analyses determine the specimen quality as well as tensile tests. The properties of the created alloy is compared to conventionally produced duplex and super duplex steels in order to show the potentials of this approach.
Effect Of Distance Between Powders On The Printing And Sintering Properties Of Metal Binder Jet 3D Printing
Authors: Osada Toshiko , Kobayashi Satoshi , Takahashi Tomo , Kato Yoshiyuki , Yokoyama Kenji
Published: November 2024

Metal binder jet 3D printing is suitable for fabricating metal parts in small quantity and many varieties in a short period of time. Fine powders for metal injection molding are used for binder jet 3D printer. Powders need to flow during recoating to the powder bed, and also after that they need to show high density for enough strength of green parts for handling. In this study, powder characteristics for binder jet 3D printing is focused, and effect of distance between powders on the printing and sintering properties of metal binder jet 3D printing is clarified.
Fabrication Of Copper Heat Sinks For Power Electronics By Composite Extrusion Additive Manufacturing And Sintering
Authors: Safar Bati Rafik , Zago Marco , Singh Gurminder , Missiaen Jean-Michel , Bouvard Didier , Chaix Jean-Marc , Balarabe Faisal , Avenas Yvan
Published: November 2024

The interest of composite extrusion modelling (CEM) for additive manufacturing of metal components is growing up due to the low cost of this process and to the possibility of using commercial MIM feedstock. In a previous study, the successive stages of the processing route of simple copper parts have been optimised with regard to the final weight density and surface roughness. The next step has consisted in fabricating components with controlled porous architecture, to be used for cooling power electronic chips with an air flow. The thermo-hydraulic properties of these components (thermal resistance, air pressure drop) have next been measured. For future practical application of this heat sink, its bonding to a copper plate has been ensured by printing the feedstock directly upon the plate and next sintering the assembly. The shear resistance of this bonding has been found to be in line with power electronics standards.
Quasi-Static And High Strain Rate Response Of Two-Layered Structures Of Titanium Based Composites Reinforced With TiC And TiB Particles
Authors: Markovsky Pavlo , Janiszewski Jacek , Stasyuk Oleksandr , Bondarchuk Vadim , Savvakin Dmytro , Cieplak Kamil , Prikhodko Sergey , Ivasishin Orest
Published: November 2024

The two-layered structures consisting of the top layer of metal matrix composites (MMC) on the base of titanium alloy Ti-6Al-4V (Ti-64) reinforced with 5, and 10 % (vol.) of TiC or TiB particles and the base layer made of the alloy Ti-64 were prepared employing press-and-sinter Blended Elemental Powder Metallurgy (BEPM) approach. The mechanical behavior of these structures was studied under quasi-static and high strain rate compression loading. Dynamic tests (820÷2880 s-1) were implemented using the split Hopkinson pressure bar technique, whereas the quasi-static tests were performed at the strain rate of 10-3 s-1. The stress-shortening curves were analyzed and the effects of phase composition, microstructure, strain rate, as well as deformation energy were evaluated. The deformation mechanism was assessed basing on a detailed analysis of tested specimens’ microstructure. The results are compared with those earlier obtained for uniform MMC tested at the same conditions.
Factors Influencing The Recyclability Of Permanent Magnets Used In V-shaped Permanent Magnet Synchronous Motors Via Hydrogen Processing And Powder Metallurgy
Authors: Grau Laura , Burkhardt Carlo , Kobe Spomenka
Published: November 2024

The rare earths are some of the most critical raw materials, yet electromobility and green energy strongly rely on Rare Earth Permanent Magnets (REPM). To secure the supply and improve the ecological footprint of REPM, a hydrogen-aided powder-metallurgical reprocessing route was successfully established and continues to be improved. A remaining obstacle is the sourcing and demounting of REPM-containing scrap. Demounting must especially be optimized towards achieving a maximum yield of high-quality material in conjunction with economic efficiency.Electric traction motors, which will be an abundant but dissipated scrap REPM source in the future, are often very hard to demount. To exploit this important raw material source, their design must accommodate efficient recycling. This paper deals with how design choices of the most common rotor permutation, the V-shaped internal Permanent Magnet Synchronous Motor rotor (VPMSM), impact the recyclability of the integrated magnets and provides a design for recycling framework.
Early Stage Sintering: Realistic Predictions Of Densification And Microstructure Evolution By Coupling DEM And Solid State Diffusion Equations
Authors: Ivannikov Vladimir , Thomsen Fritz , Ebel Thomas , Willumeit-Römer Regine
Published: November 2024

A novel discrete element method based approach for modeling of the early stage solid state sintering of metallic powders is proposed. It couples the mass transport driven evolution of geometry of individual contact pairs of spherical particles and their mechanical interaction in a 2-step staggered numerical scheme. At a given time, for each pair of contacting particles a system of mass transport equations is solved to update the parameters describing its local geometry. The changes in the distances between the centers of the particles are converted into the corresponding sintering forces. These are then applied as external loads to a DEM discretization of a compound. The developed approach was used to simulate sintering of packings with several thousands of particles. The numerically predicted neck growth and shrinkage rates agree well with the experimental data obtained for titanium powders for different sintering temperatures.
Machine Learning Based Quality Assessment Of The Feedstock Kneading Process By Computer Vision
Authors: Hein Sebastian Boris , Küppers Daniel
Published: November 2024

Kneading processes are relevant in many areas of daily life and technical fields. They are the basis of the MIM process in which powders and binders are combined to the injectable feedstock. The quality of the mixing directly influences the following process steps. Inhomogeneities in the form of binder or powder nests can cause local defects like pores or induce locally differing shrinkage and thus warpage, or make the feedstock behaviour instable. The assessment of the feedstock state during mixing is a promising way to assess quality and optimize process control. We approached this goal with a first step that made use of images, generated by video recordings of the feedstock mass during mixing. An artificial intelligence network was constructed, trained and tested to simulate the quality assessment of a human expert in two categories, "ok" and "not ok". All images and mixing states were assessed with 100 % accuracy.
Potentials Of Metal Binder Jetting Process Chains For Medical Parts
Authors: Janzen Kevin , Groß Patricia , Imgrund Philipp , Emmelmann Claus
Published: November 2024

Additive manufacturing (AM) of metal components offers enormous potential for patient-specific medical applications. Endoprostheses such as artificial hip joints are already being successfully manufactured using the laser or electron powder bed fusion (L-|E-PBF) process. Recently, however, new sinter-based AM processes have increasingly come into focus. Metal binder jetting promises lower manufacturing costs with the same or higher geometrical freedom and accuracy as L- or E-PBF. Nevertheless, concrete industrial application examples are still pending. In this paper, a possible process chain and its influences for the MBJ production of Ti-6Al-4V parts is therefore presented and investigated. For this purpose, requirements for the mechanical and chemical properties are compiled, costs and cost structure as well as data preparation are investigated and compared to L-PBF.
Investigation Of The Variance In The AM Powder Supply Chain And Its Effect On Part Properties
Authors: Blackwell Cameron , Turner Nathanael , Heikkilä Irma , Strandh Emil , Meisnar Martina , Pambaguian Laurent
Published: November 2024

The control of the entire AM process chain, encompassing the material supply, design, AM processing, post-processing, and part verification is critical to the success of the AM industry. Although intrinsically linked, existing studies evaluate one aspect of the AM process chain. Currently, an understanding of the complex relationship between powder and printed part properties is lacking. This paper establishes a holistic view of the AM process chain highlighting differences in part properties due to the variation in the powder feedstock material. Four AlSi10Mg powder batches procured from four suppliers were processed by metal laser powder bed fusion at three AM bureaus. A series of representative space parts and test bars were manufactured, followed by an exhaustive powder and part test campaign. This work has been completed as part of the ESA GSTP funded study "Additive Manufacturing Powder Supply Chain: Validation and Verification".
Direct Ink Writing Of Open And Dense NbC-Ni Matrix Cermet Structures
Authors: Huang Shuigen , Wong Eric , Göksel Berfu , Qian Jun , Vleugels Jozef
Published: November 2024

Direct Ink Writing (DIW), also known as robocasting, is a paste extrusion-based layer-by-layer additive manufacturing technique suitable for manufacturing complex geometry green compacts. In this study, NbC-Ni matrix cermets with either a porous scaffold structure or a pore-free rectangular bar geometry were prepared using a combination of DIW and sintering. The water based feedstock ink contained 40 vol% cermet powder mixture and 25 wt% pluronic F-127 hydrogel. The ink was rheologically characterized and printed using a DIW device. Thermogravimetric analysis (TGA) of the paste was performed to define the thermal debinding cycle. After debinding, the printed parts were sintered for 90 min at 1420 °C in vacuum. The microstructure and room temperature hardness of the printed parts were investigated and compared with cermets obtained by conventional press and sinter powder metallurgy.
Filling Density And Green Density Of Different Ring-shaped Parts As Affected By Filling Strategy
Authors: Zago Marco , Rambelli Alex , Foschi Davide , Cristofolini Ilaria
Published: November 2024

The influence of compaction strategy on compressibility and densification of metal powders has been extensively studied in previous work; effective compaction mechanics relationships and a densification model have been derived on experimental basis. Nevertheless, such studies also highlighted the need for further investigation concerning filling step, playing major role in obtaining high density, homogeneously distributed. This work focuses on filling step, considering the influence of both geometry, and filling strategy. Ring shaped parts with different height to thickness ratios (H|T) have been produced, also varying filling parameters as filling shoe speed, suction speed, and number of shakes of the filling shoe. Filling density was derived, as a function of above parameters, also highlighting the most critical parameters affecting filling density. Moreover, green density was measured in different points, referring to filling shoe movement, aiming at identifying the effect of filling strategy on flatness and parallelism of planes resulting from compaction.
Development Of Metallic Glasses Through Hybrid Sintering Processes: Metal Binder Jetting (MBJ) & Spark Plasma Sintering (SPS)
Authors: Baulin Oriane , Reynaud Christophe , Robbe Simon
Published: November 2024

The metallic glasses are knowing an increasing interest for the past decades. They exhibit very exceptional properties; however the main drawback is the limited size of the samples.The MBJ is a promising solution to obtain larger dimensions and high-resolution samples. Using SPS after MBJ process, ensure the production of high density, fully amorphous parts.In this study, a printing recipe has been found to get metallic glass green parts using the HERAEUS powder AMLOY ZR01. After finding that the curing and debinding steps have no influence on the amorphous character of the materials, a pre-sintering recipe in a sintering furnace has been developed. Meanwhile, after finding the parameters of the sintering process on the raw powder using SPS, the printed and pre-sintered parts have been sintered using SPS. The influence of carbon residues on the densification and stability of the materials have been discussed.
Rheological Characterization Of Water Atomized Tool Steel Powders Developed For Laser Powder Bed Fusion By Supervised And Unsupervised Machine Learning
Authors: Mutel Denis , Gélinas Simon , Blais Carl
Published: November 2024

Metal powders developed for powder-bed additive manufacturing processes need to achieve specific flow characteristics to be considered suitable. However, the relationship between powder flow and the morphological characteristics of individual particles can be difficult to establish. In this context, artificial intelligence appears to be the perfect tool to clarify the imprecision surrounding this type of interaction. The work summarized in this manuscript first uses a neural network architecture (Mask R-CNN) allowing the segmentation of individual water-atomized particles in micrographs acquired in scanning electron microscopy. The micrographs of individual particles or their shape descriptors (roundness, elongation, etc.) are then processed using different machine learning (ML) strategies, supervised or not, to relate the information collected on individual particles with the rheological properties of powder specimens. The approach developed aims to acquire new knowledge regarding specific particle characteristics that are required to optimize powder flowability for laser powder bed fusion.
Optimization Of FAST|SPS Tool Design Towadrs Reduction Of Thermal Gradients And Energy Consumption
Authors: Laptev Alexander , Wisniewska Maria , Garbiec Dariucz
Published: November 2024

The tool is a crucial part of the FAST|SPS system. The well-designed tool enables the manufacturing of sintered components with the required quality and with minimal energy expenditure. These requirements can be fulfilled only with a professionally optimized tool design. The present paper introduces the method of tool optimization supported by three examples. Two examples are related to the spark plasma sintering of WB2 sputtering targets with a diameter of 50 and 100 mm. The third example presents the sintering of a rectangular WC-based cutting plate. The tool optimization was performed by FEM modeling (ANSYS software) and a discrete optimization procedure. The temperature gradient within sintered parts and the energy consumption during sintering were considered as the objects of optimization. The optimization provided a set of tool parameters enabling sintering of discussed parts with tolerably temperature inhomogeneity at reduced energy consumption.
Effect Of Tempering Temperature And Nitrogen Content On The Heat-treated Impact Toughness Of Sintered Steels
Authors: Schneider Markus , Danninger Herbert , Gierl-Mayer Christian
Published: November 2024

Induction hardening and induction tempering gain increasing importance for heat treating of sintered steels due to high reproducibility and the chance for subsequent soft machining of not heat-treated part regions. Due to the high heating rates and the short processing times during the inductive heating the diffusion processes have to be accelerated by higher temperature. This results in higher austenitizing and tempering temperatures compared to classical furnace heat treatments. In the presence of absorbed nitrogen higher tempering temperatures might result in blue brittleness (300 °C embrittlement), an aging effect caused by the precipitation of nitrides. Based on that working hypothesis four different sintered steels were hardened and tempered under varying conditions. The hardness and the impact toughness were analyzed to check whether a drop of the toughness can be observed at a certain tempering temperature level. Moreover, the absorbed nitrogen contents were measured.
Critical Defect Sizes Derived From Kitagawa-Takahashi Diagrams
Authors: Schneider Markus , Radis Christos , Wawoczny Dennis , Maassen Robert
Published: November 2024

The Kitagawa-Takahashi approach combines two different reliability concepts. In classical high cycle fatigue testing the material is assumed as undamaged and the testing itself is responsible for the crack initiation. Depending on the failure criterion, very often defined as drop of the stiffness or resonance frequency, the subsequent crack propagation phase is not investigated. Crack propagation experiments by means of da|dN curves continue the testing in the damaged condition. If both reliability concepts are combined, a critical defect size can be defined. This critical defect size is of major importance since it defines the limit resolution of non-destructive testing methods. The loading ratio affects both testing procedures, e.g. over crack closure|opening effects and must be examined carefully. A typical sintered alloy was chosen for that study due to its large range of application. The derived critical defect sizes were compared with the maximum apparent 2D pore sizes.
Flowability Control Of Water Atomized Powder By Addition Of Nano-silica Powder For Metal Binder Jet 3D Printing
Authors: Takahashi Tomo , Osada Toshiko , Kobayashi Satoshi , Kato Yoshiyuki , Yokoyama Ken
Published: November 2024

Gas atomized powders are mainly used in binder jet (BJ) metal 3D printing. The cost of water-atomized powders is lower than that of gas-atomized powders. And surface roughness and mechanical properties of sintered body is improved by using Ultrafine powders obtained through water atomization. However, the flowability of gas atomized powder is lower and the use of them in BJ 3D printing is serious issue. In this study, the flowability of water atomized powders was controlled by addition of nano-silica powder to water atomized powders with different average particle sizes.
Manufacturing Of Mg|Si Graded 6xxx Aluminium Alloys Using Spark Plasma Sintering Of Model Alloys Powder Blends
Authors: Taurines Justine , Boulnat Xavier , Perez Michel , Dezellus Olivier , Deschamps Alexis
Published: November 2024

In this study, a compositionally-graded aluminium alloy was obtained by high-temperature consolidation using Spark Plasma Sintering (SPS) of Al-Si and Al-Mg model alloys atomised powders. The fabrication process includes: (i) SPS consolidation of multi-layer powder beds (ii) interdiffusion heat treatment (iii) homogenisation and quenching. Energy dispersive X-ray spectroscopy (EDX) and wavelength dispersive X-ray spectroscopy (WDS) ensure a well-controlled gradient in a single direction. X-ray tomography and microscopy analysis describe the microstructure evolution of the alloys depending on the chosen diffusion couple. Parts made with Al-2.6wt.%Mg and Al-2.5wt.%Si powder blends reach the targeted Mg-Si gradient length of 3 mm after an interdiffusion treatment of 10 days at 550°C, with a relative density of 99.5%. These graded alloys allow for systematic study of nanoscale-precipitation in 6xxx alloys with various Mg|Si ratios.
Influence Of Microstructural Assemblage Of Substrate On The Adhesion Strength Of TiSiN Coated PcBN Systems
Authors: Gordon Pozuelo Sandra , Jiménez Piqué Emilio , Rodriguez Suarez Teresa , M'Saoubi Rachid , Roa Joan Josep , Franca Luiz F.P. , Llanes Luis
Published: November 2024

The adhesion strength of two TiSiN-coated polycrystalline cubic boron nitride (PcBN) grades is studied in this work. Microstructural assemblage of the PcBN substrate, in terms of cBN content, binder chemical nature and average cBN grain size, is considered as main experimental variable. The present investigation implemented conical indentation to assess load levels at which cracking and delamination emerge and their evolution with increasing load. Tests were conducted on both coated and uncoated PcBN systems by using a conical diamond indenter of 200 µm in radius (Rockwell C) and applying loads from 98 to 980N. They were complemented by an extensive and detailed SEM inspection of fracture micromechanisms (i.e. type of cracking pattern and delamination). Results show that emergence and evolution of damage strongly depend on the substrate microstructural assemblage: the higher cBN-content grade (harder and tougher) exhibits a higher resistance to both cracking and delamination than the lower cBN-content one.
Simulations Of The Filament Printing Of Metal Feedstocks With Different Nozzle Designs
Authors: Kukla Christian , Schuschnigg Stephan , Cano Santiago , Hubmann Martin , Holzer Clemens , Gonzalez-Gutierrez Joamin
Published: November 2024

Material extrusion (MEX), especially fused filament fabrication (FFF), is the most widespread technology for additive manufacturing, mainly for polymers.Currently, many material extrusion printers and nozzle designs are available from different manufacturers. These different nozzle designs result in different melting and flow behaviour. Therefore, their design is critical for the printing of high-quality parts. Since feedstocks and polymers have different characteristics, we evaluated the processing of an Ampersint 1558 tool steel feedstock with two different nozzle designs (nozzle with a PTFE tube insert, all-metal nozzle) using finite element method (FEM) simulations with the programs Ansys Polyflow and Autodesk Moldflow Insight.Feedstock’s rheological and thermal properties were measured and used for simulation of FFF with the two nozzle designs at different printing speeds. Finally, the trends observed in the simulations were compared to experimental results, providing recommendations for the design of FFF nozzles for feedstocks.
VAT Photopolymerization-based 3d Printing Of Ni-Ti-Cu Metal Alloy From Elemental Powders
Authors: Mousapour Mehrdad , Salmi Mika , Partanen Jouni
Published: November 2024

Vat photopolymerization is the oldest and popular additive manufacturing technique, which can print metal and ceramic parts quickly with high dimensional accuracy. This study successfully produced a metallic alloy from elemental powders by Digital Light Processing (DLP) method. Ni-Ti-Cu powders were blended in a curable resin with a specific ratio. Then the prints were debound and sintered to obtain the final part. Finally, microstructural observation and elemental distribution were analyzed to authenticate the possibility of alloying with this technique. The results indicate that Vat photopolymerization is a fast, reliable method for producing a near net shape metal part from different elemental powders. A wide range of alloys with arbitrary chemical compositions can be made.
Sinter-based Fabrication Of Ti-6Al-4V Parts By Hybrid Gel Casting Process Under Terrestrial And Reduced Gravity
Authors: Riecker Sebastian , Sénéchal Ulf , Dittrich Robert , Studnitzky Thomas , Andersen Olaf , Weißgärber Thomas
Published: November 2024

Manufacturing light-metal components on demand and on site is a major challenge in space. So far, some AM technologies have been considered, but working with loose metal powder or large amounts of solvents are undesirable attributes of some processes. The hybrid approach of gel casting into recyclable polymer molds fabricated using FFF presents a possible alternative for use under terrestrial and reduced gravity conditions, with low equipment requirements and no loose powder. We have investigated the production of Ti-6Al-4V components and developed a metal powder suspension for this purpose. We present sintering results with 0.1 % porosity and impurity values according to the specification, as well as demo parts that we were able to manufacture with this process chain. Filling of the molds under different gravitational conditions is a specific challenge and can be predicted with a numerical simulation to analyze the flow characteristics and check for trapped gas bubbles.
Combined X-ray And Laser-based Profiler Equipment For In-line NDT Control Of PM Parts External Dimensions, Local Density And Internal Defects
Authors: Iovea Mihai , Mateiasi Gabriela , Hermann Edward , Neagu Marian , Enciu Alexandru , Stanciulescu Andrei , Poterasu Mihaela , Mirea Monica
Published: November 2024

We present our X-ray high-resolution sintered and additive manufactured parts in-line NDT investigations based on various mini|microfocus X-ray set-ups. We are introducing also our latest development, an industrial combined X-ray scanner and a Laser-based 3D profiler machine for sintered parts in-line NDT control in one short pass. With the new equipment design we combined two advanced control techniques: the Laser-based profiler for getting the parts 3D shape measurement with 2-3% accuracy, followed by an X-ray digital imaging system for parts internal defects identification, based on a minifocus X-rays source and a TDI (Time Delayed Integration) X-ray detector. The system is able to compute also the sample' local density for sintered ceramic ballistic plates and to NDT analyse the transmission digital Xray images at a pixel size of 60 microns for detecting the internal defects.
Monitoring Moisture In Additive Manufacturing Powder Feedstocks
Authors: Lefebvre Louis-Philippe , Mellin Pelle , Trublet Mylene , Talus Annika , Rigo Olivier , Lefebvre Louis-Philippe
Published: November 2024

It may be important to monitor moisture in additive manufacturing (AM) feedstocks to make sure the process is robust and the properties of the printed components are stable and as expected. However, there is presently no standard adapted for AM powder feedstocks. Karl Fisher (KF), relative humidity sensors and loss on drying (LOD) were used to monitor moisture in different feedstocks and reference materials. Moisture in as received powders is low in most metallic powders but significantly higher in polymer and ceramics. Both drying and exposure to moisture affect the moisture content. KF and relative humidity sensor results compare well together but the LOD is not sensitive enough when the moisture content is low. The relative standard deviations are decreasing when moisture content increases. Similar procedures and reference materials should be used if results obtained in different laboratories or using different techniques are compared together.
Using Discrete Simulations Of Compaction And Sintering To Predict Final Part Geometry
Authors: Nogueira Gilmar , Martin Christophe
Published: November 2024

A DEM (Discrete Element Method) model is used to simulate compaction and sintering. A double-action die has been implemented for the compaction stage. The process kinematics are decomposed into loading, unloading, and ejection of the pellet. Interactions between the particles and the die are considered elastoplastic by implementing a large-density model. A qualitative approach is used in the sintering stage. The results are in good agreement with experimental data and FEM simulations from the literature, regarding density gradient, elastic spring-back, and final geometry. The simulations show that the friction coefficient is the primary factor for the density gradient in the pellet. This density gradient induces a non-homogeneous sintering, which results in a final geometry with a so-called diabolo effect. This is the first time that it has been reproduced by DEM with the advantage of more closely reproducing the particulate microstructure of the powder.
Additive Manufacturing Of Functional Mechanical Mechanisms Using Micro Laser Powder Bed Fusion
Authors: Khademzadeh Saeed , Zhou Yijun , Persson Cecilia
Published: November 2024

Additive Manufacturing of non-assembly metallic mechanisms is highly desirable because of their potentially higher performance and low costs due to enhanced structural features and the reduced need for labour-intensive procedures. However, fabrication of such mechanisms using metal AM techniques faces many challenges. For instance, down-skin inclined surfaces suffer from an insufficient quality due to the staircase effect and partially melted attached powder particles that may deteriorate the function of the mechanism since residuary stuck material can block the clearance space. In this work, a novel scanning strategy was employed for the fabrication of non-assembly functional micromechanisms. A threshold angle was defined for activation of a new set of process parameters for down-skin surfaces. Non-assembly ball joints were additively manufactured using laser powder bed fusion technology. The effects of threshold angle, overlap between in-skin and down-skin surfaces, and input energy on the functionality of non-assembly joints was investigated using micro-computed tomography
Effect Of Gas Carburising And Low-pressure Carburising On The Performance Of Cr-alloyed PM Steels
Authors: Vattur Sundaram Maheswaran , Currit Fabien , Pantelios Petros , Andersson Michael , Chasoglou Dimitris
Published: November 2024

The properties and the performance of PM steels can be tailored and enhanced by performing an appropriate heat treatment process after sintering. Conventional gas carburising (CQT) is the most used process for PM steels, whereas for Cr-alloyed PM steels, casehardening by low-pressure carburising (LPC) is gaining interest due to its oxide free process and better control over case depth. Also, when combined with high-pressure gas quenching (GQ) it provides less distortion in the components. In this work, Cr-alloyed PM steel with and without Ni additions were evaluated after both the CQT and LPC heat treatment process. The mechanical properties and performances were evaluated, and the results obtained indicated a strong correlation between the obtained properties and resulting microstructures based on the alloying elements and optimised heat treatment process.
A Mesoscale Model Of Sintering Applied To Astaloy 85Mo Sintered Steel
Authors: Schenk Oliver , Deng Yuanbin , Kaletsch Anke , Broeckmann Christoph
Published: November 2024

A digital twin offers the potential of understanding and improving production processes by using numerical models. Although multiple approaches of digital twins were reported, most of them only focus on the macroscale. However, the microstructural evolution is often crucial for the application of products. For instance, the pore morphology which determines the final mechanical properties is highly affected by the compaction and sintering steps in the PM process chain. In this work, a digital twin was developed to model the compaction and sintering of water-atomized Astaloy 85Mo on a mesoscale. Scanning electron microscopy images of green body microstructures were used to train a generative adversarial network to predict the microstructure dependent on the powder particle size. The evolution of these artificial microstructures during sintering due to surface diffusion was subsequently simulated with the level-set-method. The obtained sintering kinetic agrees well with that calculated by analytical equations of sinter neck growth.
Design Of Sustainable Aluminium-based Feedstocks For Additive Manufacturing
Authors: Aguilar-Garcia José Luis , Ruiz-Navas Elisa María , Jiménez-Morales Antonia
Published: November 2024

This work explores Composite Extrusion Modeling (CEM) with aluminium as an alternative processing route for aluminium alloys. This process allows working with pellets to be deposited directly, layer-by-layer. For this reason, an initial study, necessary for the production of samples, has been carried out. The first challenge was the design of sustainable aluminium-based feedstock, and the production of pellets for additive manufacturing. Thanks to previous studies by the research group, the Powder Injection Moulding (PIM) technique was used as a first approach to produce good quality samples through a combination of water-soluble polymers with low CO2 emissions, PEG and CAB, respectively. For this, a microstructural characterization was carried out and the critical solid loading and rheological properties were studied, as well as the debinding conditions and sintering parameters. In the same way, the printing parameters were optimized for a proper material deposition and to obtain good quality samples.
The Effect Of Build Orientation And Infill Pattern On Mechanical Properties Of 316L Parts Made By Material Extrusion-based Additive Manufacturing
Authors: Gabilondo Nieto Maitane , Castro Francisco , Cearsolo Xabier , Arrue Mario
Published: November 2024

Extrusion-based additive manufacturing (EAM) is an alternative to the most common Additive Manufacturing (AM) technology for metal parts. As compared to Powder Bed Fusion (PBF) there are no loose powders or lasers during the manufacturing. However, the mechanical properties of the parts manufactured by EAM are generally lower than those of PBF, being necessary to study the process parameters to improve their performance. The purpose of this work is to analyse the influence of build orientation (horizontal and vertical) and infill pattern (concentric and lines) on the mechanical properties of 316L parts manufactured by EAM. Among the different EAM processes, the selected technology was Bound Metal Deposition (BMD). The experimental results showed that although both build orientation and infill pattern influenced the mechanical properties, build orientation exerted the most important influence on mechanical properties, obtaining ultimate tensile strengths (UTS) at least 160 MPa higher for horizontal specimens.
Powdercleanse: An Automated Closed-loop Powder Processing System For Additive Manufacturing
Authors: Larkin Owen , Hall Adam , Duffy John , Williams Robert , Francis Charlie , Buckley David , Beaver Tim , Galert Victor
Published: November 2024

The quality and cleanliness of metal powder used in AM directly affects process-productivity and part-integrity. Current methods for powder validation rely on the collection and testing of samples from powder batches. As the AM industry grows and production of safety critical, high value components ramps up, the volume of powder being used will greatly increase. This will require the development of efficient, high-throughput and reliable powder validation tools. The approach developed in the Innovate-UK funded PowderCleanse project addresses these requirements by combining automated sieving and in-line particle size analysis in a digitally integrated closed loop powder handling solution. This allows for full traceability and monitoring of the powder condition at each stage. In this manuscript we will give an overview of the PowderCleanse project and present operational results, demonstrating that it can successfully convey, sieve and measure the particle size distribution (PSD) of a range of AM powders.
Applications Of Metal Foam In Catalysis And Electrolysis
Authors: Walther Gunnar , Büttner Tilo , Rauscher Thomas , Bernäcker Christian Imanuel , Röntzsch Lars , Weißgärber Thomas , Bae JungSuk , Torkuhl Lars , Tillmann Andreas
Published: November 2024

Open cell metallic foams are suitable for a wide range of applications as materials for filters, catalyst supports for heterogeneous catalysis and electrodes in batteries, fuel cells and electrolyzers due to their excellent heat and mass transfer, low pressure drop, good electrical conductivity and high chemical resistance. The foam can be produced in a wide range of pure metals like nickel, iron, silver and copper. Depending on the application, high high-temperature, oxidation and corrosion resistance can be achieved by a patented powder metallurgical alloying process in industrial scale.In the current paper, results for applications of NiFeCrAl foam as catalyst for Steam Methane Reforming and silver foam for the formaldehyde synthesis are discussed. Another focus is on the application as electrode material in electrolysis. Electrochemical investigations show that modified nickel foam exhibit a much lower overvoltage than nickel sheets and thus the operating costs of electrolyzers can be significantly reduced.
Development Of AISI 304L For Metal Binder Jetting
Authors: Charron Quentin , Trump Anna , Reynaud Christophe , Baulin Oriane , Cunningham Jeff , Dary François
Published: November 2024

Processing of the AISI 304L Stainless Steel on Desktop Metal’s Binder Jetting Shop System suite (both printer and sintering furnace) has been investigated. This development has been performed in close collaboration between Desktop Metal and Cetim.Several printing and sintering parameters such as green density, sintering atmosphere or sintering temperature were studied and their impact on microstructure and mechanical properties is evaluated and discussed. It has been demonstrated that high green density and nitrogen-based atmosphere are key factors for dense parts and optimal material performance.Final material exhibits mechanical properties compliant with MIM 316L standards (MPIF Std 35 | ISO 22068) and with ASTM A420. It opens several key markets for Metal Binder Jetting, including luxury, energy…
Design Guidelines For Green Parts Manufactured From Stainless Steel In The Filament Based Material Extrusion Process For Metals (MEX|M)
Authors: Asami Karim , Herzog Dirk , Bossen Bastian , Klemp Clarissa , Geyer Leon , Emmelmann Claus
Published: November 2024

Filament-based material extrusion (MEX|M) presents a rapid and inexpensive alternative to e.g. metal injection molding, particularly for prototype production. The filament consists of metal powder in a plastic matrix and is melted and applied layer by layer until a so-called green body is created. These green parts are subsequently debinded and sintered at high temperatures to form a dense metal component. It is crucial to identify the material-specific and process-specific limits in order to be able to manufacture true to size. This paper therefore develops design guidelines for the MEX|M process for green part manufacturing for the widely used austenitic stainless steel AISI 316L (1.4404). Basic geometrical features such as walls, boreholes and overhangs are studied and influencing factors on the dimensional accuracy are assessed. Based on the results, recommendations for part design are presented.
What Makes Titanium Alloys Such A Good Fit For Additive Manufacturing?
Authors: Sears James
Published: November 2024

Over the course of the last 70 years there have been many developments in the techniques used to fabricate components using powder metallurgy Titanium (PM-Ti). The reasons for using PM-Ti for part fabrication has been well established, i.e., the associated reduction in fabrication costs (e.g., reduction in Buy-to-Fly ratio). A major impediment to a wider acceptance for the use of PM Titanium has been the high cost of Titanium powder production. Now, with the recent focus on Additive Manufacturing, the interest in using PM Ti has increased and more titanium powder producers are becoming online. Along with the developments in titanium powder production and use, a brief history of where Additive Manufacturing came from will be discuss.
Novel Interconnects Manufactured By Powder Metallurgy For Solid Oxide Cells Applications
Authors: Monterde Mari Carmen , Bernadet Lucile , Calero Jose Antonio , Jimenez-Piqué Emilio , Torrell Marc
Published: November 2024

This work presents SOC interconnects produced by powder metallurgy. Ferritic stainless steel and modified-ferritic stainless steel with Y2O3, have been studied as interconnect materials for SOC tested. Chemical composition effect and chromium content, thermal expansion coefficient, oxidation kinetics and area specific resistance were studied and discussed. In this regards, thermogravimetric analysis during 3500h at 800ºC under oxidizing atmosphere are presented and discussed. Moreover, long-term solid oxide electrolyze mode under 0.25 A.cm-2 at 800ºC in Air|90H2O|10H2 for 700h suffer a soft degradation. Use of conventional MnCo spinel chromium-getter coatings have also been studied. It was confirmed by FIB test that MnCo2O4 coating retain the volatile chromium species in order to avoid the poisoning of the cell. The obtained results indicated that ferritic stainless steel interconnect manufactured by powder metallurgy with a lower content in chromium than Plansee's interconnect are a potential alternative to be considered.
Alumina-Silver Composites With Enhanced Fracture Toughness And Antibacterial Properties
Authors: Singh Shweta , Gurjar Ankit , Pareek Shiwani , Bhatia Eshant , Krishnatrey Ishita , Negi Seema , Bhargava Parag , Srivastava Rohit
Published: November 2024

The motivation of this work is to improve fracture toughness and incorporate anti-microbial characteristics in alumina ceramics. In this work, alumina-silver composites are prepared by the addition of 2, 5, 10, and 15 wt. % silver nano-flakes. The microstructural analysis is performed using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). Mechanical properties like flexural strength, fracture toughness, and microhardness are evaluated. Flexural strength is found to decrease with increased silver content while fracture toughness improved significantly. Antibacterial properties are evaluated on E.coli bacteria. All the samples showed antibacterial activity which improved with increased silver content. The present study establishes alumina|silver composite as an antibacterial material with improved fracture toughness which makes it a potential biomaterial for dental and low load-bearing applications.
Metal Injection Moulding Of High Purity Tungsten And Molybdenum
Authors: Opschoor Jan , Bult René
Published: November 2024

Shaping high melting refractory metals like molybdenum and tungsten from powder has been proven a tough challenge because its refractoriness. A metal injection moulding (MIM) process has been developed for high purity molybdenum, tungsten and oxide dispersion strengthened tungsten (ODS). Employing MIM allows for obtaining small grain sizes, controlled doping and isotropic properties. Furthermore MIM is a net shape technique, avoiding difficult machining steps or joining processes, and reducing material waste In this presentation an overview of the manufacturing process will be given, as well as the results of microstructural and mechanical characterisation.
Effect Of Alloying Elements On Fe-Si-X Soft Magnetic Material Produced By AM And PM
Authors: Lindroos Tomi , Kinos Timo , Antikainen Atte , Kaunisto Kimmo , Riipinen Tuomas , Metsä-Kortelainen Sini , Manninen Aino , Pippuri-Mäkeläinen Jenni
Published: November 2024

Electrification of the world has significantly increased the demand for novel high performance electromechanical components. Powder Metallurgy and especially Additive Manufacturing are seen as enablers to produce components based on novel soft magnetic materials with performance and designs unattainable with conventional manufacturing. Fe-Si-X soft magnetic materials were studied by focusing to tailor material to Laser Powder Bed Fusion (L-PBF) processing. Effect of different alloying elements on magnetic, electrical and mechanical properties were studied based on simulations and experiments. The focus was paid on increasing the understanding of segregation occurring at high cooling rates and how it could be utilized in controlling electrical resistivity and consequently the mitigation of eddy current losses. Gas atomized powder corresponding the most promising alloy composition was produced and further, test components were manufactured by L-PBF accompanied by appropriate heat treatments. The results of resistivity and magnetic measurements are promising when compared against conventional Fe-Si alloy.
Biodegradation And Biocompatibility Of Molybdenum As An Implant Material
Authors: Poehle Georg , Schauer Antje , Redlich Christian , Scheibler Jakob , Weissgaerber Thomas , Barthel Peggy , Maennel Anita , Adams Volker , Linke Axel , Quadbeck Peter
Published: November 2024

Biodegradable metals have entered the implant market in recent years, but still do not show fully satisfactory degradation behaviour and mechanical properties. In contrast, it has been shown that pure molybdenum has an excellent combination of the required properties in this respect. We report on PM based screen printing of thin-walled molybdenum tubes as a processing step for medical stent manufacture. We also present data on the in vivo degradation and biocompatibility of molybdenum. The degradation of molybdenum wires implanted in the aorta of rats was evaluated by SEM and EDX. Biocompatibility was assessed by histological investigation of organs and analysis of molybdenum levels in tissue extracts and body fluids. Degradation rates of up to 13.5 µm|y were observed after 12 months. No histological changes or elevated molybdenum levels in organ tissues were observed. In summary, the results further underline that molybdenum is a highly promising biodegradable metallic material.
Fabrication Of Monodispersed Spherical Composite Granules By Electrostatic Integrated Granulation Of Nanopowder Suspensions
Authors: Nakamura Koki , Yokoi Atsushi , Tan Wai Kian , Kawamura Go , Matsuda Atsunori , Muto Hiroyuki
Published: November 2024

In nanocomposite materials fabrication, nanopowders are commonly used to obtain the desired properties. However, the drawbacks of nanopowders are agglomeration and poor handling ability. To overcome these issues, one solution is to fabricate composite granules using electrostatic integrated granulation of aqueous nanopowder suspension. By adjusting the surface charge potential of the nanopowders, electrostatic integration during the granulation process enabled the fabrication of monodispersed spherical composite granules, exhibiting good homogeneity of raw nanoparticles and improved handling ability. In this study, the parameters for composite granules formation using electrostatic integrated assembly method were investigated. From the results obtained, a process map, which enables the prediction of the granule’s formation is also proposed.