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Christopher B Williams - One of the best experts on this subject based on the ideXlab platform.
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effect of fine powder particles on quality of Binder Jetting parts
Additive manufacturing, 2020Co-Authors: Hadi Miyanaji, Kazi Moshiur Rahman, Christopher B WilliamsAbstract:Abstract Despite their desired effects on quality metrics of powder metallurgy parts, fine powder materials are rarely used in powder-based additive manufacturing as powder feedstock materials due to their poor flowability and inefficient layer recoating. As such, process-structure-property relationships of powder-based AM processes have been explored primarily for coarse powder particle sizes (i.e., 25 μm–150 μm in diameter). With the new developments in powder recoating systems in modern Binder Jetting additive manufacturing (BJ-AM) printers, it seems now feasible to process fine powder materials that have average particle size of ∼10 μm (or smaller). In the current research, the use of fine copper powders (average particle size of 5 μm) in BJ process and its effects on green and final part properties are experimentally investigated. Specially, the authors studied the effects of different powder recoating settings on the density of printed green parts. The density of the sintered parts was also explored for various sintering parameters (i.e., heating rate and peak sintering temperature). Linear/volumetric shrinkage, microstructure and mechanical characteristics of sintered specimens were explored, and the results were compared to those of copper specimens made via coarse powder materials. The results indicated that fine copper powder resulted in parts with properties (UTS of 179.4 MPa and elongation of 42.2 %) greater than bimodal powder parts, which in turn eliminates extra time and work needed for powder mixing ratio optimization and blending process.
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unraveling pore evolution in post processing of Binder Jetting materials x ray computed tomography computer vision and machine learning
Additive manufacturing, 2020Co-Authors: Yunhui Zhu, Douglas W Hartley, Jennifer M Sietins, Christopher B WilliamsAbstract:Abstract Quality control in metal additive manufacturing prioritizes the development of advanced inspection schemes to characterize the defect evolution during processing and post-processing. This involves grand challenges in detecting internal defects and analyzing large and complex defect datasets in macroscopic samples. Here, we present an inspection pipeline that integrates (i) fast, micro X-ray computed tomography reconstruction, (ii) automated 3D morphology analysis, and (iii) machine learning-based big data analysis. X-ray computed tomography and automated computer vision result in a holistic defect morphology database for the inspected macroscopic volume, based on which machine learning analysis is employed to reveal quantitative insights into the global evolution of defect characteristics beyond qualitative human observations. We demonstrate this pipeline by examining the global-scale pore evolution in post-processing of Binder Jetting additive manufacturing, from the green state, to the sintered state, and to the hot isostatic pressed state of copper. The pipeline is shown to be effective at detecting and processing the information associated with a large number (∼105) of pores in macroscopic volumes. The subsequent principal component analysis and clustering analysis extract the key morphological descriptors and categorize the detected pores into four morphological groups. By quantifying the evolution of (i) the weight of pore morphology parameters and (ii) the pore number and volume fraction of each categorized group, new understandings are developed regarding the effects of sintering and hot isostatic pressing on pore decomposition, shrinkage, and smoothing during post-processing of Binder Jetting.
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impacts of process induced porosity on material properties of copper made by Binder Jetting additive manufacturing
Materials & Design, 2019Co-Authors: Ashwath Yegyan Kumar, Yun Bai, Jue Wang, Scott T Huxtable, Christopher B WilliamsAbstract:Abstract Binder Jetting (BJ) is an efficient, economical, and scalable Additive Manufacturing (AM) technology that can be used in fabricating parts made of reflective and conductive materials like copper, which have applications in advanced thermal and electrical components. The primary challenge of BJ is in producing fully dense, homogeneous parts without infiltration. To this end, copper parts of porosities ranging from 2.7% to 16.4% were fabricated via BJ, by varying powder morphology, post-process sintering, and Hot Isostatic Pressing conditions. The aim of this study is to characterize and quantify the effects of porosity on the material properties of Binder Jet pure copper parts. Copper parts with the lowest porosity of 2.7% demonstrated a tensile strength of 176 MPa (80.2% of wrought strength), a thermal conductivity of 327.9 W/m·K (84.5% that of wrought copper), and an electrical conductivity of 5.6 × 107 S/m (96.6% IACS). The porosity-property relationship in these parts was compared against theoretical and empirical models in the literature for similar structures. These studies contribute towards developing a scientific understanding of the process-property-performance relationship in BJ of copper and other printed metals, which can help in tailoring materials and processing conditions to achieve desired properties.
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comparison of linear and 4 arm star poly vinyl pyrrolidone for aqueous Binder Jetting additive manufacturing of personalized dosage tablets
ACS Applied Materials & Interfaces, 2019Co-Authors: Emily M Wilts, Yun Bai, Christopher B Williams, Timothy Edward LongAbstract:Fabrication of personalized dosage oral pharmaceuticals using additive manufacturing (AM) provides patients with customizable, locally manufactured, and cost-efficient tablets, while reducing the probability of side effects. Binder Jetting AM has potential for fabrication of customized dosage tablets, but the resulting products lack in strength due to solely relying on the Binder to produce structural integrity. The selection of polymeric Binders is also limited due to viscosity restraints, which limits molecular weight and concentration. To investigate and ameliorate these limitations, this article reports a comprehensive study of linear and 4-arm star poly(vinyl pyrrolidone) (PVP) over a range of molecular weights as polymeric Binders for Binder Jetting AM and their effect on physical tablet properties. Formulation of varying molecular weights and concentrations of linear and 4-arm star PVP in deionized water and subsequent Jetting revealed relationships between the critical overlap concentrations (C*) and jettability on Binder Jetting systems with thermal inkjet printheads. After printing with a commercially available ZCorp Spectrum Z510 printer with an HP11 printhead with a lactose and powdered sugar powder bed, subsequent measurement of compressive strength, compressive modulus, and porosity revealed structure-property relationships between molecular weight, polymer concentration, and linear and 4-arm star architectures with physical properties of Binder jetted tablets. This study elucidated that the dominating factor to increase compressive strength of a tablet is dependent on the weight percent of the polymer in the Binder, which filled interstitial voids between powder particles. Because 4-arm star polymers have lower solution viscosities compared to linear analogues at the same molecular weights, they were jettable at higher concentrations, thus producing the strongest tablets at a compressive strength of 1.2 MPa. Finally, the inclusion of an active pharmaceutical ingredient (API), acetaminophen, revealed maintenance of the tablet physical properties across 5-50 total wt % API in each tablet.
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the effects of hot isostatic pressing on parts fabricated by Binder Jetting additive manufacturing
Additive manufacturing, 2018Co-Authors: Ashwath Yegyan Kumar, Anders Eklund, Christopher B WilliamsAbstract:Abstract Hot Isostatic Pressing (HIP) is a technique of applying high pressures through a fluid medium at high temperatures to enclosed powders, castings and pre-sintered metal parts to eliminate porosity. Due to uniform volumetric shrinkage expected from this process, it can be a useful post-processing technique for complex-geometry parts fabricated using Additive Manufacturing (AM) techniques. In order for the technique to work effectively, parts are typically required to have a minimum density of 92%, where surface porosity is closed. While HIP has been used in conjunction with powder bed fusion AM processes, its use for parts made using Binder Jetting (BJ) has not been investigated in detail due to the limitations of BJ in fabricating sufficiently high-density parts without infiltration. In this work, detailed investigations on the effect of HIP on BJ parts printed from three different powder configurations, which led to varying levels of porosity, are performed. The effects of HIP on the density, microstructure, tensile strength, and ductility of the resulting parts is reported. A maximum density of 97.32% was achieved by HIP of printed and sintered parts created via bimodal powders. Both the tensile strength and ductility were found to improve following HIP, which suggests that the reduction in porosity is predominant compared to the detrimental effects of grain coarsening.
Z J Pei - One of the best experts on this subject based on the ideXlab platform.
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Binder Jetting additive manufacturing of copper diamond composites an experimental study
Journal of Manufacturing Processes, 2021Co-Authors: Jianchi Huang, Alex Fang, Bilal Mansoor, Z J PeiAbstract:Abstract This study demonstrates the feasibility of fabricating copper/diamond (Cu/Dia) composite samples using Binder Jetting additive manufacturing for the first time. Binder Jetting fabricates parts in two steps: forming green parts with a Binder at a low temperature and consolidating the green parts by sintering. The low processing temperature makes Binder Jetting an excellent candidate to create complex-shaped Cu/Dia parts without causing diamond graphitization. In this study, mixtures of copper-coated diamond powder and pure copper powder were used to print Cu/Dia samples on a Binder Jetting printer. The printed samples were then sintered under a medium vacuum environment with flowing forming gas (95% nitrogen and 5% hydrogen). The effects of diamond volume fraction (10 vol% and 50 vol%) and sintering temperature (800 °C and 900 °C) on density and porosity, phase composition, and microstructure of Cu/Dia samples were investigated. As the diamond volume fraction increased from 10 vol% to 50 vol%, the sinterability of the powder mixture decreased. Increasing sintering temperature from 800 °C to 900 °C significantly improved sintered bulk density for samples from each powder mixture. When sintering temperature increased from 800 °C to 900 °C, the microstructure evolved from a granular structure to a network structure. In all sintered samples, the distribution of diamond was uniform and there was no sign of diamond graphitization.
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ceramic Binder Jetting additive manufacturing relationships among powder properties feed region density and powder bed density
Ceramics International, 2021Co-Authors: Guanxiong Miao, Mohammadamin Moghadasi, Z J PeiAbstract:Abstract This short communication reports an experimental investigation on the relationships among powder properties (i.e., apparent density, tap density, and Hausner ratio), feed region density, and powder bed density in ceramic Binder Jetting additive manufacturing. Seven differently sized alumina powders (from 0.05 μm to 70 μm) were used for this experimental investigation. Simple linear regression was applied to analyze the experimental data. It was found that powder bed density matched well with feed region density under all conditions of this investigation. The results also showed that apparent density was a stronger predictor than tap density and Hausner ratio for powder bed density.
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ceramic Binder Jetting additive manufacturing effects of granulation on properties of feedstock powder and printed and sintered parts
Additive manufacturing, 2020Co-Authors: Guanxiong Miao, Mohammadamin Moghadasi, Z J PeiAbstract:Abstract Because of its high sinterability, nanopowder could be beneficial for ceramic Binder Jetting additive manufacturing to achieve a high density on printed and sintered parts. However, the flowability of nanopowder is poor because of the large interparticle cohesion. This poor flowability prohibits the usage of nanopowder in ceramic Binder Jetting. In this study, to improve the flowability of nanopowder, alumina nanoparticles were granulated into micron-sized granules through spray freeze drying. The raw nanopowder and granulated powder were compared by characterizing their flowability and printability. Results showed that the granulated powder had a much better flowability than the raw nanopowder. Because of the superior flowability, the granulated powder formed a denser and smoother powder bed than the raw nanopowder and resulted in denser and smoother printed and sintered samples. These improvements indicated that the printability of nanopowder was improved by granulation.
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ceramic Binder Jetting additive manufacturing effects of particle size on feedstock powder and final part properties
Ceramics International, 2020Co-Authors: Mohammadamin Moghadasi, Z J PeiAbstract:Abstract Binder Jetting is a promising additive manufacturing process to fabricate a wide range of materials, including ceramics. The objective of this research is to investigate the effects of particle size on flowability and sinterability of the feedstock powder and resultant properties of fabricated parts. A commercial ceramic composite powder was sieved into three different particle size ranges: designated as fine, medium, and coarse powders, respectively. Flowability and sinterability measurements were performed on the sieved powders. After printing and sintering, the density of samples was measured with the Archimedes’ method. Compressive tests were performed to investigate the mechanical properties of the fabricated parts. The experimental results showed that flowability increased but sinterability decreased as particle size increased. The printed and sintered density was dependent on both flowability and sinterability: the highest density was achieved by the medium powder due to the balance between flowability and sinterability. The compressive strength was dominated by sinterability: the highest strength was achieved by the fine powder because of the highest sinterability.
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ceramic Binder Jetting additive manufacturing particle coating for increasing powder sinterability and part strength
Materials Letters, 2019Co-Authors: Wenchao Du, Xiaorui Ren, Z J PeiAbstract:Abstract The objective of this research is to test a hypothesis that particle coating increases the sinterability of ceramic powder. This method is developed for Binder Jetting additive manufacturing but tested using a pressing and sintering route for the simplicity. Binder Jetting additive manufacturing has demonstrated its considerable capability in manufacturing ceramic parts with a complex shape and/or a customized design. Currently, the density of the ceramic parts made by Binder Jetting is low and their mechanical properties are inferior. The main reason is the low sinterability of the powder feedstock. A new powder surface modification method, i.e., particle coating, was applied to increase the powder sinterability and the part strength. Specifically, coarse crystalline alumina particles (70 and 10 µm in average) were coated with amorphous alumina, in which the microsized core was designed to provide the high flowability and the amorphous shell to promote sintering due to its high activity. The coated powder was pressed into disk samples and sintered. The samples from the coated powder showed significantly higher shrinkage and compressive strength than those from the raw powder, which proved the feasibility of the particle coating method to increase the powder sinterability and part strength.
Jürgen Eckert - One of the best experts on this subject based on the ideXlab platform.
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Additive manufacturing processes: Selective laser melting, electron beam melting and Binder Jetting-selection guidelines
Materials, 2017Co-Authors: Prashanth Konda Gokuldoss, Sri Kolla, Juergen Eckert, Jürgen EckertAbstract:Additive manufacturing (AM), also known as 3D printing or rapid prototyping, is gaining increasing attention due to its ability to produce parts with added functionality and increased complexities in geometrical design, on top of the fact that it is theoretically possible to produce any shape without limitations. However, most of the research on additive manufacturing techniques are focused on the development of materials/process parameters/products design with different additive manufacturing processes such as selective laser melting, electron beam melting, or Binder Jetting. However, we do not have any guidelines that discuss the selection of the most suitable additive manufacturing process, depending on the material to be processed, the complexity of the parts to be produced, or the design considerations. Considering the very fact that no reports deal with this process selection, the present manuscript aims to discuss the different selection criteria that are to be considered, in order to select the best AM process (Binder Jetting/selective laser melting/electron beam melting) for fabricating a specific component with a defined set of material properties.
Ryan B Wicker - One of the best experts on this subject based on the ideXlab platform.
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The Influence of Printing Parameters, Post-Processing, and Testing Conditions on the Properties of Binder Jetting Additive Manufactured Functional Ceramics
Ceramics, 2020Co-Authors: Luis A. Chavez, Ryan B Wicker, Paulina Ibave, Bethany R. Wilburn, David Alexander, Calvin M. Stewart, Yirong LinAbstract:This article outlines the current state-of-the-art Binder Jetting (BJT) additive manufacturing of functional ceramics. The impact of printing parameters, heat treatment processing, and testing conditions on the observed performance of these ceramics is discussed. Additionally, this article discusses the impact of physical properties such as density and mechanical strength on the overall performance of these functional ceramics. Although printing parameters and initial feedstock are crucial for the printability of the desired parts, other factors play an important role in the performance of the ceramic. Thermal post-processing is crucial to achieve optimized functional properties, while the testing orientation is key to obtaining the maximum output from the part. Finally, future research directions for this field are also discussed.
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Binder Jetting additive manufacturing of aluminum nitride components
Ceramics International, 2019Co-Authors: Carlos A Diazmoreno, Yirong Lin, David Espalin, Abel Hurtadomacias, C A Terrazas, L E Murr, Ryan B WickerAbstract:Abstract In this work, we report on the novel fabrication of aluminum nitride (AlN) components using Binder Jetting (BJT) additive manufacturing (AM). The AlN constructs were subjected to post-fabrication thermal treatment by hot isostatic pressing (HIPing) for 8 hours at a pressure of 206 MPa and temperature of 1900 °C. This treatment resulted in a 60.1% relative density maximum densification for AlN. The BJT printed AlN specimens were analyzed using various characterization techniques. The purity, microstructure, and polycrystallinity of the AlN phase formed were confirmed by techniques that included x-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), and high-resolution transmission electron microscopy (HRTEM). Second harmonic generation (SHG) microscopy showed polarization dependence and second harmonic signal at 470 nm, indicating the potential to produce thermal and optical-mechanical devices. Mechanical properties obtained by nanoindentation resulted in an elastic modulus of ~251 GPa when measured in fully dense, contiguous crystalline regions, corresponding to an apparent, porous bulk stiffness of ~90 GPa for the final, 60.1 % dense products. Finally, the laser flash method (LFM) was used to measure the thermal conductivity of the material as a function of temperature resulting in values from 4.82 W/mK to 3.17 W/mK for the temperature range from 23 °C to 500 °C, respectively.
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fabrication of barium titanate by Binder Jetting additive manufacturing technology
Ceramics International, 2015Co-Authors: S M Gaytan, Yirong Lin, Monica Cadena, Hasanul Karim, Diego Delfin, David Espalin, Eric Macdonald, Ryan B WickerAbstract:Abstract Fabrication of barium titanate (BaTiO 3 ) specimens was accomplished with Binder Jetting additive manufacturing, and build parameters (e.g., Binder saturation and layer thickness) and sintering profiles were modified to optimize the density achieved and the crystal structures obtained in the 3D printed parts. Surface and cross sectional grain morphology was characterized by scanning electron microscopy (SEM) revealing grain growth on localized areas of BTO fabricated specimens after sintering. Crystal structure was analyzed by X-ray diffraction (XRD) where the presence of a hexagonal phase was observed for BaTiO 3 only when sintered at 1400 °C. The dielectric constant of the fabricated BaTiO 3 specimens sintered at 1260 °C was obtained by using a K u -band wave-guide and vector network analyzer setup in which the relative permittivity was measured from 8.6 to 6.23 for a frequency range of 12.4–18 GHz, respectively. When sintered at 1400 °C for 4 h, a density of 3.93 g/cm 3 was obtained, which corresponds to 65.2% of the theoretical density. Piezoelectric properties exhibited a d 33 value of 74.1 for specimens also sintered at 1400 °C. Results reported in this paper demonstrate the feasibility of BTO as a Binder Jetting material for 3D printed dielectric structures, ceramic capacitors and gas and pressure sensors.
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Characterization of ceramic components fabricated using Binder Jetting additive manufacturing technology
Ceramics International, 2015Co-Authors: J A Gonzalez, Jorge Mireles, Yun Lin, Ryan B WickerAbstract:Binder Jetting additive manufacturing is an emerging technology with capability of processing a wide range of commercial materials, including metals and ceramics (316 SS, 420 SS, Inconel 625, Iron, Silica). In this project, aluminum oxide (Al2O3) powder was used for part fabrication. Various build parameters (e.g. layer thickness, saturation, particle size) were modified and different sintering profiles were investigated to achieve nearly full-density parts (~96%). The material's microstructure and physical properties were characterized. Full XRD, compression testing, and dielectric testing were conducted on all parts. Sintered alumina parts were achieved with an average compressive strength of 131.86MPa (16h sintering profile) and a dielectric constant of 9.47-5.65 for a frequency range of 20Hz to 1MHz. The complexity offered by additive processing aluminum oxide can be extended to the manufacturing of high value energy and environmental components for environmental systems (e.g. filters and membranes) or biomedical implants with integrated reticulated structures for improved osseointegration.
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analysis of ferroelectric ceramic fabricated by Binder Jetting technology
24th International Solid Freeform Fabrication Symposium - An Additive Manufacturing Conference SFF 2013, 2013Co-Authors: S M Gaytan, Monica Cadena, Mayela Aldaz, Edward Herderick, Francisco Medina, Ryan B WickerAbstract:The M-Lab system from ExOne was used to fabricate 3D structures of BaTiO3 ceramic with applications that include dielectric capacitors, sensors, and integrated circuits. For this project, layer thicknesses of 15 and 30 μm and various percentages of Binder saturation were used to fabricate components from powder. An organic binding agent was utilized during the printing process and later burned out at ~600°C prior to sintering. Multiple building parameters and sintering profiles were analyzed and compared in an attempt to obtain dense parts while examining shrinkage percentage variations. Introduction Barium titanate IV [BaTiO3] (BTO) applications range from embedded capacitance in printed circuit board to piezoelectric devices like sensors, heaters and transducers (Buscaglia, et al. 2004) (Maison, et al. 2001). Other applications include semiconductors with positive temperature coefficient of resistivity (PTCR) (Chatterjee, Stojanovic and Maiti 2003), dynamic access memories (DRAM), and IR sensors (Sahoo, et al. 2007). Synthesis techniques for BTO preparation include the organo-metallic precursor method, coprecipitation/sol-gel calcination and hydrothermal methods, among others (Sahoo, et al. 2007). Some deposition methods are vacuum evaporation, sputtering, laser ablation, hydrothermal synthesis, radio frequency plasma sputtering and sol–gel techniques which have been used for obtaining BTO thin films (Harizanov, Harizanova and Ivanova 2004). BTO ceramics can also be processed by techniques such as Spark Plasma Sintering (SPS) (Buscaglia, et al. 2004), a change that occurs when cooling through the Curie point, resulting in the involvement of stress-related transformation. Depending on its crystal structure, BTO can be paraelectric (cubic; a=4.031A) or ferroelectric (tetragonal; a=3.994A and c=4.038A) (Chen, et al. 2005) (Maison, et al. 2001). While low calcination temperatures of ~700°C result in a metastable cubic phase, this can be transformed to tetragonal structures by using higher temperatures, as found by Maison, et al. where phase transformation and particle size were analyzed by varying calcination temperature (Maison, et al. 2001). It has been demonstrated that chemical homogeneity, material purity, and microstructure have an effect on the positive temperature coefficient of resistivity in BTO. For this reason, methods that provide less contamination, such as coprecipitation, polymerization and sol-gel, are being developed (Hur, et al. 1998). For this project, BTO powder was used to fabricate simple geometric figures with a Binder Jetting technology, the M-Lab system (ExOne, OH). These components were fabricated with different Binder saturation percentages and sintered at different temperatures to obtain maximum density. XRD data show no signs of contamination after sintering. Part shrinkage was calculated and used to obtain accurate dimensions for dielectric constant measurements. Material, processing, and investigation methods A total of 500 grams of BTO powder was purchased from Acros Organics through Fisher Scientific. As-received powder can be appreciated in Figure 1. It can be observed
Mihaela L. Vlasea - One of the best experts on this subject based on the ideXlab platform.
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tailoring green and sintered density of pure iron parts using Binder Jetting additive manufacturing
Additive manufacturing, 2018Co-Authors: Issa Rishmawi, Mehrnaz Salarian, Mihaela L. VlaseaAbstract:Abstract Binder Jetting additive manufacturing (BJAM) is a comparatively low-cost process that enables manufacturing of complex and customizable metal parts. This process is applied to low-cost water-atomized iron powder with the goal of understanding the effects of printing parameters and sintering schedule on maximizing the green and sintered densities of manufactured samples, respectively. The powder is characterized by using scanning electron microscopy (SEM) and particle size analysis (Camsizer X2). In the AM process, the effects of powder compaction, layer thickness, and liquid Binder level on green part density are investigated. Post-process heat treatment is applied to selected samples, and suitable debinding parameters are studied by using thermo-gravimetric analysis (TGA). Sintering at various temperatures and durations results in densities of up to 91.3%. Image processing of x-ray computed tomography (μCT) scans of the samples reveals that porosity distribution is affected by powder spreading, and gradients in pore distribution in the sample are largely reduced after sintering. The resulting shrinkage ranges between 6.7 ± 3.0% and 25.3 ± 2.8%, while surface roughness ranges between 11.6 ± 5.0 μm and 32.1 ± 3.4 μm. The results indicate that the sintering temperature and time might be tailored to achieve target densities anywhere in the range of 64% and 91%, with possibly higher densities by increasing sintering time.
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sinter structure analysis of titanium structures fabricated via Binder Jetting additive manufacturing
Materials & Design, 2018Co-Authors: Evan Wheat, Mihaela L. Vlasea, James Hinebaugh, Craig MetcalfeAbstract:Abstract To facilitate functional part production in metal Binder Jetting additive manufacturing, the relationship between materials, process and sintering needs to be understood. This work relates sintering theory with process outcomes. For this, commercially pure titanium was deployed to study the effect of powder size distributions on green and sintered part qualities (bulk density, relative density, particle size, pore size, sinter neck size). The powders were uni- and bi-modal blends of 0–45 μm, 45–106 μm, and 106–150 μm. Computed tomography analysis was used to evaluate non-densifying (1000 °C) and densifying (1400 °C) sintering regimes. For green parts, the relative density and powder size distribution along the build direction followed a periodic fluctuation equivalent to the 150 μm layer thickness. The relative density fluctuation range was higher (±20%) for bi-modal blends with 0–45 μm, compared to all other blends (±8%) due to powder segregation. For non-densifying sintering, parts with 0–45 μm blends displayed both densifying and non-densifying behavior. For densifying sintering, powders containing 0–45 μm blends surpassed the 70% density threshold expected for this sintering regime. Overall, the finer particles improved bulk density of sintered parts, at the expense of higher levels of shrinkage and density anisotropy along the build direction.
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data related to the sinter structure analysis of titanium structures fabricated via Binder Jetting additive manufacturing
Data in Brief, 2018Co-Authors: Evan Wheat, Mihaela L. Vlasea, James Hinebaugh, Craig MetcalfeAbstract:Abstract The adoption of metal Binder Jetting additive manufacturing (AM) for functional parts relies on a deep understanding between the materials, the design aspects, the additive manufacturing process and sintering. This work focuses on the relationship between sintering theory and process outcomes. The data included in this article provides additional supporting information on the authors’ recent publication (Wheat et al., 2018 [1]) on the sinter structure analysis of commercially pure titanium parts manufactured using powder bed Binder Jetting additive manufacturing. For this work, commercially pure titanium was deployed to study the effect of powder size distributions on green and sintered part qualities (bulk density, relative density, particle size, pore size, sinter neck size). This manuscript includes the overall computed tomography visualization methods and results for the green and sintered samples using uni- and bi-modal powders. Moreover, the effective particle and pore size for the different batches of powder are presented.
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Powder bed Binder Jetting additive manufacturing of silicone structures
Additive Manufacturing, 2018Co-Authors: Farzad Liravi, Mihaela L. VlaseaAbstract:The feasibility of a hybrid additive manufacturing (AM) method combining material extrusion and powder bed Binder Jetting (PBBJ) techniques for fabrication of structures made of silicone (polysiloxane) is investigated in this paper. A full factorial experimental design was conducted to maximize the geometrical accuracy of the parts. The rheological and morphological properties of the silicone powders, the thermal characteristics of the liquid silicone Binder, and mechanical characterization the additively manufactured parts are reported. Using this hybrid AM method, porous cylindrical structures (5 mm diameter (D) × 3 mm height (H)) with potential applications in biomedical industry were additively manufactured. The final structures are composed of ∼60% silicone powder, ∼ 30% silicone Binder, and