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Full-Text Articles in Mechanical Engineering
Impact Of Sintering Time And Temperature On Mechanical Properties In Projection Sintering Of Polyamide-12, Justin Nussbaum, Taranjot Kaur, Julie Harmon, Nathan B. Crane
Impact Of Sintering Time And Temperature On Mechanical Properties In Projection Sintering Of Polyamide-12, Justin Nussbaum, Taranjot Kaur, Julie Harmon, Nathan B. Crane
Faculty Publications
In powder bed fusion additive manufacturing (AM), the fusing process is temperature and time dependent. However, little work has been done to understand how different processing temperatures and times might impact the mechanical properties at longer sintering times than are typical in laser sintering (LS) systems. Prior results with projection sintering have shown that heating for longer times (>1s) improves part toughness compared to laser sintering. In this work, Large Area Projection Sintering (LAPS) is used to sinter entire layers of material simultaneously over the course of a few seconds with spatial control of layer temperature. This work evaluates …
Binder Jetting: A Review Of Process, Materials, And Methods, Mohsen Ziaee, Nathan B. Crane
Binder Jetting: A Review Of Process, Materials, And Methods, Mohsen Ziaee, Nathan B. Crane
Faculty Publications
Binder Jet printing is an additive manufacturing technique that dispenses liquid binding agent on powder. Layers are formed repeatedly to build up a physical article. Binder jetting (BJ) can be adapted to almost any powder with high production rates. The BJ process utilizes a broad range of technologies including printing methods, powder deposition, dynamic binder/powder interaction, and post-processing methods. A wide variety of materials have been demonstrated including polymers, metals, and ceramics, but a common challenge is developing printing and post-processing methods that maximize part performance. This article presents a broad review of technologies and approaches that have been applied …
Binder-Jet Printing Of Fine Stainless Steel Powder With Varied Final Density, Mohsen Ziaee, Eric M. Tridas, Nathan B. Crane
Binder-Jet Printing Of Fine Stainless Steel Powder With Varied Final Density, Mohsen Ziaee, Eric M. Tridas, Nathan B. Crane
Faculty Publications
Binder jetting is an additive manufacturing process that produces relatively weak porous parts that are strengthened through sintering and/or infiltration. This paper reports on two different methods of preparing fine 316 stainless steel powder and their impact on the final sintered density and dimensions relative to direct printing into -22 micron powder. The first method uses agglomerates of fine powder. In the second, nylon 12 powders are mixed with the steel powder as a fugitive space holder to increase porosity. Sintered density and sintering shrinkage of agglomerate material are shown to vary with the density of the spread powder bed. …
Freeze-Form Extrusion Fabrication Of Functionally Graded Material Composites Using Zirconium Carbide And Tungsten, Ang Li, Aaron S. Thornton, Bradley K. Deuser, Jeremy Lee Watts, Ming-Chuan Leu, Greg Hilmas, Robert G. Landers
Freeze-Form Extrusion Fabrication Of Functionally Graded Material Composites Using Zirconium Carbide And Tungsten, Ang Li, Aaron S. Thornton, Bradley K. Deuser, Jeremy Lee Watts, Ming-Chuan Leu, Greg Hilmas, Robert G. Landers
Materials Science and Engineering Faculty Research & Creative Works
Ultra-high-temperature ceramics are being investigated for future use in aerospace applications due to their superior thermo-mechanical properties, as well as their oxidation resistance, at temperatures above 2000⁰C. However, their brittleness makes them susceptible to thermal shock failure. As graded composites, components fabricated as functionally-graded materials (FGMs) can combine the superior properties of ceramics with the toughness of an underlying refractory metal. This paper discusses the grading of two materials through the use of a Freeze-form Extrusion Fabrication (FEF) system to build FGM parts consisting of zirconium carbide (ZrC) and tungsten (W). Aqueous-based colloidal suspensions of ZrC and W were developed …
Freeze-Form Extrusion Fabrication Of Composite Structures, Ming-Chuan Leu, Lie Tang, Bradley K. Deuser, Robert G. Landers, Greg Hilmas, Shi C. Zhang, Jeremy Lee Watts
Freeze-Form Extrusion Fabrication Of Composite Structures, Ming-Chuan Leu, Lie Tang, Bradley K. Deuser, Robert G. Landers, Greg Hilmas, Shi C. Zhang, Jeremy Lee Watts
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A Freeze-form Extrusion Fabrication (FEF) process capable of making three-dimensional (3D) parts and structures with graded composite materials is presented in this paper. The process development includes the design and manufacture of a gantry machine with a triple-extruder mechanism and the associated electronics hardware and computer software for fabricating functionally graded parts from multiple aqueous pastes. A rheological behavior study with Al2O3 paste is performed to identify an efficient binder for transforming the paste into a pseudoplastic with a high yield stress. A green part is first fabricated using the triple-extruder FEF machine in a layer-by-layer manner …
Freeze Extrusion Fabrication Of 13-93 Bioactive Glass Scaffolds For Bone Repair, Tieshu Huang, Nikhil D. Doiphode, M. N. Rahaman, Ming-Chuan Leu, B. Sonny Bal, D. E. Day
Freeze Extrusion Fabrication Of 13-93 Bioactive Glass Scaffolds For Bone Repair, Tieshu Huang, Nikhil D. Doiphode, M. N. Rahaman, Ming-Chuan Leu, B. Sonny Bal, D. E. Day
Materials Science and Engineering Faculty Research & Creative Works
There is an increasing demand for synthetic scaffolds with the requisite biocompatibility, internal architecture, and mechanical properties for the bone repair and regeneration. In this work, scaffolds of a silicate bioactive glass (13-93) were prepared by a freeze extrusion fabrication (FEF) method and evaluated in vitro for potential applications in bone repair and regeneration. The process parameters for FEF production of scaffolds with the requisite microstructural characteristics, as well as the mechanical and cell culture response of the scaffolds were evaluated. After binder burnout and sintering (60 min at 700°C), the scaffolds consisted of a dense glass network with interpenetrating …
Optimization Of Selective Laser Sintering Process For Fabrication Of Zirconium Diboride Parts, Ming-Chuan Leu, Shashwatashish Pattnaik, Greg Hilmas
Optimization Of Selective Laser Sintering Process For Fabrication Of Zirconium Diboride Parts, Ming-Chuan Leu, Shashwatashish Pattnaik, Greg Hilmas
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Selective Laser Sintering (SLS) was investigated to fabricate Zirconium Diboride (ZrB2) parts for ultra-high temperature applications. Experiments were conducted to determine values of SLS process parameters (laser power, scan speed, line spacing, and layer thickness) that can be used to build ZrB2 parts with high integrity and sharp geometrical features. A sacrificial plate with a proper number of layers (determined from experimentation) separated from the main part was built in order to reduce thermal gradients when building the main part. The sacrificial plate was found to assist in eliminating cracks in the bottom of the main part. …
Selective Laser Sintering Of 13-93 Bioactive Glass, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas, Mariano Garcia Velez
Selective Laser Sintering Of 13-93 Bioactive Glass, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas, Mariano Garcia Velez
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Bioactive glasses are more promising than biopolymers in fabricating scaffolds for bone tissue repair because they convert to hydroxyapatite, when implanted in vivo. Both direct and indirect selective laser sintering (SLS) methods of 13-93 bioactive glass were considered in this research to study the feasibility of fabricating scaffolds for bone repair applications. Stearic acid was used as the binder in the indirect method to fabricate the scaffolds. The green scaffolds underwent binder burnout and sintering at various soaking conditions between 675⁰C and 700⁰C, achieving a maximum compressive strength of 23.6 MPa, which is higher than that of the human cancellous …
Freeform Fabrication Of Zirconium Diboride Parts Using Selective Laser Sintering, Ming-Chuan Leu, Erik B. Adamek, Tieshu Huang, Greg Hilmas, Fatih Dogan
Freeform Fabrication Of Zirconium Diboride Parts Using Selective Laser Sintering, Ming-Chuan Leu, Erik B. Adamek, Tieshu Huang, Greg Hilmas, Fatih Dogan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Using the Selective Laser Sintering (SLS) process, both flexural test bars and 3D fuel injector components have been fabricated with zirconium diboride (ZrB2) powder. Stearic acid was selected as the binder. Values of SLS process parameters were chosen such that the green parts could be built with sharp geometrical features and that the sintered parts could have good mechanical properties. After binder burnout and sintering, the SLS fabricated ZrB2 test bars achieved 80% theoretical density, and the average flexural strength of the sintered samples was 195 MPa. These values demonstrate the feasibility of the SLS process for …