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Full-Text Articles in Mechanical Engineering
Fabricating Zirconia Parts With Organic Support Material By The Ceramic On-Demand Extrusion Process, Wenbin Li, Amir Ghazanfari, Devin Mcmillen, Andrew Scherff, Ming-Chuan Leu, Greg Hilmas
Fabricating Zirconia Parts With Organic Support Material By The Ceramic On-Demand Extrusion Process, Wenbin Li, Amir Ghazanfari, Devin Mcmillen, Andrew Scherff, Ming-Chuan Leu, Greg Hilmas
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Ceramic On-Demand Extrusion (CODE) is an extrusion-based additive manufacturing process recently developed for fabricating dense, functional ceramic components. This paper presents a further development of this process and focuses on fabricating 3 mol% yttria-stabilized zirconia (3YSZ) components that cannot be fabricated without using support structures. The 3YSZ paste is deposited through the main nozzle, and a polycaprolactone (PCL) pellet feedstock is melted and deposited through an auxiliary nozzle to build support structures. After a green part is printed and dried, the support structures are removed by heating the part to ~70 ⁰C to melt the PCL. The part is then …
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 …
Experimental Investigation Of Effect Of Environment Temperature On Freeze-Form Extrusion Fabrication, Xiyue Zhao, Michael S. Mason, Tieshu Huang, Ming-Chuan Leu, Robert G. Landers, Greg Hilmas, Samuel J. Easley, Michael W. Hayes
Experimental Investigation Of Effect Of Environment Temperature On Freeze-Form Extrusion Fabrication, Xiyue Zhao, Michael S. Mason, Tieshu Huang, Ming-Chuan Leu, Robert G. Landers, Greg Hilmas, Samuel J. Easley, Michael W. Hayes
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Freeze-form Extrusion Fabrication (FEF) is an additive manufacturing technique that extrudes ceramic loaded aqueous pastes layer by layer below the paste freezing temperature for component fabrication. A computer controlled 3-D gantry system has been developed for the FEF process. The system includes a temperature control subsystem that allows for fabrication of components below the paste freezing temperature. The low temperature environment allows for larger component fabrication. Comparisons in terms of layer thickness, self-sustaining ability, and system response were performed between 0⁰C and -20⁰C for alumina sample fabrications. The minimum deposition angles without use of support material have been determined for …
Freeform Extrusion Of High Solids Loading Ceramic Slurries, Part I: Extrusion Process Modeling, Michael S. Mason, Tieshu Huang, Robert G. Landers, Ming-Chuan Leu, Greg Hilmas
Freeform Extrusion Of High Solids Loading Ceramic Slurries, Part I: Extrusion Process Modeling, Michael S. Mason, Tieshu Huang, Robert G. Landers, Ming-Chuan Leu, Greg Hilmas
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A novel, solid freeform fabrication method has been developed for the manufacture of ceramic-based components in an environmentally friendly fashion. The method is based on the extrusion of ceramic slurries using water as the binding media. Aluminum oxide (Al2O3) is currently being used as the part material and solids loading as high as 60 vol. % has been achieved. This paper describes a novel manufacturing machine that has been developed for the extrusion of high solids loading ceramic slurries. A critical component of the machine is the deposition system, which consists of a syringe, a plunger, …
Freeform Extrusion Of High Solids Loading Ceramic Slurries, Part Ii: Extrusion Process Control, Michael S. Mason, Tieshu Huang, Robert G. Landers, Ming-Chuan Leu, Greg Hilmas
Freeform Extrusion Of High Solids Loading Ceramic Slurries, Part Ii: Extrusion Process Control, Michael S. Mason, Tieshu Huang, Robert G. Landers, Ming-Chuan Leu, Greg Hilmas
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Part I of this paper provided a detailed description of a novel fabrication machine for high solids loading ceramic slurry extrusion processes and presented an empirical model of the ceramic extrusion process, viewing ram velocity as the input and extrusion force as the output. A constant extrusion force is desirable as it correlates with a constant material deposition rate and, thus, good part quality. The experimental results used to construct the model demonstrated that a constant ram velocity will not necessarily produce a constant extrusion force. In some instances the extrusion force increased until ram motor skipping occurred, and process …
Freeze-Form Extrusion Fabrication Of Ceramics, Tieshu Huang, Michael S. Mason, Greg Hilmas, Ming-Chuan Leu
Freeze-Form Extrusion Fabrication Of Ceramics, Tieshu Huang, Michael S. Mason, Greg Hilmas, Ming-Chuan Leu
Materials Science and Engineering Faculty Research & Creative Works
A novel, environmentally friendly solid freeform fabrication method called Freeze-form Extrusion Fabrication (FEF) has been developed for the fabrication of ceramic-based components. The method is based on deposition of ceramic pastes using water as the media. The ceramic solids loading can be 50 vol. % or higher and initial studies have focused on the use of aluminum oxide (Al2O3). The FEF system components and their interaction are examined, and the main process parameters affecting part geometry defined. 3-D shaped components have been fabricated by extrusion deposition of the ceramic paste in a layer-by-layer fashion. The feasibility …