Aqueous-Based Extrusion Fabrication is an additive manufacturing technique that extrudes ceramic ... more Aqueous-Based Extrusion Fabrication is an additive manufacturing technique that extrudes ceramic slurries of high solids loading layer by layer for part fabrication. The material reservoir in a previously developed system has been modified to allow for starting and stopping of the extrusion process on demand. Design pros and cons are examined and a comparison between two material reservoir designs is made. Tests are conducted to determine the optimal deposition parameters for starting and stopping the extrudate on demand. The collected test data is used for the development of a deposition strategy that improves material deposition consistency, including reduced material buildup at sharp corners. Example parts are fabricated using the deposition strategy and hardware design.
A salt bath sintering method was developed for fabricating porous titanium constructs that potent... more A salt bath sintering method was developed for fabricating porous titanium constructs that potentially could be used as implants in bone repair. Advantages of the method include low-cost fabrication, control of the porosity and pore size, and ease of fabricating anatomically relevant shapes. Mixtures of titanium and sodium chloride (salt) particles were compacted to form a cylindrical shape, and sintered for 2 hours in a salt bath at 1200 °C. After dissolution of the salt, porous titanium constructs with controllable porosity in the range 36 to 65% and pore sizes of ~30 um to ~200 um were obtained. The compressive strength and elastic modulus of the cylindrical constructs decreased from 216 to 36 MPa and from 9.8 to 1.8 GPa, respectively, with an increase in the porosity from 36 to 65%, and showed an exponential dependence on the porosity. The porous constructs supported the proliferation of murine MLO-A5 cells (an osteogenic cell line), showing their cytocompatibility. Prototypes of a porous Ti insert that could be used to augment the fixation of femoral and tibial stems in total joint arthroplasty were produced to show the applicability of the process
A dual‐phase high‐entropy boride (HEB)/carbide (HEC) ceramic with a fine grain size was synthesiz... more A dual‐phase high‐entropy boride (HEB)/carbide (HEC) ceramic with a fine grain size was synthesized by a sequential boro/carbothermal process. In the first step, an Hf–Nb–Ta–Ti–Zr‐containing carbide was synthesized by a carbothermal reduction of oxides followed by the reaction of the carbide with B4C and ZrH2 to convert part of the carbide to boride. The resulting composition was ∼29 vol% HEB with an average grain size of ∼1.1 μm. Solid solution formation occurred at the densification temperature of 1900°C resulting in a relative density higher than 99%. The Vickers hardness was 26.5 ± 1.4 GPa. This is the first report of synthesizing dual‐phase boride–carbide high‐entropy ceramics from carbothermally synthesized, HEC powders.
A salt bath sintering method was developed for fabricating porous titanium constructs that potent... more A salt bath sintering method was developed for fabricating porous titanium constructs that potentially could be used as implants in bone repair. Advantages of the method include low-cost fabrication, control of the porosity and pore size, and ease of fabricating anatomically relevant shapes. Mixtures of titanium and sodium chloride (salt) particles were compacted to form a cylindrical shape, and sintered for 2 hours in a salt bath at 1200 °C. After dissolution of the salt, porous titanium constructs with controllable porosity in the range 36 to 65% and pore sizes of ~30 um to ~200 um were obtained. The compressive strength and elastic modulus of the cylindrical constructs decreased from 216 to 36 MPa and from 9.8 to 1.8 GPa, respectively, with an increase in the porosity from 36 to 65%, and showed an exponential dependence on the porosity. The porous constructs supported the proliferation of murine MLO-A5 cells (an osteogenic cell line), showing their cytocompatibility. Prototypes of a porous Ti insert that could be used to augment the fixation of femoral and tibial stems in total joint arthroplasty were produced to show the applicability of the process
Ceramic On-Demand Extrusion (CODE) is an extrusion-based additive manufacturing process recently ... more Ceramic On-Demand Extrusion (CODE) is an extrusion-based additive manufacturing process recently developed for fabricating dense, functional ceramic components. Presented in this paper is a further development of this process focusing on fabrication of functionally graded materials (FGM). A dynamic mixing mechanism was developed for mixing constituent ceramic pastes, and an extrusion control scheme was developed for fabricating specimens with desired material compositions graded in real time. FGM specimens with compositions graded between Al2O3 and ZrO2 were fabricated and ultimately densified by sintering to validate the effectiveness of the CODE process for FGM fabrication. Energy dispersive spectroscopy (EDS) was used to compare final compositions to the original material designs. The specimen's hardness at different locations along the gradients was examined by micro-indentation tests. The dimensions of sintered specimens were measured, and the effects of material composition gradients on the distortions of sintered FGM specimens were analyzed.
Using the Selective Laser Sintering (SLS) process, both flexural test bars and 3D fuel injector c... more 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 freeform fabrication of 3D parts with the ultra high temperature ceramic.
: Aqueous-Based Extrusion Fabrication is an additive manufacturing technique that extrudes cerami... more : Aqueous-Based Extrusion Fabrication is an additive manufacturing technique that extrudes ceramic slurries of high solids loading layer by layer for part fabrication. The material reservoir in a previously developed system has been modified to allow for starting and stopping of extrusion process on demand. Design pros and cons are examined and a comparison between two material reservoir designs is made. Tests were conducted to determine the optimal deposition parameters for starting and stopping of the extrudate on demand. The collected test data is used to create a process model that describes the relationship between ram velocity and material extrusion rate. This model allows for the development of a deposition strategy that improves material deposition consistency, including reduced material buildup at sharp corners. Example parts are fabricated using the deposition strategy and hardware design.
A novel, solid freeform fabrication method has been developed for the manufacture of ceramic-base... more 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, a ram actuated by a motor that forces the plunger down to extrude material, and a load cell to measure the extrusion force. An empirical, dynamic model of the ceramic extrusion process, where the input is the commanded ram velocity and the output is the extrusion force, is developed. Several experiments are conducted and curve fitting techniques are utilized to construct the dynamic model. ...
A novel, environmentally friendly solid freeform fabrication method called Freeze-form Extrusion ... more 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 of this process has been demonstrated by building components having a simple geometry, such as cylinders and solid or hollow cones. Hollow cones have also been fabricated to demonstrate the ability to build structures with sloped walls.
Freeze-form Extrusion Fabrication (FEF) is an additive manufacturing technique that extrudes cera... more 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 0 °C and-20 °C for alumina sample fabrications. The minimum deposition angles without use of support material have been determined for 20°C, 10 °C, 0 °C,-10 °C and-20 °C fabrications.
: A novel, solid freeform fabrication method has been developed for the manufacture of ceramic-ba... more : 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, a ram actuated by a motor that forces the plunger down to extrude material, and a load cell to measure the extrusion force. An empirical, dynamic model of the ceramic extrusion process, where the input is the commanded ram velocity and the output is the extrusion force, is developed. Several experiments are conducted and curve fitting techniques are utilized to construct the dynamic model...
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Functionally designed diamond and cemented carbide architectures were fabricated using the fibrou... more Functionally designed diamond and cemented carbide architectures were fabricated using the fibrous monolith co-extrusion process and are being considered as a replacement for traditional diamond and cemented carbides forrock drilling bits. The macrostructures of these composites consist of diamond cells with WC(Co) cell boundaries or WC(Co) cells with Co cell boundaries. As with past fibrous monoliths, these new compositions exhibit non-brittle fracture behavior as compared to traditional diamond and cemented carbide monoliths. Cellular structured diamond and WC(Co)/Co fibrous monolith drill bits inserts have been produced by co-extrusion and consolidated by either HTHP (High Temperature High Pressure) or ROC (Rapid Omnidirectional Compaction) processes. The materials show increases in fracture toughness without a significant decrease in wear resistance. Field test results and indentation results for these novel materials will be discussed.
... 19971. Bandyopadhyay, A., Panda, RK, Janas, VF, Agarwala, MK, Danforth, SC and Safari, A. 199... more ... 19971. Bandyopadhyay, A., Panda, RK, Janas, VF, Agarwala, MK, Danforth, SC and Safari, A. 1997. Processing of piezocomposites by fused deposition technique. ... View all references, Lous et al. 20009. Lous, GM, Cornejo, IA, McNulty, TF, Safari, A. and Danforth, SC 2000. ...
Aqueous-Based Extrusion Fabrication is an additive manufacturing technique that extrudes ceramic ... more Aqueous-Based Extrusion Fabrication is an additive manufacturing technique that extrudes ceramic slurries of high solids loading layer by layer for part fabrication. The material reservoir in a previously developed system has been modified to allow for starting and stopping of the extrusion process on demand. Design pros and cons are examined and a comparison between two material reservoir designs is made. Tests are conducted to determine the optimal deposition parameters for starting and stopping the extrudate on demand. The collected test data is used for the development of a deposition strategy that improves material deposition consistency, including reduced material buildup at sharp corners. Example parts are fabricated using the deposition strategy and hardware design.
A salt bath sintering method was developed for fabricating porous titanium constructs that potent... more A salt bath sintering method was developed for fabricating porous titanium constructs that potentially could be used as implants in bone repair. Advantages of the method include low-cost fabrication, control of the porosity and pore size, and ease of fabricating anatomically relevant shapes. Mixtures of titanium and sodium chloride (salt) particles were compacted to form a cylindrical shape, and sintered for 2 hours in a salt bath at 1200 °C. After dissolution of the salt, porous titanium constructs with controllable porosity in the range 36 to 65% and pore sizes of ~30 um to ~200 um were obtained. The compressive strength and elastic modulus of the cylindrical constructs decreased from 216 to 36 MPa and from 9.8 to 1.8 GPa, respectively, with an increase in the porosity from 36 to 65%, and showed an exponential dependence on the porosity. The porous constructs supported the proliferation of murine MLO-A5 cells (an osteogenic cell line), showing their cytocompatibility. Prototypes of a porous Ti insert that could be used to augment the fixation of femoral and tibial stems in total joint arthroplasty were produced to show the applicability of the process
A dual‐phase high‐entropy boride (HEB)/carbide (HEC) ceramic with a fine grain size was synthesiz... more A dual‐phase high‐entropy boride (HEB)/carbide (HEC) ceramic with a fine grain size was synthesized by a sequential boro/carbothermal process. In the first step, an Hf–Nb–Ta–Ti–Zr‐containing carbide was synthesized by a carbothermal reduction of oxides followed by the reaction of the carbide with B4C and ZrH2 to convert part of the carbide to boride. The resulting composition was ∼29 vol% HEB with an average grain size of ∼1.1 μm. Solid solution formation occurred at the densification temperature of 1900°C resulting in a relative density higher than 99%. The Vickers hardness was 26.5 ± 1.4 GPa. This is the first report of synthesizing dual‐phase boride–carbide high‐entropy ceramics from carbothermally synthesized, HEC powders.
A salt bath sintering method was developed for fabricating porous titanium constructs that potent... more A salt bath sintering method was developed for fabricating porous titanium constructs that potentially could be used as implants in bone repair. Advantages of the method include low-cost fabrication, control of the porosity and pore size, and ease of fabricating anatomically relevant shapes. Mixtures of titanium and sodium chloride (salt) particles were compacted to form a cylindrical shape, and sintered for 2 hours in a salt bath at 1200 °C. After dissolution of the salt, porous titanium constructs with controllable porosity in the range 36 to 65% and pore sizes of ~30 um to ~200 um were obtained. The compressive strength and elastic modulus of the cylindrical constructs decreased from 216 to 36 MPa and from 9.8 to 1.8 GPa, respectively, with an increase in the porosity from 36 to 65%, and showed an exponential dependence on the porosity. The porous constructs supported the proliferation of murine MLO-A5 cells (an osteogenic cell line), showing their cytocompatibility. Prototypes of a porous Ti insert that could be used to augment the fixation of femoral and tibial stems in total joint arthroplasty were produced to show the applicability of the process
Ceramic On-Demand Extrusion (CODE) is an extrusion-based additive manufacturing process recently ... more Ceramic On-Demand Extrusion (CODE) is an extrusion-based additive manufacturing process recently developed for fabricating dense, functional ceramic components. Presented in this paper is a further development of this process focusing on fabrication of functionally graded materials (FGM). A dynamic mixing mechanism was developed for mixing constituent ceramic pastes, and an extrusion control scheme was developed for fabricating specimens with desired material compositions graded in real time. FGM specimens with compositions graded between Al2O3 and ZrO2 were fabricated and ultimately densified by sintering to validate the effectiveness of the CODE process for FGM fabrication. Energy dispersive spectroscopy (EDS) was used to compare final compositions to the original material designs. The specimen's hardness at different locations along the gradients was examined by micro-indentation tests. The dimensions of sintered specimens were measured, and the effects of material composition gradients on the distortions of sintered FGM specimens were analyzed.
Using the Selective Laser Sintering (SLS) process, both flexural test bars and 3D fuel injector c... more 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 freeform fabrication of 3D parts with the ultra high temperature ceramic.
: Aqueous-Based Extrusion Fabrication is an additive manufacturing technique that extrudes cerami... more : Aqueous-Based Extrusion Fabrication is an additive manufacturing technique that extrudes ceramic slurries of high solids loading layer by layer for part fabrication. The material reservoir in a previously developed system has been modified to allow for starting and stopping of extrusion process on demand. Design pros and cons are examined and a comparison between two material reservoir designs is made. Tests were conducted to determine the optimal deposition parameters for starting and stopping of the extrudate on demand. The collected test data is used to create a process model that describes the relationship between ram velocity and material extrusion rate. This model allows for the development of a deposition strategy that improves material deposition consistency, including reduced material buildup at sharp corners. Example parts are fabricated using the deposition strategy and hardware design.
A novel, solid freeform fabrication method has been developed for the manufacture of ceramic-base... more 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, a ram actuated by a motor that forces the plunger down to extrude material, and a load cell to measure the extrusion force. An empirical, dynamic model of the ceramic extrusion process, where the input is the commanded ram velocity and the output is the extrusion force, is developed. Several experiments are conducted and curve fitting techniques are utilized to construct the dynamic model. ...
A novel, environmentally friendly solid freeform fabrication method called Freeze-form Extrusion ... more 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 of this process has been demonstrated by building components having a simple geometry, such as cylinders and solid or hollow cones. Hollow cones have also been fabricated to demonstrate the ability to build structures with sloped walls.
Freeze-form Extrusion Fabrication (FEF) is an additive manufacturing technique that extrudes cera... more 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 0 °C and-20 °C for alumina sample fabrications. The minimum deposition angles without use of support material have been determined for 20°C, 10 °C, 0 °C,-10 °C and-20 °C fabrications.
: A novel, solid freeform fabrication method has been developed for the manufacture of ceramic-ba... more : 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, a ram actuated by a motor that forces the plunger down to extrude material, and a load cell to measure the extrusion force. An empirical, dynamic model of the ceramic extrusion process, where the input is the commanded ram velocity and the output is the extrusion force, is developed. Several experiments are conducted and curve fitting techniques are utilized to construct the dynamic model...
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Functionally designed diamond and cemented carbide architectures were fabricated using the fibrou... more Functionally designed diamond and cemented carbide architectures were fabricated using the fibrous monolith co-extrusion process and are being considered as a replacement for traditional diamond and cemented carbides forrock drilling bits. The macrostructures of these composites consist of diamond cells with WC(Co) cell boundaries or WC(Co) cells with Co cell boundaries. As with past fibrous monoliths, these new compositions exhibit non-brittle fracture behavior as compared to traditional diamond and cemented carbide monoliths. Cellular structured diamond and WC(Co)/Co fibrous monolith drill bits inserts have been produced by co-extrusion and consolidated by either HTHP (High Temperature High Pressure) or ROC (Rapid Omnidirectional Compaction) processes. The materials show increases in fracture toughness without a significant decrease in wear resistance. Field test results and indentation results for these novel materials will be discussed.
... 19971. Bandyopadhyay, A., Panda, RK, Janas, VF, Agarwala, MK, Danforth, SC and Safari, A. 199... more ... 19971. Bandyopadhyay, A., Panda, RK, Janas, VF, Agarwala, MK, Danforth, SC and Safari, A. 1997. Processing of piezocomposites by fused deposition technique. ... View all references, Lous et al. 20009. Lous, GM, Cornejo, IA, McNulty, TF, Safari, A. and Danforth, SC 2000. ...
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