Final Report 15 Aug 1987 30 Mar 1988 Ceramic Process Systems Corp Cambridge Ma, Jul 1, 1988
This program has established the feasibility of manufacturing composite ceramic superconducting f... more This program has established the feasibility of manufacturing composite ceramic superconducting filaments for superconducting cable, based on copper-clad YBa2Cu3O7-x ceramic powders, to render the material in the form of flexible fine diameter green fibers by dry spinning, and to rapidly sinter the fibers to produce filaments with transport Jc as high as 2800 A/sq.cm. The sintered fibers can be handled, and the feasibility of cladding these fibers with copper by electrodeposition has been supported. The fibers are spun from a suspension of powder in a mixture of solvents containing several acrylic polymers, a plasticizer, a cross-linking agent, and a dispersant. The dry green fiber is a flexible monofilament containing 49 to 55 volume percent (85 to 87 weight percent) ceramic powder in a polymeric matrix. A multiple zone sintering process was developed to rapidly densify the YBa2Cu3O7-x fibers.
A popular and useful piezoelectric actuator is the stack. Unfortunately with this type of actuati... more A popular and useful piezoelectric actuator is the stack. Unfortunately with this type of actuation architecture the long lengths normally required to obtain necessary displacements can pose packaging and buckling problems. To overcome these limitations, a new architecture for piezoelectric actuators has been developed called telescopic. The basic design consists of concentric shells interconnected by end-caps which alternate in placement between the two axial ends of the shells. This leads to a linear displacement amplification at the cost of force; yet the force remains at the same magnitude as a stack and significantly higher than bender type architectures. This paper describes the fabrication and experimental characterization of three different telescopic prototypes. The actuator prototypes discussed in this paper mark a definitive step forward in fabrication techniques for complex piezoceramic structures. Materials Systems, Inc. has adapted injection molding for the fabrication of net shape piezoceramic actuators. Injection molding provides several advantages over conventional fabrication techniques, including: high production rate, uniform part dimensions, uniform piezoelectric properties, and reduced fabrication and assembly costs. Acrylate polymerization, developed at the University of Michigan, is similar to gelcasting, but uses a nonaqueous slurry which facilitates the production of large, tall, complex components such as the telescopic actuator, and is ideal for the rapid manufacture of unique or small batch structures. To demonstrate these fabrication processes a five tube telescopic actuator was injection molded along with a very tall three tube actuator that was cast using the acrylate polymerization method. As a benchmark, a third actuator was built from off-the-shelf tubes that were joined with aluminum end-caps. Each prototype's free deflection behavior was experimentally characterized and the results of the testing are presented within this paper. C 2001 Kluwer Academic Publishers
Si 3 N 4 /BN fibrous monoliths were prepared with 4 wt% Y 2 O 3 added as a sintering aid to the S... more Si 3 N 4 /BN fibrous monoliths were prepared with 4 wt% Y 2 O 3 added as a sintering aid to the Si 3 N 4 . Residual carbon, present in the billet before hot-pressing, was shown to influence the final microstructure. The sintering aid glass, known to migrate into the BN cell boundaries during hotpressing, was not sufficient in quantity to prevent premature shear failure when samples were tested in flexure. Increasing the hot-pressing temperature alleviated this problem. For flexure samples tested at 1400°C, fibrous monoliths fabricated with 4 wt% Y 2 O 3 demonstrated linear-elastic loading behavior at a greater stress than fibrous monoliths fabricated with 6-wt%-Y 2 O 3 /2-wt%-Al 2 O 3 sintering aids.
International Journal of Applied Ceramic Technology, Nov 1, 2011
Ceramic stereolithography (SLA) was used to fabricate a ceramic investment casting mold with the ... more Ceramic stereolithography (SLA) was used to fabricate a ceramic investment casting mold with the integral core within a ceramic mold shell, produced in a single patternless construction from refractory-grade fused silica. The SLA build material was a photopolymerizable suspension of 60 vol% fused silica dispersed in a monomer solution based on 1,6-hexanediol diacrylate. The mold had 1047 layers, each 100 mm thick. Green body dimensions before sintering were approximately 0.7% smaller than the design within the plane of the layers, and approximately 0.3% larger than the design perpendicular to the layers. The sintering shrinkage was 10.770.2% in both directions.
Journal of the American Ceramic Society, Sep 1, 1993
The fibrous monolith microstructure consists of high aspect ratio polycrystalline cells of SiC se... more The fibrous monolith microstructure consists of high aspect ratio polycrystalline cells of SiC separated by thin cell boundaries containing graphite. The SiC/100% graphite fibrous monolith has noncatastrophic fracture behavior, is damage tolerant, and is notch insensitive. The failure process is characterized by fracture along weak graphite cell boundaries. The room-temperature flexural strength is 300-350 MPa. The estimated shear strength along
The social experience of multiplayer gaming is mediated by the communications tools that are avai... more The social experience of multiplayer gaming is mediated by the communications tools that are available to use. Until recently, these have been largely text-based, but with the advent of new voiceover IP tools like Roger Wilco and Xbox Live, voice-mediated communication is becoming increasingly common. We present three studies of multiplayer gaming, where we analyse what happens in terms of the social experience when players are given the opportunity of talking to each other rather than texting. To do this we use a conceptual framework called FFIPS, which stands for Form, language Functions, Identity, Presence, and Social protocols. Our findings show that voiceover IP for multiplayer gaming appears to be well-suited to supporting a distinctive and enjoyable social experience, both by providing high 'presence' (i.e., increased energy, engagement and vividness), and by revealing information about players' real identities.
Page 1. Curing of Highly Loaded Ceramic Suspensions in Acrylates Tien-Min Gabriel ChuV and John W... more Page 1. Curing of Highly Loaded Ceramic Suspensions in Acrylates Tien-Min Gabriel ChuV and John W. HalloranV Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48105 The ...
Crack deflection and the subsequent growth of delamination cracks can be a potent source of energ... more Crack deflection and the subsequent growth of delamination cracks can be a potent source of energy dissipation during the fracture of layered ceramics. In this study, multilayered ceramics that consist of silicon nitride (Si 3 N 4 ) layers separated by boron nitride/silicon nitride (BN/Si 3 N 4 ) interphases have been manufactured and tested. Flexural tests reveal that the crack path is dependent on the composition of the interphase between the Si 3 N 4 layers. Experimental measurements of interfacial fracture resistance and frictional sliding resistance show that both quantities increase as the Si 3 N 4 content in the interphase increases. However, contrary to existing theories, high energyabsorption capacity has not been realized in materials that exhibit crack deflection but also have moderately high interfacial fracture resistance. Significant energy absorption has been measured only in materials with very low interfacial fracture resistance values. A method of predicting the critical value of the interfacial fracture resistance necessary to ensure a high energy-absorption capacity is presented.
Suspension polymerization casting of lead zirconate titanate (PZT) filled acrylamide systems was ... more Suspension polymerization casting of lead zirconate titanate (PZT) filled acrylamide systems was studied. A high solid loading (51 vol%) PZT slurry with low viscosity (about 280 mPa·s at shear rate 10 s −1 ) was obtained by optimizing the dispersant amount. The polymerization process for the monomer solution and PZT slurry were characterized with the help of the storage modulus measurement. For the monomer solution, the overall activation energy of gelation was calculated as 60-76 kJ/mol, while for the PZT slurry, this energy increased to 91 ± 9 kJ/mol. The drying, burnout and sintering processes were also addressed. C 2003 Kluwer Academic Publishers
Fibrous monolithic ceramics were fabricated in the aluminahickel system. The microstructure consi... more Fibrous monolithic ceramics were fabricated in the aluminahickel system. The microstructure consists of highaspect-ratio polycrystalline cells of alumina separated by thin cell boundaries of nickel. The nickel content in the material is 3 to 8 ~0 1 % . The fibrous monolith with uniaxially aligned cells fails noncatastrophically in flexure. Bridging ligaments of nickel, crack deflection along cell boundaries, and crack branching in the axial direction are observed in flexure bars and notched beams. Strength values range from 246 to 375 MPa. Indentations cause controlled damage on the surface but do not introduce strength-degrading flaws. The aluminahickel fibrous monoliths also show potential for use at high temperatures in oxidizing environments. Noncatastrophic fracture behavior is observed at room temperature after 10 h at 1200°C in air. The Ni cell boundary network is oxidized to a depth of 50 to 100 pm by this heat treatment. The NiO oxidation product in the cell boundaries reacts partly with alumina from the cells to form NiAI,O,, which would provide better protection.
This paper describes the investigation into the use of cathodoluminescence for distinguishing HA ... more This paper describes the investigation into the use of cathodoluminescence for distinguishing HA and β-TCP phases within the biphasic calcium phosphate ceramic microstructure. Polished samples were scanned using SEM-CL at an accelerating voltage in the range of 10-15 keV with a beam current of 5-10 nA. The grayscale images produced reveal distinctive patterns for each composition. EDS and EPMA suggest chemical differences among the contrasting regions. Image analysis of voxel values indicate that areas of bright contrast correspond to β-TCP grains with phase amounts confirmed by XRD.
Regardless of the application domain and deployment scope, the ability to retrieve information is... more Regardless of the application domain and deployment scope, the ability to retrieve information is critical to the successful functioning of any wireless sensor network (WSN) system. In general, information extraction procedures can be categorized into three main approaches: agentbased, query-based and macroprogramming. While query-based systems are the most popular, macroprogramming techniques provide a more general-purpose approach to distributed computation. Finally, the agent-based approaches tailor the information extraction mechanism to the type of information needed and the configuration of the network it needs to be extracted from. This chapter offers an extensive survey of the literature in the area of WSN information extraction, covering in Sections 1 and 2 the three main approaches above. Section 3 highlights the open research questions and issues faced by deployable WSN system designers and discusses the potential benefits of both innetwork processing and complex querying for large scale wireless informational systems. information requests that represent higher level behaviour, involve just a "subset" of the network (whether physical or logical), or require more complex in-network interactions between "subsets" in order to generate information. Furthermore, as distributed computation is not the main focus of SQLbased query languages (which support most WSN query-based approaches) implementing arbitrary aggregation, for example, is quite difficult .
Final Report 15 Aug 1987 30 Mar 1988 Ceramic Process Systems Corp Cambridge Ma, Jul 1, 1988
This program has established the feasibility of manufacturing composite ceramic superconducting f... more This program has established the feasibility of manufacturing composite ceramic superconducting filaments for superconducting cable, based on copper-clad YBa2Cu3O7-x ceramic powders, to render the material in the form of flexible fine diameter green fibers by dry spinning, and to rapidly sinter the fibers to produce filaments with transport Jc as high as 2800 A/sq.cm. The sintered fibers can be handled, and the feasibility of cladding these fibers with copper by electrodeposition has been supported. The fibers are spun from a suspension of powder in a mixture of solvents containing several acrylic polymers, a plasticizer, a cross-linking agent, and a dispersant. The dry green fiber is a flexible monofilament containing 49 to 55 volume percent (85 to 87 weight percent) ceramic powder in a polymeric matrix. A multiple zone sintering process was developed to rapidly densify the YBa2Cu3O7-x fibers.
A popular and useful piezoelectric actuator is the stack. Unfortunately with this type of actuati... more A popular and useful piezoelectric actuator is the stack. Unfortunately with this type of actuation architecture the long lengths normally required to obtain necessary displacements can pose packaging and buckling problems. To overcome these limitations, a new architecture for piezoelectric actuators has been developed called telescopic. The basic design consists of concentric shells interconnected by end-caps which alternate in placement between the two axial ends of the shells. This leads to a linear displacement amplification at the cost of force; yet the force remains at the same magnitude as a stack and significantly higher than bender type architectures. This paper describes the fabrication and experimental characterization of three different telescopic prototypes. The actuator prototypes discussed in this paper mark a definitive step forward in fabrication techniques for complex piezoceramic structures. Materials Systems, Inc. has adapted injection molding for the fabrication of net shape piezoceramic actuators. Injection molding provides several advantages over conventional fabrication techniques, including: high production rate, uniform part dimensions, uniform piezoelectric properties, and reduced fabrication and assembly costs. Acrylate polymerization, developed at the University of Michigan, is similar to gelcasting, but uses a nonaqueous slurry which facilitates the production of large, tall, complex components such as the telescopic actuator, and is ideal for the rapid manufacture of unique or small batch structures. To demonstrate these fabrication processes a five tube telescopic actuator was injection molded along with a very tall three tube actuator that was cast using the acrylate polymerization method. As a benchmark, a third actuator was built from off-the-shelf tubes that were joined with aluminum end-caps. Each prototype's free deflection behavior was experimentally characterized and the results of the testing are presented within this paper. C 2001 Kluwer Academic Publishers
Si 3 N 4 /BN fibrous monoliths were prepared with 4 wt% Y 2 O 3 added as a sintering aid to the S... more Si 3 N 4 /BN fibrous monoliths were prepared with 4 wt% Y 2 O 3 added as a sintering aid to the Si 3 N 4 . Residual carbon, present in the billet before hot-pressing, was shown to influence the final microstructure. The sintering aid glass, known to migrate into the BN cell boundaries during hotpressing, was not sufficient in quantity to prevent premature shear failure when samples were tested in flexure. Increasing the hot-pressing temperature alleviated this problem. For flexure samples tested at 1400°C, fibrous monoliths fabricated with 4 wt% Y 2 O 3 demonstrated linear-elastic loading behavior at a greater stress than fibrous monoliths fabricated with 6-wt%-Y 2 O 3 /2-wt%-Al 2 O 3 sintering aids.
International Journal of Applied Ceramic Technology, Nov 1, 2011
Ceramic stereolithography (SLA) was used to fabricate a ceramic investment casting mold with the ... more Ceramic stereolithography (SLA) was used to fabricate a ceramic investment casting mold with the integral core within a ceramic mold shell, produced in a single patternless construction from refractory-grade fused silica. The SLA build material was a photopolymerizable suspension of 60 vol% fused silica dispersed in a monomer solution based on 1,6-hexanediol diacrylate. The mold had 1047 layers, each 100 mm thick. Green body dimensions before sintering were approximately 0.7% smaller than the design within the plane of the layers, and approximately 0.3% larger than the design perpendicular to the layers. The sintering shrinkage was 10.770.2% in both directions.
Journal of the American Ceramic Society, Sep 1, 1993
The fibrous monolith microstructure consists of high aspect ratio polycrystalline cells of SiC se... more The fibrous monolith microstructure consists of high aspect ratio polycrystalline cells of SiC separated by thin cell boundaries containing graphite. The SiC/100% graphite fibrous monolith has noncatastrophic fracture behavior, is damage tolerant, and is notch insensitive. The failure process is characterized by fracture along weak graphite cell boundaries. The room-temperature flexural strength is 300-350 MPa. The estimated shear strength along
The social experience of multiplayer gaming is mediated by the communications tools that are avai... more The social experience of multiplayer gaming is mediated by the communications tools that are available to use. Until recently, these have been largely text-based, but with the advent of new voiceover IP tools like Roger Wilco and Xbox Live, voice-mediated communication is becoming increasingly common. We present three studies of multiplayer gaming, where we analyse what happens in terms of the social experience when players are given the opportunity of talking to each other rather than texting. To do this we use a conceptual framework called FFIPS, which stands for Form, language Functions, Identity, Presence, and Social protocols. Our findings show that voiceover IP for multiplayer gaming appears to be well-suited to supporting a distinctive and enjoyable social experience, both by providing high 'presence' (i.e., increased energy, engagement and vividness), and by revealing information about players' real identities.
Page 1. Curing of Highly Loaded Ceramic Suspensions in Acrylates Tien-Min Gabriel ChuV and John W... more Page 1. Curing of Highly Loaded Ceramic Suspensions in Acrylates Tien-Min Gabriel ChuV and John W. HalloranV Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48105 The ...
Crack deflection and the subsequent growth of delamination cracks can be a potent source of energ... more Crack deflection and the subsequent growth of delamination cracks can be a potent source of energy dissipation during the fracture of layered ceramics. In this study, multilayered ceramics that consist of silicon nitride (Si 3 N 4 ) layers separated by boron nitride/silicon nitride (BN/Si 3 N 4 ) interphases have been manufactured and tested. Flexural tests reveal that the crack path is dependent on the composition of the interphase between the Si 3 N 4 layers. Experimental measurements of interfacial fracture resistance and frictional sliding resistance show that both quantities increase as the Si 3 N 4 content in the interphase increases. However, contrary to existing theories, high energyabsorption capacity has not been realized in materials that exhibit crack deflection but also have moderately high interfacial fracture resistance. Significant energy absorption has been measured only in materials with very low interfacial fracture resistance values. A method of predicting the critical value of the interfacial fracture resistance necessary to ensure a high energy-absorption capacity is presented.
Suspension polymerization casting of lead zirconate titanate (PZT) filled acrylamide systems was ... more Suspension polymerization casting of lead zirconate titanate (PZT) filled acrylamide systems was studied. A high solid loading (51 vol%) PZT slurry with low viscosity (about 280 mPa·s at shear rate 10 s −1 ) was obtained by optimizing the dispersant amount. The polymerization process for the monomer solution and PZT slurry were characterized with the help of the storage modulus measurement. For the monomer solution, the overall activation energy of gelation was calculated as 60-76 kJ/mol, while for the PZT slurry, this energy increased to 91 ± 9 kJ/mol. The drying, burnout and sintering processes were also addressed. C 2003 Kluwer Academic Publishers
Fibrous monolithic ceramics were fabricated in the aluminahickel system. The microstructure consi... more Fibrous monolithic ceramics were fabricated in the aluminahickel system. The microstructure consists of highaspect-ratio polycrystalline cells of alumina separated by thin cell boundaries of nickel. The nickel content in the material is 3 to 8 ~0 1 % . The fibrous monolith with uniaxially aligned cells fails noncatastrophically in flexure. Bridging ligaments of nickel, crack deflection along cell boundaries, and crack branching in the axial direction are observed in flexure bars and notched beams. Strength values range from 246 to 375 MPa. Indentations cause controlled damage on the surface but do not introduce strength-degrading flaws. The aluminahickel fibrous monoliths also show potential for use at high temperatures in oxidizing environments. Noncatastrophic fracture behavior is observed at room temperature after 10 h at 1200°C in air. The Ni cell boundary network is oxidized to a depth of 50 to 100 pm by this heat treatment. The NiO oxidation product in the cell boundaries reacts partly with alumina from the cells to form NiAI,O,, which would provide better protection.
This paper describes the investigation into the use of cathodoluminescence for distinguishing HA ... more This paper describes the investigation into the use of cathodoluminescence for distinguishing HA and β-TCP phases within the biphasic calcium phosphate ceramic microstructure. Polished samples were scanned using SEM-CL at an accelerating voltage in the range of 10-15 keV with a beam current of 5-10 nA. The grayscale images produced reveal distinctive patterns for each composition. EDS and EPMA suggest chemical differences among the contrasting regions. Image analysis of voxel values indicate that areas of bright contrast correspond to β-TCP grains with phase amounts confirmed by XRD.
Regardless of the application domain and deployment scope, the ability to retrieve information is... more Regardless of the application domain and deployment scope, the ability to retrieve information is critical to the successful functioning of any wireless sensor network (WSN) system. In general, information extraction procedures can be categorized into three main approaches: agentbased, query-based and macroprogramming. While query-based systems are the most popular, macroprogramming techniques provide a more general-purpose approach to distributed computation. Finally, the agent-based approaches tailor the information extraction mechanism to the type of information needed and the configuration of the network it needs to be extracted from. This chapter offers an extensive survey of the literature in the area of WSN information extraction, covering in Sections 1 and 2 the three main approaches above. Section 3 highlights the open research questions and issues faced by deployable WSN system designers and discusses the potential benefits of both innetwork processing and complex querying for large scale wireless informational systems. information requests that represent higher level behaviour, involve just a "subset" of the network (whether physical or logical), or require more complex in-network interactions between "subsets" in order to generate information. Furthermore, as distributed computation is not the main focus of SQLbased query languages (which support most WSN query-based approaches) implementing arbitrary aggregation, for example, is quite difficult .
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