DESIGN, ASSEMBLY AND CHARACTERIZATION OF COMPOSITE ...

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a higher electric conductivity), a manipulation of material processing for composite structures assembled with BT:Ni=2:3 Ni(m) ink and pure BT ink is performed. A 300 °C temperature is used in the binder removal step. After 6 hours of thermal treatment in air, the Ni phase grows a thin layer of oxide on surface so that this oxide surface layer modifies the sintering kinetics of Ni(m) ink and enables co-sintering with pure BT. Figure 5.9 Co-sintered compositional graded bow-tie stripe network of BT:Ni=4:1 Ni(m) (20Ni80BT) and pure BT before annealing. A weight increase of 0.133 g (1.456% by weight) is observed due to oxidation when 9.135 g of Ni powder has been heated at 300 °C for 6 hours in air; by calculation, 5.3% of Ni has been oxidized to NiO on the Ni particle surface with negligible linear expansion. NiO has a melting temperature of 1955 °C. When sintering atmosphere is appropriate, the NiO may increase the onset temperature for sintering of Ni particles and 158
modify the sintering kinetics of the Ni(m) ink, so that co-sintering of BT and Ni(m) may be accomplished at a higher Ni volume fraction than the BT:Ni=4:1 composition. The evolution of the NiO during sintering process is not studied in detail, but it is likely that the NiO will be reduced to metal state eventually. However, this method is not considered a repeatable standard procedure, and frequently hard to control due to process variables involved. Thus, it is not described in the experimental section. Figure 5.10a shows composite lattices assembled with pure BT ink and BT:Ni=2:3 Ni(m) ink using Ø250 µm nozzle and annealed at 800 °C for 24 hours in N2. The layered pattern is designed such that interleaved layers of BT and Ni(m) form a structure similar to a multilayer capacitor. That is, the Ni(m) layers are alternately terminated to form electrodes. The BT:Ni=2:3 Ni(m) rods appear gray in color, whereas the BT rods are cream colored. The center sample has been demarcated with a numerical scheme along the bottom edge. Here, regions 1 represent the termination ends of the multilayer structure. Region 2 denotes the extension of one set of electrodes to the terminations. And, region 3 represents the active area of the multilayer structure where layers of dielectric are sandwiched between oppositely charged electrodes. The electrode scheme is more clearly demonstrated with the cross-section of Figure 5.10b. In this figure, the open, 3D lattice nature of the structure is apparent. The top numbers correspond with the regions demarcated in Figure 5.10a, whereas the left-hand side labels denote the various anode (a1, a2, etc.), dielectric (d1, d2, etc.), and cathode (c1, c2, etc.) layers. In this picture, the terminal end is connected to the anode layers. The intersections created by overlapping rods from adjacent anode, dielectric, and cathode layers form an array of parallel connected capacitors for each dielectric layer. 159
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DESIGN, ASSEMBLY AND CHARACTERIZATI
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ACKNOWLEDGEMENTS First and foremost
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CHAPTER 5 BARIUM TITANATE NICKEL CO
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Table 6.1 Formulations of aqueous c
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Figure 2.12 Schematic illustrations
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Figure 2.35 Schematic of the SHS pr
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Figure 4.9 Sintered nickel lattices
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Figure 6.12 Optical image of the cr
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1.1. Motivation CHAPTER 1 INTRODUCT
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and characterizing rheological prop
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2.1. Materials System CHAPTER 2 BAC
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2.2. Reentrant Structures and Ceram
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devices would provide self-sustaini
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a) b) Figure 2.4 Schematic illustra
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production of concept models, injec
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Fused Deposition Modeling (FDM) was
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Laser Engineered Net Shaping (LENS)
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Inkjet printing (IP) 27 is based on
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Table 2.1 Comparisons of various SF
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Figure 2.11 Processing steps involv
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2.4.1 Colloidal Inks The printing i
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Robocasting has lacked a well-desig
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Table 2.2 Example polymers that dep
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2.6. Sintering In robocasting, sint
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Figure 2.15 Sphere and plate model
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where
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2.5.3 Solid State Sintering In this
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Figure 2.18 Illustration of neck gr
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2.5.3.4 Final Stage During this sta
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Figure 2.23 Schematic diagram of th
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2.5.4.2 Rearrangement With the form
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2.5.4.6 Spreading of Sintering Aid
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Driven by reduction of free energy,
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2.5.5 Sintering Atmosphere Sinterin
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2.7. Composite Materials In this re
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Figure 2.29 Types of composite mate
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Table 2.6 Examples of composite mat
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Table 2.7 Examples of FGM applicati
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2.7.3 Processing For the fabricatio
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prepared discrete layers of uniform
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Powder densification processes gene
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The specific volume fraction beyond
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a) b) Figure 2.34 a) Volume fractio
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When the powders are densified in s
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Various FGM coating processes are a
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of FGMs, such as partially reactive
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leading to a characteristic time τ
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3.1 Introduction CHAPTER 3 AQUEOUS
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occurs in a multi-step process: fir
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a) b) Figure 3.1 a) SEM image of as
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3.2.3 Preparation of Carbon Black C
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3.2.5 Drying Shrinkage Characteriza
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the optimized surfactant concentrat
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The storage modulus of a colloidal
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For HA ink, yield stress
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In the case of the aqueous carbon b
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PPO units of Pluronic F-127 may ads
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a) b) Figure 3.6 A carbon black lat
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a) b) Figure 3.7 SEM images of a) c
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TGA plot is in agreement with previ
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a) b) Figure 3.9 Thermogravimetric
Page 123 and 124: 3.3.8 Fabrication of Complex Cerami
Page 125 and 126: c) d) 109
Page 127 and 128: 3.4 Conclusion A fugitive support m
Page 129 and 130: metal inks have been reported for R
Page 131 and 132: Midland, MI) 5% by weight stock sol
Page 133 and 134: 4.2.5. Thermal Degradation of Binde
Page 135 and 136: 4.3. Results and Discussion 4.3.1.
Page 137 and 138: 4.3.2. Preparation of Nickel Ink Su
Page 139 and 140: 260 °C for 8 hours, the residual c
Page 141 and 142: Table 4.1 Calculated residual carbo
Page 143 and 144: a) b) Figure 4.6 Sintered Ni struct
Page 145 and 146: temperature 138, 139 lead to 92-95%
Page 147 and 148: Figure 4.8 Scanning electron microg
Page 149 and 150: c) Figure 4.9 Sintered nickel latti
Page 151 and 152: 5.1. Introduction CHAPTER 5 BARIUM
Page 153 and 154: materials within the overall struct
Page 155 and 156: 40:60, 60:40, 80:20 are separately
Page 157 and 158: 5.2.3. Rheological Characterization
Page 159 and 160: 5.2.5. Co-sintering and Re-oxidatio
Page 161 and 162: mixing, BT and Ni phases appear uni
Page 163 and 164: The combined use of PAA and PAA-90K
Page 165 and 166: To quantify this difference in sint
Page 167 and 168: As the BT and Ni particles used in
Page 169 and 170: The reducing atmosphere used in the
Page 171 and 172: Figure 5.7 Vickers hardness number
Page 173: 5.3.6. Fabrication of BT-Ni composi
Page 177 and 178: a) b) Figure 5.10 Co-sintered compo
Page 179 and 180: 5.4. Conclusions Freeform fabricati
Page 181 and 182: Liquid phase sintering involves usi
Page 183 and 184: (pH=4.4, 31.5% by weight) (Adva Flo
Page 185 and 186: concentration of 7 mg/mL in the aqu
Page 187 and 188: Table 6.1 Formulations of aqueous c
Page 189 and 190: thickness. Each layer of the struct
Page 191 and 192: 6.2.6. Hardness Test Microindentati
Page 193 and 194: micrographs for these two powders.
Page 195 and 196: Second, the added LiAC∙2H2O is am
Page 197 and 198: Figure 6.3 Oscillatory behavior for
Page 199 and 200: a) b) Figure 6.4 Sintering strain c
Page 201 and 202: mass transport in LFBT network. 167
Page 203 and 204: The above discussion is mainly focu
Page 205 and 206: Figure 6.8 shows the bowtie-shaped
Page 207 and 208: Figure 6.10 A NPR composite of para
Page 209 and 210: etween BT and Ni phases. But Zn ele
Page 211 and 212: Figure 6.13 Scanning electron micro
Page 213 and 214: Figure 6.15 shows the mapping of Ti
Page 215 and 216: Figure 6.17 and Figure 6.18 show el
Page 217 and 218: Figure 6.19 shows element mapping f
Page 219 and 220: 6.3.7. Piezoelectricity and Dielect
Page 221 and 222: 6.4. Conclusions Aqueous colloidal
Page 223 and 224: geometric features, including non-s
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3. Development of aqueous colloidal
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7.2. Recommendations In the context
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gelation behavior. κ-carrageenan i
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REFERENCES 1. Larsson 9301647, 1993
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29. Simchi, A.; Petzoldt, F.; Pohl,
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61. Bouvard, D., Acta Metallurgica
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92. Morissette, S. L.; Lewis, J. A.
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120. Boehm, H. P., Some Aspects of
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150. Atkinson, A., Growth of Nio an
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APPENDICES A. Mathematical Modeling
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and
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conditions: Equation A.12 is solved
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and with
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a) b) Figure B.1 a) Freeze-dried st
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a) Figure C.1 Cr-Ni lattices of 5Cr
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E. Binary Phase Diagram of ZnO-B2O3
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References A.1. Du, Z., Sarofim, A.
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Name: Jian Xu Date of Degree: May,
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