DESIGN, ASSEMBLY AND CHARACTERIZATION OF COMPOSITE ...

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Figure 2.1 Schematic illustration of the BT unit cell (shown with tetragonal symmetry) demonstrating the offset B-site cation. Ni is a ferromagnetic metal under normal temperatures and pressures, and is relatively corrosion resistant both in bulk and in particle form, due to the formation of a protective oxide surface. At high temperatures, Ni alloys may exhibit excellent mechanical strength, creep resistance, and corrosion resistance through a similarly passivated oxide surface. Primarily used as an alloy metal, Ni finds various uses in various applications such as alloys, steels, magnets, catalysts, biomedical implants, batteries, and fuel cells. In the electronics industry, Ni is used as a base metal electrode (BME) material to replace precious metals such as Au/Pd and Pt in MLCCs. 6 Ba 2+ (A-site) O 2− Ti 4+ (B-site)
2.2. Reentrant Structures and Ceramic-Metal Composites The primary funding for this dissertation work is in support of a collaborative effort with Dr. Lisa Friis' group in the Mechanical Engineering Department at the University of Kansas. The broad objective of the project is to create a biomedical scaffold with properties that mimic natural bone. That is, the scaffold should have porosity on the order of 50%, should be a non-linear elastic material and should display slight piezoelectric behavior. The following describes the biomedical significance in greater detail. Non-linear elastic behavior is displayed by negative Poisson's ratio (NPR) structures while piezoelectricity can provide a self-sustaining electrical signal. Combined, these are hypothesized to mimic biologic bone to promote cell development through a combination of mechanical stress, electrical, and ionic fluid flow environments. Poisson's ratio ν, as illustrated in Figure 2.2, is the ratio of transverse strain to the axial strain, when an object is stretched or compressed. Most materials have a positive Poisson's ratio, i.e. expanding in transverse direction when compressed in axial direction. A NPR indicates the reverse trend, i.e., a negative transverse strain along with a negative axial strain. Few materials in nature exhibit NPR behavior and natural cork is a good example of a zero Poisson’s ratio material. Usually NPR behavior is induced in a material as a result of structural modification. The term "reentrant" refers to one type of cellular NPR structure, where struts defining the unit cell of the structure point inward. The reentrant structure has many unique mechanical properties, including nonlinear load-deformation response and good vibration damping. 7
Page 1 and 2: DESIGN, ASSEMBLY AND CHARACTERIZATI
Page 3 and 4: ACKNOWLEDGEMENTS First and foremost
Page 5 and 6: CHAPTER 5 BARIUM TITANATE NICKEL CO
Page 7 and 8: Table 6.1 Formulations of aqueous c
Page 9 and 10: Figure 2.12 Schematic illustrations
Page 11 and 12: Figure 2.35 Schematic of the SHS pr
Page 13 and 14: Figure 4.9 Sintered nickel lattices
Page 15 and 16: Figure 6.12 Optical image of the cr
Page 17 and 18: 1.1. Motivation CHAPTER 1 INTRODUCT
Page 19 and 20: and characterizing rheological prop
Page 21: 2.1. Materials System CHAPTER 2 BAC
Page 25 and 26: devices would provide self-sustaini
Page 27 and 28: a) b) Figure 2.4 Schematic illustra
Page 29 and 30: production of concept models, injec
Page 31 and 32: Fused Deposition Modeling (FDM) was
Page 33 and 34: Laser Engineered Net Shaping (LENS)
Page 35 and 36: Inkjet printing (IP) 27 is based on
Page 37 and 38: Table 2.1 Comparisons of various SF
Page 39 and 40: Figure 2.11 Processing steps involv
Page 41 and 42: 2.4.1 Colloidal Inks The printing i
Page 43 and 44: Robocasting has lacked a well-desig
Page 45 and 46: Table 2.2 Example polymers that dep
Page 47 and 48: 2.6. Sintering In robocasting, sint
Page 49 and 50: Figure 2.15 Sphere and plate model
Page 51 and 52: where
Page 53 and 54: 2.5.3 Solid State Sintering In this
Page 55 and 56: Figure 2.18 Illustration of neck gr
Page 57 and 58: 2.5.3.4 Final Stage During this sta
Page 59 and 60: Figure 2.23 Schematic diagram of th
Page 61 and 62: 2.5.4.2 Rearrangement With the form
Page 63 and 64: 2.5.4.6 Spreading of Sintering Aid
Page 65 and 66: Driven by reduction of free energy,
Page 67 and 68: 2.5.5 Sintering Atmosphere Sinterin
Page 69 and 70: 2.7. Composite Materials In this re
Page 71 and 72: 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
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3.3.8 Fabrication of Complex Cerami
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c) d) 109
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3.4 Conclusion A fugitive support m
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metal inks have been reported for R
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Midland, MI) 5% by weight stock sol
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4.2.5. Thermal Degradation of Binde
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4.3. Results and Discussion 4.3.1.
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4.3.2. Preparation of Nickel Ink Su
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260 °C for 8 hours, the residual c
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Table 4.1 Calculated residual carbo
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a) b) Figure 4.6 Sintered Ni struct
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temperature 138, 139 lead to 92-95%
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Figure 4.8 Scanning electron microg
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c) Figure 4.9 Sintered nickel latti
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5.1. Introduction CHAPTER 5 BARIUM
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materials within the overall struct
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40:60, 60:40, 80:20 are separately
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5.2.3. Rheological Characterization
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5.2.5. Co-sintering and Re-oxidatio
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mixing, BT and Ni phases appear uni
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The combined use of PAA and PAA-90K
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To quantify this difference in sint
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As the BT and Ni particles used in
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The reducing atmosphere used in the
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Figure 5.7 Vickers hardness number
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5.3.6. Fabrication of BT-Ni composi
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modify the sintering kinetics of th
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a) b) Figure 5.10 Co-sintered compo
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5.4. Conclusions Freeform fabricati
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Liquid phase sintering involves usi
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(pH=4.4, 31.5% by weight) (Adva Flo
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concentration of 7 mg/mL in the aqu
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Table 6.1 Formulations of aqueous c
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thickness. Each layer of the struct
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6.2.6. Hardness Test Microindentati
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micrographs for these two powders.
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Second, the added LiAC∙2H2O is am
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Figure 6.3 Oscillatory behavior for
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a) b) Figure 6.4 Sintering strain c
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mass transport in LFBT network. 167
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The above discussion is mainly focu
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Figure 6.8 shows the bowtie-shaped
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Figure 6.10 A NPR composite of para
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etween BT and Ni phases. But Zn ele
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Figure 6.13 Scanning electron micro
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Figure 6.15 shows the mapping of Ti
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Figure 6.17 and Figure 6.18 show el
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Figure 6.19 shows element mapping f
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6.3.7. Piezoelectricity and Dielect
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6.4. Conclusions Aqueous colloidal
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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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