DESIGN, ASSEMBLY AND CHARACTERIZATION OF COMPOSITE ...

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Figure 4.1 Temperature profile for sintering of nickel. The grain size and microstructure of sintered Ni specimens are examined by metallography. The samples are first cross-sectioned using a diamond saw (Labcut 1010, Extec, Enfield, CT) and then polished (Labpol 8-12, Extec, Enfield, CT) with diamond pastes at 3 to 0.25 µm particle size (DiaDuo, Struers, Denmark). A 10% solution of Marble's reagent (4 g CuSO4 + 20 mL HCl + 20 mL H2O) is used for etching. Optical and scanning electron micrographs are collected. 4.2.7. Hardness Test Microindentation Vickers test (0.5 kgf load for 5 seconds) is used to measure sintered Ni hardness. Green nickel specimens are printed using a space-filling pattern of 12×12×4 mm dimension, and molded using 3 mL syringe barrels (EFD, East Providence, RI) as control. After binder removal and sintering under described conditions, these Ni specimens are cross-sectioned, embedded in epoxy resin, and polished by 3-0.5 mm diamond paste. 118
4.3. Results and Discussion 4.3.1. Dispersant Selection and Concentration Determination PEI-25K at a concentration of 2mg/(g Ni powder) yields a lowest apparent ηapp, and is selected for nickel ink preparation. The ηapp of each sample at shear rate γ� = 1 s -1 is shown in Figure 4.2. The lines have no significance beyond a guide to connect the measured data points. PEI-25K and PEI-50K demonstrate similar ηapp dependence on PEI concentration, whereas the PEI-2K has a significantly higher ηapp below concentrations of about 4mg/g. This behavior is likely due to an inability of the small PEI-2K to form a sufficiently thick steric layer to overcome attractive van der Waals forces between particles until more than monolayer coverage is achieved. The minimum of ηapp = 10.3 Pa⋅s at 2mg/g for PEI-25K is taken to be the appropriate concentration. It should be noted, that without any PEI additions, the viscosity of Ni suspensions is too high for practical handling in the Robocasting process. Figure 4.3 shows the morphology and size distribution of the Ni particles used. The 5µm scale bar shows that there are no particles above 2.5µm in this powder and the range of particle size extends well below 1µm. The manufacturer reported average particle size of 0.8µm appears valid. 119
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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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Page 85 and 86: a) b) Figure 2.34 a) Volume fractio
Page 87 and 88: When the powders are densified in s
Page 89 and 90: Various FGM coating processes are a
Page 91 and 92: of FGMs, such as partially reactive
Page 93 and 94: leading to a characteristic time τ
Page 95 and 96: 3.1 Introduction CHAPTER 3 AQUEOUS
Page 97 and 98: occurs in a multi-step process: fir
Page 99 and 100: a) b) Figure 3.1 a) SEM image of as
Page 101 and 102: 3.2.3 Preparation of Carbon Black C
Page 103 and 104: 3.2.5 Drying Shrinkage Characteriza
Page 105 and 106: the optimized surfactant concentrat
Page 107 and 108: The storage modulus of a colloidal
Page 109 and 110: For HA ink, yield stress
Page 111 and 112: In the case of the aqueous carbon b
Page 113 and 114: PPO units of Pluronic F-127 may ads
Page 115 and 116: a) b) Figure 3.6 A carbon black lat
Page 117 and 118: a) b) Figure 3.7 SEM images of a) c
Page 119 and 120: TGA plot is in agreement with previ
Page 121 and 122: a) b) Figure 3.9 Thermogravimetric
Page 123 and 124: 3.3.8 Fabrication of Complex Cerami
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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: 4.2.5. Thermal Degradation of Binde
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 and 174: 5.3.6. Fabrication of BT-Ni composi
Page 175 and 176: modify the sintering kinetics of th
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
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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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