DESIGN, ASSEMBLY AND CHARACTERIZATION OF COMPOSITE ...

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2.8. Functionally Graded Materials 2.7.1 Definition Functionally graded materials (FGMs) refer to the category of engineered materials characterized by the gradual transition in composition, microstructure, and material properties. 44 Motivated by the functional performance requirements that vary with locations, the FGMs may be designed for specific functions in a manner that 44, 45 optimizes the overall performances. 2.7.2 Applications Kawasaki and Watanabe first proposed the concept of FGM in 1984 using compositionally graded ceramic-metal interlayer in a thermal barrier for aerospace application. 46 Such a FGM thermal barrier possesses superior heat resistance and sufficient toughness to stop crack propagation while effectively eliminating thermal stress concentration. Since then, a variety of processing techniques have been developed for fabrication of FGM materials. Examples of successful applications of the FGM concept are shown in Table 2.7. 58
Table 2.7 Examples of FGM applications. 45 Application Materials Processing Techniques Thermal barrier; anti-oxidation coatings Cutting tools: cemented carbides/diamond/SiC ZrO2 on Ni-Cr; SiC on C/C composite TiC-TiCN-WC-Co; diamond and SiC 59 Plasma spraying; CVD Sintering Thermaoelectric materials BiTe/PbTe/SiGe SHS*/Dynamic Pseudo Isostatic Compaction Optical film: bandpass filter SiO2-TiO Helicon sputtering * SHS stands for self-propagating high-temperature synthesis Figure 2.30 illustrates an example of Ti/hydroxyapatite FGM 47 for use as a biocompatible dental implant: the FGM implant in Figure 2.30a has its composition gradually changing from 100% Ti metal at the left end to 100% HA at the right end. The left end, as the upper part of dental implant where occlusal force is directly applied, is designed to achieve high mechanical strength; and the right end is to be implanted inside the jaw bone and requires high biocompatibility. Presumably Ti has higher mechanical strength, but inferior biocompatibility than hydroxyapatite. The use of FGM allows for combination of necessary mechanical properties and biocompatibility at different locations of the implant without formation of a discrete boundary. Figure 2.30b shows the illustration for the gradual transition in related properties of the FGM implant, and Figure 2.30c illustrates a conventional full ceramic implant for which properties such as strength and biocompatibility are constant throughout.
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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
Page 23 and 24: 2.2. Reentrant Structures and Ceram
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
Page 73: Table 2.6 Examples of composite mat
Page 77 and 78: 2.7.3 Processing For the fabricatio
Page 79 and 80: prepared discrete layers of uniform
Page 81 and 82: Powder densification processes gene
Page 83 and 84: The specific volume fraction beyond
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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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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