Ultra-High Temperature Ceramics: Materials for ExtremeEnvironment Applications -- Copyright -- Contents -- Acknowledgments -- Contributors List -- Chapter 1 Introduction -- 1.1 Background -- 1.2 Ultra-High Temperature Ceramics -- 1.3 Description of Contents -- References -- Chapter 2 A Historical Perspective on Research Related to Ultra-High Temperature Ceramics -- 2.1 Ultra-High Temperature Ceramics -- 2.2 Historic Research -- 2.3 Initial NASA Studies -- 2.4 Research Funded by the Air Force Materials Laboratory -- 2.4.1 Thermodynamic Analysis and Oxidation Behavior -- 2.4.2 Processing, Properties, Oxidation, and Testing -- 2.4.3 Phase Equilibria -- 2.5 Summary -- Acknowledgments -- References -- Chapter 3 Reactive Processes for Diboride-Based Ultra-High Temperature Ceramics -- 3.1 Introduction -- 3.2 Reactive Processes for the Synthesis of Diboride Powders -- 3.2.1 Elemental Reactions -- 3.2.2 Reduction Processes -- 3.2.3 Synthesis of Composite Powders -- 3.3 Reactive Processes for Oxygen Removing during Sintering -- 3.3.1 Oxygen Removal by Reduction Using Boron/ Carbon-Containing Compounds -- 3.3.2 Oxygen Removing by Transition Metal Carbides -- 3.4 Reactive Sintering Processes -- 3.4.1 Reactive Sintering from Transition Metals and Boron-Containing Compounds -- 3.4.2 Reactive Sintering from Transition Metals and Boron -- 3.5 Summary -- References -- Chapter 4 First-Principles Investigation on the Chemical Bonding and Intrinsic Elastic Properties of Transition Metal Diborides TMB2 (TM=Zr, Hf, Nb, Ta, and Y) -- 4.1 Introduction -- 4.2 Calculation Methods -- 4.3 Results and Discussion -- 4.3.1 Lattice Constants and Bond Lengths -- 4.3.2 Electronic Structure and Bonding Properties -- 4.3.3 Elastic Properties -- 4.4 Conclusion Remarks -- Acknowledgment -- References -- Chapter 5 Near-Net-Shaping of Ultra-High Temperature Ceramics -- 5.1 Introduction.

5.2 Understanding Colloidal Systems: Interparticle Forces -- 5.3 Near-Net-Shape Colloidal Processing Techniques -- 5.3.1 Successful Processing of UHTCs Using Colloidal Routes -- 5.3.2 Case Study: Colloidal Processing and Pressureless Sintering of UHTCs -- 5.4 Summary, Recommendations, and Path Forward -- Acknowledgments -- References -- Chapter 6 Sintering and Densification Mechanisms of Ultra-High Temperature Ceramics -- 6.1 Introduction -- 6.2 MB2 with Metals -- 6.3 MB2 with Nitrides -- 6.4 MB2 with Metal Disilicides -- 6.5 MB2 with Carbon or Carbides -- 6.6 MB2 with SiC -- 6.7 MB2-SiC Composites with Third Phases -- 6.8 Effects of Sintering Aids on High-Temperature Stability -- 6.9 Transition Metal Carbides -- 6.10 Conclusions -- Acknowledgments -- References -- Chapter 7 UHTC Composites for Hypersonic Applications -- 7.1 Introduction -- 7.2 Preparation of Continuous-Fiber-Reinforced UHTC Composites -- 7.2.1 Precursor Infiltration and Pyrolysis -- 7.2.2 Chemical Vapor Deposition -- 7.2.3 Reactive Melt Infiltration -- 7.2.4 Slurry Infiltration and Pyrolysis -- 7.2.5 Combined Processes -- 7.2.6 Functionally Graded UHTC Composites -- 7.3 UHTC Coatings -- 7.4 Short-Fiber-Reinforced UHTC Composites -- 7.5 Hybrid UHTC Composites -- 7.6 Summary and Future Prospects -- References -- Chapter 8 Mechanical Properties of Zirconium-Diboride Based UHTCs -- 8.1 Introduction -- 8.2 Room Temperature Mechanical Properties -- 8.2.1 ZrB2 -- 8.2.2 ZrB2 with SiC Additions -- 8.2.3 ZrB2 with Disilicide Additions -- 8.2.4 ZrB2-MeSi2-SiC -- 8.3 Elevated-Temperature Mechanical Properties -- 8.3.1 Elastic Modulus of ZrB2-Based Ceramics -- 8.3.2 Strength and Fracture Toughness -- 8.4 Concluding Remarks -- References -- Chapter 9 Thermal Conductivity of ZrB2 and HfB2 -- 9.1 Introduction -- 9.2 Conductivity of ZrB2 and HfB2 -- 9.2.1 Pure ZrB2.

9.2.2 ZrB2 with Solid Solution Additions -- 9.2.3 Pure HfB2 -- 9.2.4 Conclusions Regarding Phase-Pure ZrB2 and HfB2 -- 9.3 ZrB2 and HfB2 Composites -- 9.3.1 Thermal Conductivity of ZrB2 Composites -- 9.3.2 Thermal Conductivity of HfB2 Composites -- 9.3.3 Conclusions Regarding Composites -- 9.4 Electron and Phonon Contributions to Thermal Conductivity -- 9.4.1 ZrB2 and HfB2 -- 9.4.2 ZrB2 and HfB2 Composites with SiC -- 9.4.3 Conclusions Regarding ke and kp Research -- 9.5 Concluding Remarks -- References -- Chapter 10 Deformation and Hardness of UHTCs as a Function of Temperature -- 10.1 Introduction -- 10.2 Elastic Properties -- 10.3 Hardness -- 10.4 Hardness and Yield Strength -- 10.5 Deformation Mechanism Maps -- 10.6 Lattice Resistance to Dislocation Glide -- 10.7 Dislocation Glide Controlled by Other Obstacles -- 10.8 Deformation by Creep -- 10.9 Deformation of Carbides versus Borides -- 10.10 Conclusions -- References -- Chapter 11 Modeling and Evaluating the Environmental Degradation of UHTCs under Hypersonic Flow -- 11.1 Introduction -- 11.2 Oxidation Modeling -- 11.3 UHTC Behavior under Simulated Hypersonic Conditions -- 11.4 Comparing Model Predictions to Leading-Edge Behavior -- 11.5 Behavior of UHTCs under Other Test Methods -- 11.5.1 Arcjet Test -- 11.5.2 Laser Test -- 11.5.3 Oxyacetylene Torch Test -- 11.6 Summary -- References -- Chapter 12 Tantalum Carbides: Their Microstructures and Deformation Behavior -- 12.1 Crystallography of Tantalum Carbides -- 12.2 Microstructures of Tantalum Carbides -- 12.3 Mechanical Properties of Tantalum Carbides -- 12.3.1 Elastic Properties -- 12.3.2 Plastic Properties of TaC -- 12.3.3 Ductile-to-Brittle Transition -- 12.3.4 Creep -- 12.3.5 Hardness of Tantalum Carbides -- 12.3.6 Strength -- 12.3.7 Fracture Toughness -- 12.3.8 Plasticity of Ta2C -- 12.4 Summary -- Acknowledgments -- References.

Chapter 13 Titanium Diboride -- 13.1 Introduction -- 13.2 Phase Diagram, Crystal Structure, and Bonding -- 13.3 Synthesis of Titanium Diboride Powders -- 13.4 Densification of Transition Metal Borides -- 13.4.1 Pressureless Sintering -- 13.4.2 Hot Pressing -- 13.4.3 Reactive Processing -- 13.4.4 Spark Plasma Sintering -- 13.5 Mechanical Properties at Ambient and Elevated Temperatures -- 13.5.1 Hardness -- 13.5.2 Elastic Modulus -- 13.5.3 Fracture Strength -- 13.5.4 TSR -- 13.6 Physical Properties and Oxidation Resistance -- 13.6.1 CTE and Thermal Conductivity -- 13.6.2 Effects of Physical Properties on TSR -- 13.7 Oxidation Resistance -- 13.8 Tribological Properties -- 13.8.1 Wear Properties of Bulk TiB2-Based Ceramics -- 13.8.2 Tribological Properties of TiB2 Coatings -- 13.9 Applications of TiB2 -- 13.10 Conclusions -- References -- Chapter 14 The Group IV Carbides and Nitrides -- 14.1 Background -- 14.2 Group IV Carbides -- 14.3 Preparation and Processing -- 14.4 Mechanical and Physical Properties -- 14.5 Oxidation of the UHTC Carbides and Nitrides -- 14.6 Oxidation of the UHTC Carbides -- 14.7 UHTC Nitrides -- 14.8 Preparation, Diffusion, and Phase Formation -- 14.9 Mechanical and Physical Properties -- 14.10 Oxidation of Nitrides -- 14.11 Conclusions and Future Research -- Acknowledgments -- References -- Chapter 15 Nuclear Applications for Ultra-High Temperature Ceramics and MAX Phases -- 15.1 Future Nuclear Reactors -- 15.2 Current Nuclear Ceramics -- 15.3 Future Nuclear Ceramics -- 15.4 Non-Oxide Nuclear Fuels -- 15.4.1 Composite Fuels -- 15.4.2 Inert Matrix Fuels -- 15.4.3 Other Fuel Cladding Applications -- 15.5 Other Possible Future Fission and Fusion Applications -- 15.6 Thermodynamics of Nuclear Systems -- 15.7 Conclusions -- References -- Chapter 16 UHTC-Based Hot Structures: Characterization, Design, and On-Ground/In-Flight Testing.

16.1 Introduction -- 16.2 TPS: Test Articles and Prototypes -- 16.3 Plasma Tests of Nose Test Articles -- 16.4 Expert Project: Computational Fluid Dynamics Computations and Plasma Tests -- 16.5 In-Fling Testing of the Capsule "SHARK" -- 16.6 Future Work -- References -- Index -- End User License Agreement.