Voids in Materials: From Unavoidable Defects to Designed Cellular Materials

Description

All materials have voids in them, at some scale. Sometimes the voids are ignored, sometimes they are taken into account, and other times they are the focal point of the research. Voids in Materials: From Unavoidable Defects to Designed Cellular Materials takes due notice of all these occurrences, whether designed or unavoidable defects. We define, categorize, and characterize the voids (or empty spaces in materials) and we analyze the effects they have on material properties. This second edition is an updated and expanded central reference for voids in materials and covers all types of voids, intrinsic and intentional, and stochastic and nonstochastic, and the processes and conditions that are needed to create them and is a valuable resource to students in the areas of mechanical engineering, chemical engineering, materials science and engineering, physics, and chemistry, as well as scientists, researchers, and engineers in industry. Voids in Materials Copyright Dedication Contents About the authors Preface to the first edition Preface to the second edition 1 Introduction 1.1 Overview 1.2 Descriptions 1.2.1 Intrinsic and intentional voids 1.2.2 Closed and open cell porosity 1.2.3 Unreinforced and reinforced voids 1.2.4 Porosity in natural and synthetic materials 1.2.5 Stochastic, nonstochastic, and Voronoi foams 1.2.6 Material versus digital design of voids 1.3 Voids through the length scale References 2 Intrinsic voids in crystalline materials: Ideal materials and real materials 2.1 Introduction 2.2 Crystalline materials 2.2.1 Ideal materials and properties 2.2.1.1 Density 2.2.2 Defects and real properties 2.2.2.1 Types of point defects 2.2.2.2 Mechanical properties 2.2.2.3 Thermal properties 2.2.3 Density 2.3 Mechanical properties 2.3.1 Modulus 2.3.2 Effect of voids on strength 2.3.3 Griffith theory of brittle fracture 2.4 Processing and service-induced voids 2.4.1 Casting 2.4.2 Powder processing of materials 2.4.3 Voids in solders 2.5 Time-dependent properties 2.5.1 Diffusion of vacancies and voids 2.5.1.1 Fick’s first law of diffusion 2.5.1.2 Fick’s second law of diffusion 2.5.1.3 Vacancy diffusion 2.5.2 Clustering and failure 2.5.3 Kirkendall voids in crystalline materials References 3 Intrinsic voids in polymeric networks 3.1 Polymer structure 3.2 Free volume and thermomechanical behavior 3.3 Kinetic theory of polymer strength 3.4 Thermal conductivity 3.5 Role of voids in physical aging in polymers 3.6 Measurement of free volume References 4 Nanometer scale porous structures 4.1 Introduction 4.2 Nanotubes 4.3 Zeolites 4.4 Nanoporous polymers 4.5 Nanoporous organic networks 4.5.1 Covalent organic frameworks 4.5.2 Covalent triazine frameworks 4.5.3 Polymers of intrinsic microporosity (PIM) 4.5.4 Conjugated microporous polymers 4.6 Nanoporous noble metals References 5 Hollow and porous structures utilizing the Kirkendall effect 5.1 Introduction 5.2 Generalized Kirkendall mechanism for formation of hollow particles 5.2.1 Symmetric hollow particles 5.2.2 Asymmetric hollow particles 5.3 Tubes 5.4 Porous and hollow structures References 6 Techniques for introducing intentional voids into materials 6.1 Introduction 6.2 Commonalities of foam formation processes 6.3 Introduction of a gas 6.3.1 Mixing 6.3.2 Physical blowing agent 6.3.3 Chemical blowing agent 6.4 Templating or sacrificial pore former 6.4.1 Aerogels 6.5 Bonding together of spheres, fibers, powders, or particles 6.6 Additive manufacturing of cellular structures 6.7 Mechanical stretching 6.8 Exploiting chemically selective weakness in solids 6.9 Hierarchical design with voids References Further reading 7 Techniques of introducing intentional voids into particles and fibers 7.1 Introduction 7.2 Hollow and porous particles 7.2.1 Introduction 7.2.2 Processing of porous particles 7.2.3 Hollow particles 7.2.4 Hollow, porous particles 7.2.5 Porous and hollow macrometer scale particles 7.2.5.1 Hollow macrospheres 7.2.5.2 Porous macrospheres 7.3 Hollow and porous fibers 7.3.1 Carbon nanotubes 7.4 Nonspherical hollow particles References 8 Void characterization techniques 8.1 Introduction 8.2 Microscopy 8.2.1 Optical microscopy 8.2.2 Electron microscopy 8.2.2.1 Scanning electron microscopy (SEM) 8.2.2.2 Transmission electron microscopy (TEM) 8.3 Positron annihilation lifetime spectroscopy (PALS) 8.4 Three-dimensional imaging 8.5 Gas adsorption 8.6 Chromatographic porosimetry 8.6.1 Introduction 8.6.2 Inverse gas chromatography (IGC) 8.6.3 Inverse size exclusion chromatography References 9 Characteristics and properties of porous materials 9.1 Introduction 9.2 General characterization 9.2.1 Cell size 9.2.2 Open versus closed cell 9.2.3 Reinforced versus unreinforced voids 9.2.4 Density 9.2.5 Relative density 9.2.6 Energy absorption 9.2.7 Cell size distribution and regularity 9.3 Conventional foams 9.3.1 Stress–strain behavior in compression 9.3.2 Elastic constants 9.3.3 Dielectric constant 9.4 Syntactic foams 9.4.1 Growth and performance 9.4.2 Compressive stress–strain relationship 9.5 Thermal properties 9.6 Finite element analysis (FEA) 9.7 Geopolymer foams 9.8 Metallic foams References 10 Applications 10.1 Introduction 10.2 Syntactic foams 10.2.1 Deep-sea buoyancy 10.2.2 Hollow composite macrospheres and composite syntactic foams 10.2.3 Deep-sea thermal insulation 10.2.4 Syntactic foams and explosive formulations 10.2.5 Other application 10.3 Aerospace 10.3.1 Carbon nanotubes (CNT) 10.3.2 Honeycombs 10.3.3 Thermal protection systems and heat shields 10.3.4 Silica aerogel for a comet dust collector 10.3.5 Thermal barrier coatings (TBCs) 10.4 Energy 10.4.1 Lithium-ion battery 10.4.2 Electrochemical energy storage with porous metals 10.4.3 Guest–host complexes 10.4.4 Solar power 10.5 Titania and photocatalysis 10.6 Biomaterials and healthcare 10.6.1 Introduction 10.6.2 Biomaterials scaffold 10.6.3 Nerve regeneration 10.6.4 Drug delivery 10.7 Menger sponges References Glossary Author Index Subject Index