Approximately four million years of human history has passed. We have been using materials to make a variety of tools. The first materials used were naturally occurring materials such as animal bones, stones, wood etc.; and some of these familiar materials are porous. Porous materials are so familiar that they are sometimes forgotten or ignored. The taste experience of ice cream is created not only by adjusting ingre­ dients, but also by including air as an ingredient, i.e. pores that give the smooth texture of ice cream. This book is designed to describe and explain about pores, the synthesis of materials with pores (porous materials), and applications of porous materi­ als. This book is intended for engineers and scientists of different disciplines and specialities, and is expected to be useful in the design and synthesis of porous materials for existing as well as potential new applications. Let us rediscover pores. K. Ishizaki, S. Komameni and M. Nanko January 1998 1 Introduction 1.1 WHAT ARE POROUS MATERIALS? Porous materials are dermed as solids containing pores. Figure 1.1 shows different porous materials. Generally speaking, porous materials have a porosity of 0.2-0.95. The porosity means the fraction of pore volume to the total volume. Porous materials have been used in various applications from daily necessities, such as purifying drinking water by activated carbon or porous ceramics, to uses in modern industries, for example removing dusts from high purity process gases for semiconductor production.

Inhalt

Preface. 1: Introduction. 1.1. What are porous materials? 1.2. Classification of porous materials. 2: Powder compacts and green bodies for porous materials. 2.1 .Sintering as a process for producing porous materials. 2.2. The raw powder. 2.3. Green bodies. 2.4. Pore forming agents. 3: Sintering mechanisms and advanced sintering methods for porous materials. 3.1. Theory of sintering for porous materials. 3.2. Conventional sintering processes for producing porous materials. 3.3. Advanced production methods for porous materials. 4: Sol-gel processing, designing porosity, pore size and polarity, and shaping processes. 4.1. Introduction. 4.2. Factors affecting porosity, pore size and plarity. 4.3. Xerogels. 4.4. Aerogels. 5: Applications of porous materials. 5.1. Filters. 5.2. Catalysts. 5.3. Bioreactors. 5.4. Cells. 5.5. Grinding wheels. 5.6. Gas sensors. 5.7. Gas separators. 5.8. Electrodes. 5.9. Porous metal bearings. 5.10. Thermal insulators. 5.11. Capacitors. 5.12. Impact energy absorbers. 5.13. Heaters and heat exchangers. 5.14. Molds. 5.15. Surgical implants. 6: Properties and evaluation techniques for porous materials. 6.1. Density and porosity. 6.2. Pore size. 6.3. Specific surface area. 6.4. Fluid permeability. 6.5. Mechanical properties. 6.6. Entropy (surface state of porous materials). Appendix A: Entropy of porous materials. A.1. Properties of entropy. A.2. Absolute temperature. A.3. Potential energy. A.4. Basic thermodynamics. A.5. Entropy. A.6. More on potential theory and thermodynamics. A.7. Proof of nonpotentiality of the gradient of energy functions. A.8. Conclusions. Index.