ABSTRACT
This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book treats the porosity parameters impacting property dependences, characterizing porosity, and approaches to modeling porosity dependences. The diverse sources, mixes, changes, and ranges of porosity as well as issues for good measurement of porosity and microcrack effects on properties are discussed. Although there is much less information on microcracking and it is much less pervasive, its effects are also addressed because they are also important and have parallels with porosity, in part since such cracks represent one limit of pores. Most evaluation of porosity effects is done without any significant pore characterization, and claims of the validity or lack of it for various expressions are often misleading or simply wrong. Properties that are not dependent on grain size rise to various plateaus as porosity decreases with sintering, and approach limits determined by material and sintering parameters.
