ABSTRACT
This chapter considers several topics that form the basis for understanding the sintering process. The theoretical analyses and experimental studies performed an excellent qualitative understanding of sintering in terms of the driving forces, the mechanisms, and the influence of the principal processing variables such as particle size, temperature, and applied pressure. As with all other irreversible processes, sintering is accompanied by a lowering of the free energy of the system. The sources that give rise to this lowering of the free energy are commonly referred to as the driving forces for sintering. Three possible driving forces are the curvature of the particle surfaces, an externally applied pressure, and a chemical reaction. Solid-state diffusion can occur by several paths that define the mechanisms of diffusion and the mechanisms of sintering. The rate of diffusion depends on the type and concentration of defects in the solid, so an understanding of the defect structure and the changes in the defect concentration is important.
