ABSTRACT
Drying and debinding are the major heat treatment steps of the green article prior to sintering. They should be carefully controlled to limit further creation of microstructural flaws and to prevent deformation and cracking. This chapter discusses the stages and mechanisms of drying, capillary-driven liquid flow, stress development during drying of granular coatings and three-dimensional green articles, and methods to avoid deformation and cracking during drying. It explains binder removal from green articles and thermal debinding of green articles in which the void space is nearly or completely filled with organic additives. In general, debinding can be accomplished by several methods, including extraction by capillary flow into a porous surrounding material, solvent extraction, supercritical fluid extraction, and thermal decomposition. An understanding of the physical and chemical processes that occur during thermal debinding is essential for the design of improved binder systems and optimal binder removal schedules. Finally, the chapter describes methods for characterizing the microstructure of the green article.
