14 - Green Body Drying

Abstract

This chapter discusses the kinetics of drying for various conditions of temperature and solvent partial pressure in the atmosphere. The drying of ceramic green bodies has been examined in terms of its kinetics. Simultaneous mass and heat transfer equations must be solved to give a complete kinetic picture of the drying process. An analysis of the possible rate determining steps is presented, which allows the estimation of the drying time for ceramic green bodies of idealized shapes. Simultaneous heat and mass transfer in both the boundary layer surrounding the green body and the pores inside the green body are responsible for the drying kinetics. Depending on the kinetics of drying, different stresses are developed in the green body. Critical drying conditions that cause cracking in the green body are elucidated, taking into consideration the strength of the green body at various stages in the drying process. This chapter also discusses the linked differential equations for mass and heat transfer that describe the drying of a spherical green body.