Pressure Distribution and Defect Formation in Green Ceramic Bodies During Supercritical Extraction of Binder

Abstract

Supercritical extraction (SCE) with carbon dioxide at 10–40 MPa and 55°–90°C has been used to remove binder from multilayer green ceramic bodies. Defects such as cracking and delamination were occasionally observed in the green bodies following the extraction process, and these defects were attributed to pressure gradients that arise during isothermal depressurization from conditions of SCE. A model based on flow in porous media was developed to describe the temporal and spatial distribution of pressure within the green body during depressurization. The model incorporates both nonideal pressure–volume–temperature behavior and nonconstant viscosity of the supercritical fluid. The effects of the body size and gas‐phase permeability on the pressure within the green body were examined.