Debindering from Alumina Green Body by Combined Use of the Supercritical Fluid Extraction Technique and Activated Carbon

Abstract

Experiments in the extraction of low-molecular weight binder components from alumina green bodies were carried out, using supercritical CO₂. Activated carbon was placed together with the alumina green bodies in an extraction cell. High debindering rates were obtained without flowing supercritical CO₂ through the cell since binder concentrations in the supercritical fluid phase were maintained at small values due to the adsorption of extracted binders on the activated carbon. When the green bodies and the activated carbon were placed at adequate positions in the cell, natural convection of supercritical CO₂ promoted the reduction of binder concentration in the supercritical fluid phase. Effective diffusion coefficients of the binder components in the green body were obtained by the correlation of experimentally obtained extraction yields using Fick's diffusion equation.