Experimental and numerical analysis of effects of supercritical carbon dioxide debinding on Inconel 718 MIM components

Polymer extraction is a key step of the metal injection moulding (MIM) process. An innovative method for extracting an organic binder involves the use of supercritical fluid instead of a regular solvent. The supercritical fluid selected was carbon dioxide due to its affinity toward polyethylene glycol. The supercritical carbon dioxide parameters were optimised in order to complete the extraction of this polymer from the Inconel 718 superalloy feedstock. The effects on the surface quality of the components and on the microstructure of the densified component were also investigated. A finite element model, which combines the fluid model and structural mechanics, enabled the estimation of the stress distribution during the supercritical debinding step. The study was completed by a parametric analysis of the pressure variation inside the equipment with respect to the processing parameters for the MIM components. (C) 2019 Elsevier B.V. All rights reserved.