Comparative Study of Partially Water-Soluble Metal Injection Moulding Feedstock Based on Inconel 718: The Effect of Polyethylene Glycol Molecular Weight on Rheology and Debinding

摘要

Polyethylene glycol (PEG) is a common component of partially water-soluble bindersystems used for metal injection moulding (MIM) feedstocks. After injection moulding, PEG isremoved from the components by immersion in water. In this work, the processability of MIMfeedstocks based on 59 vol. % of Inconel 718 powder in a binder system containing PEGs withmolecular weight (M_w) varying in the range of 1,500 – 20,000, poly (methyl methacrylate) and stearicacid was investigated. The results of the rheological analysis showed that viscosity of feedstocks withlow M_w of PEG was more sensitive to temperature at higher shear rates, while at lower shear rates theopposite trend was found. Based on overall flow and debinding behaviour, the feedstock containingPEG with M_w of 8 000 was selected as the most suitable for the processing of Inconel 718 via MIM.