Development and Characterization of a Metal Injection Molding Bio Sourced Inconel 718 Feedstock Based on Polyhydroxyalkanoates

Abstract

Abstract:The binder plays the most important role in the metal injection molding (MIM) process. It provides fluidity of the feedstock mixture and adhesion of the powder to keep the molded shape during injection molding. The binder must provide strength and cohesion for the molded part and must be easy to remove from the molded part. Moreover, it must be recyclable, environmentally friendly and economical. Also, the miscibility between polymers affects the homogeneity of the injected parts. The goal of this study is to develop a feedstock of superalloy Inconel 718 that is environmentally friendly. For these different binders, formulations based on polyethylene glycol (PEG), because of his water solubility property, and bio sourced polymers were studied. Polyhydroxyalkanoates (PHA) were investigated as a bio sourced polymer due to its miscibility with the PEG. The result is compared to a standard formulation using polypropylene (PP). The chemical and rheological behavior of the binder formulation during mixing, injection and debinding process were investigated. The feedstock was characterized in the same way as the binders and the interactions between the powder and the binders were also studied. The results show the well adapted formulation of polymer binder to produce a superalloy Inconel 718 feedstock.

Fabrication of Micro-Parts with High-Aspect Ratio Micro-Hole Array by Micro-Powder Injection Molding

“…In the formula, assuming the particles are spherical, S b , D b , S s and D s are the specific surface area, diameter of large particles, the specific surface area and diameter of the small particles, respectively. The critical powder loading is about 60 vol% for ceramic powders with a particle size of less than 1 m [ 44 ]. When the critical powder load is used to mix the feedstock, the viscosity of the feedstock is high due to the high powder content.…”

Modelling and numerical simulation of Supercritical CO2 debinding of Inconel 718 components elaborated by Metal Injection Molding

“…The components' multi-component binder is usually composed of three different ingredients (surfactant, rheofluidifiant, the rigidifying, etc.) [6]. This study used the binder formulation previously investigated by Royer et al [6].…”

“…[6]. This study used the binder formulation previously investigated by Royer et al [6]. The multi-component binder volume is composed of 16% polypropylene (PP) provided by Sabic (Paris, France), 22% polyethylene glycol (PEG), and 2% stearic acid (SA) purchased from EMD Millipore Corporation (Billerica, MA, USA).…”

“…When it reaches the pressure needed for a supercritical state (up to the critical point, see Figure 2b), the carbon dioxide is heated by a heat exchanger (5). At the supercritical state, the CO2 is directed towards the autoclave (6), which contains the components (7). Then, thermocouples are used to control the temperature (8).…”

“…The parameter identification of Fick's model will be carried out with this experimental database. Royer et al [6] identified the optimal supercritical debinding kinetics as 40 MPa and 423.15 K to remove 100% of the PEG, with a molar weight of 20,000 g/mol, from the injected components in four hours. Knez et al [33] reported that the density of the PEG/CO 2 binary solution increased with an increasing pressure, and the molecular weight of the polymer had a slight effect on the density of the binary system.…”