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Open AccessFeature PaperArticle

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

Femto-ST Institute, 24 rue de l’épitaphe, 25000 Besançon, France
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Appl. Sci. 2017, 7(10), 1024; https://doi.org/10.3390/app7101024
Received: 13 July 2017 / Revised: 22 September 2017 / Accepted: 29 September 2017 / Published: 6 October 2017
(This article belongs to the Special Issue Powder Injection Moulding)
A debinding step using the supercritical state of a fluid has been increasingly investigated for extracting organic binders from components obtained by metal-injection molding. It consists of placing the component in an enclosure subjected to pressure and temperatures higher than the critical point to perform polymer extraction of the Metal-injection molding (MIM) component. It is an alternative to conventional solvent debinding. The topic of this study is to model and simulate the supercritical debinding stage to elucidate the mechanism of polymer degradation and stabilization with a three-dimensional model. Modelling this extraction process would optimize the process on an industrial scale. It can be physically described by Fick’s law of diffusion. The model’s main parameter is the diffusion coefficient, which is identified by using linear regression based on the least-squares method. In the model, an effective length scale is specially developed to take into account the diffusion in all directions. The tests were performed for extracting polyethylene glycol, an organic additive, using supercritical CO2 in injected components. The feedstock is composed of polypropylene, polyethylene glycol, and stearic-acid as binder mixed with Inconel 718 super-alloy powders. The identified parameters were used to calculate the diffusion coefficient and simulate the supercritical debinding step on the Comsol Multiphysics® finite-element software platform to predict the remaining binder. The obtained numerical simulation results are in good agreement with the experimental data. The proposed numerical simulations allow for the determination of the remaining polyethylene glycol (PEG) binder distribution with respect to processing parameters for components during the supercritical debinding process at any time. Moreover, this approach can be used in other formulation, powder, and binder systems. View Full-Text
Keywords: metal-injection molding; debinding; simulation; supercritical metal-injection molding; debinding; simulation; supercritical
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Agne, A.; Barrière, T. Modelling and numerical simulation of Supercritical CO2 debinding of Inconel 718 components elaborated by Metal Injection Molding. Appl. Sci. 2017, 7, 1024.

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