Powder Injection Molding of Translucent Alumina using Supercritical Fluid Debinding

Abstract

································································································································································································································Abstract The powder injection molding process having advantages in manufacturing three-dimensional precision parts essentially requires a debinding process before sintering to remove the binders used for preparing feedstock. In this study, powder injection molding of translucent alumina was performed, and carbon dioxide (CO 2 ) is used as a supercritical fluid that makes it possible to remove a large amount of binder, which is paraffin wax. The relationship between the optical property of translucent alumina and the debinding condition (temperature and pressure) of supercritical CO 2 was investigated. As temperature and pressure increased, extraction rate of the binder showed rising tendency and average grain size after sintering process was relatively fine. On the other hand, optical transmittance was reduced. As a result, the debinding condition at 50 o C and 20 MPa that represents the lowest extraction rate, 8.19 × 10 −3 m 2 /sec, corresponds to the largest grain size of 14.7 µm and the highest optical transmittance of 45.2%.

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

“…The evolution of PEG removal as a function of the temperature slightly increased from 323.15 K until 373.15 K. It was only until the temperature of 423.15 K was reached that most of PEG was removed from the component, confirming the conclusions observed by Chartier et al that extraction is easier near to the melting temperature of the binder, which needs to be reached in order to obtain the best debinding rate. Similar results were also obtained with paraffin wax [24,26].…”

“…In the MIM research field, only a few studies have explored the application of supercritical fluid extraction. The main research was performed by Chartier et al [24,25], Kim et al [26], and Shimizu et al [27] on ceramic/wax feedstocks. They obtained excellent extraction rates without damaging the components.…”