Powder Injection Molding of Translucent Alumina using Supercritical Fluid Debinding

The powder injection molding process having advantages in manufacturing three-dimensional precision partsessentially requires a debinding process before sintering to remove the binders used for preparing feedstock. In thisstudy, powder injection molding of translucent alumina was performed, and carbon dioxide (CO2) is used as a supercriticalfluid that makes it possible to remove a large amount of binder, which is paraffin wax. The relationship betweenthe optical property of translucent alumina and the debinding condition (temperature and pressure) of supercritical CO2was investigated. As temperature and pressure increased, extraction rate of the binder showed rising tendency and averagegrain size after sintering process was relatively fine. On the other hand, optical transmittance was reduced. As aresult, the debinding condition at 50oC and 20 MPa that represents the lowest extraction rate, 8.19 × 103 m2/sec, correspondsto the largest grain size of 14.7 μm and the highest optical transmittance of 45.2%