Optimization of powder injection molding of feedstock based on aluminum oxide and multicomponent water-soluble polymer binder

Abstract

Analyses crucial to optimize powder injection molding of feedstock based on aluminum oxide powder and multicomponent polymeric binder are provided with the aim to obtain defect-free, high density parts. As the critical step of the process is the flow of highly filled (60 vol %) compound into a mold cavity, rheological properties supplemented by thermal and pressure-volume-temperature characteristics are measured and described. Upon shear deformation the feedstock undergoes structural changes, which are quantified in terms of yield stresses obtained using Herschel-Bulkley and Casson methods. Further, the rheological model is developed to describe the flow behavior of the feedstock in the whole shear rate range measured. Thermogravimetric analysis is performed to optimize debinding step of the process, and two possible ways of the binder removal are proposed: purely thermal and combined solvent/thermal. The quality of the final sintered parts is demonstrated on scanning electron microscopic images of their surfaces. POLYM. ENG. SCI., 51:1376-1382, 2011. (C) 2011 Society of Plastics Engineers