Mixing Behavior and Flowing Property in Micro-Powder Injection Molding of Carbonyl Steel Feedstock

Abstract

A feedstock consisting of carbonyl steel powder and multi-component binder was developed for powder injection molding (PIM), and the mixing behavior of feedstock was investigated under different powder loading, different temperature and different binder systems. The thermal and rheological properties were investigated. The results showed that the torque of feedstock could reach a steady state in s short time of 90 min when the loading powder was 52%. The torque of feedstock at 160°C was lower than that at 150 °C before the heating time was less 90 min. The torque of feedstock could reach steady state level in a short time of 90 min when the content of SA was 10%. SA served as surface-active agent that reduced the mixture viscosity and increased the solids content of the mixture by creating an interfacial bridge between the powder and the binder. The viscosity of feedstock decreased with increasing shear rate and temperature because the agglomerations between particles were eliminated owing to the movement.