Investigation of Feedstock Preparation for Injection Molding of Oxide–Oxide Ceramic Composites

Abstract

In this fundamental work, a series of experiments were performed to define the optimal amount of dispersant and solid content for feedstock with and without ceramic fibers (Nextel 610). Based on these fixed conditions, investigations were carried out to discover the effects of binder system, fiber sizing, and increasing fiber content on mixing and viscosity. In addition, the effects of kneading temperature and time, fiber sizing, and different binder systems on fiber length were investigated using a measuring mixer, high-pressure capillary rheometer, and microscopy. Stearic acid, as a dispersant, modified the particle surface and improved the rheological properties. Moreover, increasing the solid content in the feedstocks led to an exponential growth of final torque and relative viscosity, because of the increasing friction between particles. Paraffin wax (PW)- and polyethylene glycol (PEG)-based feedstocks showed different mixing behaviors and rheological results with increasing fiber, whereas PEG-based feedstocks had higher final torques and kneading energies without fibers, whilst PEG feedstocks displayed lower viscosities. Consequently, during kneading, the amount of fiber has been predominating over fiber length, and the effect of the binder, the kneading temperature, and time did not cause significant changes.