Rheology and Applications of Particulate Composites in Additive Manufacturing

To provide different functionalities such as electrical conductivity or magnetic permeability, particulate composites have been utilized widely in additive manufacturing. These types of materials are usually formulated with different functional particles and shear thinning non-Newtonian fluids such as polymer melts and silicone. The materials are viscous non-Newtonian suspensions during formulation and printing, and their rheology is a key factor for the processing. This paper will concentrate on suspensions with micron-sized particles, and discuss the rheology and overall flow behavior in capillaries scaled appropriately for additive manufacturing applications (around 1 mm ID). Micron size glass beads and shear thinning silicone are used to demonstrate the impact of particle volume fraction on the shear thinning behavior. The impact of particle and capillary size on viscosity and jamming conditions will be discussed. Previous models based on Newtonian fluids and in free flowing conditions will also be reviewed and compared.