The Influence of Hydrodynamic Effects on the Adjustment of Gradient Patterns through Gravity Sedimentation of Polydisperse Particle Systems in Newtonian and Viscoelastic Fluids

Abstract

Gravity sedimentation of different metal and non metal powder systems has been examined as a conception for the manufacturing of gradient materials. By using the different settling behaviour of various powder fractions the sedimentation is a plain technology to achieve gradient structures. It was found that the investigation on fluid mechanic problems in Newtonian and viscoelastic fluids during the settling of polydisperse powder particles are substantial to obtain desired gradient sediments. Unlike dilute suspensions the particle settling behaviour in viscoelastic fluids can not only be modified by choosing particle and fluid properties but also by the adjustment of particle-fluid interactions. In many experiments it was figured out that the initial distribution of particles before sedimentation can also be used to change the final sediment structure. For a better understanding of particle interactions and fluid problems, various simulation techniques were applied to reflect on the nature of these complex phenomena. At selected Newtonian and viscoelastic fluids the particle settling behaviour and the forming of gradient sediments under different conditions will be lighted up. Results of microstructure analysis after compaction and sintering of the final sediments will be given.