Rheological properties of re-melted paraffin-wax suspensions used for LPIM

The influence of re-melting of suspensions of ceramic powder and paraffin-wax used for LPIM on the yield stress and the flow behaviour was investigated. As a model system we used alumina powder and paraffin-wax, which has a liquid/solid phase transition at around 58 °C. The only parameter that was changed during this study was the number of particles per unit volume and, consequently, the number of attractive, interparticle interactions in the suspensions per unit volume.During cooling the particles took up closer interparticle distances than in the prepared suspension due to the huge shrinkage associated with paraffin-wax, which occurs below the liquid–solid phase transition. This resulted in an increased, attractive interparticle interaction (and so an increased yield stress) and an increase in the strength of attractive particle network formed after re-melting, which can be destroyed by homogenization, as was shown during the flow-curve measurements, and the initial flow properties of the paraffin-wax suspensions can be regained.