Inlfuence Of Extrusion Parameters On Liquid Phase Migration In Intermittent Extrusion Process Of Aqueous Ceramic Paste

The relative movement between liquid phase and solid particles during pasteextrusion will lead to liquid phase migration (LPM). The physical essence of LPM ispaste flow driven by extrusion pressure. In this flow process, the movement velocityof liquid phase is faster than solid particle, and the liquid phase flows through thenetwork of solid particle. This phenomena will result in the nonuniform distribution ofliquid phase in paste. The rapid prototyping processes based on ceramic pasteextrusion are intermittent extrusion process. The paste extrusion is a process of"pressure building-pressure releasing-pressure building", and the paste flow and liquidphase distribution will change correspondingly. The LPM phenomena will have somedifference with conventional continuous paste extrusion. Therefore, it is necessary toinvestigate and understand the factors influencing LPM in intermittent extrusion, andso that the liquid phase migration can be effectively controlled in fabrication processof complicate ceramic parts by rapid prototyping processes based on paste extrusionprocess.Rheological properties of paste on paste extrusion process parameters a greatinfluence of rheological properties on the understanding of liquid phase migration,Theviscosity of the paste to the main line, to carry out a detailed analysis of the liquidphase migration from the three aspects of the Zeta potential of the flow curve of therheological models and equations, viscoelastic contact. The continuity of the extrusionpressure and liquid phase migration behavior was investigated in different extrusionspeeds. When the extrusion velocity is higher than0.1mm/s,there is no obvious liquidphase migration. We take the speed of liquid phase migration is not obvious for V=0.15mm/s, and V=0.2mm/s case, squeeze the average pressure stability. Theextrusion pressure of high solid content paste in paste extrusion according to theBenbow and Bridgwater.Different process parameters on the ceramic paste for liquid phase migration wasinvestigated in paste intermittent extrusion rheology of paste, extrusion velocity,intermittent extrusion characteristics of the extrusion device’s structure. Through acomparative analysis, when the viscosity of paste and the increase in pressing timeswas increased, the liquid phase migration. When the velocity is increased, theextrusion force shows the increasing velocity and the increasing of force at lowextrusion velocity for0.025mm/s is more obvious than at high extrusion velocity. When the extrusion die length is increased, the extrusion force shows the increasinglength, and increasing of force at low extrusion velocity is more obvious than that athigh extrusion velocity. When the extrusion die diameter is decreased, the extrusionforce shows the decreasing diameter, and increasing of force at low die diameter islower obvious than that at high die diameter.To solve the problem on the liquid phasemigration in paste in intermittent extrusion process,paste rheology and extrusiondevice parameters affect the liquid migration in paste in intermittent extrusion processthrough a large number of experiments.