Research On Dynamic Distribution Of Liquid Phase In Extrusion Process Of Aqueous Alumina Paste

The rapid prototyping processes based on aqueous ceramic paste extrusion canfabricate complicate and high density ceramic parts, and are friend with environment.Because the ceramic pastes used in these processes mainly use water as medium andcontain very little organic binder, the relative movement between solid particles andliquid phase is prone to occur in the ram extrusion process. It will lead to anisotropychanges of liquid distribution in paste and instability of paste flow in extrusion process,and influences the uniformity of extrudate and microstructure and properties of finalparts. The dynamic uniformity of liquid distribution is not good for precise control ofextrusion process in rapid prototyping. Therefore, the dynamic distribution of liquidphase in extrusion process of aqueous alumina paste was investigated in this paper. Thisresearch can help to reveal the relationship between the liquid distribution in extrusiondue to relative movement between solid particles and liquid phase and extrusionvelocities, and to better understand the physical change in dynamic flow process inpaste extrusion. This research can provide support for extrusion process control inceramic part fabrication process by rapid prototyping process.This thesis is divided into two parts.The former is the research on dynamicdistribution of liquid phase by stratifying sample in extrusion process,it measured thedynamic distribution of the liquid content with continuous extrusion and intermittentextrusion at different speeds by making use of segmenting extrusion and stratifyingsample,and then compared the different of the close to the center of the extrusion mouthposition,the edge position of the extrusion mouth,the extrusion head of the center andthe edge position of the extrusion head.Through the comparative found that the liquidcontent of the dynamic distribution of the rate of change with the increase in extrusionspeed,the more is smaller,and in the whole stage of the paste extrusion, the liquidcontent close to the center of the extrusion mouth position has kept a higher. the liquidcontent close to the edge position of the extrusion mouth has been reduced,and theextrusion speed is more higher,the lower the liquid content of this position reduces inthe rate increases.The liquid content of the extrusion head of the center was to slowlyincrease,and then maintained at a higher values.it was a sharp decline until the pasteextrusion was finished.The liquid content of the edge position of the extrusion head wasat a slower rate to reduce in the extrusion and has little effect of the extrusion speed.Thelatter is the research on dynamic distribution of liquid phase of magnetic resonance imaging.This part was to measure the dynamic distribution maps of liquid phase by themagnetic resonance imaging device in the different speeds of the extrusion process,andit found the difference by comparing the various dynamic distribution maps of differentspeeds.Can be found the trend of liquid content changes in the extrusion process closeto the center of the extrusion mouth position,the edge position of the extrusionmouth,the extrusion head of the center and the edge position of the extrusion head asbasically the same as the former part of the described changes.The extrusion speed has agreat effect for the whole distribution of the liquid content, the lower the rate ofchange.the liquid content of the whole distribution.