화학공학소재연구정보센터
Journal of Materials Science, Vol.33, No.20, 5059-5067, 1998
Capillary flow behaviour of microcrystalline wax and silicon carbide suspension
Suspensions of ceramic particles in low or high molecular weight polymers are shaped into various three-dimensional parts using various moulding and extrusion technologies. Such bodies are subsequently fired-up and sintered to remove the binder. The utilities of such three-dimensional ceramic bodies depend on the restrictions related to the shapeability of the ceramic suspension, hence to the flow and deformation behaviour of the suspension. In this study, factors affecting the flow and deformation behaviour of a 50% by volume of silicon carbide in a wax binder was investigated. Consistent with the previously observed behaviour of other highly filled materials, the ceramic suspension exhibited viscoplasticity, plug flow and wall slip. Furthermore, flow instabilities associated with the axial migration of the low viscosity binder under the imposed pressure gradient were observed. These results pinpoint to the various difficulties associated with the collection of rheological data and emphasize the relevance of various flow mechanisms, including wall slip and mat formation and filtration based flow instabilities, which would also occur in processing/shaping flows of such ceramic suspensions including extrusion and moulding.