Rheology of refractory coating materials used in lost foam casting process

The results of the experimental study of rheological and thermal properties of two refractory coating materials are presented in this paper. Although both coatings exhibit non-Newtonian shear and thermal thickening fluid flow behavior, one of them obeys the Casson rheological model over the shear ra te range investigated. Its parameters related to product performance and co mposition variations (limiting high-shear viscosity and yield point) are de termined as a function of temperature. The rheological data of the other type refractory coating are well fit the linear fluidity model. The parameters (limiting fluidity and structural flu idity coefficient) required to characterize the rheology of this coating ag ainst temperature are presented. A significant viscoelasticity of this refr actory coating material was demonstrated using a jet thrust measurement tec hnique. The relaxation times of this material as a function of shear rate a nd temperature are presented.