Rheology of refractory coatings used in lost foam casting

摘要

The rheological and thermal properties of two types of refractory coating materials are investigated experimentally. It has been determined that both coatings exhibit non-Newtonian shear thinning and thermal thickening fluid flow behavior. One of the coating materials obeys the Casson rheological model over the shear rate range investigated. The parameters related to product performance and composition variations (limiting high-shear viscosity and yield point) are determined as a function of temperature. The rheological data of other type refractory coating well fit the linear fluidity model. The parameters (limiting fluidity and structural fluidity coefficient) required to characterize the rheology of this coating against temperature are presented. Using a jet thrust technique demonstrated that this type of the refractory coating material possesses significant viscoelasticity. The relaxation times of this material as a function of shear rate and temperature have been determined.