Rheological Behavior of Slurries Containing Short Glass Fibers for Preparation of Investment Casting Shell

The short glass fibers were introduced into the slurries by 0%-0.5% (mass fraction of refractory powders) for preparation of fiber-reinforced shells for investment casting. The rheological properties of coatings containing different amounts of glass fibers were measured by R/S rheometer and the rheological behaviors of coatings were investigated. The results show that the apparent viscosities of coatings containing different amounts of glass fibers decrease with increasing shear rate, <i>i.e</i>., shear thinning behavior, similar to that of the coating without fibers. At the same shear rate, the apparent viscosities of coatings containing fibers are higher than that of the coating without fibers and the apparent viscosities of coatings containing 0.3% (mass fraction) fibers are higher than that of the others. The high shear viscosities of coatings containing fibers increase initially, but later decrease, with increasing amount of fibers. The high shear viscosity of the coating containing 0.3% fibers reaches a maximum value of 102.6&#215;10^-3Pa&#183;s, increased by about 31.9%, in comparison to the coating without fibers. And this coating with a maximum thixotropical loop area value of 11.8Pa&#183;s^-1 exhibits an excellent thixotropical behavior. However, it is not found that there is a noticeable effect of the amount of glass fibers on the yield stress or suspensibility of coatings