Enhancement of Ceramic Slurry Rheology in Investment Casting Process

Abstract

Investment casting (IC) process utilizes a single use ceramic shell as mold for casting. The accuracy and surface finish of the interior of the ceramic shells is transferred to the castings. The quality of the ceramic shell depends upon the constituents and characteristics of the ceramic slurry. The present exploration deals with finding a solution how to maintain the prepared primary slurry characteristics after 24 h duration for future application. The stability of the primary slurry was achieved by forming a thin layer of argon gas over the prepared primary slurry surface so that it is not exposed to atmosphere. The primary slurry properties, i.e., viscosity, density, plate weight and pH value, were determined after 24 h of exposure of the slurry to argon gas. A comparison of the aforementioned slurry characteristics was made between the slurry without (A) and with (B) coverage of argon gas at the top of slurry surface. It was found that the slurries A and B possessed viscosities of 1862 and 1563 cp, densities of 4.31 and 3.74 gm/cm³, plate weights of 0.232 and 0.209 gm/cm² and pH of 8.3 and 8.9, respectively, at the end of 24 h duration. It shows that argon gas coverlet over the slurry B led to significant improvement in preserving the slurry characteristics. Furthermore, the surface texture of the interior of the primary layer formed using slurry B was better than that by slurry A.