Effect of Slurry Composition on Plate Weight in Ceramic Shell Investment Casting

Abstract

This paper deals with the study of the effect of primary slurry parameters on the plate weight (ceramic retention test) in ceramic shell investment casting process. Four controllable factors of the zircon flour and fused-silica powder based slurries were studied at three levels each by Taguchi’s parametric approach and single-response optimization of plate weight was conducted to identify the main factors controlling its stability. Variations in coating thickness with plate weight were calculated for each slurry and ceramic shell moulds were made on wax plate using primary slurry and coarse fused-silica sand as stucco. The Scanning Electronic Microscopy (SEM) technique has been used to study the surface morphology of zircon flour and fused silca powder particles as well as primary coating (shell surface). X-ray Diffraction (XRD) analysis was done to identify the various phases present in the ceramic slurry coating. Optical profilometer has been used to measure the surface roughness of the shells. The result reveals that the surface condition of shell can be improved by increasing the plate weight, corresponding to higher filler loading in the slurry. Confirmation experiments were conducted at an optimal condition showed that the surface quality of the ceramic shell mould were improved significantly. Castings were produced using Al-7%Si alloy in recommended parameters through ceramic shell investment casting process. Surface roughness of the produced casting were measured and presented in this paper.