Influence of sawdust on the properties of the ceramic shell used in investment casting process

Abstract

The quality of the investment casting (IC) ceramic shell was enhanced using sawdust as an inexpensive and naturally available additive in the ceramic slurries. The important shell properties such as thickness, porosity, permeability and flexural strength were determined. The ceramic shell accommodated a substantial amount of sawdust because of its low particle density and porous structure which resulted in higher green strength and thickness of the shell. The same shell upon firing led to increased shell porosity and permeability with good knockability characteristic. The addition of sawdust in the secondary layers did not affect the composition of the primary layer of the ceramic shell. The mechanical properties of the aluminium-silicon (Al-Si) alloy castings obtained from the sawdust-modified shells were found to be comparatively higher than those obtained from the conventional shells.