An investigation on enhancing ceramic shell properties using naturally available additives

Abstract

The ceramic shell properties are very crucial in investment casting (IC) process. Colloidal silica based ceramic shells usually lack sufficient shell properties which causes shell cracking. Sometimes minor repairs can make up the shells. However, every time shell repairing may not be feasible which causes loss to the manufacturer. In the present work, an investigation has been made to improve the properties of colloidal silica based IC ceramic shell by addition of naturally available products such as saw dust and coconut fibres into the ceramic slurries. The important shell properties tested were shell thickness, green and fired strengths, porosity and permeability. The properties of saw dust and coconut fibre modified shells were compared with that of conventional ceramic shell using statistical analysis and it was found that the new shells were better than the conventional shell in terms of shell properties. Further, it was found that the aluminium alloy casting obtained from new shells showed comparatively increase in tensile strength and reduced porosity with that obtained from the conventional ceramic shell. The adopted method proved effective in reducing both production lead time and cost of manufacturing the qualitative IC ceramic shells.