Identification of layer thickness and rheological properties of ceramic shell slurry of investment casting

Abstract

This study explores the rheological behavior of slurries and the distribution of elements within investment casting molds, basedon microstructural analysis. The rheological characteristics of ceramic shell slurry used in investment casting are examinedthrough its microstructure. The uneven surfaces of sand grains promote mechanical interlocking at grain boundaries, leadingto effective agglomeration of ceramic shells ideal for investment casting applications. The shell mold examined comprisesaggregates such as stucco sand, mullite, and colloidal silica, which serve as inorganic binders on fungal shells. The colloidalsilica observable in the image represents the slurry's rheological flow post-sintering. Its mechanical binding capabilities areevidenced by its interaction with aggregates featuring irregular surface textures. Acting as a binding agent, the slurry enablesthe formation of consolidated ceramic molds. Slurry rheology is influenced by its viscosity and the shear rate during flowbetween the aggregates. These factors, in turn, affect the slurry’s shear stress, which is governed by applied pressure andimmersion depth. After sintering at 1050 °C, the ceramic shell displays its highest oxygen concentration, registering 56.11%,alongside silica at 20.91%, aluminum at 13.02%, and carbon at 9.10%.