COMPARISON OF MICROSTRUCTURE OF AL-CU ALLOYS CAST IN CALCITE INVESTMENT SHELL AND DRY SAND MOULDS

The investment shell moulds were fabricated with ceramic slurry containing calcite as a filler material and colloidal silica binder. The shell characteristics in terms of hot bending strength, thermal expansion and thermal conductivity were measured. The microstructure and tensile strength of Al-Cu alloys cast in calcite investment shell and dry sand moulds were compared. The thermal conductivity of calcite investment shell moulds decrease with increase of temperature. In the 5-10% Cu alloys there is little difference in structure between the as-cast alloys.