Abstract
Abstract
Investment casting is an effective method for fabricating dimensionally accurate metal components of complex shape. In the process of casting nickel superalloys, slurries based on Ludox® SK and zircon silicate (ZrSiO4) are widely used in casting shops. Ceramic moulds based on Ludox SK and ZrSiO4 alone have a major disadvantage, as they interact with the molten metal. This interaction significantly reduces the production yield. In the present study causes of the most common blade defects are explained, based on extensive examinations of slurry components by scanning electron microscopy, high-resolution electron microscope, and zeta potential analyser. Slurry rheology via changes of pH and addition of alumina or aluminium oxide (Al2O3) powders is presented. It is found that Al2O3 powder as a rheology modifier allows ceramic slurries based on Ludox SK and ZrSiO4 to be modified deliberately.