Fabrication of low-clay containing translucent whitewares using prefired materials by slip casting

Abstract

A low-clay translucent whiteware has been formulated and the studies have been carried out to establish the necessary conditions required for different whiteware manufacturing processes, such as slip casting. The aim of the present work is to identify the conditions for the preparation of stable low-clay whiteware slips with high solids content for the production of slip-cast objects with improved properties, as well as to establish a relationship between the slip properties and the final object properties. The slips containing 88 wt% nonplastic prefired materials and 12 wt% clay mixtures were prepared and the effects of type and amount of various commercial deflocculants and solids content on the casting behaviour were investigated. It was found that for each deflocculant there exists an optimum concentration range within which low viscosity is achieved for a slip of high solids content. It was determined that the addition of 0.1% Dolaflux SP NEU commercial deflocculant was enough to reduce the viscosity at a level required for successful casting. Casting trials showed that the combination of high slip solids content and slower casting rate results in objects with higher densities both in the green and fired state. For instance, the casting time of 8 minutes was enough to produce approximately 5 mm wall thickness at 47.5 vol.% solids content.