The Relationship between the Flow Properties of Clay Slurry Samples and the Properties of Ceramic Green/Sintered Products

Abstract

This study investigated the effects of various dispersants (Dolapix PC-67, Dolapix SPC 7, Darvan CN, Darvan A821 and Na2SiO3) on the flow properties of slurry prepared using ESC-3 clay to find the optimum dispersant type and dispersant dosage to produce the required properties in green and sintered products produced by slip casting. By considering the flow curves of slurry, it was determined that the most suitable dispersant was Dolapix PC-67 and the dosage was ~0.1%. Afterwards, slurry was prepared in bar-shaped samples keeping the same experimental conditions and using Dolapix PC-67 dosages of 0, 0.03, 0.1 and 1.0 wt. %. The resulting green body samples were dried and sintered at 1200°C. Some physico-mechanical tests were applied to both the green and sintered samples, as well as investigating their microstructure, crystallinity and secondary phase formations using SEM and XRD. Some of the results obtained were as follows: (i) adding dispersant to the slurry had a positive effect on the physical and mechanical properties of the green and sintered products obtained by slip casting. (ii) Determination of the optimum dispersant dosage used in the ceramic slurry by slip casting is an important factor. When the properties of the green/final products and their flow curves measured by Ford cup were considered, it can be said that the dispersant dosage at which the shortest flow duration was obtained did not always correspond to the best results for the physico-mechanical properties of green/final products. (iii) The relationship between the green and sintered samples prepared from slip casting using different dispersant dosages, and the flow curves of these slips, could not be observed from their SEM images.