Pressure slip casting method for production of ceramic compact parts

Abstract

The fundamentals of slip casting method is based on the slip gets into form of the mold by the water absorption caused by the means of capillary forces formed on the porosities of the mold after powder suspension is poured plaster of paris mold. Pressure slip casting method is developed due to the life of plaster of paris mold is short and the duration of the process is long. In this method instead of plaster of paris mold, the molds made from polymers are used and the water in the suspension is taken out by the means of pressure. This method has more advantages because of the duration of the process is much shorter and the life of the pattern is much longer. Among the high technology ceramics, Al2O3 (alumina) has the widest application due to its resistance to high temperatures and high wear resistance. In this study, aluminium oxide ceramic parts were produced by the slip casting and pressure slip casting methods. Ceramic powders (Al2O3 » 1 ¹m) were mixed with distilled water and the dispersant (sodium silicate) ball milled in a ceramic jar for a long time in order to reduce particle size. Plaster of paris mold was used in the slip casting applications. The studies of two molds were carried out for the pressure slip casting method. The designed molds comprised basically two main parts. The alumina ceramic slip was formed by the means of pressure application with the mold that joined to the hydraulic pres. The parts in the same shape and dimension were produced by a plaster of paris mold for comparison. The sintering process was carried out after having enough samples. The parts, produced using the two methods, were examined in the micro structure characterization, shrinkage, porosity and three point bending tests. Weibull analyses were done and the results were evaluated.