Porous alumina-felsite ceramic composites prepared by direct coagulation casting method: Felsite rock (central-eastern desert, Egypt)

Abstract

In this work, the direct coagulation casting method was used to shape porous alumina-felsite ceramic composites. The felsite rocks used in this work were extracted from Wadi Atalla area, central-eastern desert, Egypt. Felsite is studied geologically, microscopically, and applied as a source for silica. The effect of felsite raw material additions up to 30 wt% and the effect of firing temperatures on the alumina were also investigated. The zeta potential of the suspended ceramic slurries was studied at different Ammonium Citrate Tribasic (ACT) concentraion and at different wt.% of felsite. Also, the viscosity was measured at different wt.% of felsite. The bulk density, apparent porosity and linear shrinkage were measured as well as the mechanical properties of the fired samples. The phase composition and the microstructural evolution of the fired samples were determined by XRD and SEM, respectively. Felsite additions enhance the physical and mechanical properties of the fired samples. The DCC process yields high-strength porous ceramic bodies and highly reliable ceramic parts. The results showed that the porous ceramic composites can be fired at 1600 °C to achieve apparent porosity of 40% and compressive strength of 35 MPa at 30 wt% of felsite.