Abstract
A general ceramics processing scheme by cold uniaxial pressing and conventional sintering process have been used to prepare ceramics from mixtures of blast furnace slag (BFS) and kaolin (10%, 30% and 50% kaolin). The properties of the ceramics were studied by measuring linear shrinkage, bulk density, apparent porosity and mechanical properties of samples heated at temperatures from 800 degrees C to 1100 degrees C. The formed crystalline phases were characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM). Slag melt formed at relatively low temperatures (800-900 degrees C) modified the sintering process to liquid phase sintering mechanism. Combination of BFS with 10% kaolin gave the highest mechanical properties, densification and shrinkage at relatively low firing temperatures. The crystalline phases were identified as gehlenite (Ca2Al2SiO7) in both BFS and BFS with 10% kaolin samples. Anorthite (CaAl2Si2O8) phase increased with increasing kaolin contents. In the case of kaolin-rich mixtures (30% and 50% kaolin), increased expansion took place during firing at temperatures in the range 800-1000 degrees C. This effect could be attributed to the entrapment of released gases. (C) 2010 Elsevier Ltd. All rights reserved.