SINTERING AND PHASE FORMATION IN CERAMIC MATERIALS FROM BLAST FURNACE SLAG

The work discuses three ceramic compositions containing no feldspars and based on 30, 50 and 70 wt % Blast Furnace Slag (BFS), respectively, 30 % kaolin and quartz sand. Initially, the processes of phase formation and densification were estimated using non-isothermal Differential Thermal Analysis and Dilatometry. After that, the degree of sintering at different temperatures and times was measured by linear shrinkage and water absorption. The phase composition and the structure of final materials were evaluated with X-ray Diffraction and Scanning Electron Microscopy. The obtained ceramics are characterized by a narrow sintering interval and good degree of densification at 1200-1220 degrees C. The phase compositions and the structures of final samples highlight an elevate crystallinity and formation of pyroxene and anorthite solid solution. These promising results are explained by re-crystallization processes, taking place during the sintering and cooling of materials.