Densification mechanism of slag ceramics with different magnesium contents

Steel slag is an industrial solid waste generated during the steelmaking process and is an important secondary resource. Since steel slag is rich in aluminosilicates, it can be used to make ceramics. The use of steel slag to prepare ceramics plays an important role in the utilization of it. In this paper, the effect of the sintering temperature and holding time on the sintering process and the densification of products during the preparation of ceramics from steel slag were explored. In particular, low magnesium (Mg) and high Mg samples were chosen for study. The Mg oxide content for the low Mg sample was 2.52% and it was 10.50% for the high Mg sample. Current studies of steel slag ceramics mainly consider the amount of steel slag, the basic formula of the trial, the subsequent performance of the test specimen, the influence of a certain element on the mechanical properties, and the crystal phase of the ceramic. In this work,the preparation of the ceramics with steel slag and clay as main raw materials was considered. By establishing the kinetic description of the sintering process, the sintering activation energy with different magnesium contents could be calculated. The sintering activation energy for the low magnesium and high magnesium ceramic samples was relatively small, and was 36 kJ·mol^-1 and 54 kJ·mol^-1, respectively. Meanwhile, the densification of the ceramic samples with different magnesium contents was investigated. It is concluded that the material migration mechanism is controlled by surface diffusion when the sintering temperature of the low magnesium sample is 1000℃. At 1100℃, the volume diffusion is the main control mode. When the high magnesium sample is sintered at 1110℃ or higher, the sintering process is mainly controlled by the diffusion of the liquid phase.