Phase transformation during the sintering of γ-alumina and the simulated Ni-laden waste sludge

This study investigated the fundamental phase transformation process when incorporating simulated nickel-laden waste sludge by alumina-based ceramic system. To match the required sintering conditions for commercial ceramic products as a development of waste-to-resource strategy, the investigation focused on the nickel incorporation behavior of γ-alumina in moderate to low temperature sintering environments (1250-750 °C) under a 3 h sintering process. X-ray diffraction (XRD) and Rietveld refinement were used to show the quantitative distribution of phases. The results demonstrated that γ-alumina interacted intensively with nickel oxide at sintering temperatures above 1000 °C. Furthermore, the densification effect of the sintering process is also illustrated, as this is crucial for developing the needed mechanical strength for practical applications. The findings in this study reveal that there is good potential for achieving the stabilization of nickel by thermal treatment with a γ-alumina containing precursor via moderate ceramic sintering temperatures.