The Effects of Water Removal Process on the Properties of Magnesium Aluminate Spinel Nanopowders Synthesized by Co-Precipitation Method

Abstract

Magnesium aluminate spinel (MgAl2O4) or spinel ceramics have been widely used in engineering fields due to its attractive properties, such as high mechanical strength, good optical properties, and high refractoriness. Precipitation is one of the most common techniques for preparing spinel nanopowders because it offers many advantages including low cost, simple method, and ease of mass production. However, severe agglomeration usually takes place during water removal process, i.e. washing and drying. These hard agglomerates deteriorate sinterability of nanopowders. In this study, spinel nanopowders were prepared by co-precipitation method. The remaining water in the precipitated precursor was removed by washing the precipitated precursor with organic solvents, i.e. ethanol and acetone-toluene-acetone. Conventional drying process was also performed for comparison. The characteristics of the obtained spinel nanopowders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) method. The results showed that the water removal process did not have any significant effects on phases of the dried precursors and the calcined powders. However, washing the precipitate precursor with organic solvent is the most effective process to prepare spinel nanopowders with low degree of agglomeration. Whereas, removing water by conventional drying process led to the formation of hard agglomerates. Furthermore, the effects of water removal process on sinterability of the spinel nanopowders were also reported.