Studies on the Low-Temperature Synthesis of Fine α-Al2O3 Powder by Precipitation Route

Abstract

Fine alpha-alumina (α-Al2O3) powder was prepared by simple precipitation technique using aluminium salt and ammonia as a precipitating agent. In this method, an aqueous solution of aluminium nitrate and ammonia were mixed with continuous stirring both in the presence and in the absence of polyethylene glycol (PEG). A controlled pH range of 7.5–8.5 was maintained throughout the synthesis process. A comparative study between the alumina powder prepared in the presence and absence of PEG was drawn into attention. The washing of the precipitate was deliberately avoided in one case to study the effect of washing on phase formation temperature. The synthesized powders were calcined at different temperatures and characterized by X-ray diffraction study, thermal analysis, infrared analysis, microstructural study, and particle size analysis. The results showed less agglomerated fine alumina powder formation in its pure α-Al2O3 phase at 1050°C in the presence of PEG.