Alumina powders from aluminium nitrate-urea and aluminium sulphate- urea reactions-the role of the precursor anion and process conditions on characteristics

摘要

Precursor powders for alumina were prepared by aluminium nitrate- urea (NU-) and aluminium sulphate-urea (SU-) reactions. The role of process conditions on the reaction and characteristics of the resultant powders were studied. NU-reactions resulted in an amorphous gel that upon prolonged reflux- ing at a higher pH crystallized into boehmite powders of 0.3-0.8 μm size. These were agglomerates having elongated fibrillar morphology. SU-reactions resulted in the direct formation of amorphous powders of 2-7 μm size which were agglomerates of spherical particles.