Synthesis of α-Alumina Powder Obtained from Irradiated Pseudoboehmites

The alumina powder was obtained through a technique based on firing irradiated pseudoboehmites powder to study the radiation effects in the alumina properties. The electron beam radiation effect in a pseudoboehmite produced by sol-gel synthesis was investigated, using aluminum chloride and ammonium hydroxide as precursors. The addition of poly(vinyl alcohol) ([C2H3OH]n) solution (8 wt% in water) was also analyzed. The aluminum chloride solution was mixed with the polyvinyl alcohol and the mixture was dropped into an ammonium hydroxide solution. The work presents the effects of pseudoboehmite radiation in the structure of alumina. The alumina was obtained by pseudoboehmite calcinations. The milky-white colloidal pseudoboehmite precipitate obtained by sol-gel method was filtered, washed with distilled water, dried at 70°C, and powdered in a mortar. The sample acquired was calcined 4 hours at 1100oC, and after that X-ray powder diffraction was performed. The well defined α-alumina crystal was obtained from 1100oC treatment for some samples. The X-ray powder diffraction data shows that in some irradiated samples calcined at 1100o C for four hours presented θ-alumina and -alumina. The powder dried at 70o C was also examined by thermal analysis. The Thermo Gravimetric Analysis (TG) and Differential Thermal analysis (DTA) were used to evaluate mass loss and the pseudoboehmite endothermic and exothermic transformations. The samples were analyzed through scanning electron microscopy technique