The Heat Treatment Process of Hydrous Alumina and Caracteristics of Nanometer Al_2O_3

By means of IR, XRD, TG-DTA and TEM, the characteristics and the thermal treatment processes of hydrous alumina as the hydrolysate of aluminium alkoxide were examined, and the influence of various thermal treatment processes on the granular characteristics of nano-Al2O3 particles was also investigated. The results showed that hydrous alumina was amorphous diaspore [AlO(OH)] retaining abundant adsorptive and structural crystal water. Parts of AlO(OH) were converted into amorphous γ-Al2O3 after calcination at 300 ℃. Calcination temperature, holding time and cooling mode exerted effects on the crystal shape, size and morphology of the alu- mina particles. The influence of the calcination temperature is the most significant, followed by cooling mode. In contrast, the influence of holding time was the lowest. Spheric or fibrillar α- or γ-Al2O3 with the size of 3￣5 nm, 3￣5 nm, 5￣10 nm, 10￣15 nm and 50￣100 nm might be produced under the thermal treatment conditions of 750 ℃ for 3 h, 800 ℃ for 4 h, 900 ℃ for 4 h, 950 ℃ for 4 h and 1000 ℃ for 4 h, respectively.