勃姆石及其物相热演变的表征与溶胶-凝胶法制备氧化铝

Characterization, thermal evolution of boehmite precursor and preparation of alumina through a sol-gel process

摘要:

在溶胶-凝胶工艺制备氧化铝粉体过程中,对其前驱体结构相变的渗入研究是获取高纯氧化铝粉体的重要基础性工作。本

Abstract:

A thorough understanding in thermal evolution of alumina hydroxide precursor is fundamental to prepare high-purity alumina powders though a sol-gel process. This work contributes this by investigating the structural evolution of boehmite precursor after annealing at a wide temperature range, 300~1400 °C in air for 1 h. TG-DSC analysis revealed the transformation process of dry boehmite gel. With heat-treatment up to 1400 °C, structural evolution of dry boehmite gel was carried out by combination of XRD, FT-IR, NMR and TEM analysis. The results show that the γ-Al₂O₃ is formed from boehmite at 500 °C, which transform into δ-Al₂O₃ up to 1000 °C. After sintering at 1100 °C, the appearance of a three-phase region including δ-, θ- and initial α-Al₂O₃ is observed. The complete transformation into α-Al₂O₃ lasts until at 1200 °C. The α-Al₂O₃ powders prepared with so-gel method at 1200 °C for 1h had an average particle size of ≈50 nm with good dispersivity and narrow particle size distribution.