喷雾-胶凝法制备超细莫来石粉末

Preparation of Ultrafine Mullite Powders by Spraying-gelling Process

以水玻璃和硝酸铝为原料 ,通过喷雾 -胶凝法和共沸蒸馏技术制备莫来石前驱粉体 ,然后煅烧得到超细莫来石粉末 .用TG -DTA、XRD、TEM及BET研究了莫来石前驱粉体在煅烧过程中的热学性质、物相与比表面变化及颗粒大小与形貌变化 ,并对所制得的莫来石粉进行了表征 .结果表明 ,莫来石前驱粉体经 130 0℃煅烧 1h可制得粒径为 2 5nm～ 4 0nm ,比表面积为 4 2 5m2 /g的莫来石超细粉 ;煅烧过程中的物相变化次序为 :勃姆石 +非晶态SiO2 →非晶态Al2 O3 +非晶态SiO2 →γ -Al2 O3 +非晶态SiO2 → 3Al2 O3 ·2SiO2 .

Ultrafine mullite powders were prepared by the calcination of the mullite precursor powders obtained from water glass and aluminium nitrate via spraying_gelling method and followed by n_butanol azeotropic distillation process. TG_DTA, XRD, TEM and BET were employed to study the thermal behavior as well as the change of phase structure, specific surface area, particle size and morphology of the mullite precursor powders during calcination, and to characterize the mullite powders obtained. The results showed that ultrafine mullite powders with particle size in the range of 25nm～40nm, BET specific surface area 42.5m 2/g could be obtained by calcining mullite precursor powders at 1300℃ for 1h, and that the sequence of phase transformation of the mullite precursor powders during calcination was found to be boehmite+amorphous SiO 2→amorphous Al 2O 3+amorphous SiO 2→γ-Al 2O 3+amorphous SiO 2→3Al 2O 3·2SiO 2.