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利用非均相沉淀包裹技术,在室温于水溶液中,以球形αAl2O3、硫酸镍、硫酸亚铁和碳酸氢铵为原料,先制备了无定形碱式碳酸镍和水合氧化铁包裹氧化铝球形微粉前驱体。然后,前驱体在600℃经氢气还原2 h制备表面光滑、致密的γFeNi包裹Al2O3复合微球。利用扫描电镜、能量散射分光仪、X射线衍射和热重分析仪等表征了复合微球前驱体及还原产物的表面和断面形貌、成分以及前驱体热分解过程。对被包裹氧化铝含量、加料速度、搅拌速度、反应时间及表面活性剂等影响因素进行了分析。初步得到优化制备条件,即15 g/LαAl2O3,加料速度为5 mL/min,搅拌速度为1 000 r/min,反应时间为1 h,表面活性剂添加量为5 mL/L。γFeNi的热膨胀系数接近于氧化铝,因而使两者形成了较好的界面结合。这种γFeNi包裹Al2O3复合微球可用作新型吸波材料。
By using heterogeneous precipitation and encapsulation technology, amorphous α-Al2O3, nickel sulfate, ferrous sulfate and ammonium bicarbonate were used as raw materials to prepare amorphous spherical nickel carbonate and hydrated iron oxide-coated alumina spherical powder precursors at room temperature in aqueous solution body. Then, the precursors were hydrogenated at 600 ℃ for 2 h to prepare the γFeNi coated Al2O3 composite microspheres with smooth surface and compact structure. The surface and cross-sectional morphology, composition and precursor thermal decomposition of precursor and reduction products of composite microspheres were characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and thermogravimetric analysis. The influencing factors such as the content of alumina, feed rate, stirring speed, reaction time and surfactant were analyzed. The optimal preparation conditions were obtained as follows: 15 g / L α Al 2 O 3, 5 mL / min feeding rate, 1 000 r / min stirring speed, 1 h reaction time and 5 mL / L surfactant. The thermal expansion coefficient of γFeNi is close to that of alumina, so that the two have a good interface bonding. This γFeNi coated Al2O3 composite microspheres can be used as a new type of absorbing material.