非均相沉淀热-还原法制备金属镍包裹氧化铝球形微粉

Preparation of nickel-coated Al_2O_3 spherical micro-powders by heterogeneous precipitation-thermal reduction process

利用非均相沉淀包裹技术,在室温下的水溶液中,以球形碱式碳酸铝铵(AACH)、硫酸镍和碳酸氢铵为原料,制备了金属镍包裹氧化铝球形微粉前驱体,即碱式碳酸镍(NCH)包裹碱式碳酸铝铵微粉。然后,将前驱体在500℃下用氢气还原,成功制备了表面光滑、致密的金属镍包裹氧化铝球形微粉。研究了在非均相沉淀过程中,被包裹碱式碳酸铝铵微粉粉体浓度、硫酸镍和碳酸氢铵加料速度、反应时间、表面活性剂等因素对复合粉体前驱体制备的影响,利用SEM、EDS、XRD等手段表征了复合粉体前驱体及还原产物的表面及切面形貌、成分和结构。

Nickel carbonate hydroxide（NCH）-coated spherical ammonium aluminum carbonate hydroxide（AACH） powders as the precursor of nickel-coated alumina spherical micrometer powders were prepared at room temperature by the aqueous heterogeneous precipitation method using nickel sulfate, ammonium bicarbonate solutions and spherical AACH powders as the major starting materials. The effects of the concentration of spherical AACH powders, rate of pumping nickel sulfate and ammonium bicarbonate solutions, reaction time, surface active reagent etc on coating of NCH on AACH were examined respectively. Uniform nickel-coated alumina micro-powders were successfully produced by reducing the as-prepared NCH-coated AACH precursors in H2 atmosphere at 500℃ for 2 h and the coating thickness of NCH or the resultant Ni thickness can be tailored by controlling the precipitating factors. The powders obtained were characterized by scanning electron microscopy（SEM）, energy dispersive spectroscopy （EDS） and X-ray diffraction（XRD）.