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

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 H_2 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).