配位沉淀-直接还原法制备球形超细镍粉

以碳酸氢铵为沉淀剂、氯化镍为原料、氨为配位剂, 用配位沉淀法制备球形镍粉前驱体沉淀, 再于氢还原气氛中直接还原前驱体制备球形超细镍粉。系统地研究了前驱体制备过程中反应物浓度、pH值、添加剂、温度和直接还原过程中反应温度、还原气氛对镍粉形貌及粒度的影响。实验结果表明: 在Ni²⁺浓度为0.8 mol/L, pH值为7.5, 反应温度为室温, 添加剂PVP添加量为1%的条件下可制备出类球形、形状较规则、分散性好的镍粉前驱体; 将球形的、分散性好的前驱体粉末在350～400 ℃的N₂和H₂混合气氛中进行还原即可得到分散性好、纯度高的超细金属镍粉。

Preparation of Spherical Ultrafine Nickel Powder by Coordinated Precipitation-direct Reduction Process

The precursors, prepared by coordinated precipitation with NH₄HCO₃ as the precipitator, NiCl₂ as the raw material, and ammonia as the coordinator, were direct reduced by hydrogen to obtain a spherical nickel powder. The effects of parameters such as the concentration of reactants, pH value, additives, and reaction temperatures for precursor preparation and the reductive temperature, the composition of reductive atmosphere amid the reduction process were systematically investigated. The experimental study shows that, using 1(wt)% PVP as additive, well-dispersed precursors with a uniform spherical morphology can be obtained in a solution with Ni²⁺ concentration of 0.8mol/L and pH value of 7.5 at room temperature, while a pure and well-dispersed spherical nickel powder can be prepared by direct reduction of this precursor in a mixed atmosphere of nitrogen and hydrogen within the temperature range of 350～400 ℃.