亚微米球形镍粉的两步法可控制备与表征

Controllable preparation and characterization of sub-micron spherical Ni powder with two step method

摘要:

以H2C2O4?2H2O为沉淀剂，NiSO4?6H2O为镍源，第一步通过共沉淀法制得NiC2O4前驱体粉末；然后在H2气氛、中温条件下（250-500℃）煅烧还原，第二步制得高规则度的亚微米球形镍粉。采用扫描电子显微镜、X 射线衍射、激光粒度分析等检测手段对所制备的样品形貌、显微结构进行表征。结果表明：亚微米球形镍粉纯度高，二次颗粒粒径约为40μm左右，由大量大小均匀、分散性好的粒径0.5μm左右的一次颗粒团聚而成，这种结构保证了镍粉具有良好的成形性和烧结活性。随煅烧温度的升高，结晶度逐渐升高；亚微米球形镍粉的最佳制备工艺参数为：镍离子浓度0.7mol.L-1，反应温度40℃和煅烧温度500℃。镍粉的晶粒长大活化能为26.9 kJ?mol-1，其晶粒长大机制为界面扩散控制机制。

Abstract:

With H2C2O4?2H2O as precipitant and NiSO4?6H2O as Ni source, NiCO4 precursor was prepared through coprecipitation method in the first step. Afterwards, highly regular sub-micron spherical Ni powders were calcined and reduced under H2 atmosphere at middle temperature in the second step. Scanning electronic microscopy, X-ray diffraction and laser particle size analyzer were used to characterize the morphology and microstructure of Ni powder. The results show that the purity of Ni powder is very well. The secondary particle of Ni powder is about 40μm agglomerated with a lot of 0.5μm dispersed and uniform primary particles, which guarantees the excellent forming property and sintering activity. The crystallinity of Ni powder increases with the sintering temperature. The optimal preparing parameters are 0.7mol.L-1 Ni2+ concentration, 40℃ reactive temperature and 500℃ sintering temparature. Grain growth activation energy of Ni powder can be calculated as 26.9 kJ?mol-1 according to the relationship between grain size and sintering temperature and Ni powder’s growing mechanism is interfacial diffusion controlling mechanism.