乙醇溶液中电沉积纳米镍粉及其性能研究

发布时间：2018-03-17 06:15

本文选题：纳米镍粉　切入点：电沉积　出处：《大连理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：自20世纪80年代以来,纳米技术就被预言是21世纪的科学前沿和主导科学。磁性镍纳米粒子由于具有独特的物理、化学性质,在催化剂、磁性材料、导电浆料、纳米涂层材料、电池材料以及硬质合金粘接剂等许多领域有广泛的应用前景,引起了科学家们的高度关注。液相法制备金属纳米粉,由于操作简单、产率高、产品尺寸和形貌可控制等优势,是实验室和工业生产广泛采用的合成方法。目前,液相法制备纳米镍粉(电解法除外,一般在水溶液中进行)一般使用还原剂水合肼、NaBH4/KBH4,或者使用有机醇、亚磷酸钠等。前三种试剂有较强的毒性,后两种要么反应速率缓慢,要么引入了杂质得不到纯净的纳米镍粉。从还原性有机溶剂体系电沉积制备纳米金属粉末,既无需使用还原剂,且有机溶剂还可以阻止金属粉末氧化和团聚发生。本论文在不加还原剂的条件下,以镍盐的乙醇溶液为电解质,电沉积镍粉,并通过单因子变量实验探究了镍盐浓度、脉冲电压以及表面活性剂种类和浓度对镍粉结构、形貌和磁学性能的影响,通过X射线衍射、透射电镜、扫描电镜、振动样品磁强计和傅里叶红外光谱仪表征,得出以下结论：所制备的镍粉均具有面心立方结构,镍粉微观呈树枝晶状,平均粒径在100nm以下,镍粉表现铁磁性,饱和磁化强度大约在30-45emu/g之间,矫顽力大约在150-3500e之间。1)随着氯化镍乙醇溶液的初始浓度升高,镍粉的晶粒尺寸逐渐增大；树枝化更加明显；饱和磁化强度缓慢增加,剩磁比明显减小,矫顽力先减小后增加。2)随着电压的升高,镍粉的晶粒尺寸逐渐减小；树枝晶形貌没有明显变化；饱和磁化强度呈减小趋势,剩余磁化强度、矫顽力和剩磁比的变化趋势一致,均为从最小值激增到最大值,然后骤减,最后平稳缓慢增加。3)电解液添加聚乙烯吡咯烷酮(PVP)和十二烷基硫酸钠(SDS)后,镍粉的相结构、平均晶粒尺寸、晶粒取向度相似,后者的磁性略低于前者；改变阴离子表面活性剂浓度时,随着SDS浓度的升高,镍粉的晶粒尺寸在25±5nm范围内起伏变化；树枝晶分支数量减小,长度变短。SDS浓度11.67mg/L时,饱和磁化强度、剩余磁化强度和矫顽力随SDS浓度增大,缓慢减小；SDS浓度11.67mg/L时,饱和磁化强度、剩余磁化强度和矫顽力随SDS浓度增大,逐渐增大。剩磁比总体呈上升趋势。4)与水溶液电沉积不同的是,电沉积过程中乙醇分子参与了阳极放电过程,但并未进一步被氧化形成醛或者酸,且乙醇起到了阻碍镍粒子氧化的作用。
[Abstract]:Since 1980s, nanotechnology has been predicted to be the scientific frontier and leading science of 21th century. Magnetic nickel nanoparticles have unique physical and chemical properties in catalysts, magnetic materials, conductive pastes, nano-coated materials, Battery materials and cemented carbide adhesives have been widely used in many fields, which have attracted great attention of scientists. Due to the advantages of simple operation, high yield, controllable size and shape of products, the preparation of metal nano-powders by liquid phase method has many advantages, such as simple operation, high yield, and the size and morphology of products can be controlled. It is a widely used synthetic method in laboratory and industrial production. At present, the liquid phase method is used to prepare nano-nickel powder (except electrolysis, usually in aqueous solution), generally using the reductant hydrazine hydrate, NaBH4 / KBH4, or using organic alcohol, Sodium phosphite and so on. The first three reagents have strong toxicity, and the latter two are either slow in reaction rate or have introduced impurity not pure nano-nickel powder. The nanometer metal powder is prepared by electrodeposition from reductive organic solvent system. The oxidation and agglomeration of metal powder can be prevented by organic solvent without reducing agent. In this paper, nickel powder was electrodeposited with ethanol solution of nickel salt as electrolyte. The effects of nickel salt concentration, pulse voltage, type and concentration of surfactants on the structure, morphology and magnetic properties of nickel powder were investigated by single factor variable experiments. The results were analyzed by X-ray diffraction, transmission electron microscope, scanning electron microscope, X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM). Vibration sample magnetometer and Fourier transform infrared spectroscopy (FTIR) showed that the nickel powder had a face-centered cubic structure, the nickel powder was dendritic, the average particle size was below 100 nm, and the nickel powder was ferromagnetic. The saturation magnetization is about 30-45 emu / g, and the coercivity is about 150-3500e.) with the increase of the initial concentration of nickel chloride solution, the grain size of nickel powder increases gradually, the dendrization becomes more obvious, and the saturation magnetization increases slowly. With the increase of voltage, the grain size of nickel powder decreases gradually, the morphology of dendrite does not change obviously, the saturation magnetization decreases, and the residual magnetization decreases. The change trend of coercivity and remanent magnetic ratio is consistent, which is the phase structure of nickel powder after increasing from the minimum value to the maximum value, then to the maximum value, then to the sharp decrease, and finally to increasing steadily and slowly. 3) after adding polyvinylpyrrolidone (PVP) and sodium 12 alkyl sulfate (SDSs) into the electrolyte, The average grain size and orientation degree of nickel powder were similar, and the magnetic properties of the latter were slightly lower than those of the former. When the concentration of anionic surfactant was changed, the grain size of nickel powder fluctuated in the range of 25 卤5 nm with the increase of SDS concentration, and the number of dendritic branches decreased. The saturation magnetization, remanent magnetization and coercivity increased with the increase of SDS concentration when the length became shorter. The saturation magnetization, residual magnetization and coercivity increased with the increase of SDS concentration. The remanent magnetic ratio (R) showed an increasing trend. 4) different from the electrodeposition of aqueous solution, ethanol molecules participated in the anodic discharge process, but were not further oxidized to aldehydes or acids. Ethanol also acts as an obstacle to the oxidation of nickel particles.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;TQ153.12

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