Chemical Nickel Plating

Metal layers can be deposited from aqueous solutions not only by electric current as in electroplating but also by strong reducing agents. Chemical deposition of nickel on metallic and nonmetallic substrates, together with the long-known silvering of glass, are the most widespread examples. This remarkable reaction has recently found a variety of industrial applications mainly in the preparation of corrosion-resistant, hard, and wear-resistant protective layers, in the metallizing of plastics, and in electronics.     

Ion-pair chromatography of bis (sodium-sulfopropyl) disulfide brightener in acidic copper plating baths

Quantitative analysis of the brightener component bis (sodium-sulfopropyl) disulfide (SPS) in acidic copper plating baths poses a real challenge due to the complex chemical matrix containing large amounts of Cu(II) ion and sulfuric acid together with other organic additives and additive decomposition products. We developed a new ion-pair chromatography method to analyze micro-molar amounts of SPS directly in plating bath samples without the need for sample pre-treatment. Addition of tetra-N-methylammonium cation as ion-pairing agent to a methanol-sulfuric acid-water eluent increases the retention time of the anionic SPS2- on a C18 column sufficiently to separate this compound from Cu(II) ion and additive by-products.     

EMI shielding performance of electroless coated iron nanoparticles on graphite in low-density polyethylene composite for X-band applications

In the proposed work, an investigation of shielding effectiveness (SE) for varying compositions of Graphene, Multiwall carbon nanotubes (MWCNT), and Iron nanoparticles coated on Graphite (Fe@Graphite) was conducted in X-band (8.2 GHz–12.4 GHz). All these are mixed in an LDPE matrix. The nanomaterial was subjected to chemical characterization, i.e., Scanning electron microscopy (SEM), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). The shielding observed is dominantly due to absorption. The lattice structure which facilitates the shielding due to absorption was the hexagonal graphite structure on whose surface iron nanoparticles were embedded and used as the magnetic filler. At the same time, Graphene and MWCNT act as electrically conducting fillers. The Total shielding effectiveness(SE_T) was maximum for LDPE, MWCNT, Graphene, and Fe@Graphite, in the ratio of 50: 5: 25: 20 by weight %, and is 49 dB at 9.65 GHz for a sample thickness of 3 mm.     

添加剂对焦磷酸盐镀铜性能的影响

铜镀层的外观呈铜红色、柔软、孔隙少,常用作钢铁件多层镀铬的中间层和钢铁件镀锡和镀银的底层,以提高基体金属和表面镀层之间的结合力.     

Influence of pulse plating conditions on the structure and properties of pure and composite nickel nanocrystalline coatings

An additive-free Watts type bath containing micron- and nano-SiC particles (1 μm and 20 nm respectively), as well as ultrafine-WC particles (200 nm), was used for the production of pure Ni and nickel matrix composite electrocoatings under both direct and pulse current conditions. Moreover, nickel nanocrystalline deposits were obtained from a Watts type bath containing small amounts of 2-butyne-1,4-diol, in order to investigate the combined advantages of additives and pulse technique on the properties of the deposits. The influence of the variable electrolysis parameters, the particle size and the organic additive concentration on the surface morphology, the structure and properties of the deposits were discussed. It has been proved that the application of pulse electrodeposition affects drastically the structural characteristics and properties of the deposits and under well-defined conditions could lead to the preparation of nanostructured materials with improved mechanical properties. Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 6, pp. 802–811. The text was submitted by the authors in English.     

线性扫描阳极溶出伏安法测定微量银

以玻碳电极为工作电极,建立了线性扫描阳极溶出伏安法测定微量银的分析方法。在0.1 mol.L-1HNO3-KNO3和0.04 g.L-1聚乙烯醇的底液中,于+0.33 V处有一灵敏的氧化峰,峰电流与银离子浓度在0.01~0.40 mg.L-1范围内有良好的线性关系,检出限为5.0μg.L-1,方法应用于电镀废液、铜精矿、废照相胶卷样品中微量银的测定。     

代铬刷镀层的耐腐蚀机理的考察

对新型的代铬刷镀层Ni-Fe-W-P-S进行了耐腐蚀性能机理的分析研究。用扫描电镜(SEM)、透射电镜(TEM)、扫描隧道显微镜(STM)、X射线衍射及电子能谱(XPS)等的分析表明，基体组织为非品结构是代铬刷镀层优异耐腐蚀性的主要原因.     

化学镀法制备银壳聚苯乙烯微球

采用一种新的化学镀法合成银壳包覆聚苯乙烯微球, 通过三乙醇胺和银离子络合来减小反应的氧化还原电位差, 降低银在改性聚苯乙烯微球表面的沉积速率. 采用TEM、XRD、UV 等测试手段对样品进行了分析和表征, 并考察了不同反应条件对实验结果的影响.实验表明, 该方法可在改性聚苯乙烯微球上包覆均匀的银层.     

镀锡层上钛-磷复合体系钝化膜的制备与表征

通过钛盐与磷酸盐体系复配的方法,在镀锡层表面得到了一种钛-磷复合体系钝化膜. 利用扫描电子显微镜(SEM)、X射线光电子能谱 (XPS)、盐雾试验、Tafel极化曲线和EIS交流阻抗谱测试等方法,研究了所得钝化膜的表面形貌、组成与耐蚀性能. 结果表明,得到的钝化膜层的主要组成成分为Ti₃(PO₄)₄nH₂O和TiO₂,在镀锡层表面结晶细致并有封孔的作用,因此有很好的耐蚀性能.     

退火处理对Ni-Cr纳米电刷镀层的结构、硬度和摩擦学性能的影响

采用电刷镀技术,以Ni-Cr镀液制备了Ni-Cr纳米电刷镀层并对其进行了退火处理;采用X射线衍射仪,扫描电子显微镜,能量色散谱仪分析了不同温度下退火处理的Ni-Cr纳米镀层的形貌以及结构;分别利用MH-5-VM型显微硬度计和CSM摩擦试验机测定了刷镀层的显微硬度和摩擦磨损性能.研究结果表明:镀层晶粒的大小均为纳米级,随温度变化不大,介于10~20 nm之间,在500℃以下,Cr以固溶体形式存在于Ni的晶格中,500℃以上Cr从Ni的晶格中析出;镀层的耐磨性随退火温度的变化与镀层的硬度随温度的变化大致相同:Ni-Cr刷镀层在400℃退火处理时,硬度最大,磨损率最小.