Influence of Fe concentration on the properties of the electrodeposited Zn–Fe coatings

Electrodeposition of Zn–Fe alloys on a copper substrate from a sulfate bath with different Fe²⁺ concentration (0.05, 0.10 and 0.20 mol L^?1) at room temperature was investigated using cyclic voltammetry. The influence of the Fe²⁺ content in the plating bath on the surface morphology, structural and magnetic properties of the coatings were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Vibrating Sample Magnetometer (VSM). The results show that the morphology of Zn–Fe films changes with different Fe²⁺ concentration. The EDS analysis demonstrated that the Fe content of the coatings increased with increasing the Fe concentration in the bath. XRD measurements shows the presence of ?Zn (hcp), δ1ZnFe (hcp) and the ΓZnFe (bcc) phases with a (101) preferential orientation in all the electrodeposited films. The magnetic analysis of Zn–Fe films indicated that the saturation magnetization was largely enhanced in comparison to pure Zn, especially with 0.2 at. % Fe, while the coercivity decreased.     

In situ synthesis of hydroxyapatite coating by laser cladding

HA bioceramic coatings were synthesized on titanium substrate by laser cladding using cheap calcium carbonate and calcium hydrogen phosphate. The thermodynamic condition for synthesizing HA was calculated by software Matlab 5.0, the microstructure and phase analysis of laser clad HA bioceramic coatings were studied by electron probe microanalyser (EPMA), X-ray diffractometer (XRD) and transmission electron microscopy (TEM). The theoretical results show that the Gibbs free enthalpy for the synthesis of HA phase is satisfied, and the presence of HA phase in the clad coatings was then further verified by XRD and the selected area diffraction patterns. When the laser power is 600W and the scanning speed is 3.5mm/s, the compact HA bioceramic coatings were obtained, which have cellular dendritic structure and consist of the phases of HA, alpha-Ca(2)P(2)O(7), CaO and CaTiO(3).     

Preparation and evaluation of high-transparent scratch-resistant thin films on plasma treated polycarbonate substrate

New simple aqueous sol–gel procedure has been used for producing hard transparent organic–inorganic coatings on polycarbonate (PC). Sol-gel thins films were prepared by mixing Si and Al aqueous alkoxides and applied on the plasma treated PC. Tetraethyl orthosilicate (TEOS), 3-glycidoxypropyltrimethoxysilane (GPTMS) and aluminum tri sec-butoxide were used as main precursors. Before applying coatings PC were treated by Dielectric Barrier Discharge (DBD) system being conducted at atmosphere pressure. The effects of temperature, sols volume ratios and aging time on the coatings properties were scrutinized. Chemical, structural, morphological, optical and mechanical analyses of the samples were done by ATR-FTIR, EDS, XRD, FE-SEM, TEM, UV/vis spectroscopy, ellipsometry, pencil hardness and eraser scratch methods. TEM results showed well-dispersed nano-particles in the liquid sol. All of the films showed higher average transmittance (89 %) than the raw PC (86 %) that was stemmed from the lower refractive index (1.481) than raw PC (1.58). Films indicated good adhesion onto the plasma treated substrates (5B). The pencil hardness of the PC substrate (4B) improved to 3H (8 pencil grade increment) with just a single layer coating (775 nm thickness) due to the preparation of new hard structures of interlocked Si and Al atoms.     

AZ91D镁合金上钼改性锌系磷化膜的制备、 结构及性能

采用在磷化液中添加钼酸钠及腐蚀抑制剂的方法, 在AZ91D 镁合金表面上制备了均匀细致的锌系复合磷化膜. 用XRD对膜层的化学组成及结构进行了表征,用SEM和EDS对膜层的形貌和组分含量进行分析. 结果表明, 磷化膜主要由Zn3(PO4)2·4H2O和单质Zn组成. 在磷化液中加入钼酸钠使磷化膜组织更加细致而且无裂纹. 磷化液中的钼酸钠含量为1.5 g/L时, 磷化膜的结晶最致密, 单质锌的含量最高, 耐蚀性最好. 还提出了一种快速测量镁合金表面膜层耐蚀性的试验方法, 同时对镁合金上的磷化反应的机理进行了探讨.     

Preparation and characterization of polymer-clay nanocomposite films

Polymer/clay nanocomposite films were prepared by means of electrodeposition of aqueous suspension including cathodic electrophoretic acrylic resin (CEAR) and Na⁺-montmorillonite (NMMT). Studies of XRD, SEM and TEM indicated well-dispersed NMMT platelets in the films prepared. The ideal dispersity achieved was thought to be the result of aqueous compatibility between CEAR molecules and NMMT platelets and the result of the water-involved process as well. The modulus and strength of the polymer/clay nanocomposite coatings tested by tensile testing and nano-indentation were effectively improved compared to those of the virgin CEAR film. In addition, the adhesion strength, flexibility and water-resistance represented by Chinese national standard (GB) kept the best grades.     

CaSiO3∶Pb,Mn荧光粉的ZnO∶Al包覆研究

以Zn(NO3)2•6H2O和AlCl3•6H2O为原料, 借助CO(NH2)2的水解反应, 采用化学均相共沉淀方法和热处理工艺, 在自制CaSiO3∶Pb, Mn红色荧光粉表面包覆ZnO∶Al, 形成透明导电层. 运用数字万用表和自制测量盒对粉体的电阻率进行测量, 比较了包覆率n(Zn)/n(Ca)、n(Al)/n(Zn), 热处理温度和热处理时间对粉体电阻率的影响; 优化出包覆条件和热处理条件: n(Zn)/n(Ca)=10%, n(Al)/n(Zn)=5%, 75 ℃水解1.5 h, 500 ℃热处理45 min. 对包覆样品进行了室温光致荧光(PL)测量, X射线衍射(XRD)结构分析和透射电子显微镜(TEM)形貌观察. 结果显示, 当n(Zn)/n(Ca)=10%时, 在CaSiO3∶Pb, Mn荧光粉表面形成了连续的ZnO∶Al敷膜, 荧光粉的电阻率明显降低, 并且保持了良好的光致发光性质.     

Ga掺杂纳米TiO2薄膜的制备及其光电特性

利用射频磁控溅射法在玻璃衬底上制备了Ga掺杂的TiO₂薄膜,并在真空中于550 ℃下进行了2 h的退火处理。采用XRD、SEM、UV-Vis和PL光谱对薄膜进行了表征。XRD结果提示,在溅射功率为200 W,室温下制备的TiO₂薄膜具有混晶结构,且退火后的晶粒有长大的趋势。SEM分析表明,掺Ga薄膜的颗粒分布得较为均匀并存在尺寸变小的趋势,且出现有利于提高光催化性能的岛状结构,其平均颗粒尺寸为50 nm。UV-Vis透过谱指出,掺Ga后的TiO₂薄膜吸收边发生了明显红移,且退火后进一步红移了10~50 nm。通过接触角的测量与计算可知,550 ℃退火2 h后的薄膜具有良好的亲水性。光催化降解结果表明：样品具有较强的光催化能力。当用低功率(15 W)紫外灯照射8 h后,Ga掺杂的纳米TiO₂薄膜样品对亚甲基蓝溶液的降解率最高可达到71.8%。     

Surface Modification by Compositionally Modulated Multilayered Zn‐Fe Alloy Coatings

Compositionally modulated multilayered alloy (CMMA) coatings of Zn-Fe were developed from acid chloride baths by single bath technique. The production and properties of CMMA Zn-Fe coatings were tailored as a function of switching cathode current densities (SCCD’s) and thickness of individual layers. Corrosion rates (CR) were measured by electrochemical methods. Corrosion resistances were found to vary with SCCD’s and the number of sub layers in the deposit. SCCD’s were optimized for production of Zn-Fe CMMA electroplates showing peak performance against corrosion. The formation of discrete Zn-Fe alloy layers having different compositions in the deposits were demonstrated by scanning electron microscopy (SEM). Improvements in the corrosion resistance of multilayered alloys are due to the inherent barrier properties of CMMA coatings as evidenced by electrochemical impedance spectroscopy (EIS). Corrosion resistance afforded by Zn-Fe CMMA coatings are explained in terms of the n-type semiconductor films at the interface, supported by Mott-Schottky’s plot. It was observed that the alloy with high w(Fe) on the top showed better corrosion resistance compared to that with the less w(Fe) on top. At optimum SCCD’s of 3.0—5.5 A•dm－2, a Zn-Fe CMMA coatings with 600 sub layers showed ca. 45 times better corrosion resistance than conventional Zn-Fe alloy of the same thickness. The deposit showed no red rust even up to 1130 h in salt spray test.     

PAni-Co0.5Zn0.5Nd0.05Fe1.95O4纳米复合材料的制备及电磁损耗

采用原位聚合法制备了平均粒径约为80 nm的聚苯胺(Polyaniline, PAni)-Co0.5Zn0.5Nd0.05Fe1.95O4纳米复合材料. 采用X射线衍射仪(XRD)、透射电子显微镜(TEM)和傅里叶变换红外光谱(FTIR)等检测技术对其结构、形貌、电磁及微波吸收性能进行了研究. 结果表明, 在12.4~18.0 GHz测试频率范围内, 复合材料的介电损耗角正切(tanε)在0.22~0.34之间, 磁损耗角正切(tanμ)在0.27~0.35之间. 在频率为9.5 GHz处, 反射损耗达到最大值-7.31×10-29 C·m, 频带宽为4.5 GHz.     

Film formation of polymeric emulsions: Structure set-up and the pinhole effect characterized by microscopic techniques

Drying of emulsions of special polymeric core-shell latexes results in structured films and coatings with advantageous material properties. Here, we focus on so-called “container particles”, consisting of a low viscosity core with a low glass transition (poly(2-ethylhexyl methacrylate), PEtHMA), covered by a thin shell of a cross-linked rubber (poly(n-butyl acrylate), PBA). These particles can be regarded as model emulsions of reactive polymeric oils with a very high colloidal stability. The film formation of these latexes was studied by atomic force microscopy (AFM) in the tapping mode as well as by transmission electron microscopy (TEM). It is shown that the films stay nanostructured after the drying process, i. e. they exhibit both a controlled topography as well as a network superstructure originating from the characteristics of the original dispersions.

TEM allows to detect the whereabouts of the polar stabilizer. Both continous surfactant films as well as inverted micelles are found. A geometrically induced demixing phenomenon is found which enriches the polar components and might be the molecular reason for the so-called pinhole-effect, the failure of water-born coatings in contact with water.     

A template self-assembly strategy to synthesize free-standing TiO2-MO (M = Mg, Co, Ni, Cu or Zn) colloidal films

A series of binary free-standing colloidal films, TiO₂-MO (M = Mg, Co, Ni, Cu and Zn) have been synthesized via a self-assembly technology, utilizing sodium dodecyl sulfonate (SDS) as template and the mixture of titanium butoxide and MCl₂ as precursor. X-ray diffraction (XRD) and transmission electron microscope (TEM) have been employed to characterize TiO₂-MO samples. Results show that TiO₂-MO films are mainly composed by well-ordered nanostructures (e.g. mesoporous particles and lamellar pieces) and more importantly, the increased Ti(OC₄H₉)₄ precursor have significant effect on modifying the as-synthesized nanostructures. A structural model based on SDS micellar template, the complex metallic oxide precursor and charge-density matching between the template and precursor has been proposed. Remarkably, this template self-assembly method has a potential to design a variety of functional multicomponent materials with high-ordered nanostructures, such as high gas sensing SnO₂-ZnO films.     

Solvent dependent growth of fibrous and non-fibrous nanocrystalline thin films of ZnO

Zinc oxide thin films were prepared from three different solvents using the sol–gel technique. Zinc acetate was used as the source of Zn, and the solvents ethanol, 2-methoxy ethanol and ethylene glycol were used to prepare the sols. ZnO thin films were deposited on glass microslides by pre-heating dip coated sol layers, following which they were finally annealed at 450 °C for half an hour. The films were characterized using structural, morphological and optical techniques. XRD studies show that the films grown from all the three solvents were single phase, highly oriented (along the c axis) ZnO having the wurzite structure. Optical transmission and photoluminescence spectra confirm the good quality of the ZnO films. SEM and AFM images show that the surfaces of the ZnO films, obtained using the first two (more volatile) solvents, consist of striations or ridges of height around 100–400 nm and are made up of nanoparticles 20–40 nm in size. The surfaces of the films produced from the less volatile third solvent are however smooth and devoid of striations although they are also covered with nanoparticles.     

Influence of pH variation on structural,optical, and superparamagnetic behavior of Ni-doped ZnO (X=0.02) using a solvothermal method

Zn1-xNixO nanoparticles at a concentration (2%) with pH variation (4, 5, 8 and 9) are successfully synthesized using the solvothermal method. ZnO nanoparticle has a hexagonal wurtzite structure when synthesized at acidic and basic conditions. In pH, the solution is calculated from 4 to 9 by the composed addition of NaOH and HCl. The structural properties are studied from XRD and TEM. The average particle size is found to be 13.2 nm using the Debye Scherrer formula and optical properties are analyzed through UV–Visible, FTIR, & PL. From the absorption spectra, it is observed that the bandgap energy is inversely proportional to the particle size. UV–Vis and PL are used to study the optical behavior of the samples. The magnetic behavior of Zn1-xNixO exhibit changing behavior from paramagnetic to superparamagnetic structure with increases in their pH values.     

核壳结构Ni0.5Zn0.5Fe2O4/PANI复合纳米材料的制备及表征

采用微乳液法制备出Ni0.5Zn0.5 Fe2O4纳米颗粒以及Ni0.5Zn0.5Fe2O4/PANI核壳结构复合纳米材料,借助FT-IR、XRD、SEM、TEM、VSM等分析手段研究了材料的形貌、结构与磁性能.结果表明:得到的Ni0.5Zn0.5Fe2O4纳米颗粒平均粒径为20hm左右,Ni0.5Zn0.5 Fe2O...     

Role of the interaction between forming nanocrystals and glass surface on the structure and properties of ZnO-based films

The interaction between glass surface and forming nanocrystals plays the important role in the formation of thin ZnO coatings crystal structure. The comparative study of the crystal structure of thin ZnO-based films and powders having similar chemical compositions was performed with the use of SEM, XRD analysis, optical, and luminescent spectroscopy. The influence of different coatings parameters (chemical composition, thickness) on the spectroscopic and morphological properties of thin films and powders reveals the structural features of the interaction between forming ZnO nanocrystals and glass surface. ZnO–SnO₂ coatings and powders were prepared by liquid polymer-salt technique. This method provides the close contact between the coatings’ precursors with a surface of the glass during both the nucleation and the initial growth stage of forming oxide crystals. The interaction of nanocrystals and substrate surface is responsible for the texture formation in the ZnO films and determines some features of their optical properties.     

Biomimetic silver-containing colloids of poly(2-methacryloyloxyethyl phosphorylcholine) and their film-formation properties

The synthesis of stable dispersions of hybrid colloids comprising copolymers of biocompatible 2-hydroxyethyl methacrylate (HEMA) and zwitterionic, biomimetic 2-methacryloyloxyethyl phosphorylcholine (MPC) incorporating antibacterial AgBF(4) by inverse miniemulsion is described. The prepared hybrid colloids were designed to provide both antibacterial and antifouling properties for the formation of interesting, multifunctional films. The obtained particles had sizes in the range of 130-160 nm with two different weight ratios of MPC to HEMA (1:10 and 2:5) and AgBF(4) contents between 0% and 15%. The silver salt takes on the role of the lipophobe in stabilizing the miniemulsion droplets against Ostwald ripening and is reduced after polymerization to Ag nanoparticles by gaseous hydrazine. Subsequently, the hybrid particles are transformed into smooth and stable films with thicknesses between 145 and 225 nm by simple drop casting and solvent annealing. The dispersions and films were thoroughly characterized by DLS, TEM, SEM, EDX, TGA, UV-vis spectroscopy, ICP-OES, XRD, AFM, and contact angle measurements. After immersion into water, the films did not show detectable leakage of silver, so they could be employed as dual-functional antifouling and antibacterial coatings.     

Sol-Gel Deposition of ZrO2 Films in Air and in Oxygen-Free Atmospheres for Chemical Protection of 304 Stainless Steel: A Comparative Corrosion Study

ZrO₂ coatings for corrosion protection were deposited on 304 stainless steel by sol-gel method using zirconium propoxide as precursor and densified in air and in oxygen-free (argon or nitrogen) atmospheres. XRD and IR data of the films were practically independent of the atmosphere used in the densification step showing that the ceramic oxide is properly formed from the precursor. The corrosion behavior of the stainless steel substrate was studied by potentiodynamic polarization curves in the absence and the presence of ZrO₂ coatings prepared in air, argon or nitrogen. The coatings extended the lifetime of the material by a factor of almost eight in a very aggressive environment, independently of the preparation procedure. The possibility of depositing pure or mixed oxide films by sol-gel methods in the absence of additional oxygen will allow the preparation of specific coatings onto oxygen-reactive substrates.     

Combinatorial study of WInZnO films deposited by rf magnetron co-sputtering

The compositional dependence of co-sputtered tungsten indium zinc oxide (WInZnO) film properties was first investigated by means of a combinatorial technique. Indium zinc oxide (IZO) and WO₃ targets were used with different target power. W composition ratio [W/(In+Zn+W)] was varied between 3 and 30 at% and film thickness was reduced as the sample position moved toward WO₃ target. Furthermore, the optical bandgap energy increased gradually, which might be affected by the reduction in film thickness. All the WInZnO films showed an amorphous phase regardless of the W/(In+Zn+W) ratio. As the W/(In+Zn+W) ratio in WInZnO films increased, the carrier concentration was restricted, causing the increase in electrical resistivity. W cations worked as oxygen binders in determining the electronic properties, resulting in suppressing the formation of oxygen vacancies. Consequentially, W metal cations were effectively incorporated into the WInZnO films as a suppressor against the oxygen vacancies and the carrier generation by employing the combinatorial technique.     

溶剂热合成法制备(Zn,Hg)S微晶和薄膜

近年来，由于Ⅱ～Ⅵ族半导体纳米材料的特殊物理、化学性质及其在半导体、光学器件、激光二极管、IR探测器等方面的广泛应用，它们的制备和表征引起了人们越来越大的兴趣犤１～１１犦。现在（Zn，Hg）S微晶正被广泛而深入的研究和应用。例如：一种发蓝光的激光二极管已经设计成功，它包含一夹在两衬层间的活性层，无论是在衬层还是在活性层中都包含有（Zn，Hg）S犤５犦。Sugao也曾报道过一种以（Zn，Hg）S为基础的半导体激光器件犤６犦。Parkin曾用MCl２（M＝Zn，Cd，Hg）和Li２E（E＝O，S，Se，Te）混合热解法制备ME或MxM'yS…     

Transmission electron microscopy and X-Ray diffraction analysis of aluminum-induced crystallization of amorphous silicon in alpha-Si:H/Al and Al/alpha-Si:H structures.

Solid phase crystallization of plasma-enhanced chemical-vapor-deposited (PECVD) amorphous silicon (alpha-Si:H) in alpha-Si:H/Al and Al/alpha-Si:H structures has been investigated using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Radiative heating has been used to anneal films deposited on carbon-coated nickel (Ni) grids at temperatures between 200 and 400 degrees C for TEM studies. alpha-Si:H films were deposited on c-Si substrates using high vacuum (HV) PECVD for the XRD studies. TEM studies show that crystallization of alpha-Si:H occurs at 200 degrees C when Al film is deposited on top of the alpha-Si:H film. Similar behavior was observed in the XRD studies. In the case of alpha-Si:H deposited on top of Al films, the crystallization could not be observed at 400 degrees C by TEM and even up to 500 degrees C as seen by XRD.