Synthesis and performance of electroless Ni–P–TiCN composite coatings on Al substrate

Electroless Ni–P and Ni–P–TiCN composite coatings have been deposited successfully on Al substrates. Scanning electron microscopy (SEM) and energy dispersive X‐ray (EDX) techniques were applied to study the surface morphology and the chemical composition of the deposited films. Moreover, X‐ray diffraction (XRD) proved that Ni–P and Ni–P–TiCN deposits have amorphous structures. The properties of Ni–P–TiCN/Al composite films such as hardness, corrosion resistance and electrocatalytic activity were examined and compared with that of Ni–P/Al film. The results of hardness measurements reveal that the presence of TiCN particles with Ni–P matrix improves its hardness. Additionally, the performance against corrosion was examined using Tafel lines and electrochemical impedance spectroscopy techniques in both of 0.6 M NaCl and a mixture of 0.5 M H₂SO₄ with 2 ppm HF solutions. The results indicate that the incorporation of high dispersed TiCN particles into Ni–P matrix led to a positive shift of the corrosion potential and an increase in the corrosion resistance for all aluminum substrates after their coating with Ni–P–TiCN. In addition, Ni–P–TiCN/Al electrodes showed a higher electrochemical catalytic activity and stability toward methanol oxidation in 0.5 M NaOH solution compared with that of Ni–P/Al. Copyright © 2014 John Wiley & Sons, Ltd.     

Characterization of Biodegradable Nanocomposite Films Prepared with Glutelin from Jatropha curcas L. by Response Surface Methodology and Infrared Spectroscopy

The water vapor permeability (WVP) and hardness of biodegradable nanocomposite films based on glutelin from Jatropha curcas L. were determined and the results were analyzed by response surface methodology (RSM). The effects of independent variables constituted by the plasticizer (glycerol), nanofiller (cloisite), and pH on the physical parameters were evaluated. The regression models obtained for each physical property adequately described the measurements used in the experimental design, with regression coefficients of 0.9513 and 0.9421 for WVP and hardness. The regression coefficients show that pH has the most significant effect on the WVP, whereas the cloisite content has the largest influence on the hardness of the nanocomposite film. Fourier transform infrared spectroscopy provided confirmation of the results obtained by RSM. Corroboration that the gluteline structure is in a similar form as the WVP and primarily influenced by pH was obtained using conventional and second derivative infrared spectra. However, the hardness of the film primarily depends on the cloisite content. This methodology may be useful for the design and elaboration of nanocomposite films based on J. curcas L. with specific barrier and mechanical properties.     

复合电沉积的最新研究动态

综述近年来国内外复合电沉积技术最新研究动态.重点探讨纳米复合镀层,电催化复合镀层以及光活性复合镀层等方面的研究现状和发展趋势.纳米复合镀层比一般的复合镀层具有更高的硬度,更好的耐磨性和耐蚀性;电催化复合镀层则可在纯金属电极,合金电极的基础上进一步降低电极反应的过电位.以金属氧化物,导电聚合物作为基质材料的电催化复合镀层已为现代复合电沉积技术开辟了一个新领域.     

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.     

Synthesis,Characterization, and Fluorescence Sensor Property of Polyurethane/Ag2S Nanostrips

A polyurethane/silver sulfide nanocomposite film was synthesized by a biomineralization sim-ulated method. The effect of the Ag₂S nanoparticles on the physical properties of the com-posite was studied by Fourier transform infrared, differential scanning calorimetry (DSC), scanning electron microscopy. The thermal stability of the composite was measured by DSC. The fluorescence emission of the nanocomposite films was found to be very sensitive to Ni(II) ions, with a small amount of Ni(II) ions making the emissions increase dramatically. The films are predicted to have the potential to be developed into excellent sensing films of Ni(II) ions in the water.     

Growth mechanism of Nb-doped TiO<Subscript>2</Subscript> sol–gel multilayer films characterized by SEM and focus/defocus TEM

TiO₂ and Nb-doped TiO₂ films were prepared by sol–gel processing, their microstructure was adjusted by varying the number of subsequent coating-firing cycles that resulted in final total film thickness of ~100 nm. When only few subsequent coatings are stacked (large single layer thickness) granular polycrystalline microstructures are observed. Doping with Nb reduces the crystallite size compared to the respective pure anatase films. When the single layer thickness is reduced, the film growth is successively dominated by the nucleation of subsequent films on the underlying crystalline material resulting in a columnar dense film structure. The multilayer architecture of such films can be demonstrated by defocus TEM imaging even if crystalline columns exceed single film boundaries. Results indicate that Nb is homogeneously incorporated into the anatase lattice by substitution of Ti, nevertheless the electric conductivity after H₂ post annealing is significantly lower than reported for analogous films prepared by magneton sputtering or pulsed laser deposition.     

Surface analysis and corrosion resistance of new nickel base thin film alloys

Electroless Zn–Ni–P thin films were deposited on low carbon steel from an alkaline non‐cyanide aqueous electrolyte. The newly developed ternary alloys structure and microstructure investigations were carried out via X‐ray diffraction and SEM. Chemical composition of the coatings was investigated via energy dispersive spectroscopy. Polarization tests were used to study the corrosion properties of the coatings in a 3.5 wt.% NaCl solution. The results confirmed the high corrosion resistance of Zn–Ni–P alloy plated steel sheet. The surface analysis of the thin film samples before and after corrosion was performed by XPS. The incorporation of Zn in Ni–P thin film is proven for all initial samples to be as a mixture of zinc and zinc oxide, while nickel exists in +2 and +3 oxidized states. A passive film of a mixture of oxide and hydroxide of zinc and nickel forms on the surface and prevents the Zn–Ni–P thin films from corrosion. Copyright © 2014 John Wiley & Sons, Ltd.     

Corrosion properties of nickel coatings obtained from aqueous and nonaqueous electrolytes

Nickel was deposited on a copper substrate from aqueous and nonaqueous ethanol electrolytes. X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy and chronovoltametry, scanning electron microscopy, and atomic force microscopy were used to study the effect of the solvent on the surface and corrosion properties of the Ni coatings formed. Unifom and relatively smooth Ni films were obtained as measured with microscopy techniques. The formation of a passive film in acidic, alkaline, and neutral chloride-containing media was confirmed with X-ray photoelectron spectroscopy. The water-based nickel-plating electrolyte makes it possible to deposit coatings with higher corrosion resistance as compared with coatings deposited from ethanol electrolyte in NaOH and NaCl media. The proposed mechanism of corrosion in a 0.5 M H₂SO₄ solution involves cycles of active-passive surface behavior due to its passivation by corrosion products.     

The synthesis and characterization of polyorganosiloxane nanoparticles from 3-mercaptopropyltrimethoxysilane for preparation of nanocomposite films via photoinitiated thiol-ene polymerization

This article describes the synthesis of modified silica nanoparticles (SiO₂-MPTMS) via the condensation reaction carried out between silanol moieties of silica nanoparticles and the trialkoxy silyl groups of (3-mercaptopropyl) trimethoxysilane (MPTMS). Then, SiO₂-MPTMS nanoparticles in certain amounts (0.5 wt %, 1 wt %, 2.5 wt % and 5 wt %) were incorporated into thiol-ene resins consisting of bisphenol A glycerolate dimethacrylate and trimethylolpropane tris(3-mercaptopropionate) to prepare nanocomposite films via the photoinitiated thiol-ene polymerization in presence of 2,2-Dimethoxy-2-phenylacetophenone 99% as a photoinitiator. Fourier transform infrared spectroscopy, dynamic light scattering, scanning transmission electron microscopy, thermal gravimetric analyzer, and X-ray photoelectron spectrometer were employed to characterize SiO₂-MPTMS nanoparticles. It was revealed that the nanosilica surface was successfully grafted by MPTMS with the grafting ratio of 22.9%. Properties of the nanocomposite films such as decomposition temperature, thermal glass transition temperature, tensile strength, hardness, and particle distribution were investigated and the results were compared with each other and neat film. The addition of MPTMS-modified silica particles did not improve the thermal stability of the films. In scanning electron microscopy study, it was seen that 2.5 wt % of these nanoparticles used as additives were about 200 nm in size and dispersed homogeneously in the polymer matrix. The increase in tensile strength of nanocomposite films compared to the neat film was measured as 77.3% maximum.     

The structure and tribological properties of aluminum/carbon nanocomposite thin films synthesized by reactive magnetron sputtering

Hydrogenated nanocomposite aluminum/carbon thin films (Al/a‐C:H) were fabricated on stainless steel and silicon wafer substrates via unbalanced reactive magnetron sputtering from an Al target in CH₄/Ar plasma. The composition and structure of Al/a‐C:H films were investigated by high‐resolution transmission electron microscope (HRTEM), XPS and micro‐Raman spectroscopy. Nanoindenter, interferometer and ball‐on‐disc tribometer were carried out to evaluate the hardness, internal stress and tribological properties of Al/a‐C:H films. HRTEM observations confirmed that the metallic Al nanocrystallites were uniformly dispersed in the amorphous carbon matrix. XPS and Raman analyses indicated that the sp² content increased with the increase of Al content in the films. Nanoindenter and interferometer tests exhibited that the uniform incorporation of Al nanocrystallites can diminish drastically the magnitude of internal stress with maintaining the higher hardness of as‐deposited films. Especially, the ball‐on‐disc tribometer measurements revealed that the nanocomposite film with 2.3 at.% Al content exhibited relatively better wear resistance and self‐lubrication performance with a friction coefficient of 0.06 and wear rate of 3.1 × 10^?16 m³/ N·m under ambient air, which can be attributed to the relatively higher hardness, the formation of continuous graphitized transfer film on counterface and the reduced reaction of oxygen with carbon. Copyright © 2010 John Wiley & Sons, Ltd.     

物理蒸镀Ni-Al镀膜与高速融射MCrAlY涂层之抗热循环氧化性比较

本研究乃以阴极电弧放电离子被覆技术在Inconel 6 0 0超合金上被覆Ni_Al镀层 ,与目前常用的高速融射CoCrAlY涂层同时进行 1 1 0 0℃高温循环氧化试验 ,比较二者的抗高温循环氧化性 .研究结果显示 :使用Ni52 Al4 8,Ni6 0 Al4 0 及Ni70 Al30 3种靶材分别得到富铝成份的Ni35Al6 5,Ni4 0 _Al6 0 以及Ni53Al4 7的镀膜 .在 1 1 0 0℃热循环氧化测试下 ,由于富铝的Ni_Al镀膜表面能快速生成Al2 O3层以阻止内部持续氧化 ,因而有较CoCrAlY涂层为低的氧化重量增加率     

Carbon-metal (Ni or Ti) nanocomposite thin films for functional applications

A comparison between structure and mechanical properties of dc sputtered C–Ni and C–Ti nanocomposite thin films has been made in the growth temperature range of 25–800 °C. C–Ni films undergo morphological and phase change at 400 °C deposition temperature, while the C–Ti films possess the same phase state and morphological character in the whole range of deposition temperatures. Despite the structural differences the dependence of hardness (H) and elastic modulus (E) on the deposition temperature shows very similar behavior. The same character of the hardness and modulus curves is mostly influenced by the structure and the morphology of the carbon matrix. The difference in absolute value between the H and E curves of C–Ni and C–Ti could be related to the C-metal bonds, chemical stability and mechanical properties of the corresponding carbide phase.     

Surface activation influencing the microstructure of Zn(Ca) phosphate coatings

Zinc and zinc calcium phosphate coatings on steel were formed by dipping in commercial baths. A surface activation with titanium phosphate influences not only the film morphology but also the composition of the conversion films. Qualitative phase analysis of the polycrystalline deposits reveals a typical phosphophyllite crystal growth apart from hopeite and scholzite respectively. The growth rate depends on the free surface of the steel; the contact area to the solution controls the rate of iron pickling.     

Thin films composed of multiwalled carbon nanotubes, gold nanoparticles and myoglobin for humidity detection at room temperature.

Optically transparent and electrically conductive nanocomposite thin films consisting of multiwalled carbon nanotubes (MWCNTs), gold nanoparticles (GNPs) and myoglobin molecules that glue GNPs and MWCNTs together are fabricated for the first time on glass substrates from aqueous solution. The nanocomposite thin film is capable of varying its resistance, impedance or optical transmittance at room temperature in response to changes in ambient humidity. The conductometric sensitivity to relative humidity (RH) of the nanocomposite thin film is compared with those of the pure and Mb-functionalized MWCNT layers. The pure MWCNT layer shows a small increase in its resistance with increasing RH due to the effect of p-type semiconducting nanotubes present in the film. In contrast, a four times higher sensitivity to RH is observed for both the nanocomposite and Mb-functionalized MWCNT thin films. The sensitivity enhancement is attributable to swelling of the thin films induced by water absorption in the presence of Mb molecules, which increases the inter-nanotube spacing and thereby causes a further increase of the film resistance. A humidity change as low as DeltaRH=0.3 % has been readily detected by conductometry using the nanocomposite thin film.     

Electrochemical Behavior of Dental Ni‐Cr Wirolloy Coated with Eco‐friendly Films in Artificial Saliva

The electrochemical corrosion behavior of the non‐precious Ni‐Cr Wirolloy, being used in dentistry, was investigated before and after applying of two types of eco‐friendly coatings, polyvinyl silsesquioxane (PVS) and nano‐hydroxyapatite (nHAP) separately in artificial saliva solution at 37 °C for 14 d of immersion. The study aimed to investigate the effectiveness of the introduced coating films in enhancing the corrosion resistance of the alloy, and in decreasing the leaching of the toxic Ni ions from the alloy into the environment. The electrochemical corrosion investigation methods used are; open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The evaluated results revealed that the electrochemically coated alloy with PVS. prepared at cathodic potential showed higher corrosion resistance and more stable film compared to that prepared by conventional dip‐coating method. At the same time, the nHAP electrochemically coated film provided the best anti‐corrosion properties over all examined time intervals. The obtained results were confirmed via surface analysis, which assured the formation of the prepared coatings on the alloy surface. Chemical analysis of the corrosion product/solutions showed that the effect of electrochemically deposited nHAP and PVS. polymer films in suppression of Ni ions leaching is similar and slightly higher than that of the chemically coated PVS. one; however, all of them are efficient in decreasing the leaching of the risky Ni ions into the solution.     

Development of multifunctional polydimethylsiloxane (PDMS)‐epoxy‐zinc oxide nanocomposite coatings for marine applications

Multifunctional epoxy‐polydimethylsiloxane nanocomposite coatings with antifouling and anticorrosion characteristics have been developed via in situ polymerization method at different loading (1, 3, and 6.5 wt.%) of ZnO nanoparticles to cater marine applications. A detailed comparative analysis has been carried out between epoxy‐polydimethylsiloxane control (EPC) and ZnO‐reinforced coatings to determine the influence of ZnO loading on various properties. The incorporation of ZnO in EPC led to increase in root mean square (RMS) roughness to 126.75 nm and improved hydrophobicity showing maximum contact angle of 123.5° with low surface energy of 19.75 mN/m of nanocomposite coating as compared with control coating. The differential scanning calorimetry (DSC) result indicated improved glass transition temperature of nanocomposite coatings with highest T_g obtained at 83.69°C in case of 1 wt.% loading of ZnO. The increase in hydrophobicity of the system was accompanied by upgraded anticorrosion performance exhibiting 98.8% corrosion inhibition efficiency (CIE) as compared with control coating and lower corrosion rate of 0.12 × 10^?3 mm/year. The Taber abrasion resistance and pull‐off adhesion strength results indicated an increment of 34.7% and 150.7%, respectively, in case of nanocomposite coating as compared with the control coating. The hardness of nanocomposite coatings was also improved, and maximum hardness was found to be 65.75 MPa for nanocomposite coating with 1 wt.% of ZnO. Our study showed that the nanocomposite coating was efficient in inhibiting accumulation of marine bacteria and preventing biofouling for more than 8 months. The developed environment‐friendly and efficient nanocomposite material has a promising future as a high‐performance anticorrosive and antifouling coating for marine applications.     

Preparation of nanostructure Ni doped CdO thin films by sol gel spin coating method

The nanostructure Ni-doped CdO films have been prepared by sol gel spin coating method. Atomic force microscopy results indicate that the CdO films are formed from the nanoparticles and the grain size is changed with nickel content. X-ray diffraction patterns of the films indicate that the undoped and Ni-doped CdO films have polycrystalline structure with a cubic sodium chloride structure, showing two main characteristic peaks assigned to the (111) and (200) planes. The optical band gap values of undoped and Ni-doped CdO films were determined by optical absorption method. The E_g values of the CdO films were found to be in the range of 2.26–2.60 eV. The E_g values of the CdO films increase with the content of Ni dopant (up to 6% Ni). It is evaluated that the optical band gap and grain size of the CdO film can be controlled by doping with nickel atoms.     

Impact of Al nanoparticles upon the microstructure and wear properties of Ni-Cr-Al nanocomposite coatings

Ni–7Cr and Ni–7Cr–2Al (wt.%) nanocomposite coatings were fabricated by co-electrodeposition of Ni with Cr (40 nm) or and Al (75 nm) nanoparticles from a nickel sulfate bath, their microstructure, friction and wear performance were comparably evaluated in order to elucidate the effect of Al nanoparticles on the properties of nanocomposite coatings. The results indicated that the co-deposition of minor Al nanoparticles significantly increases the microhardness and wear resistance because Al nanoparticles with surface amorphous oxides layers exert the dispersion-strengthening effect like Al₂O₃ nanoparticles.     

镍基彩色电沉积Cu_2O椭圆偏振光谱研究

应用电化学方法在Ni基底上沉积Cu2O彩色膜层以期提高装饰效果.X光电子能谱(XPS)、扫描电子显微镜(SEM)和能量色散谱(EDS)测试表明,膜层由Cu2O组成,沉积层光滑平整,且Cu2O层均匀覆盖Ni基底.椭圆偏振光谱表征不同沉积时间的膜层,提出膜层内存在由Ni逐渐变为Cu2O的过渡层,建立"空气—Cu2O层—过渡层—Ni基底"4层膜模型,并借助梯度有效介质近似解析椭圆偏振光谱,得到不同沉积时间的膜层厚度以及厚度随时间线性增长关系.     

Characteristics of Ti–Nb,Ti–Zr and Ti–Al containing hydrogenated carbon nitride films

Nanocomposite Me–C–N:H coatings (Me is TiNb, TiZr or TiAl), with relatively high non-metal/metal ratios, were prepared by cathodic arc method using TiNb, TiZr and TiAl alloy cathodes in a CH₄ + N₂ atmosphere. For comparison purposes, a-C–N:H films were also produced through evaporating a graphite cathode in a similar atmosphere. The films were characterized in terms of elemental and phase compositions, chemical bonds, texture, hardness, adhesion and friction behavior by GDOES, XPS, Raman spectroscopy and XRD techniques, surface profilometry, hardness and scratch adhesion measurements, and tribological tests. The nanocomposite films consisted of a mixture of crystalline metal carbonitride and amorphous carbon nitride. The non-metal/metal ratio in the films composition was found to range between 1.8 and 1.9. For the metal containing nanocomposites, grain size in the range 7–23 nm, depending on the metal nature, were determined. As compared with the a-C–N:H, the Me–C–N:H films exhibited a much higher hardness (up to about 39 GPa for Ti–Zr–C–N:H) and a better adhesion strength, while the coefficients of friction were somewhat higher (0.2–0.3 for Me–C–N:H and 0.1 for a-C–N:H).