电解质对锌在薄层液膜下腐蚀规律的影响

设计了一套适合于研究金属材料在薄层液膜下腐蚀的三电极电化学测量电池。Cl^-浓度的增大，促进了Zn在大量溶液中的阳极反应，降低了传递电阻和自腐蚀电位，从而导致腐蚀速率增大。在0.01mol/L的NaCl溶液中，随着液膜厚度的减小，传递电阻增大，腐蚀速度降低。在同浓度、不同电解质的大量溶液中，Na2SO4溶液对Zn的腐蚀最严重，其次是NaN03，腐蚀最轻的是NaCl；而在薄层液膜下，对Zn的腐蚀作用最明显的是NaCl；其次是Na2SO4；再次是NaN03，最轻的是Na2CO3。     

Cerium(III) chloride and sodium octylthiopropionate as an effective inhibitor mixture for zinc corrosion in 0.5 M NaCl

It has been reported that cerium(III) chloride CeCl₃ and sodium octylthiopropionate C₈H₁₇S(CH₂)₂COONa (NaOTP) are effective inhibitors for zinc corrosion in 0.5 M NaCl. In this study, synergistic inhibition of zinc corrosion in an aerated 0.5 M NaCl solution by a mixture of these inhibitors was investigated by polarization measurements after immersion of a zinc electrode in the solution for many hours. The inhibition efficiency of 1×10⁻⁴ M CeCl₃ plus 1×10⁻⁵ M NaOTP mixture was high, 95.1% after both 3 and 120 h. X-ray photoelectron spectroscopy and electron-probe microanalysis for the inhibited electrode revealed that the zinc surface was covered with a protective film composed of an hydrated or hydroxylated Ce-rich oxide, a small amount of Zn(OH)₂ and a trace of Zn(OTP)₂ chelate. The inhibition effect of 1×10⁻⁵ M NaOTP in the NaCl solution for the zinc electrode previously treated in 1×10⁻³ M CeCl₃ for 30 min was also examined, indicating a higher inhibition efficiency, 96.3% after immersion of the electrode in the solution for 120 h.     

On the pitting corrosion currents of zinc by chloride anions

The changes in the pitting corrosion current density with time on zinc electrode concerning the concentration of both the passivating borate and the aggressive chloride anions were followed using a simple electrolytic cell. The pitting corrosion currents started to flow after an induction period, τ. This period is found to be a function of the concentration of Cl⁻ anion, according to the relation logτ=β−γlogC_Cl⁻. The pitting corrosion currents finally reached a steady-state value, which depended on the concentration of both B₄O₇²⁻ and Cl⁻ anions. At a constant B₄O₇²⁻ anion concentration, the pitting corrosion current varied with the concentration of Cl⁻ anion according to the relation logi_pit=a₁+b₁logC_Cl⁻. It also varies at constant Cl⁻ anion concentration and various B₄O₇²⁻ anion concentration according to the relation logi_pit=a₂−b₂logC_B4O7²⁻. The susceptibility of the passivating zinc to pitting corrosion was found to be increasing as the temperature and pH of the solution increases. Results are discussed on the basis of adsorption of the aggressive anion on the passivating film, followed by penetration through the film and incorporation in it. This undermines the oxide film and causes pitting corrosion.     

Zinc modified polypyrrole coating on mild steel

Polypyrrole (PPy) films (∼ 1.7 μm thick) have been electrodeposited on mild steel (MS) substrates from 0.1 M pyrrole containing aqueous oxalic acid solution, by using cyclic voltammetry technique. Then, the polymer coatings were modified with deposition of zinc particles (∼ 1 mg/cm²), at a constant potential value of − 1.20 V in 0.2 M ZnSO₄ solution. The corrosion performance of zinc modified PPy coating has been investigated in 3.5% NaCl solution, by using electrochemical impedance spectroscopy and anodic polarisation curves. Also, the corrosion behaviours of zinc modified PPy coated platinum and single PPy coated MS samples have been investigated, for comparison. It was shown that zinc modified coating exhibited very low permeability and provided important cathodic protection to MS for considerably long immersion period. The voluminous zinc corrosion products are formed during exposure time in aggressive solution, giving rise to a blocking effect on the porous structure and led to effective barrier behaviour of zinc modified PPy coating, even after 96 h of exposure time to corrosive solution.     

Annealing effects on the structural, electrical and H2 sensing properties of transparent ZnO thin films, grown by pulsed laser deposition

Transparent zinc oxide thin films were grown by reactive pulsed laser deposition on glass substrates. The substrates were kept at 200 °C constant temperature. Post-deposition heat treatment, applied to further promote crystallization and overcome any oxygen deficiency, yielded transparent thin films. Structural investigations carried out by atomic force microscopy (AFM) and X-ray diffraction (XRD), have shown a strong influence of deposition technique parameters and post-annealing on the crystallinity of the zinc oxide films. The gas sensing characteristics of these films were investigated towards different hydrogen concentrations (5000-30,000 ppm) at a selected operating temperature within the 150-230 °C range.     

A task specific basic ionic liquid for synthesis of flower-like ZnO by hydrothermal method

Flower-like ZnO morphology, with different shapes, have been successfully synthesized via a novel and environment-friendly hydrothermal method using zinc acetate and a task specific dicationic dibasic ionic liquid, [mmpim]₂[OH]₂, which plays an important role in fabrication of ZnO structure. The structure and morphology of the product were characterized by X-ray diffraction and scanning electron microscopy, which show different flower-like morphologies. Photoluminescence spectrum of the product exhibits a strong ultraviolet emission at 391 nm and two weak blue-green emissions at about 450 and 500 nm.     

Characterization of the corrosion products of electrodeposited Zn, Zn–Co and Zn–Mn alloys coatings

The morphology, composition, phase composition and corrosion products of coatings of pure Zn (obtained from two types of electrolytic bath: an acidic bath (Zn_acid) and a cyanide-free alkaline bath (Zn_alkaline)) and of Zn–Mn and Zn–Co alloys on steel substrates were studied. To achieve this, diverse techniques were used, including polarization curves, atomic force microscopy (AFM), scanning electron microscopy (SEM), glow discharge spectroscopy (GDS), X-ray diffraction (XRD), and the salt spray test. In the salt spray test, the exposure time required for the coatings to exhibit red corrosion (associated with the oxidation of steel) decreased in the following order: Zn–Mn_(432h) > Zn–Co_(429h) > Zn_{alkaline(298h)} > Zn_acid(216h). The shorter exposure times required for corrosion of the pure Zn coatings are related to the coating composition and the crystallographic structure. Analysis of the corrosion products disclosed that Zn₅(OH)₈Cl₂·H₂O was a corrosion product of all of the coatings tested. However, the formation of oxides of manganese (MnO, Mn_0.98O₂, Mn₅O₈) in the Zn–Mn coating, and the formation of the hydroxide Zn₂Co₃(OH)₁₀·2H₂O in the Zn–Co coating, produced more compact and stable passive layers, with lower dissolution rates.     

VxWorks汉字的显示支持

VxWorks作为嵌入式实时操作系统的龙头老大．在国内应用已非常广泛，其中包括工业控制、医疗设备、家庭视听、车栽电子等许多需要本地显示的行业。作为国内的显示应用，汉字显示是必不可少的，而VxWorks原厂商没有直接提供完备的汉字显示的解决方案．本文就这个热点论题．通过对汉字编码以及VxWorks显示组件的分析．具体给出一种汉字显示的方案。     

Temperature effects on ZnO electrodeposition

A thermochemical study of the temperature effects on the Zn-Cl-H₂O system by means of potential-pH, solubility and species repartition diagrams is presented with the view to better understand the effect of temperature on the deposition mechanism and composition of zinc oxide thin films. These calculations have been completed by film preparation at different temperatures between room temperature and 90 °C. Below 34 °C, we observe the absence of continuous film growth and surface passivation. The oxide nucleation and film growth start above 34 °C, whereas the optimum film transparency and crystallinity is obtained from 40 °C. Above, the main effect of the temperature is to raise the film texturation with the c-axis perpendicular to the substrate surface.