The effect of ionic liquids with imidazolium and pyridinium cations on the corrosion inhibition of mild steel in acidic environment

Ionic liquids with chemical formula 1,3-dioctadecylimidazolium bromide and N-Octadecylpyridinium bromide were synthesized by conventional and microwave-assisted reactions, respectively. Ionic liquids tested as corrosion inhibitors after polarization curves displayed corrosion protection efficiency within 82-88% at 100 ppm for mild steel in a 1 M aqueous solution of sulfuric acid. Standard free energy indicated that corrosion inhibition occurred by a chemical adsorption process. Surface analysis (SEM, EDX) completed by XRD and Mössbauer spectroscopy indicated the presence of carbon species pertaining to inhibitor and corrosion products, which was rationalized in an inhibition mechanism.     

Microstructure and analysis of oxide scales formed on Cr-Si-Ni compacts in air and H2O-containing atmosphere

The purpose of this study was to characterize the oxide scales formed on various Cr-Si-Ni compacts at 1273 K in air and H₂O-containing atmosphere by TEM. It was found that CrSi₂-(5-20)mass%Ni compacts form double layer scales, consisting of an outer Cr₂O₃ layer and an inner SiO₂ layer. The oxide scale changed from SiO₂- to Cr₂O₃-based scale with an increase in the Ni concentration. However, it was observed that the oxide scale formed in H₂O-containing atmospheres showed local SiO₂ growth into the substrate. This result suggests that the inward oxidant diffusion promotes the local growth of SiO₂ in the H₂O-containing atmospheres.     

Structure and water-barrier properties of vanadate-based corrosion inhibitor films

Uniform, crack-free vanadium-based corrosion inhibitor films were grown on aluminum alloy 2024. Neutron and X-ray reflectivity were utilized to investigate the structure, water-barrier properties and speciation of the inhibitor film. The top part of the alloy participates in the formation of vanadate film. The similarity of films prepared from H₂O and D₂O implies the vanadate film is not hydrated. The film has a layered structure with vanadium enriched at the alloy interface. The film behaves as an effective water barrier when the thickness is greater than 800 Å. Films grown without K₃Fe[CN]₆ accelerator are found to be extremely thin.     

Investigation of a single pit/defect evolution during the corrosion process

The investigation of a single pit/defect evolution due to localized corrosion that is commonly observed in a wide range of aluminum alloys is reported. Electrochemical experiments, microscopy and computations were used to predict stresses around a single pit/defect. It was observed that the pit/defect profile changing its shape from slightly conical to more hemispherical shape with increasing corrosion time. Also, stress distribution and levels vary non-linearly around a single pit/defect. The results also indicate that the evolution of these pits/defects may lead to nucleation of a crack over time, which can be predicted from these stresses.     

The corrosion behaviour of WC-VC-Co hardmetals in acidic media

The effect of increasing vanadium carbide (VC) content on the corrosion behaviour of tungsten carbide - 10 wt% cobalt hardmetals was investigated in 1 M hydrochloric (HCl), and sulphuric (H₂SO₄) acids solutions. Increasing VC content makes the open circuit potential (OCP) in the test solutions more negative than the base alloy. Specimens exhibited pseudo passivation in all the test solutions. Increasing VC led to decreasing corrosion current density. However, the corrosion current densities during chronoamperometric tests were lower for 0 wt% VC. XRD and Raman spectroscopy showed that hydrated WO₃ formed in the surface films of all specimens in hydrochloric acid (HCl), while hydrated vanadyl sulphate also formed for higher VC content specimens in sulphuric acid (H₂SO₄).     

Kinetics of isothermal decomposition in polycrystalline β CuAlBe alloys

The kinetics of the microstructural evolution of the metastable β phase during isothermal aging in a Cu–22.60Al–3.26Be (at%) polycrystalline shape memory alloy has been studied by electrical resistivity measurements and microscopical examinations. With an isothermal treatment at around 820 K, the alloy rapidly decomposes into γ₂ phase with dendritic morphology, while between 670 K and 760 K the formation of α′ phase followed by the eutectoid decomposition is observed. A TTT diagram was estimated and the stability boundaries of the β phase in the studied alloy were compared with those of other Cu-based shape memory alloys.     

焊接系统中参数显示的数字控制设计

为了克服焊接系统中模拟控制带来的困难,介绍了一种自动埋弧焊数字控制系统参数显示的设计方法,该设计方法适用于各种焊接系统中行走电机速度、送丝电机速度和系统其他数据的显示。控制系统以DSP为中央处理器,以ARM作为系统专用液晶显示芯片,控制器之间通过串行接口交换数据。由ARM芯片处理焊接系统数据的设置、显示、记忆和管理,使埋弧焊机成为一个真正的智能焊接系统。     

社区OA办公系统的设计与实现

科技高速发展的今天,传统的社区办公方式渐渐在社区管理中变得力不从心。工作效率低已经成为妨碍社区管理的主要问题,而社区OA办公系统正式处理这一问题的主要手段。系统采用B/S架构、SQL Server数据库、MVC模式等实现社区OA系统。系统具有办事处日常处理、社区工作人员交流区、文件的上传和下发、社区通讯录、管理社区的增加与合并等功能。管理员对系统整体进行管理、对社区人员和办事处人员进行管理。     

WCDMA无线网络规划探讨

主要介绍了WCDMA无线网络规划的特点、流程和方法,重点分析了用现网话务预测话务分布和网络规划的结果配置基站信道板,实现了科学规划和合理设计,进而提高了网络投资效益.     

Heterostructured dysprosium vanadate – ZnO for photo-electrocatalytic and self-cleaning applications

In this article, we report fabrication of 5 wt% of Dy as DyVO₄ supported ZnO by template-free hydrothermal-thermal decomposition method and its photocatalytic activity towards degradation of azo dyes Rhodamine-B (Rh-B) and Trypan Blue (TB) in solar light, Electrocatalytic activity in methanol oxidation and Self-cleaning properties. The as prepared DyVO₄-ZnO was characterized by surface analytical and spectroscopic techniques. The results suggested that Dysprosium vanadate doping on ZnO has increased its photocatalytic efficiency with high reusability. DyVO₄-ZnO exhibits higher electrocatalytic activity than prepared ZnO for methanol electrooxidation in alkaline medium, revealing its promising potential as the anode in direct methanol fuel cells. Hydrophobicity of ZnO increases by doping of DyVO_4.