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.     

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.     

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).     

LED的寿命,你真正理解了吗?

LED技术起始于半导体行业,却带给照明行业应用上的大发展。作为一个新兴事物,有很多问题都在探索当中。LED一个显著的特点就是超长寿命。但没有确切的试验,这超长寿命是如何得来的?它与传统照明理解的寿命有什么不同吗?本文将从LED寿命这个看似简单的问题作为出发点,来系统的分析和梳理LED元件及系统的寿命问题。通过比较与传统照明的异同点,分析当今最新标准来帮助LED的使用者和系统制造商理解和推导真正的LED的寿命。     

基于间隔的图模一体化电网拓扑的分析方法

间隔是一组相互电气关联的完成一定功能的设备集合。本文基于图模一体化编辑工具的电网编辑工具形成的原始静态拓扑,提出了一种面向间隔的分析方法,将变电站中的设备按包含了基本连接关系的间隔进行归类,并且将结果保存在关系数据库中。生成的间隔拓扑可以提供给倒闸规则生成,间隔状态分析和变电所、调度智能倒闸开票所用。基于B/S模式的实际应用,证明了该方法的可靠性。     

基于B/S模式的电厂工作票系统

在对传统的Web三层结构进行改进的基础上, 以.NET为软件平台设计开发了一套基于B/S模式的实用化工作票系统。系统提供了手工填写和标准票两种开票方式,并实现了工作票流转过程中不同级别权限的控制以及对工作票的管理等。该工作票系统具有较强的适应性及灵活性,对页面及接口模块作相应的改动,即可适应不同系统的要求。该系统在电厂的长期运行及其良好的使用效果,证明了本系统的有效性和正确性。     

基于STC12C系列单片机的DS18B20编程

针对新一代高性能单时钟／机器周期的STC12C系列单片机由于执行速度远高于传统的51单片机而不能直接使用原有单片机程序的问题,采用Keil软件的性能分析器来计算Atmel单片机的执行时间;通过手工计算修改程序段的执行时间,使STC12C系列单片机的执行时间满足数字温度传感器DS18B20的时序要求。测试结果表明STC12C2052能正确读取DS18B20的温度转换值,此方法对于具有时序要求的可编程器件的使用具有一定的参考价值。     

基于H.264的时间可分级编码结构的研究

阐述了基于H.264/AVC的时间可分级编码结构,等级B图像编码和运动补偿时间滤波(Motion-compensated Temporal Filtering,MCTF)技术,从编码效率和信噪比可分级两个方面对这两种技术进行了实验仿真,并从多个方面进行了对比和理论分析.