Eis and XPS study of surface modification of 316LVM stainless steel after passivation

The effects of surface finish, nitric acid passivation and ageing in air on corrosion resistance of 316LVM stainless steel in 0.5% H₂SO₄ have been investigated by EIS, potentiodynamic polarization measurements and XPS. The results indicate that a smoother surface exhibits to a higher corrosion resistance. The effectiveness of the passivation treatment strongly depends on nitric acid concentration, passivation time and temperature. The passivation treatment significantly increases the corrosion resistance due to a high Cr content in the passive film and increased film thickness. Ageing after passivation increases the corrosion resistance whereas ageing before passivation has little effect.     

杂散电流干扰和阴极保护作用下碳钢腐蚀规律研究

目的探讨杂散电流和阴极保护二者共同作用对碳钢腐蚀的影响。方法在碳钢管表面手工涂刷涂层并制造小块破损点,研究Q235碳钢在涂层破损后,受单纯直流杂散电流干扰、单纯阴极保护以及二者共同作用时随时间变化的电化学交流阻抗图谱(EIS),通过图谱信息以及图谱数据拟合进行分析。结果所有条件下,Bode图低频阻抗和Nyquist图容抗弧半径都随时间延长而逐渐增加。通过图谱和数据拟合发现,单纯杂散电流条件下,杂散电流越大,电化学阻抗越小,浸泡15天时,20 m A杂散电流条件下的极化电阻达到200 m A条件下的4倍。阴极保护对杂散电流腐蚀具有防护作用,无论是单独施加阴保,还是杂散+阴保共同作用,-1000 m V(vs.CSE)与-850 m V(vs.CSE)横向对比,总是-1000 m V条件下的极化电阻更高。一定程度上,阴保电位越负,极化电阻越大,保护效果越好。结论在一定范围内,不论是单独施加,还是共同作用,总是杂散电流越小,阴极保护电位越负,对碳钢的保护效果越好,腐蚀程度越轻。利用电化学交流阻抗技术监测管道腐蚀状况是可行的。     

A study of oxygen reduction on improved Pt-WC/C electrocatalysts

Pt on a tungsten carbide nanocrystalline support (Pt-WC/C) has been prepared by the direct reduction of a platinum salt precursor combined with intermittent microwave heating (IMH). The Pt-WC/C electrocatalyst shows better performance for oxygen reduction in acidic media than that of pure Pt/C or Pt-WC/C prepared by a mechanical mixing method. The results reveal that the Pt-WC/C electrocatalyst prepared by present method is very active for oxygen reduction reaction (ORR) with an onset potential of 1.05 V versus standard hydrogen electrode (SHE) at ambient temperature, which is over 150 mV more positive compared to that of commercial Pt/C electrocatalysts.     

The effect of C60 doped interlayer for lifetime improvement of phosphorescent light emitting diodes

The effect of C60 doped interlayer between poly(3,4-ethylenedioxythiophene:poly(styrenesulfonate) (PEDOT) and light emitting layer on the lifetime of phosphorescent organic light emitting diodes was investigated by changing the C60 content from 0% to 3%. Doping of C60 in 1,3,5-tris(N,N-bis-(4,5-methoxyphenyl)-aminophenyl)benzol (TDAPB) resulted in the increase of lifetime by more than 100% compared with lifetime of non-doped devices.     

Passive testing of communicating systems with timeouts

ContextThe design of complex systems demands methodologies to analyze its correct behaviour. It is usual that a correct behaviour is determined by the compliance with temporal requirements. Currently, testing is the most used technology to validate the correctness of systems. Although several techniques that take into account time aspects have been proposed, most of them require the tester interacts with the system. However, if this is not possible, it is necessary to apply a passive testing approach where the tester monitors the behaviour of the system.ObjectiveThe aim of this paper is to propose a methodology to perform passive testing on communicating systems in which the behaviour of their components must fulfill temporal restrictions associated with both performance and delays/timeouts.MethodOur framework uses algorithms for checking traces collected from the systems against invariants which formally represent the most relevant properties that must be fulfilled by the system. In order to support the feasibility of the methodology, we have performed an empirical study on a complex system for automatic recognition of images based on a pipeline architecture. We have analyzed the correctness of the system’s behaviour with respect to a set of invariants. Finally, an experiment, based on mutations of the system, was conducted to study the level of detection of a set of invariants.ResultsDifferent errors were detected and fixed along the development of the system by means of the proposed methodology. The results of the experiments with the mutated versions of the system indicated that the designed set of invariants was more effective in finding errors associated to temporal aspects than those related to communication among components.ConclusionThe proposed technique has been shown to be very useful for analyzing complex timed systems, and find errors when the tester has no control over their behaviour.     

Structural Transformation by Crystal Engineering Endows Aqueous Zinc-Ion Batteries with Ultra-long Cyclability

Manganese oxide is a promising cathode material for aqueous zinc batteries. However, its weak structural stability, low electrical conductivity, and sluggish reaction kinetics lead to rapid capacity fading. Herein, a crystal engineering strategy is proposed to construct a novel MnO₂ cathode material. Both experimental results and theoretical calculations demonstrate that Al-doping plays a crucial role in phase transition and doping-superlattice structure construction, which stabilizes the structure of MnO₂ cathode materials, improves conductivity, and accelerates ion diffusion dynamics. As a result, 1.98% Al-doping MnO₂ (AlMO) cathode shows an incredible 15 000 cycle stability with a low capacity decay rate of 0.0014% per cycle at 4 A g⁻¹. Additionally, it provides superior specific capacity of 311.2 mAh g⁻¹ at 0.1 A g⁻¹ and excellent rate performance (145.2 mAh g⁻¹ at 5.0 A g⁻¹). To illustrate the potential of 1.98%AlMO to be applied in actual practice, flexible energy storage devices are fabricated and measured. These discoveries provide a new insight for structural transformation via crystal engineering, as well as a new avenue for the rational design of electrode material in other battery systems.