时间、pH和Cl~-对既成膜管线钢腐蚀电化学行为的影响

采用极化曲线和EIS技术研究了时间、pH和Cl-对既成膜管线钢X65和X70腐蚀电化学行为的影响。结果表明,两种既成膜管线钢的电化学阻抗谱均由高频容抗和低频感抗组成,含两个时间常数;各条件下形成的既成膜覆盖度较高但致密性不好,发生进一步活性溶解有限;时间、pH和Cl-对腐蚀电化学行为的影响与既成膜的特性密切相关,当成膜充分且无内应力破裂时,既成膜X70钢比X65更难发生进一步腐蚀,且对Cl-浓度变化不敏感。     

Detectability of corrosion damage with circumferential guided waves in reflection and transmission

There is an increasing interest in high frequency short range guided waves to screen or monitor for corrosion. This contrasts with long range guided waves (LRGWs) which screen pipes for large patches of corrosion and have been successfully used in corrosion management for the past twenty years. The fundamental setup described in this paper uses circumferential guided waves, which are excited at a single location on a pipe and travel around the pipe wall and are detected at the same location. The study uses a finite element model assisted method to evaluate the detection capability of two short range circumferential guided wave setups which use both the reflected and transmitted signals. The setups themselves consist of either an axial array of transducers, for monitoring, or a single transducer which axially scans a pipe. Both setups have an array or scan pitch between either adjacent transducers or measurements. The detection capability of the fundamental Lamb wave modes (A0 and S0) in both reflection and transmission have been compared, as well as a hybrid shear horizontal wave setup, which uses the SH0 mode in reflection and the SH1 mode in transmission. A sensitivity analysis was conducted using two separate methods to determine the probability of detection (POD) for either the reflection or transmission signals. Both methods determine a POD for a specific defect, noise level, and array or scan pitch. Probability images are produced which map the POD for a range of defect sizes. For the parameters investigated in this study, it was found that in transmission large diameter defects have a higher detectability, whereas deep, narrow diameter defects are more detectable in reflection. A generalised overview of the sensitivity of short range guided waves is presented by combining both the reflection and transmission PODs. The data fused sensitivity of the S0 and SH hybrid modes are given as 0.6% and 0.75% cross sectional area (CSA) respectively, allowing for the comparison with LRGWs. The A0 mode was excluded from the POD analysis because it was much less sensitive than the other two modes.     

Simflowny: A general-purpose platform for the management of physical models and simulation problems

Simflowny is a software platform which aims to formalize the main elements of a simulation flow. It allows users to manage (i) formal representations of physical models based on Initial Value Problems (hyperbolic, parabolic and mixed-type partial differential equations), (ii) simulation problems based on such models, and (iii) discretization schemes to translate the problem to a finite mesh. Additionally, Simflowny generates automatically code for general-purpose simulation frameworks. This paper first presents an introductory example of such problems. Then, formal representations are explained. Afterwards, it summarizes the platform’s architecture. Finally, validation results are provided.     

Influence of Inactivation Treatment of Ship's Ballast Water on Corrosion Resistance of Ship Steel Plate

The effect of seawater after ultraviolet inactivation on corrosion of a shipbuilding steel plate was investigated by means of natural corrosion potential experiments and immersion corrosion test. The effects of natural seawater and treated seawater after ultraviolet inactivation on corrosion of the selected steel plate samples were compared with each other. The results showed that there was no obvious change in the chemical composition of treated seawater compared with natural seawater. The corrosion potential slightly increased by 10 mV, whereas the corrosion rate rose significantly by 20%. The experiments verified the naturally formed biofilm in the natural seawater for the inhibition of corrosion on the shipbuilding steel plate. The possible influences of ballast water treatment on biofilm by ultraviolet and electrolysis inactivation under the condition of practical usage were also investigated. And it was found that ballast water treatment methods with no continuous disinfection could protect original tank biofilm structure, reducing the intensity of tank corrosion.     

应用热波成像技术检测飞机结构隐蔽腐蚀的实验研究

利用热波成像技术,对加速腐蚀试样和实际飞机结构腐蚀件进行了隐蔽腐蚀检测的实验研究。结果表明:这一技术可以很好地检测出隐蔽腐蚀,不受腐蚀产物残留与否以及表面漆层的影响,对于剥层腐蚀特别有效;该方法获得的腐蚀坑的图像细节丰富、直观易懂;同时,该技术能够检测胶结缝内部的缺胶和脱胶。     

Do ‘passive’ medical titanium surfaces deteriorate in service in the absence of wear?

Globally, more than 1000 tonnes of titanium (Ti) is implanted into patients in the form of biomedical devices on an annual basis. Ti is perceived to be ‘biocompatible’ owing to the presence of a robust passive oxide film (approx. 4 nm thick) at the metal surface. However, surface deterioration can lead to the release of Ti ions, and particles can arise as the result of wear and/or corrosion processes. This surface deterioration can result in peri-implant inflammation, leading to the premature loss of the implanted device or the requirement for surgical revision. Soft tissues surrounding commercially pure cranial anchorage devices (bone-anchored hearing aid) were investigated using synchrotron X-ray micro-fluorescence spectroscopy and X-ray absorption near edge structure. Here, we present the first experimental evidence that minimal load-bearing Ti implants, which are not subjected to macroscopic wear processes, can release Ti debris into the surrounding soft tissue. As such debris has been shown to be pro-inflammatory, we propose that such distributions of Ti are likely to effect to the service life of the device.     

干粉煤气化装置配套变换装置中的腐蚀

简述了干粉煤气化装置配套变换装置中的腐蚀种类和腐蚀机理,并对相应的选材要求进行了说明。     

Influence of corrosion on the interface between zinc phosphate steel fiber and cement

The interface bond between steel fibers and concrete matrix is a key factor influencing bearing capacity of steel fiber reinforced concrete (SFRC). In order to improve the interface bond strength and corrosion resistance, a kind of method was put forward by depositing zinc phosphate (ZnPh) coating on steel fiber surface in this paper. The corrosion behavior was investigated in 5% NaCl solution by using linear polarization measurement. Microstructure analysis (SEM and EDX) and fiber pull‐out test in combination with linear polarization measurement were carried out. The results prove that ZnPh coatings fabricated on the carbon steel surface can not only protect steel fiber against corrosion, but also enhance the mechanical interlocking bonds between fibers and matrix.     

Acoustic emission characterization of steel in H2S solution subjected to tensile load

Abstract

This paper investigates the characteristics of acoustic emission (AE) signals generated from hydrogen induced cracking (HIC) and sulfide stress corrosion cracking (SSCC) for a medium strength steel in hydrogen sulfide (H₂S) solution. The experiments performed in this study include the constant load test (CLT) and the constant extension rate test (CERT).

From the results of the CLT, the AE count rate caused by SSCC was found to be much higher than that resulted from the HIC; and the increase of the AE count rate was observed to be approximately proportional to the increase of the applied loading. In addition, the AE frequency distribution diagrams obtained from these tests were found to contain potential information for distinguishing the mechanisms of HIC and SSCC. From the results of CERT, the AE signals detected from the specimens tested in the H₂S solution were compared with those obtained from the specimens tested in the air. In addition, the AE count rate detected from the tensile specimens was studied according to the different deformation stages of the specimens. From this study, the variation of the AE count rate in each deformation stage was described.