Edge Corrosion Research Articles

A novel technology for sequestration of corrosive ions in comparison with benzotriazole: a review

PurposeHexavalent chromium has been a benchmark corrosion inhibitor before it was phased out because of its carcinogenic properties. However, because it was phased out, many alternative corrosion inhibitors have been introduced but failed to meet the performance of this benchmark inhibitor. Consequently, benzotriazole (BTA) was reported to exhibit chromate-like inhibition performance. Subsequently, Intelli-ion was reported by researchers to exhibit chromate-like performance also with claims of being a unique alternative. This paper aims to review the inhibition performance of these two alternatives. Above all, promotes the unique inhibition performance of Intelli-ion that makes it suitable for application in many sectors.Design/methodology/approachIn this paper, the corrosion inhibition performances of BTA and Intelli-ion were compared systematically by reviewing some related literatures based on the opinion of the authors.FindingsDifferent methodologies for measuring the inhibition performance of BTA showed that it’s an inhibitor of choice. However, the cut edge corrosion performance of Intelli-ion and BTA corrosion inhibitors on galvanized steel of 55% Wt.% Al, 44% Wt.% Zn and 1% Wt.% Si in 5 Wt.% NaCl solution was compared when subjected to scanning vibrating electrode technique (SVET) for 24 h. The results showed faint blue-colored region depicting negative cathodic current density for the Intelli-ion while there was a high-intensity of red-colored region depicting a positive anodic current density for BTA. In other words, the Intelli-ion inhibitor had a better overall cut-edge corrosion inhibition performance than the BTA inhibitor.Originality/valueThis paper compares and further, summarizes the corrosion inhibition performance of Intelli-ion and BTA by evaluating SVET results from the literature. In addition, it serves as an overview and reference for the unique inhibition performance of Intelli-ion when applied in field applications.

Influence of polycarboxylate superplasticizer and polyacrylamide on mirror effect of fair-faced concrete

This work successfully prepared fair-faced concrete with mirror effect. The gray value standard deviation, porosity, crack rate and glossiness of the concrete surface were used to characterize the apparent quality of fair-faced concrete. The effect of polycarboxylate superplasticizer and polyacrylamide viscosity-modifying admixture on mirror effect of fair-faced concrete was investigated. The changes of hydration products and microstructure of fair-faced concrete were monitored by the measurements of X-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM) and mercury intrusion porosity (MIP), and the potential mechanism was analyzed. The results indicate that the polyacrylamide reduces the number and size of Ca(OH)2 and change the morphology of Ca(OH)2 crystals from large-size parallel stacking state to small-size edge corrosion structure. The polyacrylamide can refine the pore size of concrete, the most probable pore size at the optimum dosage is 13.73 nm, which is much lower than that at other dosages. The usage of the polycarboxylate superplasticizer will introduce air, which has adverse effect on the concrete surface. But polycarboxylate superplasticizer can also improve the flowability of concrete and make bubbles easy to discharge. The combined action of polycarboxylate superplasticizer and polyacrylamide contributes the fair-faced concrete for better mirror effect.

Corrosion inhibition alternatives and a novel chromate-like option: Review

Abstract Hexavalent chromium has dominated the corrosion inhibitor’s market as a benchmark alternative due to its unparalleled excellent corrosion inhibition properties. However, it was phased out because of its carcinogenic effects. Subsequently, many alternative inhibitors have been introduced into the inhibitor’s market but failed to meet the performance of this benchmark inhibitor. Recently, intelli-ion (AX1) was reported as a new alternative to hexavalent chromium based on Scanning Kelvin Probe (SKP) carried out on hot-dip galvanized steel (HDG) substrates for chromate and intelli-ion inhibitors. The intelli-ion system showed impressive performance at generation 1, with increased protection offered by the generation 2 product, showing no visible failure after 4 days test procedure. To further validate this, the cut edge corrosion performance of intelli-ion (AX1) and benzotriazole (BTA) was studied on galvanized steel specimen in 5wt.% NaCl solution using Scanning Vibrating Electrode Technique (SVET). From the SVET current density maps of AX1 (specimen A and B) vs. BTA (specimen C) after 24 h in 5 wt.% NaCl solution. The AX1 inhibitor had a better overall cut edge corrosion inhibition performance than the BTA.

Effect of polyvinyl alcohol on the performance of carbon fixation foam concrete

The introduction of carbon fixation components (calcium hydroxide) can improve the carbon fixation performance of foam concrete, however, it will reduce its mechanical properties. In order to solve the adverse effects of carbon fixation components on the mechanical properties and optimize carbon absorption properties, a specific amount of polyvinyl alcohol (PVA) is incorporated. In this study, a serial of test was employed to study the production process of nano-modified foam, and some basic properties of the foam concrete of interest. Further, the micromorphology and pore structure of the samples were analyzed by scanning electron microscope and mercury injection test. The evolution of mineral phases was examined by X-ray diffraction and thermogravimetric analysis. The results show that the carbon sequestration efficiency of foam concrete increases significantly as the amount of calcium hydroxide is increased, however, the cementitious properties of materials deteriorate, resulting in a decrease in strength. When PVA is added as a water-soluble admixture, it can enhance the mechanical properties of test blocks. It can also strengthen the bubble film of nano stabilized foam, increase bubble stability, and refine the internal pore structure of carbon fixation foam concrete. In addition, PVA can modify the calcium hydroxide morphology from a laminar structure to a smaller volume edge corrosion structure, which improves the reaction activity of calcium hydroxide with CO2 and boosts the efficiency of carbon sequestration.

Review of the Typical Damage and Damage-Detection Methods of Large Wind Turbine Blades

With global warming and the depletion of fossil energy sources, renewable energy is gradually replacing non-renewable energy as the main energy in the future. As one of the fastest growing renewable energy sources, the safety and reliability of wind energy have been paid more and more attention. The size of modern wind turbines is becoming larger and larger. As the main component of wind turbines to capture energy, the blade is often damaged by various complex environments and irregular loads. Therefore, the health monitoring and damage identification of wind turbine blades have become a main research focus. At present, in addition to the overview of various detection methods of wind turbine blades, there is a lack of comprehensive classifications and overviews of the main damage types, damage-generation mechanisms, and basic principles of the damage-detection technology of wind turbine blades. In this paper, firstly, the common fault types of wind turbine blades, such as trailing edge cracking, lightning strike, leading edge corrosion pollution, icing, and delamination, as well as their generation mechanism, are comprehensively analyzed. Then, the basic principles and the latest research progress of the current main detection technologies, such as vision, ultrasonic, thermal imaging, vibration, acoustic emission, and so on, are comprehensively reviewed. The advantages and limitations of the various detection technologies for practical application are summarized. Finally, through a comparative analysis of the various damage-detection technologies, we try to find potential future research directions, and draw conclusions. This paper will provide a reference for understanding the mechanism behind the main damage types and the damage-detection methods of wind turbine blades. It has important reference value for further promoting practical research of wind turbine blade damage-detection technology and grasping this research direction.

The Role of Calcite Dissolution and Halite Thermal Expansion as Secondary Salt Weathering Mechanisms of Calcite-Bearing Rocks in Marine Environments

This research focuses on the analysis of the influence of two secondary salt weathering processes on the durability of rocks exposed to marine environments: chemical dissolution of rock forming minerals and differential thermal expansion between halite and the hosting rock. These processes are scarcely treated in research compared to salt crystallisation. The methodology followed in this paper includes both in situ rock weathering monitoring and laboratory simulations. Four different calcite-bearing rocks (a marble, a microcrystalline limestone and two different calcarenites) were exposed during a year to a marine semiarid environment. Exposed samples show grain detachment, crystal edge corrosion, halite efflorescences and microfissuring. Crystal edge corrosion was also observed after the laboratory simulation during a brine immersion test. Calcite chemical dissolution causes a negligible porosity increase in all the studied rocks, but a significant modification of their pore size distribution. Laboratory simulations also demonstrate the deterioration of salt-saturated rocks during thermal cycles in climatic cabinet. Sharp differences between the linear thermal expansion of both a pure halite crystal and the different studied rocks justify the registered weight loss during the thermal cycles. The feedback between the chemical dissolution and differential thermal expansion, and the salt crystallisation of halite, contribute actively to the rock decay in marine environments.

Investigation and modelling of edge corrosion of e‐coated galvanized steel with respect to the spatial edge orientation

AbstractThe effect of the spatial orientation of e‐coated hot dip galvanized test sheets on edge corrosion is investigated. Therefore paint delamination from corrosion sample edges at different steps in time of samples at different angles relative to the horizontal during a corrosion test is analysed. Two general relations are found: Horizontally oriented edges exhibit significantly increased coating delamination compared with vertically oriented edges. This is due to increased exposure to the electrolyte, resulting from the pinning of electrolyte droplets along the upper edge. With increasing angular displacement relative to the ground, electrolyte exposure and edge delamination decrease. The edges of the upward‐facing specimen side showed a higher delamination width compared with the downward‐facing side at the same angle. These results are supported by electrochemical impedance spectroscopy and a wetting test. Ultimately, a semi‐empirical model to numerically predict the edge delamination over time, incorporating electrochemical impedance spectroscopy and polarization curves, is presented.

Edge delamination width prediction of 3D body‐in‐white part by finite element‐based corrosion simulation and neural networks

AbstractThe edge corrosion simulation of Kapfer et al. is used to extract time‐dependent delamination widths of metal sheet edges with different spatial orientations, encoded by edge classes and angular displacements with respect to the ground. The corrosion behavior of the edges of a body‐in‐white part is examined with respect to the spatial orientation and compared to the simulated delamination widths, demonstrating that the edge corrosion simulation is also able to model more complex structures. Since scaling the finite element method‐based corrosion simulation to the whole part requires a lot of memory and computational time, different neural network types are evaluated to predict the delamination widths. Together with the geometric properties of the part edges, a fast and accurate prediction of edge delamination of body‐in‐white parts is possible, requiring few time‐consuming corrosion simulations only in the training phase of the networks.

Inspection Robot for Submarine Pipeline Based on Machine Vision

In order to improve the intelligence of submarine pipeline inspection, reduce manpower and material resources, and improve inspection efficiency, an underwater pipeline inspection robot based on machine vision is proposed. This paper introduces the existing pipeline inspection methods and technologies, and analyzes the feasibility of pipeline inspection and inspection technologies based on image processing. On the basis of this subject, the corresponding circuit and embedded system are designed, and the related images are sampled, processed and analyzed, and the images are subjected to threshold segmentation, binarization, edge corrosion and other operations. Furthermore, the experimental site and underwater robot were built, and the pipeline defects were detected in real time by using the recognition method based on neural network.

A New Method of Edge Crack Suppression in the Rolling Process of Magnesium Alloy Sheet and Study on the Method of Cathodic Protection

A new method is proposed to solve edge cracking and corrosion in rolling process of the magnesium alloy plate. Usually in the process, the edge cracking is caused by the great temperature difference between the edge and the center of the alloy plate and the corrosion is by water in air. The method uses hot air wrapped around the plate to perfectly prevent edge cracking and corrosion. The method also includes cathodic protection for the magnesium alloy based on electrochemistry. The suppression of cathodic protection on the chemical activity of the magnesium alloy was studied. The experiment shows that the new method of edge heating with hot air wrapping is effective to prevent edge cracking and corrosion. Also, the cathodic protection can effectively suppress the chemical activity of the magnesium alloy and improve the surface quality in the rolling process of the magnesium plate, which provides a new concept in rolling process of the magnesium alloy.

Corrosion Monitoring Method of Porous Aluminum Alloy Plate Hole Edges Based on Piezoelectric Sensors.

Corrosion damage to the aircraft structure can significantly reduce the safety performance and endanger flight safety. Especially when the corrosion occurs in a stress concentration region, such as hole edges, it can easily threaten the entire structure. In this paper, an on-line imaging qualitative monitoring algorithm based on piezoelectric sensors is proposed for detecting hole edge corrosion damage of porous aluminum alloy structures. The normalized amplitude is used to characterize the correlation between the initial Lamb wave signal and the damage signal, which is as an image reconstruction parameter in the algebraic iterative probability reconstruction algorithm. Moreover, a homogenization algorithm is proposed to process the reconstruction results. The experimental results of single hole and double hole corrosion for porous aluminum alloy plate show that the method can effectively achieve the location and quantification of corrosion damage to one and two holes of the porous structure.

The Relationship between Shunt Currents and Edge Corrosion in Flow Batteries

Shunt currents occur in electrochemical reactors like flow batteries, electrolyzers, and fuel cells where many bipolar cells that are connected in series electrically contact a mobile electrolyte through one or more common fluid distribution manifolds. Shunt currents reduce energy efficiency, and can cause unwanted side reactions including corrosion and gas generation. Equivalent-circuit models have been widely used to examine shunt currents in multi-cell electrochemical reactors. However, a detailed investigation of the interesting electrochemical processes occurring at the edges of the active areas has not been presented. In this work, the generation of shunt currents and their tendency to drive corrosion at the edges of positive electrodes in the most positive cells in a reactor stack are investigated with a comprehensive numerical model. An analytical model based on the penetration of current into a semi-infinite electrode, that can be used in conjunction with traditional equivalent-circuit models to assess the tendency for shunt currents to drive corrosion, is developed and compared to the numerical model. The models provided here can be used to set requirements on maximum allowable port currents in order to achieve a particular durability goal.

Role of steel and zinc coating thickness in cut edge corrosion of coil coated materials in atmospheric weathering conditions; Part 2: Field data and model

Abstract Paint delamination from cut edges of model coil coated hot dip galvanized materials exposed at a marine test site for 5 years increased with steel thickness and decreased with zinc coating thickness. It was larger in sheltered locations than for openly exposed cut edges whereas red rust protection was more efficient on sheltered edges due to higher electric conductivity of deposits. The rate of paint delamination increased or decreased in time depending on the relative amount of zinc ions available for formation of the protective film on steel controlled by the initial steel substrate and zinc coating thicknesses.

Role of steel and zinc coating thickness in cut edge corrosion of coil coated materials in atmospheric weathering conditions; Part 1: Laboratory study

Abstract Cathode surface area and its ability to reduce oxygen controlled the rate of zinc dissolution and paint delamination from cut edges of hot dip galvanised steel sheets. Zinc corrosion products deposited on steel in atmospheric exposure conditions inhibited oxygen reduction decreasing galvanic current and zinc dissolution and paint delamination. The opposite effect was observed for iron corrosion products. The initial steel substrate and zinc coating thicknesses affected the availability of zinc ions for formation of the protective film.

Critical Constraints Responsible to Solar Glass Mirror Degradation

Abstract The degradation of solar glass mirrors is analyzed as a function of various constraints such as temperature, humidity, rain and solar irradiation. In order to understand the degradation mechanisms, two kinds of tests have been performed: simple tests to identify the effect of each constraint and complex tests to highlight the effects of synergy and to reproduce the natural ageing. The study of the paints coat degradation evidences that UV exposure is one of the most aggressive constraints for paint binder. But results show also a strong effect of liquid water on paint degradation and particularly on pigments loss and blistering phenomenon. Whereas temperature in dry environment is not a very degrading factor for coats, presence of liquid water is a strong accelerating constraint at high temperature. Agreement between outdoor ageing and indoor ageing with a new procedure involving UV, temperature and rain also shows that liquid water is the critical constraint responsible to edge corrosion of silver layer and paint delamination. This work shows also that relation between paint degradation and corrosion of silver layer is not obvious. Homogeneous corrosion by pitting was observed without any deep chemical deterioration of the paint coat system.

Coil-coated Zn–Mg and Zn–Al–Mg: Effect of climatic parameters on the corrosion at cut edges

We studied the effect of temperature, wet/dry cycling, pH, and the type and concentration of the corrosion activator on cut edge corrosion of painted Zn–15Mg and Zn–1.5Al–1.5Mg coated steel. In most accelerated tests, paint delamination and red rust formation were reduced compared to hot dip galvanised steel (HDG), and Zn–15Mg outperformed Zn–1.5Al–1.5Mg; however, Zn–1.5Al–1.5Mg showed better results when exposed outdoors. The alloyed materials were particularly resistant when HDG was prone to elevated corrosion, i.e. under permanent wetness, at higher temperatures, with high chloride loadings and in the presence of sulphate. Oxygen reduction on steel cut edges was inhibited by the alloying elements.

SECM imaging of the cut edge corrosion of galvanized steel as a function of pH

Scanning electrochemical microscopy (SECM) and the scanning vibrating electrode technique (SVET) were employed to identify the local reactivity and the cathodes and anodes on a cut edge of galvanized steel. The SECM was used in the amperometric feedback mode, using a redox mediator, for sensing the conductivity of the surface and also in the redox competition mode for locating the depletion of the cathodic reactant. Good agreement was observed in acidic solution between the location of the conductive regions of the surface and the depletion of oxygen estimated from amperometric lines across the cut edge. In nearly neutral medium, non-uniform activity of the steel surface was observed and correlated well with the ionic current flows in solution and with the accumulation of zinc corrosion products on steel. In alkaline medium the entire steel surface operated as electron source for the regeneration cycle of the redox mediator. Irrespective of the pH of the solution, a maximum of the feedback observed over the cut edge is consentaneous with the thermodynamic stability of iron in the reduced form. SECM provided useful information regarding the steel conductivity, whereas the zinc anodes could only be resolved by the SVET.

Visual analytics for the clustering capability of data

Clustering analysis is an unsupervised method to find hidden structures in datasets and has been widely used in various fields. However, it is always difficult for users to understand, evaluate, and explain the clustering results in the spaces with dimension greater than three. Although high-dimensional visualization of clustering technology can express clustering results well, it still has significant limitations. In this paper, a visualization cluster analysis method based on the minimum distance spectrum (MinDS) is proposed, aimed at reducing the problems of clustering multidimensional datasets. First, the concept of MinDS is defined based on the distance between high-dimensional data. MinDS can map any dataset from high-dimensional space to a lower dimension to determine whether the data set is separable. Next, a clustering method which can automatically determine the number of categories is designed based on MinDS. This method is not only able to cluster a dataset with clear boundaries, but can also cluster the dataset with fuzzy boundaries through the edge corrosion strategy based on the energy of each data point. In addition, strategies for removing noise and identifying outliers are designed to clean datasets according to the characteristics of MinDS. The experimental results presented validate the feasibility and effectiveness of the proposed schemes and show that the proposed approach is simple, stable, and efficient, and can achieve multidimensional visualization cluster analysis of complex datasets.

Investigation of the cut-edge corrosion of organically-coated galvanized steel after accelerated atmospheric corrosion test

The cut edge corrosion of organically coated (epoxy, polyurethane and polyester) galvanized steel was investigated using electrochemical impedance spectroscopy (EIS). Measurements were performed on specimens that had been tested in an accelerated atmospheric corrosion test. The samples were subjected to 10s fogging and 1h awaiting cycles in an exposure cabinet (120 and 180days) with artificial acid rain solution. According to the investigation, the coatings were damaged from the cut edge into the sheet, this distance was about 0.8cm. These defects were more pronounced at after 180days in proportion to after 120days.

Optimization of Image Processing in Video-based Traffic Monitoring

The video-based traffic monitoring systems have been widely used. The system usually reads real time monitoring video and converts it into images for processing. However, such systems are often limited by image processing algorithms and don’t behavior as well as expected. We hereby propose optimization approaches for of image processing. As in image processing, getting a binary image is usually a fundamental step, we first present an adaptive thresholds approach for binary conversion. The approach takes into consideration the space information of the pixel and chooses thresholds by adaptively according to each pixel and its neighboring pixels. Then we introduce a three-dimension Gaussian filter, which has best quantity-time tradeoff, to remove noise in the image. Although widely used, background subtraction is limited by background refreshing. We propose a generative model approach that is based on Gaussian model and Gaussian distribution, to generate background so that we can update background at any time. We also add in moving objects shadow detection and removing mechanism in moving objects segmentation. In real world monitoring, removing disturbs from burst noise is a hard problem. We, taking advantage of the characteristic that most of the burst noise is sudden and short-term, put forward a burst noise eliminating algorithm that uses several continuous frames to wipe off such sudden noise. Particularly, we studied the characteristics of H, S and V component of reflection light band, and assert that removal of the reflection light band is to eliminate negative effect from high-energy reflection light. We use Gaussian model and Sobel operator to achieve reflection light band removing; we also as utilize Canny algorithm to wipe off edge corrosion. Finally we achieved an integrated optimized solution on traffic monitoring system by making a tradeoff between time and effect. DOI: http://dx.doi.org/10.5755/j01.eee.18.8.2634