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1 – 10 of 44Yang Liu, Jialing Wang, Huayang Cai, Yawei Shao, Zhengyi Xu, Yanqiu Wang and Junyi Wang
Epoxy zinc-rich coatings are widely used in harsh environments because of the long-lasting cathodic protection of steel surfaces. The purpose of this paper is to use flake zinc…
Abstract
Purpose
Epoxy zinc-rich coatings are widely used in harsh environments because of the long-lasting cathodic protection of steel surfaces. The purpose of this paper is to use flake zinc powder instead of the commonly used spherical zinc powder to reduce the zinc powder content.
Design/methodology/approach
In this paper, the authors have prepared an anticorrosive zinc-rich coating using a flake zinc powder instead of the conventional spherical zinc powder. The optimal dispersion of scaly zinc powder in zinc-rich coatings has been explored by looking at the surface and cross-sectional morphology and studying the cathodic protection time of the coating.
Findings
The final epoxy zinc-rich coating with 35 Wt.% flake zinc powder content was prepared using sand-milling dispersions. It has a similar cathodic protection time and salt spray resistance as the 60 Wt.% spherical zinc-rich coating, with a higher low-frequency impedance modulus value.
Originality/value
This study uses flake zinc powder instead of the traditional spherical zinc powder. This reduces the amount of zinc powder in the coating and improves the corrosion resistance of the coating.
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Clément Génin, Marc Jeannin, Anne-Marie Grolleau and Philippe Refait
The purpose of this study is to investigate cathodic protection (CP) efficiency in the tidal zone and its associated processes.
Abstract
Purpose
The purpose of this study is to investigate cathodic protection (CP) efficiency in the tidal zone and its associated processes.
Design/methodology/approach
Specific features of CP in the tidal zone, that is, persistence of a thin seawater film and insufficient cathodic potential due to ohmic drop, were addressed. In this preliminary study, carbon steel electrodes were polarized at two cathodic potentials (correct or insufficient protection) while immersed in 1 mm or 5 mm thick natural seawater layers. After CP interruption, the protective ability of the layers covering the steel electrodes was studied using various electrochemical methods, including electrochemical impedance spectroscopy. The layers were characterized by XRD.
Findings
The protective ability of calcareous deposits was increased in thin seawater films. Insufficient CP could promote protective aragonite/corrosion products layer.
Originality/value
The combined effects of thin seawater film and applied potential were never addressed, and the conclusions drawn from this preliminary study give new insight on the efficiency of CP in the tidal zone.
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Nehal Elshaboury, Tarek Zayed and Eslam Mohammed Abdelkader
Water pipes degrade over time for a variety of pipe-related, soil-related, operational, and environmental factors. Hence, municipalities are necessitated to implement effective…
Abstract
Purpose
Water pipes degrade over time for a variety of pipe-related, soil-related, operational, and environmental factors. Hence, municipalities are necessitated to implement effective maintenance and rehabilitation strategies for water pipes based on reliable deterioration models and cost-effective inspection programs. In the light of foregoing, the paramount objective of this research study is to develop condition assessment and deterioration prediction models for saltwater pipes in Hong Kong.
Design/methodology/approach
As a perquisite to the development of condition assessment models, spherical fuzzy analytic hierarchy process (SFAHP) is harnessed to analyze the relative importance weights of deterioration factors. Afterward, the relative importance weights of deterioration factors coupled with their effective values are leveraged using the measurement of alternatives and ranking according to the compromise solution (MARCOS) algorithm to analyze the performance condition of water pipes. A condition rating system is then designed counting on the generalized entropy-based probabilistic fuzzy C means (GEPFCM) algorithm. A set of fourth order multiple regression functions are constructed to capture the degradation trends in condition of pipelines overtime covering their disparate characteristics.
Findings
Analytical results demonstrated that the top five influential deterioration factors comprise age, material, traffic, soil corrosivity and material. In addition, it was derived that developed deterioration models accomplished correlation coefficient, mean absolute error and root mean squared error of 0.8, 1.33 and 1.39, respectively.
Originality/value
It can be argued that generated deterioration models can assist municipalities in formulating accurate and cost-effective maintenance, repair and rehabilitation programs.
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Yongtao Zhao, Weili Li, Xiaoyang Xuan, Jianbang Gao, Jue Wang, Liang Dong, Dawei Zang, Mingjian Wang and Xiankang Zhong
This study aims to evaluate the protection performance of zinc as sacrificial anode for ABS A steel in the presence of H2S under different temperatures, pH and salinities.
Abstract
Purpose
This study aims to evaluate the protection performance of zinc as sacrificial anode for ABS A steel in the presence of H2S under different temperatures, pH and salinities.
Design/methodology/approach
In this paper, weight loss measurements and electrochemical measurements are used to evaluate the corrosion degree of zinc and ABS A steel.
Findings
Under the conditions involved in this work, it is shown that zinc is a nice sacrificial anode with the reason of its stable potential and excellent anode current efficiency according to the relevant standard. And it is also found that the hydrogen evolution does not occur on ABS A steel specimens. The potential difference between cathode and anode is suitable; thus, it can be concluded that each steel is well protected.
Originality/value
To the best of the authors’ knowledge, no other study has analyzed the protection mechanism and effect of zinc as sacrificial anode in H2S-containing environments under high temperature at present.
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Minakshi Koundal, Ajay Kumar Singh and Chhaya Sharma
This paper aims to investigate the eco-friendly neodymium tartrate (NdTar) inhibitor for mild steel in sodium chloride (NaCl) solution.
Abstract
Purpose
This paper aims to investigate the eco-friendly neodymium tartrate (NdTar) inhibitor for mild steel in sodium chloride (NaCl) solution.
Design/methodology/approach
The mild steel 1010 coupon was considered for the current study. Weight loss and the electrochemical methods were used to evaluate the inhibitory effects of neodymium chloride (NdCl3) and NdTar on mild steel in NaCl solution. Scanning electron microscopy, energy-dispersive X-ray analysis and attenuated total reflectance-Fourier transform infrared spectroscopy measurements were carried out to study the morphology and composition of the film, nature of deposits and corrosion products formed in test media on the corroded steel, with the objective of further analyzing the observed behavior of the two inhibitors.
Findings
Of the two, NdTar performs better than NdCl3 because it shields mild steel surfaces for longer. According to the results, when NdCl3 is present in a corrosive solution, the protective film only comprises Nd/Fe oxide/hydroxide/carbonate. However, when neodymium is coupled with the tartrate group (an organic group) and then added to the NaCl solution, the inhibitor film comprises both bimetallic complexes (Fe-Tar-Nd) and metal oxide/hydroxide/carbonate, which results in a more compact film and has higher inhibition efficiency.
Originality/value
This study evaluated the combined effects of inorganic and organic inhibitors with those of an inorganic inhibitor used alone for mild steel in NaCl solution.
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Shuangjiu Deng, Chang Li, Xing Han, Menghui Yu and Han Sun
The restoration and strengthening of QT600 is an industry bottleneck challenge. The Co-12 cladding layer has great wear and corrosion resistance. The purpose of this paper is to…
Abstract
Purpose
The restoration and strengthening of QT600 is an industry bottleneck challenge. The Co-12 cladding layer has great wear and corrosion resistance. The purpose of this paper is to quantitatively reveal the transient evolution law of the corrosion process of Co-12 cladding layer on QT600 surface.
Design/methodology/approach
In this paper, a three-dimensional numerical model of the corrosion process of Co-12 cladding layer by QT600 laser cladding is established. The interaction between pitting pits and corrosion medium is considered to reveal the transient evolution of ion concentration, electrode potential, pH and corrosion rate at different locations.
Findings
The calculation shows that the ion concentration in pitting pit changes Cl−>Co2+>Na+, pH value decreases from top to bottom and corrosion rate at bottom is greater than that at top. The electrochemical corrosion test of Co-12 cladding layer was carried out. It is shown that the current density of QT600 increases by an order of magnitude compared to the Co-12 cladding layer, and the corrosion rate is 4.862 times higher than that of the cladding layer.
Originality/value
The results show that Co-12 cladding layer has great corrosion resistance, which provides an effective way for QT600 protection.
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Yingying Li, Lanlan Liu, Jun Wang, Song Xu, Hui Su, Yi Xie and Tangqing Wu
The purpose of this paper is to study the corrosion behavior of Q235 steel in saturated acidic red and yellow soils.
Abstract
Purpose
The purpose of this paper is to study the corrosion behavior of Q235 steel in saturated acidic red and yellow soils.
Design/methodology/approach
The corrosion behavior of Q235 steel in saturated red and yellow soils was compared by weight-loss, SEM/EDS, 3D ultra-depth microscopy and electrochemical measurements.
Findings
Rp of the steel gradually increases and icorr gradually decreases in both the red and yellow soils with time. The Rp of the steel in the red soil is lower, but its icorr is higher than that in the yellow soil. The uniform corrosion rate, diameter and density of the corrosion pit on the steel surface in the red soil are greater than those in the yellow soil. Lower pH, higher contents of corrosive anions and high-valence Fe oxides in the red soil are responsible for its higher corrosion rates and local corrosion susceptibility.
Originality/value
This paper investigates the difference in corrosion behavior of carbon steel in saturated acidic red and yellow soils, which can help to understand the mechanism of soil corrosion.
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The complexity of atmospheric corrosion, further compounded by the effects of climate change, makes existing models inappropriate for corrosion prediction. The commonly used…
Abstract
The complexity of atmospheric corrosion, further compounded by the effects of climate change, makes existing models inappropriate for corrosion prediction. The commonly used kinetic model and dose-response functions are restricted in their capacity to represent the non-linear behaviour of corrosion phenomena. The application of artificial intelligence (AI)-driven machine learning algorithms to corrosion data can better represent the corrosion mechanism by considering the dynamic behaviour due to changing climatic conditions. Effective use of materials, coating systems and maintenance strategies can then be made with such a corrosivity model. Accurate corrosion prediction will help to improve climate change resilience of the social, economic and energy infrastructure in line with the UN Sustainable Development Goals (SDGs) 7 (Affordable and Clean Energy), 9 (Industry, Innovation and Infrastructure) and 13 (Climate Action). This chapter discusses atmospheric corrosion prediction in relation to the SDGs and the influence of AI in overcoming the challenges.
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Dongdong Song, Wenxiang Qin, Qian Zhou, Dong Xu and Bo Zhang
The anticorrosion coatings used in marine and atmospheric environment are subjected to many environmental factors. And the aging failure has been puzzling researchers. The purpose…
Abstract
Purpose
The anticorrosion coatings used in marine and atmospheric environment are subjected to many environmental factors. And the aging failure has been puzzling researchers. The purpose of this study is to find the correlation between the initial aging of epoxy coatings and the typical marine atmospheric environmental factors.
Design/methodology/approach
The epoxy coatings were subjected to a one-year exposure in three typical marine atmospheres. Meanwhile, principal component analysis, linear regression and Spearman and gray correlation analysis were applied to quantify the environmental characteristics and establish correlations with the coating aging.
Findings
The results indicate that the coating will undergo macroscopic fading and chalking upon exposure to the marine atmosphere, while microscopic examination reveals holes, cracks and partial peeling. The adhesion performance and electrochemical properties of the coating deteriorated with prolonged exposure, coating aging mainly occurs with the generation of O-H bonds and the breakage of molecular chains such as C-N and C-O-C. The coating was most deeply aged after exposure to the Xisha, followed by Zhoushan and finally Qingdao. Environmental factors affect the photooxidative aging and hydrolytic degradation processes of coatings and thus coating aging. To further demonstrate the correlation between environmental factors and coating aging, principal component analysis was used. The correlation model between environmental factors and coating aging was subsequently obtained. The correlation model between the rate of coating adhesion loss (E) and the comprehensive evaluation parameter of environmental factors (Z) is expressed as E = 0.142 + 0.028Z. Meanwhile, the Spearman correlation analysis and gray correlation method were used to investigate the impact of each environmental factor on coating aging. Solar irradiation, relative humidity and wetting time have the highest correlation with coating aging, which are all above 0.8 and have the greatest influence on coating aging; wind speed and temperature have the smallest correlation with coating aging, which are about 0.6 and have the least influence on coating aging.
Originality/value
This paper establishes a correlation between typical marine environmental factors and coating aging performance, which is crucial for predicting the service life of other coatings in diverse environments.
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Yuchen Xi, Qinying Wang, Yafei Wu, Xingshou Zhang, Lijin Dong, ShuLin Bai and Yi Yang
The purpose of this study is to investigate the crevice corrosion behavior and mechanism of laser additive manufacturing (LAM) nickel-based alloy under wedge-shaped crevice.
Abstract
Purpose
The purpose of this study is to investigate the crevice corrosion behavior and mechanism of laser additive manufacturing (LAM) nickel-based alloy under wedge-shaped crevice.
Design/methodology/approach
First, the opening size of the wedge-shaped crevice was designed to 0.1, 0.3 and 0.5 mm by controlling the thickness of silicon rubber and the double-side adhesive tape. Then, one side of the glass sheet was stuck on the silicon strip and keep the electrodes of Rows 1 and 2 outside the crevice as a reference, and the opposite side was stuck to the wire beam electrode by silica gel.
Findings
The current density with a maximum value of 5.7 × 10−6 A/cm2 was observed at the crevice opening of 0.5 mm, while the lowest value of 9.2 × 10−7 A/cm2 was found at the crevice opening of 0.1 mm. In addition, the corrosion resistance at the inside of the crevice is higher than that at the outside and the middle of the crevice. It means that the internal width of the wedge-shaped crevice tends toward 0, which hinders the migration of ions in the corrosive medium. The generation of corrosive products further reduce the crevice size to cause the inhibition of corrosion at the inside of the crevice as well.
Originality/value
The multilayer and multipath LAM component is prepared to show the complex microstructure, which made the corrosion behavior and mechanism at wedge-shaped crevice nondeterminacy.
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