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1 – 10 of 59Yinghong Li, Wei Tan, Wenjie Pei and Guorui Zhu
The purpose of this paper is to investigate the effect of NaCl solution with different concentrations on impact-sliding fretting corrosion behavior of Inconel 690TT steam…
Abstract
Purpose
The purpose of this paper is to investigate the effect of NaCl solution with different concentrations on impact-sliding fretting corrosion behavior of Inconel 690TT steam generator heat transfer tubes.
Design/methodology/approach
The optical 3D profiler was used to measure the wear profile and calculated the wear volume. Corrosion behavior was studied using open circuit potential monitoring and potentiodynamic polarization testing. The morphologies and elemental distributions of wear scars were analyzed using scanning electron microscopy and energy-dispersive spectroscopy. The synergism of wear and corrosion was analyzed according to the ASTM G119 standard.
Findings
The corrosion tendency reflected by OCP and the corrosion current calculated by Tafel both increased with the increase of NaCl concentration. The total volume loss of the material increased with concentration, and it was known from the synergism that the volume loss caused by corrosion-enhanced wear accounted for the largest proportion, while the wear-enhanced corrosion also made a greater contribution to volume loss than tangential fretting corrosion. Through the analysis of the material morphologies and synergism of wear and corrosion, the damage mechanism was elucidated.
Originality/value
The research findings can provide reference for impact-sliding fretting corrosion behavior of Inconel 690TT heat transfer tubes in NaCl solution with different concentrations.
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This study aims to investigate the individual electrochemical transients arising from local anodic events on stainless steel, to uncover the potential mechanisms producing…
Abstract
Purpose
This study aims to investigate the individual electrochemical transients arising from local anodic events on stainless steel, to uncover the potential mechanisms producing different types of transients and to derive appropriate parameters indicative of the corrosion severity of such transient events.
Design/methodology/approach
An equivalent circuit model was used for the transient analysis, which was performed using a local current allocation rule based on the relative instant cathodic resistance of the coupled electrodes, as well as the kinetic parameters derived from the electrochemical polarization measurement.
Findings
The shape and size of the electrochemical current transients arising from SS 316 L were influenced by the film stability, local anodic dissolution kinetics and the symmetry of the cathodic kinetics between the coupled electrodes, where the ultralong transient might correspond to the propagation of film damage with a slow anodic dissolution rate. The dynamic cathodic resistance during the final stage of transient current growth can serve as a characteristic parameter that reflects the loss of passive film protection.
Originality/value
Estimation of the local anodic current trace opens a new way for individual electrochemical transient analysis associated with the charges involved, local current densities and changes in film resistance throughout localized corrosion processes.
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Xi Jin, Hui Xu, Qifeng Zhao, Hao Zeng, Bing Lin, Ying Xiao, Junlei Tang, Zhen Nie, Yan Yan, Zhigang Di and Rudong Zhou
This study aims to report the development and experimental evaluation of two kinds of PANI@semiconductor based photocathodic anti-corrosion coating, for application on stainless…
Abstract
Purpose
This study aims to report the development and experimental evaluation of two kinds of PANI@semiconductor based photocathodic anti-corrosion coating, for application on stainless steel substrates.
Design/methodology/approach
PANI was in situ chemical polymerized on TiO2 and BiVO4 particles, and FT-IR and SEM/EDS were used to understand the characteristics and elemental distribution of the composite particles. Composite coatings, which consisted of epoxy, PANI@TiO2 or PANI@BiVO4 and graphene, were prepared on the 304L stainless steel. Photoelectrochemical response measurement, electrochemical tests and immersion tests were used to assess the anti-corrosion performance of the prepared coatings in 45°C 3.5 wt.% NaCl solution. And the corrosion protection mechanism was further explained by combining with surface observation.
Findings
The photoelectrochemical response tests revealed the good photocathodic effect of the coatings, and the reversible oxidation-reduction properties of PANI (pseudocapacitive effect) leading to the repeated usage of the coatings. Consequently, the anti-corrosion mechanism of the composite coating is attributed to the physical barrier effect of the coating, the anodic protection effect of PANI and the photocathodic and energy store effect.
Originality/value
These kind coatings could prevent corrosion from day to night for stainless steel, which has great engineering application prospects on stainless steel corrosion protection.
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Zhiwei Li, Dingding Li, Yulong Zhou, Haoping Peng, Aijun Xie and Jianhua Wang
This paper aims to contribute to the performance improvement and the broader application of hot-dip galvanized coating.
Abstract
Purpose
This paper aims to contribute to the performance improvement and the broader application of hot-dip galvanized coating.
Design/methodology/approach
First, the ability to provide barrier protection, galvanic protection, and corrosion product protection provided by hot-dip galvanized coating is introduced. Then, according to the varying Fe content, the growth process of each sublayer within the hot-dip galvanized coating, as well as their respective microstructures and physical properties, is presented. Finally, the electrochemical corrosion behaviors of the different sublayers are analyzed.
Findings
The hot-dip galvanized coating is composed of η-Zn sublayer, ζ-FeZn13 sublayer, δ-FeZn10 sublayer, and Γ-Fe3Zn10 sublayer. Among these sublayers, with the increase in Fe content, the corrosion potential moves in a noble direction.
Research limitations/implications
There is a lack of research on the corrosion behavior of each sublayer of hot-dip galvanized coating in different electrolytes.
Practical implications
It provides theoretical guidance for the microstructure control and performance improvement of hot-dip galvanized coatings.
Originality/value
The formation mechanism, coating properties, and corrosion behavior of different sublayers in hot-dip galvanized coating are expounded, which offers novel insights and directions for future research.
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Chong Zhang, Jiayi Xiang and Qifan Wen
Due to the harsh underground environment in coal mining, the surface of hydraulic support columns corrodes severely, resulting in significant economic losses. Therefore, a highly…
Abstract
Purpose
Due to the harsh underground environment in coal mining, the surface of hydraulic support columns corrodes severely, resulting in significant economic losses. Therefore, a highly corrosion-resistant coatings is needed to extend the service life of the columns.
Design/methodology/approach
This study aims to compare the corrosion resistance of ST-Cr3C2-NiCr (sealed treatment Cr3C2-NiCr) coatings with industrially applied chromium plating. The corrosion failure mechanism of the coatings was investigated.
Findings
The results demonstrated that the ST-Cr3C2-NiCr coatings exhibited excellent corrosion resistance. After sealing treatment, the corrosion potential of Cr3C2-NiCr coatings was −0.215 V, and the corrosion current density of Cr3C2-NiCr coatings was lower than that of the plated parts.
Practical implications
ST-Cr3C2-NiCr coatings prepared by supersonic atmospheric plasma spraying could provide excellent corrosion resistance in the coal industry.
Originality/value
The low porosity and the presence of the NiCr phase were crucial factors contributing to the preferable corrosion resistance exhibited by the ST-Cr3C2-NiCr coatings. The corrosive process of the coatings involved layer-by-layer delamination of surface oxide film, sub-surface pitting, formation and degradation of sub-surface passive film, as well as severe block-like delamination.
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He Wang, Zhiguo Li, Haifei Zhou, Zhengqiang Zhou, Wei Lu, Pengzhen Wang, Jiagang Zhang, Jin Gao and Pan Yi
This paper aims to compare the aging behavior of water-based coatings and solvent-based coatings in sulfuric acid environments and to discuss the related mechanism.
Abstract
Purpose
This paper aims to compare the aging behavior of water-based coatings and solvent-based coatings in sulfuric acid environments and to discuss the related mechanism.
Design/methodology/approach
A sulfuric acid solution with a concentration of 5 Wt.% was selected for immersion test at 23°C. The failure behavior of the coating was studied by combining the transformation rules of the macroscopic morphology and basic properties with the results of electrochemical impedance spectrum analysis.
Findings
The results showed that the surface smoothness of the water-based coating was lower than that of the solvent-based coating. The glossiness, thickness and hardness of the water-based coating exhibited more significant changes. The electrochemical test also indicated that the water-based coating was infiltrated by a large number of corrosive media, which may have induced corrosion under the coating. In contrast, the solvent-based coating showed good shielding properties, but the adhesion was seriously affected by the corrosive medium.
Originality/value
This work clarified the difference of failure behavior and mechanism between water-based coatings and solvent-based coatings in acidic environment and provided a theoretical basis for the selection and mechanism research of anticorrosive coatings.
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Pan Hao, Yuchao Dun, Jiyun Gong, Shenghui Li, Xuhui Zhao, Yuming Tang and Yu Zuo
Organic coatings are widely used for protecting metal equipment and structures from corrosion. Accurate detection and evaluation of the protective performance and service life of…
Abstract
Purpose
Organic coatings are widely used for protecting metal equipment and structures from corrosion. Accurate detection and evaluation of the protective performance and service life of coatings are of great importance. This paper aims to review the research progress on performance evaluation and lifetime prediction of organic coatings.
Design/methodology/approach
First, the failure forms and aging testing methods of organic coatings are briefly introduced. Then, the technical status and the progress in the detection and evaluation of coating protective performance and the prediction of service life are mainly reviewed.
Findings
There are some key challenges and difficulties in this field, which are described in the end.
Originality/value
The progress is summarized from a variety of technical perspectives. Performance evaluation and lifetime prediction include both single-parameter and multi-parameter methods.
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Shan Gao, Bin Wang, Xinjie Yao and Quan Yuan
This paper aims to characterize the surface film formed on Alloys 800 and 690 in chloride and thiosulfate-containing solution at 300°C.
Abstract
Purpose
This paper aims to characterize the surface film formed on Alloys 800 and 690 in chloride and thiosulfate-containing solution at 300°C.
Design/methodology/approach
Alloy 800 and 690 were immersed in chloride and thiosulfate-containing solution at 300°C up to five days, and then the surface film was analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and energy dispersive X-ray spectrometers (EDX).
Findings
Through static immersion experiments in a high-temperature and high-pressure water environment, the alloy samples covered by surface film after five days of immersion were obtained. The morphology of the surface film was characterized at both horizontal and cross-sectional scales using SEM and focused ion beam-TEM techniques. It was observed that due to the influence of the quartz lining, the surface film primarily exhibited a bilayered structure. The first layer contained a significant amount of SiO2, with a higher content of metal hydroxides compared to metal oxides. The second layer was predominantly composed of Fe, Ni and Cr, with a higher content of metal oxides compared to metal hydroxides.
Originality/value
The results showed that the materials of the lining of the autoclave could significantly influence the film composition of the tested material, which should be paid attention when analyzing the corrosion mechanism at high temperature.
Song Tang, Xiaowen Chen, Defen Zhang, Wanlin Xie, Qingzheng Ran, Bin Luo, Han Luo and Junwei Yang
The purpose of this study is to investigate the influence of varying concentrations of nano-SiO2 particle doping on the structure and properties of the micro-arc oxidation (MAO…
Abstract
Purpose
The purpose of this study is to investigate the influence of varying concentrations of nano-SiO2 particle doping on the structure and properties of the micro-arc oxidation (MAO) coating of 7075 aluminum alloy. This research aims to provide novel insights and methodologies for the surface treatment and protection of 7075 aluminum alloy.
Design/methodology/approach
The surface morphology of the MAO coating was characterized using scanning electron microscope. Energy spectrometer was used to characterize the elemental content and distribution on the surface and cross section of the MAO coating. The phase composition of the MAO coating was characterized using X-ray diffractometer. The corrosion resistance of the MAO coating was characterized using an electrochemical workstation.
Findings
The results showed that when the addition of nano-SiO2 particles is 3 g/L, the corrosion resistance is optimal.
Originality/value
This study investigated the influence of different concentrations of nano-SiO2 particles on the structure and properties of the MAO coating of 7075 aluminum alloy.
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Haonan Guo, Chunxia Wang and Hui Liu
This study aims to investigate a chromium-free sealing treatment process to replace the chromate sealing process in response to the environmental hazards caused by chromate in the…
Abstract
Purpose
This study aims to investigate a chromium-free sealing treatment process to replace the chromate sealing process in response to the environmental hazards caused by chromate in the Phosphate chemical conversion (PCC) coating post-treatment sealing process.
Design/methodology/approach
In this paper, chromium-free sealing technology was used to post-treat PCC coatings. Scanning electron microscopy was used to investigate the structure of the surface of the PCC coatings after the sealing treatment, and the corrosion resistance, hydrophobicity and bonding were tested using an electrochemical workstation, a copper sulfate spot-drop test, a lacquer bonding test, a contact angle meter and a neutral salt spray test.
Findings
Chromium-free closure makes the grain distribution on the surface of the PCC coating more uniform and dense, and forms an organic film on the surface of the coating, which significantly improves the corrosion resistance and hydrophobicity of the PCC coating, does not affect the coating film bonding force and has similar performance with potassium dichromate solution.
Originality/value
The results show that the corrosion resistance of PCC coatings after chromium-free sealing treatment is improved, and chromium-free sealing has the potential to replace chromium sealing.
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