Local corrosion mechanism of Al-Zn-Mg-Cu alloy in oxygenated chloride solution: Cathode activity of quenching-induced η precipitates

With suitable pretreatment, a compact and even nickel-phosphorus alloy coating was obtained on W-Cu alloy by electroless deposition from solutions containing nickel sulphate as a source of nickel and sodium hypophosphite as the reducing agent and a source of phosphorus. The Ni-P coating was normally prepared from acidic baths at high temperature of the order of 90oC with the pH of 4.8 and it was smooth and uniform and exhibited high crystal refinement and high microhardness and superior corrosion resistance. The microhardness, adhesion and corrosion resistance mechanism of Ni-P deposit were studied. The microhardness of the Ni-P alloy deposit increases greatly by tempering at various temperatures. The Ni-P deposit has a strong adhesive force with W-Cu alloy substrate checked by thermal shock test and scribe test. The anti-corrosion ability of Ni-P coating and its anti-corrosion mechanism were measured using immersion experiment and potentiodynamic polarization techniques. The results showed that the corrosion resistance of Ni-P coating was higher than that of W-Cu alloy substrate in the 10vol.% sulfuric acid, monitoring sweat solution and 3.5wt.% sodium chloride solution. The anti-corrosion mechanism of electroless Ni-P coating immersed in 3.5wt.% sodium chloride solution was studied using potentiodynamic polarization techniques. The surface micromorphological morphology and structure of the Ni-P coating were investigated using Scanning Electronic Microscope (SEM) and X-ray Diffraction (XRD). The results indicated that the Ni-P alloy coating consisted of microcrystals and it was amorphous in structure, and the electrochemical measurement showed passive film formed on Ni-P coating during immersion test in the 3.5wt.% sodium chloride solution.

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Electrochemical and Salt Spray Corrosion Behavior of Copper Alloy Contact Wires in Chloride Solution

Materials Science Forum ◽

10.4028/www.scientific.net/msf.789.622 ◽

2014 ◽

Vol 789 ◽

pp. 622-626

Author(s):

Peng Chao Zhang ◽

Jian Zhang ◽

Jin Chuan Jie ◽

Yuan Gao ◽

Yong Dong ◽

...

Keyword(s):

Corrosion Behavior ◽

Corrosion Test ◽

Chloride Solution ◽

Copper Alloys ◽

Salt Spray ◽

Electrochemical Corrosion ◽

Corrosion Current ◽

Corrosion Mechanism ◽

Salt Spray Corrosion ◽

Surface Morphologies

The effect of different alloying elements on corrosion behavior of copper alloys was investigated using electrochemical corrosion and salt spray corrosion test in NaCl solution. Cu-Ag has the most stable corrosion current in the potentiostatic scanning test, exhibiting a better corrosion resistant performance. It can be analyzed from corrosion surface morphologies that Cu-Ag presents exfoliation corrosion mechanism while Cu-Sn shows crevice corrosion mechanism. Cu-Mg has a complex corrosion process caused by multiple corrosion mechanism. In the salt spray corrosion test, the corrosion degree of Cu-Ag is lighter than those of Cu-Sn and Cu-Mg after 24h test. Therefore, the Cu-Ag alloy exhibits the best corrosion resistance in chloride solution.

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Improvement of pitting corrosion resistance for Al-Cu alloy in sodium chloride solution through equal-channel angular pressing

Progress in Natural Science Materials International ◽

10.1016/s1002-0071(12)60062-8 ◽

2011 ◽

Vol 21 (4) ◽

pp. 307-313 ◽

Cited By ~ 7

Author(s):

Dan SONG ◽

Ai-bin MA ◽

Jing-hua JIANG ◽

Ping-hua LIN ◽

Liu-yan ZHANG

Keyword(s):

Corrosion Resistance ◽

Sodium Chloride ◽

Equal Channel Angular Pressing ◽

Pitting Corrosion ◽

Chloride Solution ◽

Sodium Chloride Solution ◽

Angular Pressing ◽

Cu Alloy ◽

Pitting Corrosion Resistance

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Correlation of Surface Alloyed Microstructure of Pure Magnesium With its Corrosion Behavior

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.472-475.161 ◽

2012 ◽

Vol 472-475 ◽

pp. 161-164

Author(s):

Yu Gao Liu

Keyword(s):

Corrosion Resistance ◽

Corrosion Behavior ◽

Chloride Solution ◽

Diffusion Time ◽

Point Of View ◽

Pure Magnesium ◽

Corrosion Mechanism ◽

Cross Sectional ◽

Microstructure Characteristics ◽

Solid Diffusion

This paper represents a summary of experimental results dealing with the time dependence of surface diffusion alloyed microstructure and its corrosion behavior at given temperature. The experiments were performed at 485°C for different solid diffusion time (6h, 12h, 18h ) and thus the surface alloyed microstructure of pure magnesium has been obtained. Optical and electrical microscopy and EDS compositions analysis were used to examine the cross sectional microstructure characteristics of alloyed layers of treated samples. It is shown that the new phases formed and its continuity, depending on the diffusion treated time at given temperature, have a noticeable influence on corrosion resistance and corrosion mechanism. The new formed phase Al5Mg11Zn4 was inert to the chloride solution compared with pure magnesium and acted as a corrosion barrier. It was concluded that the continuous Al5Mg11Zn4 phase was beneficial from the point of view of corrosion resistance.

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Investigation on the Corrosion Behavior of Zn27Al3Cu Alloy in 3.5 wt.% NaCl Solution

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.482-484.537 ◽

2012 ◽

Vol 482-484 ◽

pp. 537-540

Author(s):

Yong Tan ◽

Cheng Gang Hao ◽

De Zhi Li ◽

Zhi Liu Hu ◽

Jian Min Zeng

Keyword(s):

Weight Loss ◽

Corrosion Behavior ◽

Corrosion Products ◽

Corrosion Mechanism ◽

Attenuation Relationship ◽

Nacl Solution ◽

Cu Alloy ◽

Weight Loss Method ◽

Loss Method ◽

Scanning Electron

The corrosion behavior of Zn27Al3Cu in 3.5 Wt.% NaCl solution is investigated through weight loss method. The morphology of corrosion products were observed and analyzed with optical microscopy (OM), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The experimental results indicate that weight loss of the alloy with time follows the exponential attenuation relationship. Corrosion mechanism of Zn27Al3Cu alloy are intergranular corrosion and preferential corrosion in 3.5 Wt.% NaCl solution, the main corrosion products are compound oxide and chloride.

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Mechanism of Localized Corrosion of Steel Pipe Pile Foundation for Offshore Wind Turbines and Corrosive Action

The Open Civil Engineering Journal ◽

10.2174/1874149501610010685 ◽

2016 ◽

Vol 10 (1) ◽

pp. 685-694

Author(s):

Kui Wang ◽

Zhanqiang Li ◽

Mingjie Zhao

Keyword(s):

Wind Turbine ◽

Ultimate Strength ◽

Pile Foundation ◽

Local Corrosion ◽

Steel Pipe ◽

Corrosion Mechanism ◽

General Corrosion ◽

Splash Zone ◽

Pipe Pile ◽

Steel Pipe Pile

The wind turbine foundation serves as a permanent construction in the harsh marine corrosive environment, its anti-corrosion design is essential to the safe use of the wind turbine structure. At present, there is a significant controversy over the local corrosion mechanism (such as pitting corrosion, and crevice corrosion) and its diffusion mechanism in the academic circle. In the paper, the Faraday electrochemistry formula was used to compute the local corrosion degree of the steel pipe pile for the wind turbine and obtain the general corrosion equivalent. The local corrosion effect of the offshore steel pipe pile for the wind turbine was converted into homogeneous corrosion thickness loss of certain length, and then the ultimate strength of the offshore steel pipe pile foundation for the wind turbine was analyzed under the conditions of local corrosion. The result indicates that the maximum ultimate strength reductionof the steel pipe pile for the wind turbine induced by the local corrosion in the splash zone is 80.8% of the non-corrosive ultimate strength. The maximum ultimate strength reduction of the steel pipe pile for the wind turbine induced by the local corrosion in the continuous immersion zone is 63% of the non-corrosive ultimate strength. Once the local corrosion rate in the splash zone exceeds 10%, the ultimate strength of the steel pipe pile for the wind turbine will exhibit a negative exponential decrease. The local corrosion in the continuous immersion zone has a huge effect on its ultimate strength. There are no significant signs of the structural strength loss. The areas prone to local corrosion should be prioritized in anti-corrosion design of the steel pipe pile for the wind turbine.

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Investigation of a Steel Local Corrosion in Chloride-Containing Media

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.872.7 ◽

2021 ◽

Vol 872 ◽

pp. 7-13

Author(s):

Varvara Rumyantseva ◽

Viktoriya Konovalova

Keyword(s):

Chloride Solution ◽

Sodium Chloride Solution ◽

Protective Coatings ◽

Aggressive Medium ◽

Electrochemical Corrosion ◽

Steel Corrosion ◽

Chloride Ions ◽

Local Corrosion ◽

Local Damage ◽

Corrosion Of Steel

Aspects of the development of local corrosion on the metal surface under the influence of aggressive media containing chloride ions are presented. The main mechanisms leading to the formation and development of local damage of the surface of metals are described. The process of electrochemical corrosion of steel under the influence of chloride-containing medium is experimentally investigated. By constructing corrosion diagrams, the main indicators of steel corrosion in a 10% sodium chloride solution were determined, which allows one to judge the rate of development of corrosion processes with local damage to the protective coating and the degree of steel resistance depending on the aggressiveness of the medium. It is shown that protective coatings, such as modified phosphate and oxide-phosphate films, prevent the penetration of an aggressive medium to the surface of the protected metal and, accordingly, the anodic dissolution of the metal.

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