SEM-EDX and AFM analysis for the surface corrosion morphology structure and roughness on embedded X70 external pipeline in acidic soil (peat) environment

The effect of artificial aging on the corrosion properties of 6063 Al alloy was investigated by optical microscope, field emission scanning electron microscope and accelerated corrosion test. Accelerated corrosion test revealed that the alloy was susceptible to intergranular corrosion (IGC) in the artificial aged conditions according to the surface corrosion morphology, and the IGC resistance was reduced as the aging time was prolonged, resulting from more Mg2Si grain boundary precipitates formed. However, the corroded cross-sections showed that the IGC was very local. Additionally, the surface corrosion morphology also showed that pitting corrosion took place, resulting from galvanic corrosion between (FeMn)3Si12Al15 particles and matrix Al.

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Investigation of Surface Corrosion Morphology and Mass Change of Three Aluminum Aerospace Alloys As It Pertains to Corrosion Rate at Various Atmospheric Exposure Sites

ECS Meeting Abstracts ◽

10.1149/ma2020-02131320mtgabs ◽

2020 ◽

Vol MA2020-02 (13) ◽

pp. 1320-1320

Author(s):

Douglas Hansen ◽

David Borth ◽

Gregory Wolters ◽

Thao Truong ◽

Brant Hlavin ◽

...

Keyword(s):

Corrosion Rate ◽

Mass Change ◽

Corrosion Morphology ◽

Surface Corrosion ◽

Aerospace Alloys ◽

Atmospheric Exposure

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Effects of Gallium Addition on the Microstructure and Electrochemical Properties of Al-Zn-Bi Series Alloy Anode

Materials Science Forum ◽

10.4028/www.scientific.net/msf.686.107 ◽

2011 ◽

Vol 686 ◽

pp. 107-112

Author(s):

Qing Guo Hao ◽

Jiu Ba Wen ◽

Jun Guang He ◽

Jing Ling Ma

Keyword(s):

Current Efficiency ◽

Open Circuit Potential ◽

Electrochemical Impedance ◽

Current Method ◽

Open Circuit ◽

Constant Current ◽

Anode Surface ◽

Electrochemical Impedance Spectra ◽

Corrosion Morphology ◽

Surface Corrosion

The open circuit potential, working potential and current efficiency of Al-5Zn-0.5Bi and Al-5Zn-0.5Bi-0.015Ga alloys in artificial seawater were tested by constant current method. The corrosion characteristics of the anode alloys in 3.5% NaCl solution were studied by polarization curves and electrochemical impedance spectra. The surface corrosion morphology and microstructures of the alloys were observed and investigated by metallographic microscopy, scanning electron microscopy and X-ray energy dispersive analysis. The results show that the open circuit potential shifts towards negative, working potential becomes stable and the current efficiency becomes high through the addition of gallium in the alloy. Gallium can be uniformly dissolved in aluminum alloy and effectively reduce the segregation of Bi. The cations can deposit back to the anode surface forming into the Ga-Al amalgam, which promotes its homogeneous dissolution and improve comprehensive electrochemical performance.

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Corrosion Crack Nucleation Mechanism in the Welded Structures of X65 Steel in Natural Seawater

Advances in Materials Science and Engineering ◽

10.1155/2018/8973150 ◽

2018 ◽

Vol 2018 ◽

pp. 1-14 ◽

Cited By ~ 2

Author(s):

Linyue Bai ◽

Lei Gao ◽

Kebin Jiang

Keyword(s):

Residual Stress ◽

Weld Joint ◽

Corrosion Damage ◽

Nucleation Mechanism ◽

Fusion Line ◽

Natural Seawater ◽

Corrosion Morphology ◽

Corrosion Failure ◽

Welded Structures ◽

Surface Corrosion

The nucleation mechanism of corrosion cracks in welded structures in natural seawater has been revealed through investigation on the corrosion behavior of X65-welded structures in natural seawater. The evolution laws of surface corrosion morphology, residual stress, and areas of welded structures with the most serious corrosion damage were analyzed by microstructure observation, corrosion morphology observation, residual stress detection, and magnetic field detection. The results show that the main factors of determining surface corrosion morphology evolution law of welded structures are microstructures of the weld joint, heat-affected zone (HAZ), and the fusion line. Due to the difference of corrosion rates between the weld joint, HAZ, and the coarse Widmänstatten structure in fusion line, the fusion line of welded structures receives the most serious damage while being corroded. Meanwhile, mutual reinforcement of residual stress and corrosion damage on the surface of welded structures further accelerate the nucleation of corrosion cracks. Under the influences of microstructure, residual stress, and corrosion, corrosion cracks that are parallel to weld joints generate first in the fusion line of welded structures. Therefore, it makes welded structures the source of marine steel structures’ corrosion failure.

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Atmospheric Corrosion State Evaluation Based on Surface Corrosion Morphology for Electrical Metal Frame Equipment in Chongqing Power Grid

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.815.89 ◽

2019 ◽

Vol 815 ◽

pp. 89-95 ◽

Cited By ~ 1

Author(s):

Gao Lin Wu ◽

Yao Zhong ◽

Xiao Ren ◽

Jian Hao ◽

Qian Wang ◽

...

Keyword(s):

Atmospheric Corrosion ◽

Power Transmission ◽

Electrical Equipment ◽

Test Method ◽

Metal Corrosion ◽

Atmospheric Environment ◽

Corrosion Morphology ◽

Surface Corrosion ◽

Metal Frame ◽

Corrosion State

This paper studies the atmospheric corrosion characteristics of grid metal frame equipment in Chongqing. Through the standard field test method of atmospheric corrosion -"exposure" method, this study carried out the substation site hanging test of the Q235 steel of the power transmission and transformation engineering structural material in the atmospheric environment, and mastered the corrosion data of Q235 steel in different corrosion stages. It was found that the morphology, quantity and characteristics of corrosion products on the metal surface varied greatly with the progress of corrosion. According to the metal corrosion morphology of different corrosion time, combined with image processing technology and wavelet transform algorithm, the parameters such as gray mean M, corrosion standard deviation σm, corrosion energy E, and energy percentage of wavelet image coefficient were selected as corrosion characteristic variable. At the same time, the BP neural network algorithm was used to qualitatively evaluate the corrosion state of the electrical equipment metal. By testing the on-site samples of the two substations, the corrosion state values of the samples were 0.946 and 0.8071, respectively, which is consistent with the actual corrosion degree, and the system had a good evaluation result.

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Corrosion Behaviour and Surface Modification of Intra-orally Engaged Orthodontic Ni-Ti Wires

Revista de Chimie ◽

10.37358/rc.17.5.5615 ◽

2017 ◽

Vol 68 (5) ◽

pp. 1077-1080

Author(s):

Krisztina Martha ◽

Alexandru Ogodescu ◽

Cristina Ioana Bica ◽

Cristina Molnar Varlam

Keyword(s):

Chemical Structure ◽

Corrosion Behaviour ◽

Sem Analysis ◽

Orthodontic Appliance ◽

Orthodontic Wires ◽

Surface Corrosion ◽

Patient Health ◽

Almost All ◽

Scanning Electron Microscope Method ◽

Surface Changes

Almost all orthodontic wires suffer from corrosion as they are intra-orally engaged. This chemical structure alteration appears on the surface of these wires, surface topography can be easily visualised with scanning electron microscope method. The aim of our study was to assess the intraoral corrosion of the retrieved orthodontic Ni-Ti archwires. Archwire retrieval procedure yielded approximately 30 retrieved wires, placed intra-orally for 1-5 months. SEM analysis was performed and surface changes were interpreted. Our SEM results showed, that surface corrosion and pitting can be seen on the surface of retrieved Ni-Ti wires, the depth of corrosion depends on the time wires have been engaged in the oral cavity. With regards of metal liberation consequently surface corrosion, practitioners should be avare of these chemical changes which can affect the resistence of the orthodontic appliance and patient health.

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