Electrochemical Formation Mechanism of Microdroplets on Pure Iron

The electrochemical formation mechanism of microdroplets formed around a primary droplet of 3.5% NaCl solution on an iron-plated film was investigated by quartz crystal microbalance (QCM) and concentric three-electrode array (CTEA) measurements. During the initial stage, the microdroplets mainly originate from evaporation owing to cathodic polarization and electric current of the localized corrosion cell under the primary droplet. The maximal electrochemical potential difference between the anode and cathode was measured to be 0.36 V and acted as the driving force for the formation of microdroplets. The maximums of anodic and cathodic electric current density of pure iron under the NaCl droplet are 764 and −152 μA/cm2, respectively. Propagation of microdroplets in the developing stage attributes to horizontal movement of the electrolyte, water evaporation, and recondensation from primary and capillary condensation from moist air. The results of the study suggest that the initiation and propagation of microdroplets could promote and accelerate marine atmospheric corrosion.

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Sintering driving force of Al2O3 powders at the initial stage of pulse electric current sintering under thermoelastic diffusion

International Journal of Mechanical and Materials Engineering ◽

10.1186/s40712-018-0095-9 ◽

2018 ◽

Vol 13 (1) ◽

Author(s):

Zhang Long ◽

Zheng Heng-wei

Keyword(s):

Electric Current ◽

Driving Force ◽

Thermoelastic Diffusion ◽

Pulse Electric Current ◽

Initial Stage ◽

Pulse Electric

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A Superhydrophilic Aluminum Surface with Fast Water Evaporation Based on Anodic Alumina Bundle Structures via Anodizing in Pyrophosphoric Acid

Materials ◽

10.3390/ma12213497 ◽

2019 ◽

Vol 12 (21) ◽

pp. 3497 ◽

Cited By ~ 5

Author(s):

Daiki Nakajima ◽

Tatsuya Kikuchi ◽

Taiki Yoshioka ◽

Hisayoshi Matsushima ◽

Mikito Ueda ◽

...

Keyword(s):

Contact Angle ◽

Oxide Film ◽

High Speed ◽

Porous Alumina ◽

Aluminum Surface ◽

Water Evaporation ◽

Water Contact ◽

Initial Stage ◽

Angle Measuring ◽

Pyrophosphoric Acid

A superhydrophilic aluminum surface with fast water evaporation based on nanostructured aluminum oxide was fabricated via anodizing in pyrophosphoric acid. Anodizing aluminum in pyrophosphoric acid caused the successive formation of a barrier oxide film, a porous oxide film, pyramidal bundle structures with alumina nanofibers, and completely bent nanofibers. During the water contact angle measurements at 1 s after the water droplet was placed on the anodized surface, the contact angle rapidly decreased to less than 10°, and superhydrophilic behavior with the lowest contact angle measuring 2.0° was exhibited on the surface covered with the pyramidal bundle structures. As the measurement time of the contact angle decreased to 200–33 ms after the water placement, although the contact angle slightly increased in the initial stage due to the formation of porous alumina, at 33 ms after the water placement, the contact angle was 9.8°, indicating that superhydrophilicity with fast water evaporation was successfully obtained on the surface covered with the pyramidal bundle structures. We found that the shape of the pyramidal bundle structures was maintained in water without separation by in situ high-speed atomic force microscopy measurements.

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Microstructural Changes and Straining Behavior in Transformation Superplasticity in Iron and Steels

MRS Proceedings ◽

10.1557/proc-196-105 ◽

1990 ◽

Vol 196 ◽

Author(s):

Yasunori Saotome ◽

Nobuhiro Iguchi

Keyword(s):

Pure Iron ◽

Secondary Phase ◽

Intermediate Stage ◽

Eutectoid Steel ◽

Grid Pattern ◽

Principal Mechanism ◽

Microstructural Changes ◽

Initial Stage ◽

Sliding Mechanism ◽

Polycrystalline Structures

ABSTRACTThe microstructural changes associated with phase transformation and the straining behavior in polycrystalline structures during transformational superplastic deformation have betransformatonal superplasticen investigated. In-situ observations have been carried out with specially designed hot-stage microscopes. The strain distribution has been examined by microscopic strain analyses using a micro-grid pattern with 12.7 and 6 μm intervals in pure iron, 0.1%C steel and eutectoid steel. The results are as follows: (1) In the initial stage of Ac3 transformation in pure iron, superplastic strain is induced by the sliding at o/y interface along the prior ferrite grain boundaries and by the grain rotation. In the intermediate stage, the sliding deformation is generated at the migrating tranformation interface associated with the growth of austenite grains. (2) Accumulated strain by sliding has been observed within the previously transformed region during Ac3 transformation in 0.1%C steel. (3) The characteristic straining behavior in the eutectoid steel is due to the behavior at the transformation interface in the microstructure including secondary phase Fe3C particles. These observations suggest that a sliding mechanism at the migrating interface is a principal mechanism of transformation superplasticity.

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Inhibiting Localized Corrosion of Aluminum and Aluminum Alloy by Rare Earth Metal Compounds: Behaviors and Characteristics Observed Using an Electrochemically Integrated Multi-Electrode Array

Journal of The Electrochemical Society ◽

10.1149/2.068304jes ◽

2013 ◽

Vol 160 (4) ◽

pp. C147-C158 ◽

Cited By ~ 4

Author(s):

Yongjun Tan ◽

Tie Liu

Keyword(s):

Aluminum Alloy ◽

Rare Earth ◽

Rare Earth Metal ◽

Electrode Array ◽

Earth Metal ◽

Localized Corrosion ◽

Metal Compounds ◽

Multi Electrode Array

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Temperature-Dependence of Water Bridge Formation in Atomic Force Microscopy

Microelectromechanical Systems ◽

10.1115/imece2003-41762 ◽

2003 ◽

Author(s):

Brent A. Nelson ◽

Mark A. Poggi ◽

Lawrence A. Bottomley ◽

William P. King

Keyword(s):

Temperature Dependence ◽

Capillary Condensation ◽

Heated Surface ◽

High Surface ◽

Water Evaporation ◽

Water Bridge ◽

Force Microscopy ◽

Atomic Force ◽

Localized Heating ◽

Low Humidity

When an Atomic Force Microscope (AFM) is operated in air, capillary condensation induces meniscus formation between the AFM tip and substrate. At present, no models account for the temperature-dependence of meniscus formation. This paper describes experiments measuring capillary forces between an AFM tip and mica at various temperatures and times. At low humidity, the capillary force decreases with increasing surface temperature in a manner unaccounted for by merely the dependence of water surface energy on temperature. We propose that this is due to water evaporation off the heated surface. The adhesion is also shown to decrease significantly with time until stabilizing after approximately an hour of experiments. Localized heating of the surface by the AFM laser is proposed as the cause of adhesion decrease. The decrease in force occurring at high surface temperatures implies a reduction in meniscus size that may potentially improve the resolution of AFM-based nanolithography techniques.

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Understanding the influences of temperature and microstructure on localized corrosion of subsea pipeline weldment using an integrated multi-electrode array

Ocean Engineering ◽

10.1016/j.oceaneng.2019.106351 ◽

2019 ◽

Vol 189 ◽

pp. 106351 ◽

Cited By ~ 3

Author(s):

Yesen Zhu ◽

Yunze Xu ◽

Mingyu Wang ◽

Xiaona Wang ◽

Gang Liu ◽

...

Keyword(s):

Electrode Array ◽

Localized Corrosion ◽

Subsea Pipeline ◽

Multi Electrode Array

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Formation and Evolution of Liquid Pools Entrapped within Primary Particles of In Situ Mg2Si/AM60B Composite with Fine-Grains during Partial Remelting

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.446-447.55 ◽

2013 ◽

Vol 446-447 ◽

pp. 55-61

Author(s):

Su Qing Zhang ◽

Ti Jun Chen ◽

Ying Ma ◽

Yuan Dong Li ◽

Yuan Hao

Keyword(s):

Phase Transformations ◽

Formation Mechanism ◽

Partial Remelting ◽

Initial Stage ◽

Primary Particles ◽

Formation And Evolution ◽

Liquid Pools ◽

Two Stages

The formation mechanism and evolution of liquid pools entrapped within solid grains have been investigated during partial remelting of in-situ Mg2Si/AM60B composite with fine-grains during partial remelting. The results indicate that the merging of dendrite arms during the initial stage of partial remelting is the main cause for the formation of the entrapped liquid pools. In view of phase transformations, the formation of the entrapped liquid pools is attributed to the reactions of α+β→L and α→L, essentially. The evolution of the liquid pools during latter heating can be divided into two stages: the agglomeration of each others and connection with intergranular liquid.

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