1
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Dong H, Zhao C, Kong N, Zhou Y, Zhou J. Coupling Process between Droplet and Iron Investigated by Reactive Molecular Dynamics Simulations. ACS OMEGA 2024; 9:20410-20424. [PMID: 38737081 PMCID: PMC11079893 DOI: 10.1021/acsomega.4c01236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 04/16/2024] [Accepted: 04/19/2024] [Indexed: 05/14/2024]
Abstract
The droplet-to-iron electrochemical reaction is common in nature and industrial production, and it causes damage to the economy, safety, and the environment. The electrochemical reaction of droplet-to-iron is a coupling process of wetting and corrosion. Presently, investigations into electrochemical reactions mainly focus on the corrosions caused by a solution, and wetting is rarely considered. However, for the droplet-to-iron electrochemical reaction, the mechanism of charge transfer in the process is still unclear. In this paper, a reactive molecular dynamics simulation model for the droplet-to-iron electrochemical reaction is developed for the first time. The electrochemical reaction of droplet-to-iron is studied, and the interaction between droplet wetting and corrosion on iron is investigated. The effects of temperature, electric field strength, and salt concentration on the electrochemical reaction are explored. Results show that droplet wetting on the iron surface and the formation of a single-molecular-layer ordered structure are prerequisites for corrosion. The hydroxyl radicals that penetrate the ordered structure acquire electrons from iron atoms on the substrate surface under the action of Coulomb forces and form iron-containing oxides with these iron atoms. The corrosion products and craters lead to a reduced droplet height, which promotes droplet wetting on iron and further intensifies the droplet-to-iron electrochemical reaction.
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Affiliation(s)
- Hang Dong
- School
of Mechanical Engineering, Xinjiang University, Urumqi 830046, China
| | - Can Zhao
- School
of Mechanical Engineering, Xinjiang University, Urumqi 830046, China
| | - Na Kong
- Xinjiang
Uygur Autonomous Region Science and Technology Project Service Center, Urumqi 830011, China
| | - Yu Zhou
- State
Key Laboratory of Mechanical System and Vibration, School of Mechanical
Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jianping Zhou
- School
of Mechanical Engineering, Xinjiang University, Urumqi 830046, China
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2
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Zhang F, Wu R, Zhang H, Ye Y, Chen Z, Zhang A. Novel Superhydrophobic Copper Mesh-Based Centrifugal Device for Edible Oil-Water Separation. ACS OMEGA 2024; 9:16303-16310. [PMID: 38617616 PMCID: PMC11007822 DOI: 10.1021/acsomega.3c10436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 02/25/2024] [Accepted: 02/29/2024] [Indexed: 04/16/2024]
Abstract
Edible oil is essential for people's daily life but also results in a large amount of oily wastewater simultaneously. Oil-water separation is a practical route that can not only purify wastewater but also recycle valuable edible oil. In this study, the superhydrophobic copper mesh (SCM) was prepared by chemical etching, and a novel oil-water centrifugal device was designed for high-efficiency separation of edible oil wastewater. The kernel is a self-prepared SCM, which has a water contact angle (WCA) of 155.1 ± 1.8° and an oil contact angle (OCA) of 0°. Besides, the separation performance of the SCM for edible oil-water mixtures was studied in this study. The results showed that the SCM exhibited excellent oil/water separation performance, with a separation efficiency of up to 96.7% for sunflower seed oil-water wastewater, 93.3% for corn oil-water wastewater, and 98.3% for peanut oil-water wastewater, respectively. Moreover, the separation efficiency was still over 90% after 18 cycles. A model was established to analyze the oil-water separation mechanism via centrifugation. The oil-water centrifugal separation device has great potential for scale-up applications.
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Affiliation(s)
- Fengzhen Zhang
- School
of Chemical Engineering, Sichuan University
of Science & Engineering, Zigong 643000, China
| | - Ranhao Wu
- School
of Chemical Engineering, Sichuan University
of Science & Engineering, Zigong 643000, China
| | - Huanhuan Zhang
- School
of Chemical Engineering, Sichuan University
of Science & Engineering, Zigong 643000, China
| | - Yuling Ye
- School
of Chemical Engineering, Sichuan University
of Science & Engineering, Zigong 643000, China
- National
Engineering Laboratory of Circular Economy, Sichuan University of Science and Engineering, Zigong 643000, China
- Sichuan
Engineering Technology Research Center for High Salt Wastewater Treatment
and Resource Utilization, Sichuan University
of Science and Engineering, Zigong 643000, China
| | - Zhong Chen
- Chongqing
Institute of Green and Intelligent Technology, Chinese Academy of
Sciences, Chongqing 400714, China
| | - Aiai Zhang
- School
of Chemical Engineering, Sichuan University
of Science & Engineering, Zigong 643000, China
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3
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Grishina A, Filatov I, Shchedrina N, Prokopiev V, Davydova E, Suslov R, Romanova G. Laser-Assisted Structures for Efficient Fluid Management on Stainless Steel Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:5632-5638. [PMID: 38449101 DOI: 10.1021/acs.langmuir.3c02814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
The article presents a high-productivity laser-structuring method combined with a hydrophobic post-treatment to create zone-structured surfaces with a decreasing wetting angle on AISI 304 stainless steel surfaces. We have investigated the impact of laser processing modes and hydrophobic substances on wetting and hysteresis angles and successfully demonstrated autonomous droplet movement over this zone-structured surface. A critical condition for autonomous fluid flow is the need for the drop to touch the boundary between the two zones. This can be achieved by settling the droplet directly on the boundary of the two zones or by using droplets whose surface contact diameter is on the order of magnitude or higher than the zone size. The zone-structured surface showed reusability, maintaining its properties even after 30 droplet passages. The zone-structured surfaces with a decreasing wetting angle can be used for moving a droplet along a complex trajectory as well as for mixing various liquids.
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Affiliation(s)
- Alena Grishina
- Institute of Laser Technologies, ITMO University, 49 Kronversky Pr., St. Petersburg 197101, Russia
| | - Ilya Filatov
- Institute of Laser Technologies, ITMO University, 49 Kronversky Pr., St. Petersburg 197101, Russia
| | - Nadezhda Shchedrina
- Institute of Laser Technologies, ITMO University, 49 Kronversky Pr., St. Petersburg 197101, Russia
| | - Vladislav Prokopiev
- Institute of Laser Technologies, ITMO University, 49 Kronversky Pr., St. Petersburg 197101, Russia
| | - Evgeniya Davydova
- Institute of Laser Technologies, ITMO University, 49 Kronversky Pr., St. Petersburg 197101, Russia
| | - Roman Suslov
- Institute of Laser Technologies, ITMO University, 49 Kronversky Pr., St. Petersburg 197101, Russia
| | - Galina Romanova
- Institute of Laser Technologies, ITMO University, 49 Kronversky Pr., St. Petersburg 197101, Russia
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4
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Tai X, Liu C, Chen W, Mai Y, Zhang L, Wu X, Jie X. Electroplated wear and corrosion–resistant Co-Mo/CeO2 composite coatings for reducing mold fouling application. J Solid State Electrochem 2022. [DOI: 10.1007/s10008-022-05361-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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5
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Recent advances in nanostructured superhydrophobic surfaces: fabrication and long-term durability challenges. Curr Opin Chem Eng 2022. [DOI: 10.1016/j.coche.2021.100790] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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6
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Elzaabalawy A, Meguid SA. Advances in the development of superhydrophobic and icephobic surfaces. INTERNATIONAL JOURNAL OF MECHANICS AND MATERIALS IN DESIGN 2022; 18:509-547. [PMID: 37520670 PMCID: PMC9132174 DOI: 10.1007/s10999-022-09593-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 03/26/2022] [Indexed: 08/01/2023]
Abstract
Superhydrophobicity and icephobicity are governed by surface chemistry and surface structure. These two features signify a potential advance in surface engineering and have recently garnered significant attention from the research community. This review aims to simulate further research in the development of superhydrophobic and icephobic surfaces in order to achieve their wide-spread adoption in practical applications. The review begins by establishing the fundamentals of the wetting phenomenon and wettability parameters. This is followed by the recent advances in modeling and simulations of the response of superhydrophobic surfaces to static and dynamic droplets contact and impingement, respectively. In view of their versatility and multifunctionality, a special attention is given to the development of these surfaces using nanocomposites. Furthermore, the review considers advances in icephobicity, its comprehensive characterization and its relation to superhydrophobicity. The review also includes the importance of the use of superhydrophobic surface to combat viral and bacterial contamination that exist in fomites.
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Affiliation(s)
- Assem Elzaabalawy
- Mechanics and Aerospace Design Lab, University of Toronto, Toronto, M5S 3G8 Canada
| | - Shaker A. Meguid
- Mechanics and Aerospace Design Lab, University of Toronto, Toronto, M5S 3G8 Canada
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7
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Yin K, Wang L, Deng Q, Huang Q, Jiang J, Li G, He J. Femtosecond Laser Thermal Accumulation-Triggered Micro-/Nanostructures with Patternable and Controllable Wettability Towards Liquid Manipulating. NANO-MICRO LETTERS 2022; 14:97. [PMID: 35394233 PMCID: PMC8993985 DOI: 10.1007/s40820-022-00840-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Accepted: 03/07/2022] [Indexed: 05/03/2023]
Abstract
Versatile liquid manipulating surfaces combining patternable and controllable wettability have recently motivated considerable attention owing to their significant advantages in droplet-solid impacting behaviors, microdroplet self-removal, and liquid-liquid interface reaction applications. However, developing a facile and efficient method to fabricate these versatile surfaces remains an enormous challenge. In this paper, a strategy for the fabrication of liquid manipulating surfaces with patternable and controllable wettability on Polyimide (PI) film based on femtosecond laser thermal accumulation engineering is proposed. Because of its controllable micro-/nanostructures and chemical composition through adjusting the local thermal accumulation, the wettability of PI film can be tuned from superhydrophilicity (~ 3.6°) to superhydrophobicity (~ 151.6°). Furthermore, three diverse surfaces with patternable and heterogeneous wettability were constructed and various applications were successfully realized, including water transport, droplet arrays, and liquid wells. This work may provide a facile strategy for achieving patternable and controllable wettability efficiently and developing multifunctional liquid steering surfaces.
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Affiliation(s)
- Kai Yin
- Hunan Key Laboratory of Nanophotonics and Devices, School of Physics and Electronics, Central South University, Changsha, 410083, People's Republic of China
- The State Key Laboratory of High Performance and Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha, 410083, People's Republic of China
| | - Lingxiao Wang
- Hunan Key Laboratory of Nanophotonics and Devices, School of Physics and Electronics, Central South University, Changsha, 410083, People's Republic of China
| | - Qinwen Deng
- Hunan Key Laboratory of Nanophotonics and Devices, School of Physics and Electronics, Central South University, Changsha, 410083, People's Republic of China
| | - Qiaoqiao Huang
- Hunan Key Laboratory of Nanophotonics and Devices, School of Physics and Electronics, Central South University, Changsha, 410083, People's Republic of China
| | - Jie Jiang
- Hunan Key Laboratory of Nanophotonics and Devices, School of Physics and Electronics, Central South University, Changsha, 410083, People's Republic of China.
| | - Guoqiang Li
- Key Laboratory of Testing Technology for Manufacturing Process of Ministry of Education, Southwest University of Science and Technology, Mianyang, 621010, People's Republic of China.
| | - Jun He
- Hunan Key Laboratory of Nanophotonics and Devices, School of Physics and Electronics, Central South University, Changsha, 410083, People's Republic of China.
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8
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Thin Protective Coatings on Metals Formed by Organic Corrosion Inhibitors in Neutral Media. COATINGS 2022. [DOI: 10.3390/coatings12020149] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Protection of metals in neutral media with pH 5.0–9.0 (in humid atmospheres and various aqueous solutions) can be achieved by formation of thin coatings (up to several tens of nm) on their surfaces due to adsorption and more complex chemical interactions of organic corrosion inhibitors (OCIs) with the metal to be protected. The review contains three sections. The first section deals with coatings formed in aqueous solutions, while the second one, with those formed in organic and water-organic solvents. Here we consider metal protection by coatings mainly formed by the best-known classes of OCI (carboxylates, organophosphates and phosphonates) and estimation of its efficiency. The third section discusses the peculiarities of protection of metals in the vapor-gas phase, i.e., by volatile OCIs, and a relatively new type of metal protection against atmospheric corrosion by the so-called chamber inhibitors. OCIs with relatively low volatility under normal conditions can be used as chamber OCIs. To obtain a protective coating on the surfaces of metal items, they are placed in a chamber inside which an increased concentration of vapors of a chamber OCI is maintained by increasing the temperature. This review mainly focuses on the protection of iron, steels, copper and zinc.
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9
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Chen S, Li A, Sun M, Ma Z, Zhang Y, Wang W. Polyvinyl butyral/3‐Hydroxy‐2‐naphthoic hydrazide/Poly (methylhydrosiloxane) Composite Coatings for Improved Stainless Steel Anticorrosion in Salt, Acid, and Alkali Solution. ChemistrySelect 2022. [DOI: 10.1002/slct.202103453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Sifan Chen
- School of Material Science and Engineering Ocean University of China Qingdao Shandong 266100 PR China
| | - Anhang Li
- School of Material Science and Engineering Ocean University of China Qingdao Shandong 266100 PR China
| | - Min Sun
- School of Material Science and Engineering Ocean University of China Qingdao Shandong 266100 PR China
| | - Zhidong Ma
- School of Material Science and Engineering Ocean University of China Qingdao Shandong 266100 PR China
| | - Yue Zhang
- School of Material Science and Engineering Ocean University of China Qingdao Shandong 266100 PR China
| | - Wei Wang
- School of Material Science and Engineering Ocean University of China Qingdao Shandong 266100 PR China
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10
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Effect of Steam Flow Rate and Storage Period of Superhydrophobic-Coated Surfaces on Condensation Heat Flux and Wettability. Processes (Basel) 2021. [DOI: 10.3390/pr9111958] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The jumping-droplet phenomenon occurring on superhydrophobic (SHPhob) surfaces under special conditions may be beneficial for numerous systems using condensation, due to the reported increased heat transfer coefficients. One technique to create a SHPhob surface is coating, which can be applied to larger areas of existing elements. However, challenges are associated with coating stability and the realization of continuous dropwise condensation. This research examined the condensation of steam at different flow rates (2, 4 and 6 g/min) and its influence on heat flux and water contact angles on the SHPhob spray-coated aluminum samples. Special emphasis on the impact of time was addressed through a series of one and five-hour condensation experiments on the samples with different storage periods (coated either one year ago or shortly before testing). Over the experimental series at a higher steam flow rate (6 g/min), heat flux decreased by 20% through the old-coated samples and water contact angles transferred from the superhydrophobic (147°) to hydrophobic (125°) region. This can be attributed to the joint effects of the partial coating washout and the adsorption of the condensed water within the porous structures of the coating during steam condensation. The new-coated samples could sustain more than fifty hours of condensation, keeping the same heat fluxes and SHPhob characteristics.
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11
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Fabrication of a novel hydrophobic anti-corrosion film based on Eu2O3/stearic acid on steel surface; Experimental and detailed computer modeling studies. J Taiwan Inst Chem Eng 2020. [DOI: 10.1016/j.jtice.2020.09.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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12
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Current Status and Future Prospects of Applying Bioinspired Superhydrophobic Materials for Conservation of Stone Artworks. COATINGS 2020. [DOI: 10.3390/coatings10040353] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The development of innovative materials is one of the most important focus areas in heritage conservation research. Eligible materials can not only protect the physical and chemical integrity of artworks but also preserve their artistic and aesthetic features. Recently, as one of the hot research topics in materials science, biomimetic superhydrophobic materials have gradually attracted the attention of conservation scientists due to their unique properties. In fact, ultra-repellent materials are particularly suitable for hydrophobization treatments on outdoor artworks. Owing to their excellent hydrophobicity, superhydrophobic materials can effectively prevent the absorption and penetration of liquid water as well as the condensation of water vapor, thus greatly relieving water-induced decay phenomena. Moreover, in the presence of liquid water, the superhydrophobic surfaces equipped with a self-cleaning property can clean the dirt and dust deposited spontaneously, thereby restoring the artistic features simultaneously. In the present paper, besides the basic principles of wetting on solid surfaces, materials, and methods reported for preparing bioinspired ultra-repellent materials, the recently proposed materials for art conservation are also introduced and critically reviewed, along with a discussion on the droplet impact and durability of the artificial superhydrophobic surfaces. Lastly, the current status and the problems encountered in practical application are also pointed out, and the focus of future research is presented as well.
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13
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Tong W, Karthik N, Li J, Wang N, Xiong D. Superhydrophobic Surface with Stepwise Multilayered Micro- and Nanostructure and an Investigation of Its Corrosion Resistance. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:15078-15085. [PMID: 31682454 DOI: 10.1021/acs.langmuir.9b02910] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We develop a fluorine-free preparation of the superhydrophobic surface on an aluminum alloy with anticorrosion performance and mechanical robustness. The surface morphology, chemical composition, and water repellency were determined with SEM, CLSM, EDS, FT-IR, TG, and contact-angle measurements, respectively. The aluminum matrix superhydrophobic surface (STA-PDMS-ZnO sample) was able to display excellent repellency to water with a WCA of 152° and a WSA of 2°. The outstanding superhydrophobicity on the as-prepared surface was greatly related to the construction of stepwise multilayered micro- and nanostructure within the superhydrophobic surface. Because of the special surface structure, the mechanical robustness and corrosion resistance of the STA-PDMS-ZnO sample were improved. Notably, the anticorrosion mechanism by air pockets was explained by the comparison of two superhydrophobic surfaces prepared with the same low-surface-energy chemicals. The superhydrophobic surface with a multilayered micro- and nanostructure (STA-PDMS-ZnO sample) showed greater corrosion resistance than the surface coated by superhydrophobic modification (control sample). This is because of the entrapments of numerous air pockets within the aluminum matrix superhydrophobic surface, thus strengthening the corrosion resistance. On the basis of the results, the multidimensional superhydrophobic surface is promising for having a good application future in the field of metal corrosion protection.
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Affiliation(s)
- Wei Tong
- School of Materials Science & Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Namachivayam Karthik
- School of Materials Science & Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Jianliang Li
- School of Materials Science & Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Nan Wang
- Automotive Engineering Research Institute , Jiangsu University , Zhenjiang 212013 , China
| | - Dangsheng Xiong
- School of Materials Science & Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
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14
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Rasitha TP, Vanithakumari SC, George RP, Philip J. Template-Free One-Step Electrodeposition Method for Fabrication of Robust Superhydrophobic Coating on Ferritic Steel with Self-Cleaning Ability and Superior Corrosion Resistance. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:12665-12679. [PMID: 31479612 DOI: 10.1021/acs.langmuir.9b02045] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The corrosion of ferritic steel, a widely used structural material in the power and nuclear industries exposed to humid coastal environments, is a major concern. Here, we present a template-free one-step electrodeposition method for the fabrication of a robust superhydrophobic (SHP) coating on ferritic steel with excellent mechanical stability, enhanced corrosion resistance, and self-cleaning ability. By varying the electrodeposition time and potential, the micronanoscale hierarchical surface structures were optimized. The coated SHP surfaces were characterized by water contact angle measurement, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The coated surfaces showed a characteristic cauliflower morphology of cerium myristate with micronanoscale features. The maximum water contact angle achieved was 162.8 ± 2.4°. Shear abrasion testing showed good mechanical durability for the prepared coatings. The as-prepared SHP coating showed a five order reduction in corrosion current density (4.14 × 10-11 A/cm2) and corrosion rate (4.63 × 10-7 mm/y) as compared to the bare sample. Further, a six order enhancement in the polarization resistance (1.55 × 109 Ω) was also observed in agressive chloride solution, which confirmed the excellent corrosion resistance of the SHP coating. Electrochemical impedance spectroscopy (EIS) studies showed a high impedance modulus for SHP coated surfaces due to the presence of a compact protective layer of cerium myristate. This observed impedance modulus of the SHP surface was approximately four orders higher than the reported value on magnesium alloys. This study provides a new platform for obtaining a robust, mechanically stable, and corrosion resistant SHP coating with a self-cleaning ability on ferritic steel substrates that may be adapted for a range of materials in practical applications.
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Affiliation(s)
- T P Rasitha
- Corrosion Science and Technology Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute , Indira Gandhi Centre for Atomic Research , Kalpakkam - 603 102 , India
| | - S C Vanithakumari
- Corrosion Science and Technology Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute , Indira Gandhi Centre for Atomic Research , Kalpakkam - 603 102 , India
| | - R P George
- Corrosion Science and Technology Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute , Indira Gandhi Centre for Atomic Research , Kalpakkam - 603 102 , India
| | - John Philip
- Corrosion Science and Technology Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute , Indira Gandhi Centre for Atomic Research , Kalpakkam - 603 102 , India
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15
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Abstract
The preparation of the Nb coating was performed on the bare Ti–6Al–4V alloy using the double glow discharge plasma technique. It was characterized that the Nb coating exhibited a face centered cubic (fcc) crystal structure and a pronounced (200) preferred orientation. The SEM micrograph of the cross section for the coating displayed dense microstructure with a thickness of approximately 18 µm. The critical load (Lc) of the coating was determined to be about 83.5 N by the scratch tests. The electrochemical corrosion resistance of the coating was examined in Ringer’s solution at 37 °C by a series of electrochemical techniques, including open-circuit potential (OCP), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and a Mott–Schottky analysis. As the result of the potentiodynamic polarization, the Nb coating possessed a more positive corrosion potential and lower corrosion current density than the Ti–6Al–4V substrate. EIS fitting date showed that the Nb coating always possessed a higher value of impedance and lower effective capacitance than those of the substrate during the five days of immersion testing. The main component of the passive film developed on the Nb coating was Nb2O5, confirmed by an X-ray photoelectron spectroscopy (XPS) analysis. A Mott–Schottky analysis demonstrated typical n-type semiconductor characteristics of the Nb coating, and both the donor density and flat band potential of the coating were lower than those of the substrate at all the given formation potential. These investigations demonstrate that the Nb coating can significantly improve the corrosion protection of uncoated Ti–6Al–4V and is thus a promising coating for the surface protection of bioimplants.
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