https://profdoc.um.ac.ir/articles/a/1087371.pdf

Science and Engineering of Superhydrophobic Surfaces: Review of Corrosion Resistance, Chemical and Mechanical Stability

Biomimetic nanosurfaces with distinct wettability and versatility have found special enthusiasm in both fundamental research and industrial applications. With the advent of nanotechnology, it is doable to acclimate surface architecture and surface chemistry to attain superhydrophobicity. The uniqueness of superhydrophobic surfaces arises from various phenomenal advances, and its progress is expected to continue for decades in the future. In this Review Article, we discuss recent progress made in defining physical aspects of numerical modeling, experimental practices adopted, and applications of superhydrophobic surfaces. First, we revisit various classical models of superhydrophobicity and recent theoretical advances achieved related to the wetting phenomena. Subsequently, we emphasize various precursors and advance fabrication strategies adopted to fabricate superhydrophobic surfaces. In the following section, we take up various potential applications and appropriate working principles to explain wettability phenomena. Finally, some general conclusions are drawn along with proposed guidelines for designing robust superhydrophobic coatings.

Superhydrophobic Surfaces: Insights from Theory and Experiment.

Subtractive manufacturing of stable hierarchical micro-nano structures on AA5052 sheet with enhanced water repellence and durable corrosion resistance

There has been tremendous interest in the development of different innovative wear-resistant materials, which can help to reduce energy losses resulted from friction and wear by ≈40% over the next 10-15 years. This paper provides a comprehensive review of the recent progress on designs, properties, and applications of wear-resistant materials, starting with an introduction of various advanced technologies for the fabrication of wear-resistant materials and anti-wear structures with their wear mechanisms. Typical strategies of surface engineering and matrix strengthening for the development of wear-resistant materials are then analyzed, focusing on the development of coatings, surface texturing, surface hardening, architecture, and the exploration of matrix compositions, microstructures, and reinforcements. Afterward, the relationship between the wear resistance of a material and its intrinsic properties including hardness, stiffness, strength, and cyclic plasticity is discussed with underlying mechanisms, such as the lattice distortion effect, bonding strength effect, grain size effect, precipitation effect, grain boundary effect, dislocation or twinning effect. A wide range of fundamental applications, specifically in aerospace components, automobile parts, wind turbines, micro-/nano-electromechanical systems, atomic force microscopes, and biomedical devices are highlighted. This review is concluded with prospects on challenges and future directions in this critical field.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/advs.202003739

Recent Progress on Wear-Resistant Materials: Designs, Properties, and Applications.

Designing reduced graphene oxide/zinc rich epoxy composite coatings for improving the anticorrosion performance of carbon steel substrate

Aluminum alloys with novel binary anti-corrosion structures on the surface showing superhydrophobic properties were fabricated via chemical etching, anodic oxidation and chemical modification. Surface morphologies and chemical elements of the as-prepared films were investigated by Fourier transform infrared spectrometer, scanning electron microscopy and confocal laser scanning microscope. Surface wettability was investigated by the contact angle meter. Manipulation of surface morphology by anodic oxidation current density and the influence of surface chemical modification on the wettability were investigated. The anti-corrosion properties of the as-prepared films were characterized using an electrochemistry workstation. The results showed that surface water contact angle could reach 156° after chemical modification when the current density of anodic oxidation was 5 A dm−2. The corrosion potential (Ecorr) was positively increased from −1189 mV for bare Al alloys to −304 mV for the samples anodized at 5 A dm−2. The synergetic effect between the protective properties of air trapped in a low adhesion superhydrophobic surface and good barrier properties of the barrier layer of anodic oxidation film was remarkably enhanced the corrosion resistance of aluminum alloys. Influences of the anodic oxidation current density and the self-assembled films on the anti-corrosion performance were discussed in detail.

Fabricating binary anti-corrosion structures containing superhydrophobic surfaces and sturdy barrier layers for Al alloys

In the present work, the novel anodic oxide film (AOF) with self-sealing layer was successfully fabricated on 2024Al alloys by using an improved anodic oxidation method. The presence of the self-sealing layer on the porous layer of AOF was verified by Field emission scanning electron micro scope. Confocal laser scanning microscope (CLSM) and X-ray photoelectron spectroscopy (XPS) were used to evaluate the morphology and the corrosion products of the AOF after salt spray test. The microhardness test showed that the self-sealing AOFs still displayed high hardness even after salt spray test. Electrochemical test and salt spray test results illustrated the excellent corrosion performance of the novel structured self-sealing anodic oxide film (SAOF) compared with common porous AOFs. The narrow diameter makes it difficult for chlorine ions ingress into the pores of SAOFs. The self-sealing layer played an important role in protecting the SAOF from corrosion.

/pdf/novel-anodic-oxide-film-with-self-sealing-layer-showing-sjie6g3tbs.pdf

Novel anodic oxide film with self-sealing layer showing excellent corrosion resistance

The fabrication of porous structures on aluminum surfaces can be performed readily and routinely using anodic oxidation technology. However, the design and preparation of smooth and compact films on the porous structures is difficult to achieve. In this work, by replacing Al cathode with graphite cathode and also by tailoring the Al3+ concentration, anodic oxide films (AOFs) possessing novel multilayer structures which contain compact surface layers, porous sublayers and barrier layers and which show excellent wear resistance were fabricated via common anodic oxidation technology. The surface morphologies and chemical compositions of the as-prepared films were investigated by scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The results showed that the surface layer was amorphous aluminum oxide. The surface microhardness of the as-prepared AOFs was 2 to 7 times that of the untreated Al alloys. The thicknesses of the surface layer and porous sublayer were manipulated by the anodic current density and the concentration of sulfuric acid. The wear resistance properties of the anodic oxide film were characterized using a UMT-3 tribometer. When the sample was anodized in a 90 mg mL−1 sulfuric acid bath and the current density was 5 A dm−2 (AOF2-A), the wear rate significantly decreased to 1.81 × 10−5 mm3 N−1 m−1 under dry sliding and 7.54 × 10−6 mm3 N−1 m−1 under seawater sliding. The wear rate of the AOF2-A sample was 3 orders of magnitude lower than that of 2024 Al alloys. It was found that the surface layer of the AOF2-A sample, which showed high hardness and excellent toughness, presented the lowest wear rate owing to columnar wear debris in the wear track, which acted as a rolling log in the sliding process. The influences of the anodic oxidation current density and the concentration of sulfuric acid on the wear resistance and the self-lubrication mechanism of desquamated wear debris in the sliding process were discussed in detail.

Novel structured anodic oxide films containing surface layers and porous sublayers showing excellent wear resistance performance

We report an electrically controlled micro-flow of liquid on Au-patterned glass surfaces with a driving voltage lower than 10 volts. The Joule heating produced by electrical current passing through the Au layer activates the selective wetting of liquids, performing complicated micro-flow control over pre-designed circuits. Transportation and serial dilution of the dye molecules in the liquid are further demonstrated.

/pdf/low-voltage-driven-surface-micro-flow-by-joule-heating-3bzm280z6k.pdf

Wurong Wang

Papers

Fabricating binary anti-corrosion structures containing superhydrophobic surfaces and sturdy barrier layers for Al alloys

Novel anodic oxide film with self-sealing layer showing excellent corrosion resistance

Novel structured anodic oxide films containing surface layers and porous sublayers showing excellent wear resistance performance

Low voltage driven surface micro-flow by Joule heating