Superhydrophobic Magnesium Alloy Research Articles

Study on Hydrophobic Surface of Magnesium Alloy Prepared by Femtosecond Laser and its Corrosion Resistance

Due to their excellent barrier and shielding effects, superhydrophobic magnesium alloy surfaces are increasingly interested in corrosion protection. This paper proposes a method for producing a stable superhydrophobic surface by laser scanning ablation of AZ31B magnesium alloy on its surface. The prepared layered micro-nanoemulsion convex structure with a lotus-like surface exhibited excellent superhydrophobicity after modification by stearic acid, and the static water droplet contact angle reached 163°. After 90 days in outdoor air, droplet pressure-based experiments show that the superhydrophobic surface possesses a long-term stable Cassie state. In addition, The superhydrophobic surface showed excellent corrosion resistance against magnesium alloy in a Neutral 3.5 wt.% NaCl solution. The results of the dynamic potential polarization tests showed that the existence of a gas layer cavity on the lotus-like surface structure caused the corrosion current density of superhydrophobic AZ31B (3.86±1 uA/cm2) to decrease by 2 orders of magnitude compared with that of the extruded AZ31B (103±1 uA/cm2). We believe the proposed method is simple, efficient, and non-polluting, especially for medical magnesium alloys in the field of in vivo implant materials to slow down corrosion and promote clinical applications.

Bio-inspired superhydrophobic magnesium alloy surfaces with active anti-corrosion and self-healing properties

Bio-inspired superhydrophobic magnesium alloy surfaces with active anti-corrosion and self-healing properties

Electroplated super-hydrophobic Zn-Fe coating for corrosion protection on magnesium alloy

A superhydrophobic Zn-Fe alloy coating was prepared on the surface of a reactive magnesium alloy using a simple, low-cost, eco-friendly method. Firstly, the Zn-Fe coating was obtained in a neutral glycerol Zn-Fe plating solution, which is green, compositionally stable, and non-corrosive to the equipment. And then the superhydrophobic surface with a flower-like microstructure was obtained by grafting myristic acid onto the Zn-Fe coating via a chelation reaction. The water contact angle was >150° and the rolling angle was 3°-4°. The corrosion rate of the two groups of superhydrophobic magnesium alloy samples with electrodeposition time of 30 and 50 min, respectively, was reduced by about 87% compared to that of the bare magnesium alloy. The prepared superhydrophobic coatings exhibit high performance in self-cleaning, abrasion resistance, and corrosion resistance.

Thermally Induced Gradient of Properties on a Superhydrophobic Magnesium Alloy Surface

Fabrication of superhydrophobic coatings for magnesium alloys is in high demand for various industrial applications. Such coatings not only extend the service life of metal structures, but also impart additional useful functional properties to the coated surface. In this study, we show that nanosecond laser processing of long, thin stripes of magnesium alloys followed by the deposition of a hydrophobic agent onto the magnesium oxide layer is a simple, convenient, and easily reproducible method for obtaining superhydrophobic surfaces with property gradient along the sample. The mechanism of the gradient in wettability and electrochemical properties of the magnesium alloy surface is discussed based on the high-temperature growth of magnesium oxide and its following degradation. The latter is related to the development of internal stresses and the formation of cracks and pores within the oxide layer at prolonged exposure to high temperatures during the interaction of a laser beam with the substrate. The effect of heating during laser processing of magnesium materials with limited sizes on the protective properties of the forming coatings is elucidated.

A Facile Method to Prepare a Superhydrophobic Magnesium Alloy Surface.

The application of superhydrophobic materials has been handicapped by complex processes and poor environmental friendliness. Magnesium alloys are widely used in daily production due to their low density and good casting properties. A facile and environmentally friendly method was proposed to prepare a superhydrophobic layer with coral-like microstructure on the surface of AZ91D magnesium alloy by high temperature heating. The prepared superhydrophobic surface has a contact angle of 159.1° and a rolling angle of 4.8°. The corrosion current of superhydrophobic surface has been reduced by about two orders of magnitude relative to the magnesium alloy substrate and its inhibition efficiency is 96.94%, which demonstrates its great corrosion resistance. In addition, the superhydrophobic surface has great thermal stability. When the temperature rises to 190 °C, the contact is still above 150°. Excellent self-cleaning and advantages in preparation efficiency, environmental protection and cost-effectiveness will boost its good application prospects.

Comparative Study of Structure and Property Changes in Corrosive Media for Self-cleaning Superhydrophobic Magnesium Alloys

Magnesium alloys with superhydrophobicity are constructed by controlling rough surface structure and grafting long hydrophobic alkyl chains. Changes of morphology, phase structure, chemical composition as well as wettability, corrosion resistance of superhydrophobic magnesium alloy upon immersing in corrosive media are investigated comparatively. Meanwhile, the contaminating particles on as-prepared superhydrophobic surfaces can be taken away easily by rolling water droplets. Therefore, the results show that as-prepared superhydrophobic magnesium alloys exhibit enhanced corrosion resistance and self-healing performance. Finally, anti-corrosion and self-cleaning mechanisms are deduced. It can be concluded that it is an effective strategy of preparing superhydrophobic surfaces for improving the corrosion resistance and selfcleaning performance of magnesium alloys.

Preparation of Superhydrophobic Magnesium Alloy Surface via Fabrication of Micro/Nano Binary Structure and Modification with Perfluropolysilane

Preparation of Superhydrophobic Magnesium Alloy Surface via Fabrication of Micro/Nano Binary Structure and Modification with Perfluropolysilane

One-step hydrothermal process to fabricate superhydrophobic surface on magnesium alloy with enhanced corrosion resistance and self-cleaning performance

Superhydrophobic surfaces can exhibit anti-corrosion, anti-fogging, and self-cleaning performance due to their high water repellence. It is significant for industrial fabricating of superhydrophobic surface with a simple and environment-friendly method. Herein, a facile, environment-friendly, and cost-effective one-step hydrothermal route is proposed to fabricate the superhydrophobic surface on magnesium alloy. The as-prepared superhydrophobic magnesium alloy surface presents the rough and hierarchical micro/nano- structure grafted with long hydrophobic alkyl chains via covalent bonds. Both electrochemical corrosion test and long term immersion in 3.5wt.% of NaCl solution demonstrate that the superhydrophobic surface greatly improves the corrosion resistance of magnesium alloy. Meanwhile, the superhydrophobic magnesium alloy exhibits excellent self-cleaning performance. It is supposed that this facile method and remarkable properties of resultant superhydrophobic magnesium alloys have a promising future in expanding the application of magnesium alloys.

Mimicking the hierarchical surface topography and superhydrophobicity of the lotus leaf on magnesium alloy AZ31

Surface modification of biodegradable magnesium alloys to control their degradation rate and give optimum biocompatibility is essential for the application of these materials in medicine. In this letter, chemical etching coupled with the deposition of a biocompatible siloxane coating has been employed to produce a biomimetic superhydrophobic magnesium alloy surface with excellent stability in aqueous solution. Characterization of the topography of the superhydrophobic surface show that these surfaces have a hierarchical surface structure composed of microscale spherical features and nanoscale rod-like structures that closely mimic the surface structure of the lotus leaf.

One step phase separation process to fabricate superhydrophobic PVC films and its corrosion prevention for AZ91D magnesium alloy

A one step, simple fabrication method to prepare independent superhydrophobic polyvinyl chloride (PVC) coating is reported in this paper. The rough surface structure and low surface energy could be simply obtained only by a phase separation process. The independent PVC superhydrophobic film was also applied on AZ91D magnesium alloy. Scanning electron microscopy (SEM), water contact angle measurements, electrochemical test and adhesion tests have been performed to characterize the surface morphology, wettability, anti-corrosion and adhesion strength of independent PVC film and superhydrophobic magnesium alloy respectively. The results indicated that whether it was the PVC film or superhydrophobic magnesium, they show static contact angles higher than 150°, excellent anti-corrosion effect and adhesion strength. We believed that the presented method could provide a straightforward and simple route to fabricate low-cost and anti-corrosion coating on various substrate materials. Moreover, this one step process may find potential application in the field of industry because of its simplicity and universality.

Fabrication of superhydrophobic surface with controlled adhesion by designing heterogeneous chemical composition

In this paper, a simple method for fabricating tunable adhesion superhydrophobic surface based on heterogeneous chemical composition was reported. By simply changing the ratio of HOOC(CH2)8COOH in the mixed modification solution, the slide angles (SA) of water droplet can be adjusted from extremely low (less than 10°) to very high (180°). Besides, the influence of surface chemical composition on the surface adhesion was also examined. Noticeably, the anti-corrosion performance of magnesium alloy was greatly improved after being modified. In addition, the tunable adhesion superhydrophobic magnesium alloy showed high hydrophobicity not only for pure water but also for corrosive liquids, such as acid, alkali, salt, cola, milk and coffee. Based on the great anti-corrosion performance and continuous adhesion, a proof of droplet-based microreactor and selective transportation of waters with different volume was provided. This study provides a new method for preparation of superhydrophobic surfaces with tunable adhesion, which not only offers the further principle for the fabrication of tunable adhesive superhydrophobic surfaces, but also can be potentially used in many important applications, such as micro-fluidic devices and chemical microreactors.

Fabrication and corrosion resistance of superhydrophobic magnesium alloy

A superhydrophobic magnesium alloy (AZ91) is successfully fabricated by sulfuric acid etching, AgNO3 treatment, and dodecyl mercaptan (DM) modification. The effect of the fabrication procedure, the concentration and treatment time of sulfuric acid, AgNO3, and DM on morphology, phase structure, surface wettability, and surface composition of the AZ91 is investigated in detail. Consequently, the optimal treatment parameters are selected, and the superhydrophobic magnesium alloy with a water contact angle of 154° and a sliding angle of 5° is fabricated. The acid etching endows the AZ91 surface with rough structure while the AgNO3 treatment results in more protrusions and grooves. Meanwhile, the long hydrophobic alkyl chains are self-assembled onto the rough AZ91 surface upon DM modification. As a result, the multilayer of netlike surface with protrusions and grooves together with the coral-like structure is obtained. Additionally, the magnesium alloy with higher water contact angle has better corrosion resistance, while the magnesium alloy with the superhydrophobic property has the best corrosion resistance.

Fabrication of superhydrophobic magnesium alloy through the oxidation of hydrogen peroxide

In this study, a superhydrophobic film was successfully fabricated on the surface of magnesium alloy AZ31 by a rapidly hydrothermal process in the presence of hydrogen peroxide without using any template and surfactant, and then covered with fluoroalkylsilane (FAS) molecules. The superhydrophobic surface was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), respectively. The results showed the surface was composed of a large amount of spheres, the random stack of these spheres induces the unique rough structure, and the superhydrophobic surface exhibited good water repellency with a static water contact angle of 164°. The corrosion resistance of the superhydrophobic magnesium alloy was assayed by electrochemical potentiodynamic measurements, and the results revealed that superhydrophobic film considerably improved the corrosion resistance performance of magnesium alloy.

Corrosion Study of Superhydrophobic Magnesium Alloy AZ31 Surfaces Prepared by Wet Chemical Etching Process

Superhydrophobic surfaces were fabricated on magnesium alloy (AZ31) substrates by chemical etching using H2SO4 and H2O2 solutions, successively. The generated surface layer was characterized using grazing incidence X-ray diffraction, X-ray photoelectron spectroscopy and micro-Raman spectroscopy, and magnesium hydroxide was found to be the chief component. Field emission scanning electron microscopy displayed flower-like microstructure with two types of nanostructures, viz., nanoneedles in dense cluster form and nanosheets in the form of a network. As a result, the etched specimens were very rough and porous. Due to entrapped air in the pores, the droplets were present in Cassie state and so the contact angle measurements demonstrated high static water contact angles (about 154°). The superhydrophobic property was lost after a few minutes immersion in water, due to a transition to the Wenzel state. A decrease in corrosion resistance of the superhydrophobic samples as compared to the polished substrate was also observed through potentiodynamic polarization measurements.

Rapid Fabrication of Large-Area, Corrosion-Resistant Superhydrophobic Mg Alloy Surfaces

A superhydrophobic magnesium (Mg) alloy surface was successfully fabricated via a facile electrochemical machining process, and subsequently covered with a fluoroalkylsilane (FAS) film. The surface morphologies and chemical compositions were investigated using a scanning electron microscope (SEM) equipped with an energy-dispersive spectroscopy (EDS) and a Fourier-transform infrared spectrophotometer (FTIR). The results show hierarchal rough structures and an FAS film with a low surface energy on the Mg alloy surfaces, which confers good superhydrophobicity with a water contact angle of 165.2° and a water tilting angle of approximately 2°. The processing conditions, such as the processing time and removal rate per unit area at a constant removal mass per unit area, were investigated to determine their effects on the superhydrophobicity. Interestingly, when the removal mass per unit area is constant at approximately 11.10 mg/cm(2), the superhydrophobicity does not change with the removal rate per unit area. Therefore, a superhydrophobic Mg alloy surface can be rapidly fabricated based on this property. A large-area superhydrophobic Mg alloy surface was also fabricated for the first time using a small-area moving cathode. The corrosion resistance and durability of the superhydrophobic surfaces were also examined.

Facile Formation of Biomimetic Color-Tuned Superhydrophobic Magnesium Alloy with Corrosion Resistance

The design of color-tuned magnesium alloy with anticorrosive properties and damping capacity was created by means of a simple and inexpensive method. The vertically self-aligned nano- and microsheets were formed on magnesium alloy AZ31 by a chemical-free immersion process in ultrapure water at a temperature of 120 °C, resulting in the color expression. The color changed from silver with metallic luster to some specific colors such as orange, green, and orchid, depending on the immersion time. The color-tuned magnesium alloy showed anticorrosive performance and damping capacity. In addition, the colored surface with minute surface textures was modified with n-octadecyltrimethoxysilane (ODS), leading to the formation of color-tuned superhydrophobic surfaces. The corrosion resistance of the color-tuned superhydrophobic magnesium alloy was also investigated using electrochemical potentiodynamic measurements. Moreover, the color-tuned superhydrophobic magnesium alloy showed high hydrophobicity not just for pure water but also for corrosive liquids, such as acidic, basic, and some aqueous salt solutions. In addition, the American Society for Testing and Materials (ASTM) standard D 3359-02 cross cut tape test was performed to investigate the adhesion of the color-tuned superhydrophobic film to the magnesium alloy surface.