In this study, we created a robust and stable nanostructure coated on the surface of a stainless steel mesh via the electrodeposition of copper thin films and chemical modification with polydimethylsiloxane (PDMS) to enhance the mechanical durability of the stainless steel mesh surface with superhydrophobic performance. The obtained stainless steel mesh was tested by immersion in solutions of different pH values and abrasion cycling tests with sandpaper. The results showed that the coated stainless steel mesh retained excellent superhydrophobic and superoleophilic properties. Using the superhydrophobic and superoleophilic stainless steel mesh, we achieved the recycling of oil automatically and continuously via a vacuum pump.

Strain-induced phase transformation of austenite into martensite often results in the hardening and strengthening of metastable austenite stainless steel; thus, pin-on-disc friction experiments were carried out to investigate the effect of strain-induced martensite on the tribocorrosion of AISI 316L austenitic stainless steels in artificial seawater. The obtained results demonstrate that high load is beneficial for the formation of strain-induced martensite, which is closely related to the improvement of hardness and wear resistance of AISI 316L. Macroscopic and microscopic galvanic corrosion products were formed by martensite and austenite retained on the worn surface during sliding. Therefore, the total mass loss of 316L in artificial seawater was mainly due to mechanical wear and the synergistic effect of corrosion on wear, particularly at high load conditions. Thus, the tribocorrosion behavior of austenitic stainless steel was dominated by the formation and corrosion of strain-induced-martensite with metastable austenite.

Strain-induced phase transformation of austenite into martensite often results in the hardening and strengthening of metastable austenite stainless steel; thus, pin-on-disc friction experiments were carried out to investigate the effect of strain-induced martensite on the tribocorrosion of AISI 316L austenitic stainless steels in artificial seawater. The obtained results demonstrate that high load is beneficial for the formation of strain-induced martensite, which is closely related to the improvement of hardness and wear resistance of AISI 316L. Macroscopic and microscopic galvanic corrosion products were formed by martensite and austenite retained on the worn surface during sliding. Therefore, the total mass loss of 316L in artificial seawater was mainly due to mechanical wear and the synergistic effect of corrosion on wear, particularly at high load conditions. Thus, the tribocorrosion behavior of austenitic stainless steel was dominated by the formation and corrosion of strain-induced-martensite with metastable austenite.

•Superhydrophilic surface with porous structure is used to investigate the drag reduction effect.•The addition amount of the surface active agent can control the shape and the size of the holes.•The superhydrophilic property comes from the thermally effects of the heat treatment.•The drag reduction effect is depended on the surface morphology•The simulation result shows that porous morphology can reduce friction resistance and increase pressure resistance.In this paper, different apertures of superhydrophilic porous TiO2 films are fabricated by sol-gel method with PEG2000 additive. The drag reduction effect of the films is investigated through experiment of falling-ball method and FEM simulation. The larger PEG2000 content, the bigger size and the more regular and homogeneous of the pores. The joint action of anatase crystal, hydroxyl groups and water molecules absorbed on the surface and porous structure causes the superhydrophilicity. The resistance test shows that when the addition amount of PEG2000 changes from 0.25 g to 2 g, the drag reduction efficiency increases from − 17.9% to 8.6% and − 16.8% to 9.4% with 12 mm and 25 mm diameter balls. The drag reduction mechanism can be obtained from Finite Element Method simulation. The result shows that vortexes are formed in the pore which can reduce the frictional drag by lowering the velocity gradient and giving a frictional driving force. Meanwhile, an “extra press drag” is formed between the front and back wall. If the degree of friction drag reduction is greater than the degree of press drag increase, the film will show the effect of drag reduction overall.

Polysulfone (PSf) membrane has been widely used in water separation and purification, although, membrane fouling is still a serious problem limiting its potential. We aim to improve the antifouling of PSf membranes via a very simple and efficient method. In this work, antifouling PSf membranes were fabricated via in situ cross-linked polymerization coupled with non-solvent induced phase separation. In brief, acrylic acid (AA) and vinyltriethoxysilane (VTEOS) were copolymerized in PSf solution, then directly casted into membranes without purification. With the increase of monomers concentration, the morphology of the as-cast membranes changed from a finger-like morphology to a fully sponge-like structure due to the increased viscosity and decreased precipitation rate of the polymer solutions. Meanwhile, the hydrophilicity and electronegativity of modified membranes were highly improved leading to inhibited protein adsorption and improved antifouling property. Furthermore, in order to further find out the different roles player by AA and VTESO, the modified membrane without VTEOS was prepared and characterized. The results indicated that AA is more effective in the membrane hydrophilicity improvement, VTEOS is more crucial to improve membrane stability. This work provides valuable guidance for fabricating PSf membranes with hydrophilicity and antifouling property via in situ cross-linked polymerization.Download high-res image (100KB)Download full-size image

In this paper, stainless steel meshes with superhydrophobic and superoleophilic surfaces were fabricated by rapid and simple one-step immersion in a solution containing hydrochloric acid and stearic acid. The apparent contact angles were tested by a video contact angle measurement system (CA). Field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) were conducted to characterize the surface topographies and chemical compositions. The SEM results showed that mesh surfaces were covered by ferric stearate (Fe[CH3(CH2)16COO]2) with low surface energy. The CA test results showed that the mesh had a maximum apparent contact angle of 160 ± 1.0° and a sliding angle of less than 5.0° for the water droplet, whereas the apparent contact angle for the oil droplet was zero. Ultrasound oscillation and exposure tests at atmospheric conditions and immersion tests in 3.5 wt % NaCl aqueous solution were conducted to confirm the mesh with excellent superhydrophobic and superoleophilic properties. On the basis of the superhydrophobic mesh, a miniature separation device pump was designed to collect pure oil from the oil/water mixture. It showed that the device was easier and convenient. The techniques and materials presented in this work are promising for application to wastewater and oil spill treatment.

Siloxane modified acrylic resin coatings with positive and negative replication textures were successfully fabricated by biomimicking the surface structures of natural lotus leaf and white crab shell via a replication method. The physical and chemical properties of the as-prepared coatings were systematically characterized by FT-IR spectroscopy, SEM, AFM and contact angle measurements. Moreover, the antifouling (AF) property of the biomimetic textured surfaces was tested via the settlement assay with two microalgae of different sizes. The results indicated that the micromastoids and microdimples of the lotus leaf and white crab shell could significantly inhibit the settlement of microalgae. Both biomimetic textured coatings with positive and negative lotus leaf morphology can reduce 73% attachment of Closterium and 74% attachment of Navicula. Both biomimetic textured coatings with positive and negative white crab shell morphology could reduce over 65% attachment of Closterium and Navicula. Different antifouling mechanisms of the biomimetic textured coatings were analyzed based on three key factors, including surface wettability, morphology, and algae size.

In order to improve the mechanical durability, polyurethane (PU) needs to be modified to enhance the tribological and anti-corrosion properties. In this work, we fabricated a series of PU composite coatings reinforced with functionalized graphene (FG) and functionalized graphene oxide (FGO). The structural and morphological features of the composite coatings were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The results showed that the dispersion and compatibility of graphene and graphene oxide were improved via chemical modification. Moreover, they effectively enhanced the tribological and anti-corrosion properties of PU composite coatings, whose optimized additive range was between 0.25 wt% and 0.5 wt%. The effect depends on the balance of lubrication and barrier of fillers and cracks generated by them. Finally, in comparison with FG/PU coatings, the FGO/PU coatings exhibited a better tribological property but worse anti-corrosion property owing to the abundant oxygenated groups of GO. They led to stronger interfacial interactions between FGO and the PU matrix, but destroyed the graphene lattice structure to some extent.

As an environmentally friendly antifouling strategy, a series of textured modified silicone surfaces with different textures, shapes and surface roughnesses were fabricated by mimicking the microstructures of abrasive paper via a simple replication method. The physical and chemical properties of the as-prepared coatings were systematically characterized by FT-IR spectroscopy, SEM and contact angle measurements. The antifouling efficacy of all coatings was evaluated by recording the settlement of fouling microalgae, including Nitzschia closterium f. minutissima, Phaeodactylum tricornutum and Chlorella, in the laboratory. The results indicated that the positive and negative replicas of both 800-grit and 1200-grit abrasive paper with morphology feature sizes larger than algae size encouraged the algae settlement. Only the positive replica of 5000-grit abrasive paper whose morphology feature size was smaller than algae size was effective in inhibiting N. closterium, P. tricornutum and Chlorella, and the reduction ratios were 49%, 75% and 81%, respectively. The positive replica of 7000-grit abrasive paper can reduce the amount of N. closterium and P. tricornutum by 29% and 57%, respectively. But it can't inhibit the settlement of Chlorella. The effect of surface morphology and wettability on the antifouling performance of textured coatings was discussed.

The nucleation mechanism of the preparation of a Ni–P deposit by the synergetic effect of electrochemical deposition and chemical deposition was studied using an electrochemical analysis method. Cathode polarization and chronoamperometry were performed to explore the effect of the reducing reaction (chemical deposition) on the electrochemical Ni deposition. It was found that the addition of reducing agent to the solution induced depolarization phenomena and decreased or removed the double electric layer capacitance. The chronoamperometry experimental data were analyzed and fitted according to the Scharifker–Hills rule to discover the difference in mechanism between the Ni nucleation and Ni–P nucleation. The morphology of Ni–P and the pure Ni deposits was measured by TEM and SEM demonstrating the ball-like particle shape of Ni–P and flat pure Ni deposits. Based on these experimental results, the nucleation mechanism was illustrated in which the active Ni atoms, produced by electrochemical deposition, act as a catalyst for the reduction of the nickel ions with the reducing agent NaH2PO2 on the cathode surface. The occurrence of the reducing reaction of the nickel ions with NaH2PO2 hindered the in-plane growth of crystalline nickel particles, generating the ball-like particle shape of the deposit. This work provides researchers new insights into the nucleation and growth process of synergetic deposition and offers novel ideas for the fabrication of functional materials by liquid deposition.

•Three curing agents with different molecular structures were used to cure epoxy resins (EP).•The effect of molecular structures on the tribological and anti-corrosion properties of EP was evaluated.•The tribological and anti-corrosion mechanisms of EP coatings were analyzed.In order to study the influence of curing agent molecular structure on the tribological and corrosion behaviors of epoxy resin (EP) coatings, EP coatings were cured by three kinds of curing agents with different molecular structures including diethylenetriamine (DETA), isophorone diamine (IPDA) and m-phenylenediamine (m-PDA). The curing degree of EP coatings was identified by flourier transform infrared spectrometer (FTIR). The element composition and chemical bond structure of the as-prepared coatings were tested by X-ray photoelectron spectrometer (XPS). The tribological properties of the as-prepared coatings were assessed by UMT-3 multi-functional tribology test equipment and surface profiler. The anti-corrosion behaviors of the coatings were evaluated by an electrochemistry workstation in 3.5 wt% NaCl. The internal structure and wear trace morphologies of the coatings were observed by scanning electron microscopy (SEM). Using of curing agents with different molecular structures resulted in different tribological and anti-corrosion properties for EP coating. While the coefficient of friction (COF) of EP coating cured by m-PDA was the highest, the one cured by DETA was the lowest, which may be due to the linear and flexible chain offered less resistance during the sliding process and hence it displayed the lowest COF. Besides, the anti-corrosion performance of EP coating cured by IPDA was the best and the one cured by m-PDA was the poorest, which may be attributed to molecular structure and molecular weight which can influence the crosslink network and interface structure of EP coatings significantly. At last, the tribological and anti-corrosion mechanisms of EP coatings with different molecular structures were discussed in detail.Fracture surfaces morphologies of EP coatings cured by three kinds of curing agents with different molecular structures. (a) DETA cured; (b) IPDA cured and (c) m-PDA cured.

In order to improve the tribological properties of aluminum alloy cylinders and cylinder bore walls, WC-reinforced Ni-WC coatings were deposited on an aluminum substrate by atmospheric plasma spraying. The composition and microstructure of Ni-WC coatings with different WC contents were investigated and the tribological properties were tested under oil lubrication, lean oil lubrication and dry friction. The results showed that Ni-WC coatings consisted of a lamellar structure. Friction and wear testing results demonstrated that Ni-WC coatings had much better tribological performance than gray cast iron under different lubricating conditions. These Ni-WC composite coatings exhibited excellent mechanical properties and tribological properties due to the strengthening effect of the WC phase.

Aluminum alloy surfaces with micro/nano-structures were fabricated via a simple chemical etching (CE) method. After chemical modification with perfluorodecyltriethoxysilane (PFDS), n-octadecyltriethoxysilane (OTS) and aminopropyltriethoxysilane (APS), surfaces with different wettability were obtained. The morphology and chemical elements of the as-prepared surfaces were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). In addition, the influence of the surface morphology and chemical modification on the wetting/dewetting properties was investigated. Finally, the anti-corrosion and tribological properties of the as-prepared self-assembled monolayers (SAMs) were characterized using an electrochemical workstation and UMT-3 tribometer. The influence of surface morphology and SAMs on the anti-corrosion and tribological performances is discussed in detail. The results showed that the optimal preparation conditions consisted of a 40% volume fraction of hydrochloric acid with a CE time of 2 min. The corrosion resistance of the surfaces chemically modified with hydrophobic groups was much better than that of those modified with hydrophilic groups. Also, the combination of micro/nano-structures and suitable SAMs on aluminum alloy surfaces could greatly enhance the friction reduction and wear resistance behavior.