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•Superhydrophobic GP was prepared by one step reaction between POSS-NH2 and GO.•The graft of POSS in GP nanosheets was greatly improved the dispersity of GO.•Anti-corrosion and ...anti-wear abilities of EP was enhanced by superhydrophobic GP.
Super-hydrophobic polyhedral oligomeric silsesquioxane functionalized graphene oxide (GP) was synthesized by one-step condensation reaction. Addition of 0.5 wt% GP into epoxy matrix (0.5 wt% GP/EP) could enhance the impedance by 2 orders of magnitude after 150 days immersion compared with pure epoxy (EP) coating. Moreover, the 0.5 wt% GP/EP specimen displayed better lubrication properties than EP, 0.5 wt% GO/EP, and 1 wt% GP/EP composites. Such outstanding anti-corrosion and wear-resistant abilities were ascribed to the comprehensive action of repellent GP with excellent shielding effect, the self-lubrication of GP with well dispersibility and the great improvement of mechanical property.
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•Convenient in-situ preparation strategy of MgAl-LDH coatings on Mg was proposed.•The prepared superhydrophobic coating has long-lasting anti-corrosion performance.•The anti-corrosion ...mechanism of MgAl-LDH coatings modified by different long-chain molecules has been clarified.
Layered double hydroxides (LDHs) have been widely used as “smart” containers in the field of metal corrosion protection, and have broad industrial prospects. It is environmentally friendly and feasible to use aliphatic carboxylates and corresponding acids as substitutes for harmful corrosion inhibitors. However, previous studies rarely involved comparing the anti-corrosion mechanisms of different aliphatic acids modified on the LDH surface, and the durability of the prepared coatings also needs to be improved. In this work, MgAl-LDH laminates were grown in situ on AZ31 substrates by a hydrothermal method, and then modified by sodium laurate (SL) and sodium dodecylbenzene sulfonate (SDBS). Due to the physical barrier effect of the LDH layers, the spatial repulsion effect of the air film and the ion exchange reactions in the interlayer galleries, the functional coatings prepared exhibit smart and superior anti-corrosion performance on the magnesium substrates in 3.5 wt.% NaCl solution. Compared with LDH-SDBS-8 coating, the obtained superhydrophobic LDH-SL-8 coating shows more excellent long-term corrosion protection owing to the stronger intercalation capacity.
The VAlTiCrMo and (VAlTiCrMo)Nx coatings were prepared by sputtering V–Al–Ti–Cr–Mo splicing targets. The microstructure and chemical composition were analyzed by means of X-ray diffraction (XRD), ...scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and transmission electron microscope (TEM). The high-entropy alloy coating and the corresponding nitride coating have body-centered cubic (BCC) and face-centered cubic (FCC) structures respectively. Nitriding changes the phase structure and growth mode of the high-entropy coating, and the synthesized high-entropy nitride coatings are more compact. Meanwhile, the introduction of nitrogen leads to severe lattice distortion, which improves the mechanical properties of the high-entropy coating. As the nitriding degree increases, the corrosion resistance of the high-entropy nitride coatings in 3.5 wt% NaCl solution is improved. The synthesized (VAlTiCrMo)Nx coating exhibits optimized mechanical properties and nobler corrosion resistance when the N2 flow is 800 sccm.
Corrosion inhibition by the microstructures of the VAlTiCrMo and its nitride coatings. Display omitted
•VAlTiCrMo high-entropy alloy coating and its nitride coatings prepared by splicing targets.•The change of coating structure is more obvious with the increase of nitrogen flow rate.•The introduction of nitrogen changed the structure of the coating from BCC to FCC.
The use of graphene and multi-walled carbon nanotubes (MWCNTs) additives as lubricants has received considerable interest because of their excellent mechanical and frictional properties. Given their ...structural differences, both carbon nano-additives are expected to have different synergistic effects at various conditions (from boundary to mixed lubrication). For applications in space, the tribological properties of graphene and MWCNTs additives in diamond-like carbon/ionic liquids hybrid films in different lubricating states at high vacuum were compared. The wear surfaces, transfer films, wear debris, and microstructures of the hybrid films were analyzed via Raman spectroscopy, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. The results showed that MWCNTs and graphene present the different nano-scale tribological mechanisms and produce different lubricating effect on the hybrid films at different lubricating states.
The MoN/VN multilayer films with three modulation periods (Λ) were deposited on 718 alloy steel substrates by magnetron sputtering. The effects of Λ on microstructure, mechanical properties, and ...friction performance of the MoN/VN multilayer films at variously typical temperatures were systematically investigated. The results indicated that the cross-section of as-prepared films were all typically columnar structure, and the hardness and elastic modulus of the MoN/VN multilayer films increase with the reduction of the modulation period. The MoN/VN multilayer films with Λ = 22.66 nm showed the maximum
H
/
E
value of 0.052 among all the as-prepared films. In addition, the MoN/VN multilayer films exhibited better tribological properties under room temperature (25 ℃) and 700 °C due to the formation of slight wear and self-lubricating oxide films, respectively. Especially, the friction coefficient and wear rate of the MoN/VN multilayer films with Λ = 22.66 nm were as low as 0.29 and 1.37 × 10
–6
mm
3
/Nm at 700 °C, respectively. Diagrams of worn surface of the MoN/VN multilayer films with Λ = 22.66 nm and Λ = 4.77 nm at different tests temperature: (a, e) RT, (b, f) 300 °C, (c, g) 500 °C and (d, h) 700 °C.
Graphic Abstract
Titanium alloys are characterized by poor tribological performance, and their conventional use has been restricted to non-tribological applications. Surface films and surface texturing are effective ...methods to improve the tribological properties of sliding surfaces. In this study, the patterns of micro-dimples with different densities and diamond-like carbon (DLC) films were fabricated on the surface of titanium alloy by laser surface texturing and magnetron sputtering, respectively. The effects of dimple densities and DLC phase transformation on the tribological behavior of the titanium alloy under dry friction and liquid lubrication conditions were investigated. The results showed that DLC film with appropriate dimple area density (44%) are effective in enhancing reducing-friction property of titanium alloy substrate because of the entrapment of wear particles in the dimples and dimple-induced graphitization during sliding motions, while the 24% textured specimen exhibited outstanding wear resistance.
•Combining LST technology with DLC coatings achieved a low friction and wear.•An appropriate number of dimples trapped wear debris and maintained coating hardness.•Dimples and dimples-induced DLC graphitization generated the friction-reducing.•Entrapment of wear debris and low DLC graphitization improved the wear-resistance.
Diamond-like carbon (DLC) films have been extensively studied over the past decades due to their unique combination of properties; in particular, silicon-doped DLC (Si-DLC) films are of significant ...interest for tribological effects. But there are contradictory reports in the literature with regard to the effect of silicon content on the properties of DLC films. In this study, Si-DLC films were deposited by hollow cathode plasma immersion ion implantation (HCPIII) method, using mixtures of C2H2, Ar and diluted SiH4 (SiH4/Ar 10:90). The influences of Si addition on the surface morphology, structure, mechanical and tribological properties were investigated by a combination of surface analysis methods, nanomechanical and friction measurements. It was observed that addition of Si into DLC films lead to a decrease in the Raman band intensity ratio ID/IG. The root mean square values of Si-DLC films were increased along with the increase of Si concentration. Both the hardness and elastic modulus suffered degradation when the silicon concentration was low, but these properties recovered when Si concentration increased. The Si-DLC film with tensile stress and compressive stress can be obtained by choosing distinct contents of Si in the film. The coefficient of friction (COF) of Si-DLC films against GCr 15 steel ball under atmosphere firstly increased as the Si concentration increased up to 8.41at.%, then COF of Si-DLC films decreased with a further increase of Si concentration. The mismatch in the bond length, the difference of the mechanical property and the alteration of the colliding particles' energy were determined to be the basis for the changes in these properties.
•A rang of Si doped DLC films were prepared by HCPIII method.•Si-DLC film with tensile stress and compressive stress can be tailored.•Both the H and E suffer degradation when the Si concentration is low.•Tribological behavior of Si-DLC film is improved when Si reaches to a certain value.
Transition metal dichalcogenides (TMDs) are easily oxidized in the humid atmosphere, leading to a decrease in their lubricating properties and limiting their application. In this study, a MoS
2
/WS
2
...multilayer film doped with tantalum (MoS
2
/WS
2
-Ta) is fabricated by magnetron sputtering to improve the corrosion and oxidation resistance of TMDs. Results show that doping of Ta makes the structure of the MoS
2
/WS
2
multilayer film more compact, and the MoS
2
and WS
2
crystals exhibit a stronger (0002) preferred orientation than that of un-doped sample. Such compact structure and (0002) preferred orientation of MoS
2
/WS
2
-Ta can realize a high corrosion resistance,
i.e.
, a more positive corrosion potential and a lower corrosion current density in comparison with the MoS
2
/WS
2
multilayer. Furthermore, the friction properties of MoS
2
/WS
2
multilayer film doped with 1.1 at% of Ta are improved remarkably under both of high temperature (370 °C in air) and vacuum conditions, the result is attributed to its high mechanical properties and (0002) preferred orientation. In a word, the combination of multilayer structure and doping of Ta into the films is a promising approach to accurately design the TMDs toward a wide temperature range and environmentally adaptive lubricants.
Graphical abstract
Plasma nitriding was used to improve the tribological properties of AlCrTiV and AlCrTiVSi high-entropy alloy (HEA) films. The results indicated that after plasma nitriding, the microstructure and ...tribological property were improved greatly. For plasma-nitrided AlCrTiV, it is still composed of a single BCC solid solution but with a decreased lattice constant, while for plasma-nitrided AlCrTiVSi, a new V4.75Si3N0.58 nitride phase forms in the amorphous matrix, which all lead to the increase of nano-hardness, promoting the reduction of wear degree or wear rate against GCr15 and Al2O3. Due to the perfect balance of hardness and toughness, the plasma-nitrided AlCrTiV HEA film has the lowest friction coefficient (against Al2O3) and the best wear-resistance.
•Plasma nitriding was used to improve the microstructure of AlCrTiV and AlCrTiVSi HEA films.•N atoms are solidly dissolved to the BCC solid solution of AlCrTiV.•N atoms mainly react with metal elements in AlCrTiVSi to form V4.75Si3N0.58 phase.•Plasma nitriding leads to increased nano-hardness and improved tribological property.•Plasma-nitrided AlCrTiV HEA film has the lowest friction coefficient and the best wear-resistance.
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In this work, two new imidazoline derivatives were successfully synthesized, and the molecular structure of which has been proved by IR, Raman and elemental analysis. The corrosion ...inhibition performance of the imidazoline derivatives for carbon steel in 3.5 wt% sodium chloride simulation-concrete-pore solution was investigated. The weight loss and electrochemical test results exhibited that compared to the blank systems, the corrosion inhibition efficiency was effectively enhanced with increasing the concentrations of two imidazoline derivatives, the maximum corrosion inhibition efficiency of weight-loss test is 96.02%. The inhibition efficiency of Electrochemical impedance spectroscopy and Potentiodynamic polarization were 95.95% and 90.69%. EDS analysis confirmed that two new imidazoline derivatives could effectively adsorb on the Q235 steel surface, which was further supported by density functional theory (DFT) and molecular dynamics simulations. This work confirmed that two new imidazoline derivatives exhibited a potential application in engineering and equipment.
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