Oxide coatings on AM60B magnesium alloy were prepared using the microarc oxidation(MAO) technique in silicate-KOH electrolyte with addition of 0-6.0 g/L Na2WO4. The MAO processes in base electrolyte with different con...Oxide coatings on AM60B magnesium alloy were prepared using the microarc oxidation(MAO) technique in silicate-KOH electrolyte with addition of 0-6.0 g/L Na2WO4. The MAO processes in base electrolyte with different concentrations of Na2WO4 were studied. The microstructure, compositions and mechanical tribological characteristics of the oxide coatings were also investigated by SEM, XRD, XPS, microhardness analysis and ball-on-disc friction testing, respectively. It is found that the addition of Na2WO4 into the base electrolyte has direct effect on the characteristics of voltage—time curves and breakdown voltage in MAO process. The number of micropores at top of the coating surface is increased by the addition of Na2WO4. The fraction of forsterite Mg2SiO4 in the oxide coating increases with increasing concentration of Na2WO4 in base electrolytes. Furthermore, the microhardness and wear resistance of oxide coatings are enhanced as well.展开更多
A process for preparation of solid lubricating films on micro-arc oxidation(MAO) coating was introduced to provide self-lubricating and wear-resistant multilayer coatings for aluminum alloys. The friction and wear beh...A process for preparation of solid lubricating films on micro-arc oxidation(MAO) coating was introduced to provide self-lubricating and wear-resistant multilayer coatings for aluminum alloys. The friction and wear behavior of various burnished and bonded solid lubricating films on the as-deposited and polished micro-arc oxidation coatings sliding against steel and ceramic counterparts was evaluated with a Timken tester and a reciprocating friction and wear tester, respectively. The burnished and bonded solid lubricating films on the polished micro-arc oxidation coatings are superior to the as-deposited ones in terms of the wear resistant behavior, because they lead to strengthened interfacial adhesion between the soft lubricating top-film and the hard polished MAO sub-coating, which helps increase the wear resistance of the solid lubricating film on multilayer coating. Thus the multilayer coatings are potential candidates as self-lubricating and wear-resistant coatings for Al alloy parts in engineering applications.展开更多
The tribological characteristics of carbon fiber reinforced polymer composites under distilled-water-lubricated-sliding and dry-sliding against stainless steel were comparatively investigated. Scanning electron micros...The tribological characteristics of carbon fiber reinforced polymer composites under distilled-water-lubricated-sliding and dry-sliding against stainless steel were comparatively investigated. Scanning electron microscopy (SEM) was utilized to examine composite microstructures and modes of failure. The typical chemical states of elements of the transfer film on the stainless steel were examined with X-ray photoelectron spectroscopy (XPS). Wear testing and SEM analysis show that all the composites hold the lowered friction coefficient and show much better wear resistance under water lubricated sliding against stainless steel than those under dry sliding. The wear of composites is characterized by plastic deformation, scuffing, micro cracking, and spalling under both dry-sliding and water lubricated conditions. Plastic deformation, scuffing, micro cracking, and spalling, however, are significantly abated under water-lubricated condition. XPS analysis conforms that none of the materials produces transfer films on the stainless steel counterface with the type familiar from dry sliding, and the transfer of composites onto the counterpart ring surface is significantly hindered while the oxidation of the stainless steel is speeded under water lubrication. The composites hinder transfer onto the steel surface and the boundary lubricating action of water accounts for the much smaller wear rate under water lubrication compared with that under dry sliding. The easier transfer of the composite onto the counterpart steel surface accounts for the larger wear rate of the polymer composite under dry sliding.展开更多
Edible Lubricant-Infused Surface(ELIS)was fabricated through antisolvent method by adding ethyl oleate(lubricant/antisolvent),ethanol(solvent)and shellac(solute/base layer of ELIS)into an all-in-one solution to in-sit...Edible Lubricant-Infused Surface(ELIS)was fabricated through antisolvent method by adding ethyl oleate(lubricant/antisolvent),ethanol(solvent)and shellac(solute/base layer of ELIS)into an all-in-one solution to in-situ prepare ELIS through single step of solvent evaporation.The ELIS comprising sub-micro-to micro-scaled shellac particles shows water and food liquid slippery,transparency,stability against abrasion and lubricant retaining ability against sheer force.Using all edible material to fabricated ELIS is a more efficient route for application when compared with other Lubricant-Infused Surface(LIS).Traditional fabrication for LIS included steps such as:base layer fabrication,lubricant infusion,excess lubricant removal,UV light treatment and chemical etching.The method proposed in this article could further simplify the preparation to an all-in-one solution and simplify the synthesis process to only 60-degree heating.Furthermore,Shellac ELIS coating could withstand abrasion and hold performance when compared with other ELIS coatings.展开更多
Superamphiphobic surfaces have great potential applications in flame resistance,anti-icing,self-cleaning,anti-adhesion,micro-flow control and so on.However,the surface durability is poor owing to the limitation of des...Superamphiphobic surfaces have great potential applications in flame resistance,anti-icing,self-cleaning,anti-adhesion,micro-flow control and so on.However,the surface durability is poor owing to the limitation of design principles.In recent years,a lot of efforts have been carried out on the morphology,structure,and stability of superamphiphobic surfaces,resulting in significant improvement in their surface superwetting properties.In this review,we present a brief classification of the morphological types of superamphiphobic surfaces and summary of the recent progress of researches on the stability of superamphiphobic surfaces.Several testing methods of mechanical and chemical stability are listed in the article,together with the characteristic results,to provide a better and more detailed understanding of the current research status on superamphiphobic surface stability,which will be of considerable importance as a reference guide for our future researches.Of course,there are still some issues that need to be addressed for the application of superamphiphobic surfaces at large scale,and this is where our future researches will be directed.Finally,we discuss the challenges as well as the prospects in the study of superamphiphobic surfaces.展开更多
Complex-shaped optical lenses are of great interest in the areas of laser processing,machine vision,and optical communications.Traditionally,the processing of complex optical lenses is usually achieved by precision ma...Complex-shaped optical lenses are of great interest in the areas of laser processing,machine vision,and optical communications.Traditionally,the processing of complex optical lenses is usually achieved by precision machining combined with post-grinding or polishing,which is expensive,labor-intensive and difficult in the processing of ultra-complex optical lenses.Additive manufacturing is an emerging technology that provides significant advantages in producing highly intricate optical devices.However,the layer-by-layer method employed in such manufacturing processes has resulted in low printing speeds,as well as limitations in surface quality.To address these challenges,we apply tomographic volumetric printing(TVP)in this work,which can realize the integrated printing of complex structural models without layering.By coordinating the TVP and the meniscus equilibrium post-curing methods,ultra-fast fabrication of complex-shaped lenses with sub-nanometric roughness has been achieved.A2.5 mm high,outer diameter 9 mm spherical lens with a roughness value of RMS=0.3340 nm is printed at a speed of 3.1×10^(4)mm^(3)h^(-1).As a further demonstration,a complex-shaped fly-eye lens is fabricated without any part assembly.The designed spherical lens is mounted on a smartphone’s camera,and the precise alignments above the circuit board are captured.Upon further optimization,this new technology demonstrates the potential for rapid fabrication of ultra-smooth complex optical devices or systems.展开更多
Due to the mutual repulsion between their hydrophilic surface terminations and the high surface energy facilitating their ran-dom restacking,2D MXene nanosheets usually cannot self-assemble into 3D macroscopic gels wi...Due to the mutual repulsion between their hydrophilic surface terminations and the high surface energy facilitating their ran-dom restacking,2D MXene nanosheets usually cannot self-assemble into 3D macroscopic gels with various applications in the absence of proper linking agents.In this work,a rapid spontaneous gelation of Ti3C2Tx MXene with a very low dispersion concentration of 0.5 mg mL^(-1) into multifunctional architectures under moderate centrifugation is illustrated.The as-prepared MXene gels exhibit reconfigurable internal structures and tunable rheological,tribological,electrochemical,infrared-emissive and photothermal-conversion properties based on the pH-induced changes in the surface chemistry of Ti_(3)C_(2)T_(x) nanosheets.By adopting a gel with optimized pH value,high lubrication,exceptional specific capacitances(~635 and~408 F g^(-1) at 5 and 100 mV s^(-1),respectively),long-term capacitance retention(~96.7%after 10,000 cycles)and high-precision screen-or extrusion-printing into different high-resolution anticounterfeiting patterns can be achieved,thus displaying extensive potential applications in the fields of semi-solid lubrication,control-lable devices,supercapacitors,information encryption and infrared camouflaging.展开更多
Polytetrafluoroethylene (PTFE) is a commonly used seal material for oil-free engine that is well known for its excellent tribological properties. In this work, the nano-ZrO2 particles were used as the friction modifie...Polytetrafluoroethylene (PTFE) is a commonly used seal material for oil-free engine that is well known for its excellent tribological properties. In this work, the nano-ZrO2 particles were used as the friction modifiers to improve the friction and wear performance of PTFE-PPS composites. The friction and wear characteristics of PTFE/PPS-nano-ZrO2 composites were investigated by a block-on-ring tester under dry friction sliding condition. The worn surfaces, counterpart transfer films and wear debris were studied by scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that the increase of nano- ZrO2 content could effectively reduce the coefficient of friction and enhance the anti-wear ability of PTFEPPS composites. Especially, the best tribological properties of the composites were obtained when the particle content of nano-ZrO2 was 10 vol%, the anti-wear performance of composite is 195 times better than that of the unfilled PTFE-PPS composite. Under different conditions, the coefficient of friction of PTFE/PPS-nano-ZrO2 composites was more affected by the applied load while the wear rate was more affected by the sliding velocity.展开更多
Mg(OH)_(2)/graphene oxide(GO)composite film was electrochemical deposited on AZ91D magnesium alloys at constant potential.The characteristics of the Mg(OH)_(2)/GO composite film were investigated by scanning electron ...Mg(OH)_(2)/graphene oxide(GO)composite film was electrochemical deposited on AZ91D magnesium alloys at constant potential.The characteristics of the Mg(OH)_(2)/GO composite film were investigated by scanning electron microscope(SEM),energy-dispersive X-ray spectrometry(EDS),X-ray diffractometer(XRD)and Raman spectroscopy.It was shown that the flaky GO randomly distributed in the composite film.Compared with the Mg(OH)_(2)film,the Mg(OH)_(2)/GO composite film exhibited more uniform and compact structure.Potentiodynamic polarization tests revealed that the Mg(OH)_(2)/GO composite film could significantly improve the corrosion resistance of Mg(OH)_(2)film with an obvious positive shift of corrosion potential by 0.19 V and a dramatic reduction of corrosion current density by more than one order of magnitude.展开更多
A reliable,high-performance coating procedure was developed using PDMS to modify a duplex MAO/DLC coating on an AZ31B Mg alloy.First,the duplex MAO/DLC coating was fabricated via a combined MAO and unbalanced magnetro...A reliable,high-performance coating procedure was developed using PDMS to modify a duplex MAO/DLC coating on an AZ31B Mg alloy.First,the duplex MAO/DLC coating was fabricated via a combined MAO and unbalanced magnetron sputter process.Subsequently,a PDMS solution was used to modify the MAO/DLC coating via a conventional dip-coating method.The surface characteristics,bond strength,hardness,tribological behaviour,and corrosion resistance of the coated samples were evaluated via SEM,CA,Raman spectroscopy,friction and wear behaviour,polarisation curve,and NSS tests.The PDMS modification reduced the HIT of MAO/DLC coating from 15.96 to 8.34GPa;this is ascribed to the penetration of PDMS,which has good rheological properties to form a viscoelastic Si-based organic polymer layer on the MAO/DLC coating.However,the PDMS-modified MAO/DLC coating was denser,hydrophobic,and had higher bond strength compared with MAO-and MAO/DLC-coated samples.Moreover,the PDMS modification reduced the COF and wear rate of the duplex MAO/DLC coating.This indicates that the PDMS improved the tribological behaviour owing to the transferred Si oxide that originated from the Si-O network of the PDMS,as well as the low graphitisation of the DLC layer during sliding.Furthermore,the corrosion current density of the MAO/DLC-coated sample modified by PDMS for 10min decreased by two order of magnitude compared with that of the MAO/DLC-coated sample but by five orders of magnitude compared with that of the bare substrate.The NSS tests proved that the PDMS layer slowed the corrosion of the Mg alloy under long-term service,enhancing the corrosion protection efficiency.The results are attributed to the high bond strength and lubricant MAO/DLC layer,and the dual role of sealing and hydrophobicity of PDMS.Therefore,PDMS modification is promising for the fabrication of protective materials for Mg alloys that require corrosion and wear resistance.展开更多
Tungsten-doped silver films were prepared by immersing hydrogen-terminated silicon wafers into the solution of 2.5 mmol/L[Ag2WO4]+0.1 mol/L HF at 50℃.Their growth and composition were characterized with atomic force ...Tungsten-doped silver films were prepared by immersing hydrogen-terminated silicon wafers into the solution of 2.5 mmol/L[Ag2WO4]+0.1 mol/L HF at 50℃.Their growth and composition were characterized with atomic force microscopy and X-ray photoelectron spectroscopy,respectively.The effect of tungstate ions on the deposition of silver was investigated by X-ray diffraction(XRD)and scanning electron microscopy(SEM)by comparing W-doped Ag film with Ag film.It is found that the molar fraction of tungsten in the deposits is about 2.3%and the O to W molar ratio was about 4.0 and W-doped Ag films have good anti-corrosion in air at 350℃.The doping of tungsten cannot change the deposition of silver.展开更多
Nano-ZrO2 and PEEK particles were synergistically filled in unfilled PTFE to improve the wear resistance and maintain a relatively low friction coefficient,and the materials were studied using a reciprocating sliding ...Nano-ZrO2 and PEEK particles were synergistically filled in unfilled PTFE to improve the wear resistance and maintain a relatively low friction coefficient,and the materials were studied using a reciprocating sliding friction and wear tester.In the friction tests,the evolution of various tribological characteristics in both the contact interfaces and debris was observed,and the wear mechanism of the PTFE composites was investigated.The results showed that the wear rate of the PTFE composites synergistically filled with nano-ZrO2 and PEEK was lower and its friction coefficient was slightly higher than that of the unfilled PTFE;the uniformity and continuity of the transfer film generated by the composite with nano-ZrO2 and PEEK were the best,and the particle size of the debris was minimal in comparison to that in other sample systems.展开更多
A nanocomposite of MPNS/(Styrene-maleic anhydride) was prepared by the polymerization of methacryloxypropyl nano SiO2 (MPNS), styrene (ST) and maleic anhydride (MA) with benzoyl peroxide (BPO) as initiator in toluene....A nanocomposite of MPNS/(Styrene-maleic anhydride) was prepared by the polymerization of methacryloxypropyl nano SiO2 (MPNS), styrene (ST) and maleic anhydride (MA) with benzoyl peroxide (BPO) as initiator in toluene. The prepared samples were characterized by Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscope (TEM). Meanwhile, the nanocomposite was applied as a tanning agent in leather making and the results showed that leather treated with MPNS/SMA nanocomposite has excellent quality.展开更多
The films deposited at low temperature(LT-films) have increasingly attracted theoretical and technical interests since such films exhibit obvious difference in structure and performances compared to those deposited at...The films deposited at low temperature(LT-films) have increasingly attracted theoretical and technical interests since such films exhibit obvious difference in structure and performances compared to those deposited at room temperature.Studies on the tribological properties of LT-films are rarely reported in available literatures.In this paper,the structure,morphology and tribological properties of Ag films,deposited at LT(166 K) under various Ar pressures on AISI 440C steel substrates by arc ion plating(AIP),are studied by X-ray diffraction(XRD),atomic force microscopy(AFM) and a vacuum ball-on-disk tribometer,and compared with the Ag films deposited at RT(300 K).XRD results show that(200) preferred orientation of the films is promoted at LT and low Ar pressure.The Crystallite sizes are 70 nm-80 nm for LT-Ag films deposited at 0.2 Pa and 0.8 Pa and larger than 100 nm for LT-Ag films deposited at 0.4 Pa and 0.6 Pa,while they are 55 nm-60 nm for RT-Ag films deposited at 0.2 Pa-0.6 Pa and 37 nm for RT-Ag films deposited at 0.8 Pa.The surfaces of LT-Ag films are fibre-like at 0.6 Pa and 0.8 Pa,terrace-like at 0.4 Pa,and sphere-like at 0.2 Pa,while the surfaces of RT-Ag films are composed of sphere-like grains separated by voids.Wear tests reveal that,due to the compact microstructure LT-Ag films have better wear resistances than RT-Ag film.These results indicate that the microstructure and wear resistance of Ag films deposited by AIP can be improved by low temperature deposition.展开更多
Lithium-ion hybrid supercapacitors(LIHSs), also called Li-ion capacitors, are electrochemical energy storage devices that combining the advantages of high power density of supercapacitor and high energy density of Li-...Lithium-ion hybrid supercapacitors(LIHSs), also called Li-ion capacitors, are electrochemical energy storage devices that combining the advantages of high power density of supercapacitor and high energy density of Li-ion battery. However, high power density and long cycle life are still challenges for the current LIHSs due to the imbalance of charge-storage capacity and electrode kinetics between capacitor-type cathode and battery-type anode. Therefore, great efforts have been made on designing novel cathode materials with high storage capacity and anode material with enhanced kinetic behavior for LIHSs. With unique two-dimensional form and numerous appealing properties, for the past several years, the rational designed graphene and its composites materials exhibit greatly improved electrochemical performance as cathode or anode for LIHSs. Here, we summarized and discussed the latest advances of the stateof-art graphene-based materials for LIHSs applications. The major roles of graphene are highlighted as(1) a superior active material,(2) ultrathin 2D flexible support to remedy the sluggish reaction of the metal compound anode, and(3) good 2D building blocks for constructing macroscopic 3D porous carbon/graphene hybrids. In addition, some high performance aqueous LIHSs using graphene as electrode were also summarized. Finally, the perspectives and challenges are also proposed for further development of more advanced graphene-based LIHSs.展开更多
The self-assembled method was introduced to successfully obtain rare earth(RE) nanofilm on a single-crystal silicon substrate. The resultant film was characterized by means of X-ray photoelectron spectroscopy (XPS), e...The self-assembled method was introduced to successfully obtain rare earth(RE) nanofilm on a single-crystal silicon substrate. The resultant film was characterized by means of X-ray photoelectron spectroscopy (XPS), ellipsometer, contact angle meter and atomic force microscopy (AFM). The scratch experiment was performed for interfacial adhesion measurement of the RE film. The friction and wear behavior of RE nanofilm was examined on a DF-PM reciprocating friction and wear tester. The results indicate the RE nanofilm is of low coefficient of friction (COF) and high wear resistance. These desirable characteristics of RE nanofilm together with its nanometer thickness, strong bonding to the substrate and low surface energy make it a promising choice as a solid lubricant film in micro electromechanical system (MEMS) devices.展开更多
Nanoparticles are increasingly being used to improve the friction and wear performance of polymers. In this study, we investigated the tribological behavior and energy dissipation characteristics of nano-Al_2O_3-reinf...Nanoparticles are increasingly being used to improve the friction and wear performance of polymers. In this study, we investigated the tribological behavior and energy dissipation characteristics of nano-Al_2O_3-reinforced polytetrafluoroethylenepolyphenylene sulfide(PTFE-PPS) composites in a sliding system. The tribological behaviors of the composites were evaluated under different normal loads(100–300 N) at a high linear velocity(2 m/s) using a block-on-ring tester. Addition of the nano-Al_2O_3 filler improved the antiwear performance of the PTFE-PPS composites, and the friction coefficient increased slightly. The lowest wear rate was obtained when the nano-Al_2O_3 content was 3%(volume fraction). Further, the results indicated a linear correlation between wear and the amount of energy dissipated, even though the wear mechanism changed with the nano-Al_2O_3 content, independent of the normal load applied.展开更多
Monodisperse ZrO2 nanoparticles capped by trioctylphosphine oxide (TOPO) were prepared in non-aqueous solvent using in-situ synthesis method. Transmission electron microscopy(TEM), X-ray diffraction(XRD), X-ray photoe...Monodisperse ZrO2 nanoparticles capped by trioctylphosphine oxide (TOPO) were prepared in non-aqueous solvent using in-situ synthesis method. Transmission electron microscopy(TEM), X-ray diffraction(XRD), X-ray photoelectron spectrometer(XPS), Fourier transformation infrared spectroscopy (FTIR), and thermogravimetric analysis(TGA) were adopted to characterize and investigate the size, structure, composition, and the binding manners between organic capping agent TOPO and inorganic ZrO2 nanocores of the as-prepared nanoparticles. In addition, the nanoparticles were also studied to determine their solubility and relative stability. The experimental results show that the prepared nanoparticles contain about 25% organic capping shell TOPO, 75% inorganic ZrO2 nanocores, and can be easily dissolved and be stably disersed in non-polar organic solvents.展开更多
In order to improve wear resistance and decrease the cost, carbon and carbon nanotubes reinforced copper matrix composites were fabricated by the power metallurgy method. The effects of carbon (carbon and carbon nanot...In order to improve wear resistance and decrease the cost, carbon and carbon nanotubes reinforced copper matrix composites were fabricated by the power metallurgy method. The effects of carbon (carbon and carbon nanotubes) volume fraction and applied load on the friction coefficient and wear rate under dry sliding of the composites were investigated at room temperature. By scanning electron microscopy (SEM), the worn surfaces and debris were observed, and wear mechanism was also analyzed and discussed. The experimental wear process consists of the run-in, steady wear and severe wear process with the increasing of sliding distance. Both the friction coefficient and wear rate of the composites first decrease and then increase with the increasing of carbon volume fraction. The minimum friction coefficient and wear rate are obtained when carbon is 4.0vol%. The wear mechanisms of the composites change from the adhesive wear and delamination wear to abrasive wear with the increasing of carbon volume fraction.展开更多
In order to clarify the influence of methane concentration and deposition time on self-organized nano-multilayers,three serial copper-carbon films have been prepared at various methane concentrations with different de...In order to clarify the influence of methane concentration and deposition time on self-organized nano-multilayers,three serial copper-carbon films have been prepared at various methane concentrations with different deposition times using a facile magnetron sputtering deposition system. The ratios of methane concentration(CH4/Ar+CH4) used in the experiments are 20%, 40%, and 60%, and the deposition times are 5 minutes, 20 minutes, and 40 minutes, respectively.Despite the difference in the growth conditions, self-organizing multilayered copper-carbon films are prepared at different deposition times by changing methane concentration. The film composition and microstructure are investigated by x-ray photoelectron spectroscopy(XPS), x-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), and high-resolution transmission electron microscopy(HRTEM). By comparing the composition and microstructure of three serial films, the optimal growth conditions and compositions for self-organizing nano-multilayers in copper-carbon film are acquired. The results demonstrate that the self-organized nano-multilayered structure prefers to form in two conditions during the deposition process. One is that the methane should be curbed at low concentration for long deposition time,and the other condition is that the methane should be controlled at high concentration for short deposition time. In particular, nano-multilayered structure is self-organized in the copper-carbon film with copper concentration of 10-25 at.%.Furthermore, an interesting microstructure transition phenomenon is observed in copper-carbon films, that is, the nanomultilayered structure is gradually replaced by a nano-composite structure with deposition time and finally covered by amorphous carbon.展开更多
基金Projects(50432020, 50575218) supported by the National Natural Sicence Foundation of China
文摘Oxide coatings on AM60B magnesium alloy were prepared using the microarc oxidation(MAO) technique in silicate-KOH electrolyte with addition of 0-6.0 g/L Na2WO4. The MAO processes in base electrolyte with different concentrations of Na2WO4 were studied. The microstructure, compositions and mechanical tribological characteristics of the oxide coatings were also investigated by SEM, XRD, XPS, microhardness analysis and ball-on-disc friction testing, respectively. It is found that the addition of Na2WO4 into the base electrolyte has direct effect on the characteristics of voltage—time curves and breakdown voltage in MAO process. The number of micropores at top of the coating surface is increased by the addition of Na2WO4. The fraction of forsterite Mg2SiO4 in the oxide coating increases with increasing concentration of Na2WO4 in base electrolytes. Furthermore, the microhardness and wear resistance of oxide coatings are enhanced as well.
文摘A process for preparation of solid lubricating films on micro-arc oxidation(MAO) coating was introduced to provide self-lubricating and wear-resistant multilayer coatings for aluminum alloys. The friction and wear behavior of various burnished and bonded solid lubricating films on the as-deposited and polished micro-arc oxidation coatings sliding against steel and ceramic counterparts was evaluated with a Timken tester and a reciprocating friction and wear tester, respectively. The burnished and bonded solid lubricating films on the polished micro-arc oxidation coatings are superior to the as-deposited ones in terms of the wear resistant behavior, because they lead to strengthened interfacial adhesion between the soft lubricating top-film and the hard polished MAO sub-coating, which helps increase the wear resistance of the solid lubricating film on multilayer coating. Thus the multilayer coatings are potential candidates as self-lubricating and wear-resistant coatings for Al alloy parts in engineering applications.
基金Project(59925513) supported by theNational Natural Science Foundation of China Project(9905) supported by the State Key Laboratory of Fluid Power Transmission and Control of Zhejiang University, China
文摘The tribological characteristics of carbon fiber reinforced polymer composites under distilled-water-lubricated-sliding and dry-sliding against stainless steel were comparatively investigated. Scanning electron microscopy (SEM) was utilized to examine composite microstructures and modes of failure. The typical chemical states of elements of the transfer film on the stainless steel were examined with X-ray photoelectron spectroscopy (XPS). Wear testing and SEM analysis show that all the composites hold the lowered friction coefficient and show much better wear resistance under water lubricated sliding against stainless steel than those under dry sliding. The wear of composites is characterized by plastic deformation, scuffing, micro cracking, and spalling under both dry-sliding and water lubricated conditions. Plastic deformation, scuffing, micro cracking, and spalling, however, are significantly abated under water-lubricated condition. XPS analysis conforms that none of the materials produces transfer films on the stainless steel counterface with the type familiar from dry sliding, and the transfer of composites onto the counterpart ring surface is significantly hindered while the oxidation of the stainless steel is speeded under water lubrication. The composites hinder transfer onto the steel surface and the boundary lubricating action of water accounts for the much smaller wear rate under water lubrication compared with that under dry sliding. The easier transfer of the composite onto the counterpart steel surface accounts for the larger wear rate of the polymer composite under dry sliding.
基金The authors thank The National Key R&D Program of China(No.2022YFB3806401).
文摘Edible Lubricant-Infused Surface(ELIS)was fabricated through antisolvent method by adding ethyl oleate(lubricant/antisolvent),ethanol(solvent)and shellac(solute/base layer of ELIS)into an all-in-one solution to in-situ prepare ELIS through single step of solvent evaporation.The ELIS comprising sub-micro-to micro-scaled shellac particles shows water and food liquid slippery,transparency,stability against abrasion and lubricant retaining ability against sheer force.Using all edible material to fabricated ELIS is a more efficient route for application when compared with other Lubricant-Infused Surface(LIS).Traditional fabrication for LIS included steps such as:base layer fabrication,lubricant infusion,excess lubricant removal,UV light treatment and chemical etching.The method proposed in this article could further simplify the preparation to an all-in-one solution and simplify the synthesis process to only 60-degree heating.Furthermore,Shellac ELIS coating could withstand abrasion and hold performance when compared with other ELIS coatings.
基金supported by the National Nature Science Foundation of China(nos.51735013,51905520 and 52165040)the Gansu Provincial Natural Science Foundation of China(no.21JR7RA350)the Education Department of Gansu Province:Young Doctor Fund Project(no.2021QB-125).
文摘Superamphiphobic surfaces have great potential applications in flame resistance,anti-icing,self-cleaning,anti-adhesion,micro-flow control and so on.However,the surface durability is poor owing to the limitation of design principles.In recent years,a lot of efforts have been carried out on the morphology,structure,and stability of superamphiphobic surfaces,resulting in significant improvement in their surface superwetting properties.In this review,we present a brief classification of the morphological types of superamphiphobic surfaces and summary of the recent progress of researches on the stability of superamphiphobic surfaces.Several testing methods of mechanical and chemical stability are listed in the article,together with the characteristic results,to provide a better and more detailed understanding of the current research status on superamphiphobic surface stability,which will be of considerable importance as a reference guide for our future researches.Of course,there are still some issues that need to be addressed for the application of superamphiphobic surfaces at large scale,and this is where our future researches will be directed.Finally,we discuss the challenges as well as the prospects in the study of superamphiphobic surfaces.
基金supported by the National Natural Science Foundation of China(Grant No.51875253 and No.51935012)the Jiangsu Provincial Key Research and Development Program(BE2022069-2)the Western Light Project of Chinese Academy of Sciences(sbzg-zdsys-202007)。
文摘Complex-shaped optical lenses are of great interest in the areas of laser processing,machine vision,and optical communications.Traditionally,the processing of complex optical lenses is usually achieved by precision machining combined with post-grinding or polishing,which is expensive,labor-intensive and difficult in the processing of ultra-complex optical lenses.Additive manufacturing is an emerging technology that provides significant advantages in producing highly intricate optical devices.However,the layer-by-layer method employed in such manufacturing processes has resulted in low printing speeds,as well as limitations in surface quality.To address these challenges,we apply tomographic volumetric printing(TVP)in this work,which can realize the integrated printing of complex structural models without layering.By coordinating the TVP and the meniscus equilibrium post-curing methods,ultra-fast fabrication of complex-shaped lenses with sub-nanometric roughness has been achieved.A2.5 mm high,outer diameter 9 mm spherical lens with a roughness value of RMS=0.3340 nm is printed at a speed of 3.1×10^(4)mm^(3)h^(-1).As a further demonstration,a complex-shaped fly-eye lens is fabricated without any part assembly.The designed spherical lens is mounted on a smartphone’s camera,and the precise alignments above the circuit board are captured.Upon further optimization,this new technology demonstrates the potential for rapid fabrication of ultra-smooth complex optical devices or systems.
基金This work is financially supported by the Hundred Talents Program of Chinese Academy of Sciences(E30247YB)the Special Talents Program of Lanzhou Institute of Chemical Physics(E0SX0282)+1 种基金the National Natural Science Foundation of Shandong Province(ZR2022QB190)the Innovative Research Funds of Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai(E1R06SXM07,E1R06SXM09 and E2R06SXM14).
文摘Due to the mutual repulsion between their hydrophilic surface terminations and the high surface energy facilitating their ran-dom restacking,2D MXene nanosheets usually cannot self-assemble into 3D macroscopic gels with various applications in the absence of proper linking agents.In this work,a rapid spontaneous gelation of Ti3C2Tx MXene with a very low dispersion concentration of 0.5 mg mL^(-1) into multifunctional architectures under moderate centrifugation is illustrated.The as-prepared MXene gels exhibit reconfigurable internal structures and tunable rheological,tribological,electrochemical,infrared-emissive and photothermal-conversion properties based on the pH-induced changes in the surface chemistry of Ti_(3)C_(2)T_(x) nanosheets.By adopting a gel with optimized pH value,high lubrication,exceptional specific capacitances(~635 and~408 F g^(-1) at 5 and 100 mV s^(-1),respectively),long-term capacitance retention(~96.7%after 10,000 cycles)and high-precision screen-or extrusion-printing into different high-resolution anticounterfeiting patterns can be achieved,thus displaying extensive potential applications in the fields of semi-solid lubrication,control-lable devices,supercapacitors,information encryption and infrared camouflaging.
基金Funded by the National Natural Science Foundation of China(Nos.51165022,51675509)
文摘Polytetrafluoroethylene (PTFE) is a commonly used seal material for oil-free engine that is well known for its excellent tribological properties. In this work, the nano-ZrO2 particles were used as the friction modifiers to improve the friction and wear performance of PTFE-PPS composites. The friction and wear characteristics of PTFE/PPS-nano-ZrO2 composites were investigated by a block-on-ring tester under dry friction sliding condition. The worn surfaces, counterpart transfer films and wear debris were studied by scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that the increase of nano- ZrO2 content could effectively reduce the coefficient of friction and enhance the anti-wear ability of PTFEPPS composites. Especially, the best tribological properties of the composites were obtained when the particle content of nano-ZrO2 was 10 vol%, the anti-wear performance of composite is 195 times better than that of the unfilled PTFE-PPS composite. Under different conditions, the coefficient of friction of PTFE/PPS-nano-ZrO2 composites was more affected by the applied load while the wear rate was more affected by the sliding velocity.
基金The financial support from the“Hundred Talents Program”of Chinese Academy of Sciences(J.Liang)is gratefully acknowledged.
文摘Mg(OH)_(2)/graphene oxide(GO)composite film was electrochemical deposited on AZ91D magnesium alloys at constant potential.The characteristics of the Mg(OH)_(2)/GO composite film were investigated by scanning electron microscope(SEM),energy-dispersive X-ray spectrometry(EDS),X-ray diffractometer(XRD)and Raman spectroscopy.It was shown that the flaky GO randomly distributed in the composite film.Compared with the Mg(OH)_(2)film,the Mg(OH)_(2)/GO composite film exhibited more uniform and compact structure.Potentiodynamic polarization tests revealed that the Mg(OH)_(2)/GO composite film could significantly improve the corrosion resistance of Mg(OH)_(2)film with an obvious positive shift of corrosion potential by 0.19 V and a dramatic reduction of corrosion current density by more than one order of magnitude.
基金This work was supported by Special Fund for Local Science and Technology Development from the Ministry of Science and Technology of China(2020ZYD053)Science and Technology Planning Project of Zigong(2019YYJC22)Opening Project of Key Laboratories of Fine Chemicals and Surfactants in Sichuan Provincial Universities(2020JXY05).
文摘A reliable,high-performance coating procedure was developed using PDMS to modify a duplex MAO/DLC coating on an AZ31B Mg alloy.First,the duplex MAO/DLC coating was fabricated via a combined MAO and unbalanced magnetron sputter process.Subsequently,a PDMS solution was used to modify the MAO/DLC coating via a conventional dip-coating method.The surface characteristics,bond strength,hardness,tribological behaviour,and corrosion resistance of the coated samples were evaluated via SEM,CA,Raman spectroscopy,friction and wear behaviour,polarisation curve,and NSS tests.The PDMS modification reduced the HIT of MAO/DLC coating from 15.96 to 8.34GPa;this is ascribed to the penetration of PDMS,which has good rheological properties to form a viscoelastic Si-based organic polymer layer on the MAO/DLC coating.However,the PDMS-modified MAO/DLC coating was denser,hydrophobic,and had higher bond strength compared with MAO-and MAO/DLC-coated samples.Moreover,the PDMS modification reduced the COF and wear rate of the duplex MAO/DLC coating.This indicates that the PDMS improved the tribological behaviour owing to the transferred Si oxide that originated from the Si-O network of the PDMS,as well as the low graphitisation of the DLC layer during sliding.Furthermore,the corrosion current density of the MAO/DLC-coated sample modified by PDMS for 10min decreased by two order of magnitude compared with that of the MAO/DLC-coated sample but by five orders of magnitude compared with that of the bare substrate.The NSS tests proved that the PDMS layer slowed the corrosion of the Mg alloy under long-term service,enhancing the corrosion protection efficiency.The results are attributed to the high bond strength and lubricant MAO/DLC layer,and the dual role of sealing and hydrophobicity of PDMS.Therefore,PDMS modification is promising for the fabrication of protective materials for Mg alloys that require corrosion and wear resistance.
基金Projects(5072106250835009)supported by the National Natural Science Foundation of China
文摘Tungsten-doped silver films were prepared by immersing hydrogen-terminated silicon wafers into the solution of 2.5 mmol/L[Ag2WO4]+0.1 mol/L HF at 50℃.Their growth and composition were characterized with atomic force microscopy and X-ray photoelectron spectroscopy,respectively.The effect of tungstate ions on the deposition of silver was investigated by X-ray diffraction(XRD)and scanning electron microscopy(SEM)by comparing W-doped Ag film with Ag film.It is found that the molar fraction of tungsten in the deposits is about 2.3%and the O to W molar ratio was about 4.0 and W-doped Ag films have good anti-corrosion in air at 350℃.The doping of tungsten cannot change the deposition of silver.
基金Supported by the National Natural Science Foundation of China(No.51165022)Lanzhou Science and Technology Bureau Foundation(No.20122117)the Natural Science Foundation of Gansu Province(No.1310RJZA036).
文摘Nano-ZrO2 and PEEK particles were synergistically filled in unfilled PTFE to improve the wear resistance and maintain a relatively low friction coefficient,and the materials were studied using a reciprocating sliding friction and wear tester.In the friction tests,the evolution of various tribological characteristics in both the contact interfaces and debris was observed,and the wear mechanism of the PTFE composites was investigated.The results showed that the wear rate of the PTFE composites synergistically filled with nano-ZrO2 and PEEK was lower and its friction coefficient was slightly higher than that of the unfilled PTFE;the uniformity and continuity of the transfer film generated by the composite with nano-ZrO2 and PEEK were the best,and the particle size of the debris was minimal in comparison to that in other sample systems.
文摘A nanocomposite of MPNS/(Styrene-maleic anhydride) was prepared by the polymerization of methacryloxypropyl nano SiO2 (MPNS), styrene (ST) and maleic anhydride (MA) with benzoyl peroxide (BPO) as initiator in toluene. The prepared samples were characterized by Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscope (TEM). Meanwhile, the nanocomposite was applied as a tanning agent in leather making and the results showed that leather treated with MPNS/SMA nanocomposite has excellent quality.
基金supported by National Basic Research Program of China(973 Project,Grant No.2007CB607601)National Natural Science Foundation of China (Grant No. 50301015)
文摘The films deposited at low temperature(LT-films) have increasingly attracted theoretical and technical interests since such films exhibit obvious difference in structure and performances compared to those deposited at room temperature.Studies on the tribological properties of LT-films are rarely reported in available literatures.In this paper,the structure,morphology and tribological properties of Ag films,deposited at LT(166 K) under various Ar pressures on AISI 440C steel substrates by arc ion plating(AIP),are studied by X-ray diffraction(XRD),atomic force microscopy(AFM) and a vacuum ball-on-disk tribometer,and compared with the Ag films deposited at RT(300 K).XRD results show that(200) preferred orientation of the films is promoted at LT and low Ar pressure.The Crystallite sizes are 70 nm-80 nm for LT-Ag films deposited at 0.2 Pa and 0.8 Pa and larger than 100 nm for LT-Ag films deposited at 0.4 Pa and 0.6 Pa,while they are 55 nm-60 nm for RT-Ag films deposited at 0.2 Pa-0.6 Pa and 37 nm for RT-Ag films deposited at 0.8 Pa.The surfaces of LT-Ag films are fibre-like at 0.6 Pa and 0.8 Pa,terrace-like at 0.4 Pa,and sphere-like at 0.2 Pa,while the surfaces of RT-Ag films are composed of sphere-like grains separated by voids.Wear tests reveal that,due to the compact microstructure LT-Ag films have better wear resistances than RT-Ag film.These results indicate that the microstructure and wear resistance of Ag films deposited by AIP can be improved by low temperature deposition.
基金supported by the National Nature Science Foundations of China(Grant No.21673263,21573265)the Independent Innovation Plan Foundations of Qingdao City of China(Grant No.16-5-1-42-jch)the western Young Scholars Foundations of Chinese Academy of Sciences
文摘Lithium-ion hybrid supercapacitors(LIHSs), also called Li-ion capacitors, are electrochemical energy storage devices that combining the advantages of high power density of supercapacitor and high energy density of Li-ion battery. However, high power density and long cycle life are still challenges for the current LIHSs due to the imbalance of charge-storage capacity and electrode kinetics between capacitor-type cathode and battery-type anode. Therefore, great efforts have been made on designing novel cathode materials with high storage capacity and anode material with enhanced kinetic behavior for LIHSs. With unique two-dimensional form and numerous appealing properties, for the past several years, the rational designed graphene and its composites materials exhibit greatly improved electrochemical performance as cathode or anode for LIHSs. Here, we summarized and discussed the latest advances of the stateof-art graphene-based materials for LIHSs applications. The major roles of graphene are highlighted as(1) a superior active material,(2) ultrathin 2D flexible support to remedy the sluggish reaction of the metal compound anode, and(3) good 2D building blocks for constructing macroscopic 3D porous carbon/graphene hybrids. In addition, some high performance aqueous LIHSs using graphene as electrode were also summarized. Finally, the perspectives and challenges are also proposed for further development of more advanced graphene-based LIHSs.
文摘The self-assembled method was introduced to successfully obtain rare earth(RE) nanofilm on a single-crystal silicon substrate. The resultant film was characterized by means of X-ray photoelectron spectroscopy (XPS), ellipsometer, contact angle meter and atomic force microscopy (AFM). The scratch experiment was performed for interfacial adhesion measurement of the RE film. The friction and wear behavior of RE nanofilm was examined on a DF-PM reciprocating friction and wear tester. The results indicate the RE nanofilm is of low coefficient of friction (COF) and high wear resistance. These desirable characteristics of RE nanofilm together with its nanometer thickness, strong bonding to the substrate and low surface energy make it a promising choice as a solid lubricant film in micro electromechanical system (MEMS) devices.
基金Project(51165022)supported by the National Natural Science Foundation of ChinaProject(20122117)supported by the Lanzhou Science and Technology Bureau Foundation,ChinaProject(1310RJZA036)supported by the Natural Science Foundation of Gansu Province,China
文摘Nanoparticles are increasingly being used to improve the friction and wear performance of polymers. In this study, we investigated the tribological behavior and energy dissipation characteristics of nano-Al_2O_3-reinforced polytetrafluoroethylenepolyphenylene sulfide(PTFE-PPS) composites in a sliding system. The tribological behaviors of the composites were evaluated under different normal loads(100–300 N) at a high linear velocity(2 m/s) using a block-on-ring tester. Addition of the nano-Al_2O_3 filler improved the antiwear performance of the PTFE-PPS composites, and the friction coefficient increased slightly. The lowest wear rate was obtained when the nano-Al_2O_3 content was 3%(volume fraction). Further, the results indicated a linear correlation between wear and the amount of energy dissipated, even though the wear mechanism changed with the nano-Al_2O_3 content, independent of the normal load applied.
基金Funded by the Natural Science Foundation of Shannxi Province of China(No.2010JM2016)the Foundation of Shannxi Educational Committee(No.2010JK469)
文摘Monodisperse ZrO2 nanoparticles capped by trioctylphosphine oxide (TOPO) were prepared in non-aqueous solvent using in-situ synthesis method. Transmission electron microscopy(TEM), X-ray diffraction(XRD), X-ray photoelectron spectrometer(XPS), Fourier transformation infrared spectroscopy (FTIR), and thermogravimetric analysis(TGA) were adopted to characterize and investigate the size, structure, composition, and the binding manners between organic capping agent TOPO and inorganic ZrO2 nanocores of the as-prepared nanoparticles. In addition, the nanoparticles were also studied to determine their solubility and relative stability. The experimental results show that the prepared nanoparticles contain about 25% organic capping shell TOPO, 75% inorganic ZrO2 nanocores, and can be easily dissolved and be stably disersed in non-polar organic solvents.
基金Funded by the National Natural Science Foundation of China (50873047)the Natural Science Foundation of Gansu Province (3ZS061-A25-039)
文摘In order to improve wear resistance and decrease the cost, carbon and carbon nanotubes reinforced copper matrix composites were fabricated by the power metallurgy method. The effects of carbon (carbon and carbon nanotubes) volume fraction and applied load on the friction coefficient and wear rate under dry sliding of the composites were investigated at room temperature. By scanning electron microscopy (SEM), the worn surfaces and debris were observed, and wear mechanism was also analyzed and discussed. The experimental wear process consists of the run-in, steady wear and severe wear process with the increasing of sliding distance. Both the friction coefficient and wear rate of the composites first decrease and then increase with the increasing of carbon volume fraction. The minimum friction coefficient and wear rate are obtained when carbon is 4.0vol%. The wear mechanisms of the composites change from the adhesive wear and delamination wear to abrasive wear with the increasing of carbon volume fraction.
基金supported by the National Natural Science Foundation of China(Grant Nos.51472250,U1637204,and 51775537)
文摘In order to clarify the influence of methane concentration and deposition time on self-organized nano-multilayers,three serial copper-carbon films have been prepared at various methane concentrations with different deposition times using a facile magnetron sputtering deposition system. The ratios of methane concentration(CH4/Ar+CH4) used in the experiments are 20%, 40%, and 60%, and the deposition times are 5 minutes, 20 minutes, and 40 minutes, respectively.Despite the difference in the growth conditions, self-organizing multilayered copper-carbon films are prepared at different deposition times by changing methane concentration. The film composition and microstructure are investigated by x-ray photoelectron spectroscopy(XPS), x-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), and high-resolution transmission electron microscopy(HRTEM). By comparing the composition and microstructure of three serial films, the optimal growth conditions and compositions for self-organizing nano-multilayers in copper-carbon film are acquired. The results demonstrate that the self-organized nano-multilayered structure prefers to form in two conditions during the deposition process. One is that the methane should be curbed at low concentration for long deposition time,and the other condition is that the methane should be controlled at high concentration for short deposition time. In particular, nano-multilayered structure is self-organized in the copper-carbon film with copper concentration of 10-25 at.%.Furthermore, an interesting microstructure transition phenomenon is observed in copper-carbon films, that is, the nanomultilayered structure is gradually replaced by a nano-composite structure with deposition time and finally covered by amorphous carbon.
