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The primary aim of the present study was to investigate the effect of dexmedetomidine (DEX) on postoperative pain and early cognitive impairment in old male patients, who underwent laparoscopic cholecystectomy (LC). A total of 97 old patients, subjected to LC at the 980 Hospital of the Joint Service Support Force of the People's Liberation Army of China, were randomly divided into two groups, namely the DEX and normal saline groups. Patients in the DEX group received an intravenous infusion of 0.8 µg/kg DEX within 10 min following general anesthesia, followed by a maintenance infusion of 0.5 µg/(kg/h). Furthermore, patients in the normal saline group were treated with an equivalent volume of normal saline. Cognitive function was assessed using the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) tests at 6 h, 1, 2 and 3 days, postoperatively. The incidence of postoperative cognitive dysfunction (POCD) and postoperative adverse events were recorded for both groups. In addition, the Visual Analogue Scale (VAS) pain score was utilized to assess the pain level of all patients, while the Quality of Recovery-15 (QoR-15) scale was employed to analyze the postoperative recovery results. Therefore, the MoCA score was higher in the DEX group compared with the normal saline group at 6 h and day 1 postoperatively. Additionally, the MMSE score was higher at 6 h postoperatively in the DEX group compared with the normal saline group. Correspondingly, the incidence of POCD was lower in the DEX group compared with the normal saline group at 6 h and day 1, after LC (P<0.05). VAS score in resting state for patients in the DEX group was significantly lower compared with the normal-saline group (P<0.05). Furthermore, the QoR-15 scale score in patients in the DEX group was notably increased compared with the normal saline group on the first and second days after the operation (P<0.05). Overall, the present study verified that the continuous infusion of DEX at a rate of 0.5 µg/(kg/h) during LC could effectively reduce the incidence of early POCD and alleviate postoperative pain in old male patients, thus facilitating postoperative recovery. [ABSTRACT FROM AUTHOR]

Abstract Characteristic porous microstructure causes poor wear resistances of sputtered transition metal dichalcogenides (TMDs) films that have important applications in space technology. TMDs/metal multilayer films exhibit improved microstructural and tribological properties, but which are unreliable due to the mismatch in thermal/mechanical properties between them as well as the metal sensibility to atomic oxygen (AO). In this study, MoS 2 /WS 2 nano-scale multilayer films were fabricated to improve the microstructural, mechanical, tribological and environment-adaptive properties of TMDs films. Results revealed that as compared with MoS 2 or WS 2 single-layer film, the multilayer film exhibited a dense microstructure, strong (002) texture and high hardness. Correspondingly, it showed a significantly improved wear resistance in vacuum, whose wear life was ~one order longer than those of single-layer films. Simulation tests revealed that even drastic thermal shock could not cause the delamination of multilayer film, which was observed from TMDs/metal multilayer system; and the oxidation from AO irradiation was restricted into film surface layer (≤10 nm). These results indicated that the microstructural, mechanical and tribological properties of TMDs films were significantly improved by the nano-scale multilayer design, and the fabricated multilayer film had potential applications in space technology. Graphical abstract Unlabelled Image Highlights • WS 2 /MoS 2 nano-scale multilayer film was designed and fabricated. • Porous microstructure was significantly restrained by multilayer fabrication. • Multilayered film exhibited better mechanical, wear-resistant and space-environment-resistant properties. [ABSTRACT FROM AUTHOR]

Abstract To clarify the ability of reactive metals alloyed transition metal disulfides (TMDs) films resistant to low-earth-orbit (LEO) space exposure, the MoS 2 -16 at. % Ag film was sputtered and exposed in long-term atomic oxygen (AO) environment. Results revealed the MoS 2 -Ag composite film could be severely oxidized by the AO irradiation. The 2H-MoS x O y matrix was severely oxidized to MoO 3 and MoO 2 , and the alloyed Ag was partially oxidized to Ag 2 O. The volume expansion from the oxidation of Ag to Ag 2 O was responsible for the cracking and thereby severe oxidation of brittle 2H-MoS x O y platelets in the composite film. Furthermore, the re-growth of Ag induced by the AO irradiation was also observed in the initial stage of AO irradiation. Due to the oxidization, the film morphology was changed from the characteristic dentrite-like surface for the non-irradiated film to the terrace-like one for the irradiated film and eventually to the chrysanthemum-like one as increasing the AO fluence. Wear tests revealed that the wear resistance of MoS 2 film in vacuum environment could be significantly improved. However, the wear resistance of MoS 2 -Ag composite film was obviously deteriorated because of the severe oxidation from the AO irradiation. The wear life of MoS 2 -Ag composite film was sharply reduced from ∼7.6 × 105 cycles before the AO irradiation to ∼4.9 × 104 cycles after the AO irradiation of 5.6 × 1026 atoms∙m−2. These results indicated that for the selection of solid lubricants in LEO space environment, the reactive metals alloyed TMDs films should be excluded as possible as to eliminate potential risks. Graphical abstract Image 1 Highlights • MoS 2 -Ag composite film could be severely oxidized by long-term AO irradiation. • The oxidation production was mainly MoO 3 , MoO 2 and Ag 2 O. • The AO irradiation caused not only the oxidation but also the re-growth for the doped Ag. • The oxidation led to the cracking and morphological change of MoS 2 -Ag film. • Wear endurance of MoS 2 -Ag film was significantly reduced by AO irradiation. [ABSTRACT FROM AUTHOR]

The work reports on the morphologies and the tribological properties of MoS 2 films deposited onto the as-deposited or textured TiN and WC interlayers. The closed-field unbalanced magnetron sputtered MoS 2 film exhibited dense structure without obvious voids or columnar morphology. Meanwhile, plenty of MoS 2 nanowires or nanorods were grown on the film surface. With the laser-textured TiN or WC interlayer introduced, both the textured TiN/MoS 2 film and WC/MoS 2 film exhibited a long lubricating life higher than 8.0 × 105 sliding cycles, much higher than that for the un-textured films or pure MoS 2 film. • MoS 2 films with textured TiN, WC interlayer were deposited by a closed-field unbalanced-magnetron sputtering system. • The deposited MoS 2 film exhibited a dense structure with plenty of nanowires or nanorods grown between the MoS 2 columnar. • The textured TiN/MoS 2 film and WC/MoS 2 film exhibited a long lubricating life higher than 8.0 × 105 sliding cycles. [ABSTRACT FROM AUTHOR]

Thin Cr-Nb-N films with Nb content ranging from 5.1 to 19.5 at.% were prepared onto the AISI 440C substrates by reactive magnetron sputtering of the Cr and Nb in Ar-N 2 gas mixture. The effects of the Nb content on the microstructure and the corrosion behavior in 3.5 wt% NaCl solution were investigated. All the deposited films showed a typical surface feature of granular structure. The Cr-Nb-N films with 5.1 at.% and 10.9 at.% Nb showed a duplex layers consisting of a dense and coherent layer near film-substrate interface, followed by a columnar layer differed from the uniform columnar structure for pure CrN. While for Cr-Nb-N films with higher Nb content, there was no obvious dense layer but a columnar structure. The low Nb content Cr-Nb-N coated samples showed a positive shift of both corrosion potential and the pitting potential compared to the pure CrN coated sample while the pitting potential decreased for high Nb content Cr-Nb-N coated samples. The Cr-Nb-N film with Nb content of 10.9 at.% possesses the best corrosion resistance due to the high polarization resistance resulted from the modification of the microstructure by the Nb incorporation. [ABSTRACT FROM AUTHOR]

• Defect and phase are tuned for the sodium storage of TiO 2-X nanotube arrays. • The oxygen vacancy and phase of TiO 2-X nanotube arrays show unique evolution rule. • The black TiO 2-X nanotube arrays show superior sodium storage performance. • The sodium storage mechanism is clarified by CV analysis and DFT calculation. Defect engineering and phase engineering are two powerful strategies for regulating the intrinsically sluggish electronic and ionic kinetics of TiO 2 to enhance sodium storage. However, synergetic control of the defects and phases in TiO 2 nanomaterials remains a major challenge. Herein, we clarify the phase and defect synergetic evolution regularities of self-supported TiO 2-X nanotube arrays (TNTAs) with different annealing processes, which amazingly demonstrate different characteristics from traditional TiO 2 nanoparticles. The phase composition and oxygen vacancy (OV) concentration tuning strategies are combined to systematically clarify how these two important synergetic factors influence the sodium storage properties of TNTAs. In particular, unique porous-wall black amorphous TNTAs annealed at 300 ℃ in air and core-shell black anatase TNTAs annealed at 600 ℃ in N 2 show the best sodium storage performance among all amorphous and anatase samples, respectively. Cyclic voltammetry (CV) kinetics analysis demonstrates that both pseudocapacitive and diffusion-controlled charge storage mechanism exist in the TNTAs. The correlations of the pseudocapacitive capacity and the diffusion-controlled capacity with the OV concentrations and phases are clarified in detail. Both the pseudocapacitive capacity and diffusion-controlled capacity are enhanced in samples with high OV concentration in the amorphous and anatase TNTAs. Density functional theory (DFT) calculations further indicate that a high OV density corresponds to a low sodium insertion energy and high capacity, which matches the experimental results. [ABSTRACT FROM AUTHOR]

The oxidation and erosion of atomic oxygen are considered to be the most dangerous environmental factors for materials exposed to the aerospace environment. In order to investigate the effect of atomic oxygen on the lubricating film and improve the tribological properties, MoS2–WS2 composite film was prepared by the sputtering technique. The film structure and mechanical behavior were characterized and their vacuum tribological properties were evaluated by a friction tester. The composite film possessed better atomic oxygen (AO) resistance than pure film because of the dense structure. The tribological performance of composite film was different under the conditions after AO-irradiation and sliding and during AO-irradiation. After AO-irradiation, the tribological properties of composite film were similar to those before AO-irradiation. However, high friction noise, wear rate, and reduced wear duration were observed for the composite film under the AO-irradiation/friction process because of the continuous damage of the lubricating film due to the AO-irradiation. The addition of 16 at.% WS2 to the MoS2-based film changed the composite film structure and improved the oxidation resistance of the film, making the composite film exhibit better tribological performance than pure MoS2. [ABSTRACT FROM AUTHOR]

In this paper, WS2-Al nanocomposite films were deposited by closed-field unbalanced magnetron sputtering to improve the microstructure and wear resistance of pure WS2 film. Results revealed that pure WS2 film presented a columnar microstructure, but the growth of WS2 platelets could be significantly suppressed by doping Al. Correspondingly, the WS2-Al composite film showed a dense fiber-like microstructure at low Al content (~ 3 at.%) and a featureless one at higher Al content (~ 6-12 at.%). The film densification resulted in a significantly improved hardness from ~ 0.3 GPa for pure WS2 film to 2.9 GPa for WS2-3 at.% Al film and to 4.7-5.7 GPa for WS2 composite films with higher Al contents of ~ 6-12 at.%, but the composite films with higher Al contents were brittle. As a result, only the composite film with Al content of ~ 3 at.% exhibited a much better wear resistance than pure WS2 film. In vacuum environment, the wear life of WS2-3 at.% Al composite film about 1.5 × 106 cycles was much higher than that of pure WS2 film ~ 6.5 × 105 cycles, exhibiting a potential application in space technology. [ABSTRACT FROM AUTHOR]

Many failures and anomalies of spacecrafts originated from space environmental factors. Meanwhile, MoS 2 based films have been widely used in space technology as solid lubricants. In this paper, the compact MoS 2 -Sb 2 O 3 composite film was rf-sputtered and exposed in low earth orbit (LEO) environment, which was aboard the exterior of Shenzhou-7 Manned Spaceship (SZMS-7). The results revealed that the space exposure effect on MoS 2 -Sb 2 O 3 composite film mainly exhibited the oxidation at the film surface layer less than 3.5 nm. No severe oxidation and cracking phenomena were observed from the space-exposed MoS 2 -Sb 2 O 3 composite film, which was normal for many space materials. Namely, the MoS 2 -Sb 2 O 3 composite film exhibited a better capability resistant to LEO space environment. [ABSTRACT FROM AUTHOR]

The goal of this paper was to investigate the structural/mechanical properties of arc-ion-plated Ti film deposited at ultralow temperature (166 K, LT-Ti film) and its effect as an interlayer on the wear resistance of sputtered WS 2 film. The results revealed that the LT-Ti film mainly exhibited ω-phase structure due to the insufficient mobility of Ti adatoms at LT surface, while the α-phase was predominated in the Ti film deposited at room temperature (RT-Ti film). The LT-Ti film showed a higher hardness than the RT-Ti film as well as the better toughness and film-substrate adhesion on steel substrates. The wear resistance of sputtered WS 2 film could be significantly improved by employing the Ti films as its interlayer, especially for the LT-Ti film. [ABSTRACT FROM AUTHOR]

The microstructure and wear resistance of sputtered MoS 2 films can be improved by adding some amount of metals. However, the oxidation-resistance of MoS 2 -metals films would be worried because some metals are sensitive to atomic oxygen (AO). In this paper, the inert Sb 2 O 3 was introduced into the MoS 2 film, and its effect on the structure and anti-oxidation ability of the MoS 2 film was clarified. XRD and SEM results revealed that due to the addition of Sb 2 O 3 , the growth of MoS 2 micro-platelets was almost suppressed, and so the composite film was amorphous and very compact. XPS analysis indicated that for the composite film, the influence by the AO irradiation was restricted into the film surface layer. Namely, the composite film exhibited a better anti-oxidation ability in the AO environment. [ABSTRACT FROM AUTHOR]

Due to the crystal anisotropy, highly oriented films normally exhibit unique properties and performances. In this paper, Ag films were deposited using arc ion plating (AIP) at different substrate temperatures, substrate bias voltages and Ar pressures, and the relationship between the preferred orientation and deposition parameter of the films was investigated. The results exhibited that the preferred orientation of Ag films was influenced significantly by the deposition parameter due to the competition between the surface- and strain-energy minimization, and so both Ag films that exhibited highly preferred orientations of (1 1 1) and (2 0 0), respectively, were obtained at the optimum conditions. The relatively low friction was observed from the Ag film with highly preferred orientations of (1 1 1) because the (1 1 1) plane was the slip plane of face-centred cubic crystals. [ABSTRACT FROM AUTHOR]

The easy oxidation and poor corrosion resistance of the sputtered WS 2 film would limit its application in spacecraft due to the sharp deterioration of lubricity resulting from the contact with the marine atmosphere inevitably with the increasing space launch from sea or seaside. In this study, the active metal Ta was skillfully introduced into the WS 2 film through co-sputtering of the WS 2 and Ta targets. The influence of the doped Ta related microstructure regulation on the tribological and anti-corrosion properties of the prepared composite films was investigated. It showed that the incorporation of the active Ta would activate the residual O atoms to form Ta 2 O 5 phase while making the WS 2 phase partly oxidized to form the WS x O y and WO 3. WS 2 –Ta composite films with low Ta content exhibited low friction coefficient and long wear life more than 3 times of that for pure WS 2 film. In addition, the corrosion resistance of WS 2 –Ta film was improved by a positive shift of corrosion potential in salt spray with increasing the Ta content, originating from the passivation effect of the Ta 2 O 5 phase and the WS x O y phase in the film as well as the dense structure. • WS 2 –Ta composite films with different Ta contents were prepared by magnetron sputtering system. • The incorporation of the much active Ta would activate the residual O atoms to form the Ta 2 O 5 and partly WS x O y. phase. • WS 2 –Ta composite film exhibited significantly improved tribological property and corrosion resistance. [ABSTRACT FROM AUTHOR]

MoS 2 -Au/Au multilayer film was sputtered and exposed in low earth orbit environment aboard Chinese Shenzhou-7 manned spaceship to develop a solid film combining good lubricity and space-environment resistance together. The results revealed that space exposure caused the oxidation of MoS 2 -Au/Au multilayer film, but which was restricted into film surface. Importantly, the delaminating behavior was not observed from the space-exposed MoS 2 -Au/Au multilayer film, which was normal for other MoS 2 /metal multilayer film. As a result, the space-exposed MoS 2 -Au/Au multilayer film still exhibited a good lubricity (friction coefficients at ∼0.02–0.05), but a relatively high initial friction coefficient about 0.08 due to the surface oxidation. These results indicated that this multilayer lubrication film had a good capability resistant to space environment and potential application as solid lubricant in space technology. Image 1 • Sputtered MoS 2 -Au/Au multilayer film was exposed in LEO space environment. • Oxidation of MoS 2 -Au/Au multilayer film by AO was restricted into film surface. • No delaminating was observed from space-exposed MoS 2 -Au/Au multilayer film. • Space-exposed MoS 2 -Au/Au multilayer film displayed a low friction behavior. [ABSTRACT FROM AUTHOR]

To achieve the desired levels of performance and durability for bearings applied in space, a novel solid-liquid dual lubricating system was established via the WS2-MoS2 composite films sliding against oil-impregnated porous polyimide (PPI), in which polyalphaolefin (PAO) oils with different viscosities were used, respectively. The contact angle measurement indicated that the PAO oil had good wettability on the surfaces of the composite film and the PPI. The vacuum tribological behaviors of single WS2-MoS2 composite film and the dual lubricating system were mainly evaluated under different loads and speeds. In comparison with single WS2-MoS2 composite film, the dual lubricating system exhibited the low friction coefficient and synergistic lubricating effect for the low-viscosity PAO oil under severe sliding conditions. It was concluded that the cleavages of the WS2 and MoS2 crystals along the basal plane were more sufficient and formed small and thin WS2 and MoS2 platelets in the dual lubricating system. Meanwhile, it was found that oil-impregnated PPI readily released PAO lubricating oil with low viscosity, which further decreased friction on the contact interface. The lubricating mechanism of the dual lubricating system was also revealed after correlating the tribological behaviors of the different lubricating systems. [ABSTRACT FROM AUTHOR]

Abstract A novel approach by texturing the WS 2 film with the nanocone-array Ni interlayer was adopted to improve the tribological property of WS 2 film particularly prolonging the wear life for application in space. The WS 2 /Ni bilayer films were prepared by sputtering WS 2 layer onto electrodeposited Ni interlayers with different surface morphologies. The micro-structures and the tribological properties of the prepared WS 2 /Ni bilayer films were investigated. The results showed that with the existence of the nanocone-array Ni interlayer, the textured WS 2 film showed a cabbage-like structure due to the growth of the WS 2 columnar plates surrounding the Ni nanocones. The cabbage-like WS 2 /Ni bilayer thin film was benefited for improving the lubrication properties with a long wear life of 4.9 × 105 cycles while the wear life was only 0.7 × 105 cycles for the pure WS 2 and 3.2 × 105 cycles for rough Ni textured WS 2 film. The improved tribological property was mainly attributed to the reserve of the WS 2 lubricate by the Ni nanocones as well as the relative low friction coefficient of the nanocone-array Ni interlayer due to the obvious reduced real contact area. Highlights • A novel cabbage-like WS 2 /Ni bilayer film was prepared without any template. • The cabbage-like WS 2 /Ni bilayer lubricating film showed an improved lifetime. • Reservoir of the WS 2 lubricates by Ni nanocones resulted in the improved property. [ABSTRACT FROM AUTHOR]

Abstract The WS 2 /CrN bilayered films with different interface morphologies between WS 2 and CrN layer were prepared by physical vapor deposition. By controlling the deposition parameters, the surface of CrN interlayer exhibited compact granular structure when deposited under low partial pressure of Ar while a cone array-like surface appeared under high Ar partial pressure. The surface texture of the CrN interlayer had a great effect on the tribological performance of the WS 2 /CrN film. The compact CrN textured WS 2 film exhibited a wear life about 2.6 × 105 cycles while the optimal cone array-like CrN textured WS 2 film showed a much longer wear life reaching to 6.8 × 105 cycles, which was more than 2.6 times of that for compact CrN textured WS 2 film and 3.5 times of that for WS 2 film without the CrN interlayer. The improved tribological property of the optimal cone array-like CrN textured WS 2 film was attributed to the high adhesion between the WS 2 layer and the CrN interlayer. Meanwhile, the reservoir and replenishment of the WS 2 lubricant by the CrN nanocones during the friction made a significant contribution for the long wear life. Highlights • Compact and cone array-like CrN interlayers were deposited under different Ar partial pressure. • Different tribological performances would be resulted by tailoring the interface of WS 2 /CrN bilayered film. • The reservoir and replenishment of the WS 2 lubricates by CrN nanocone array contribute to the tribological performances. [ABSTRACT FROM AUTHOR]

Tribological properties and wear mechanisms of TiN films deposited by arc ion plating (AIP) against Si 3 N 4 , Al 2 O 3 and steel balls were comparatively investigated under different loads and speeds. The tribological properties of the TiN films were evidently influenced by load, speed and counterball. The different friction coefficients were related to the real contact state of the friction interface of the tribopair. The TiN films against the ceramic balls mainly were typical polishing wear, which resulted from the interaction between the preferential formation of the Ti oxide layer on the wear track surface and the small particles from ceramic balls. For steel ball, the platelets of Fe 3 O 4 adhered to the wear track surface did not generate polishing effect. [ABSTRACT FROM AUTHOR]

The rf-sputtered MoS 2 -Au composite films were exposed in real low earth orbit (LEO) space environment by a space environment exposure device (SEED) aboard China Shenzhou-7 manned spaceship. The ability of the composite films resistant to atomic oxygen (AO) was investigated using X-ray photoelectron spectroscope (XPS), X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) equipped with an X-ray energy dispersive spectroscopy (EDS). The results showed that the microstructure of the composite film was densified because the growth of MoS 2 platelets was suppressed to some content due to the addition of Au, although it was still characterized by a typical dendrite-like morphology. No obvious change in the morphology, phase structure, element composition and friction property was observed from the space exposed and non-exposed composite films, indicating that the composite film exhibited a better anti-oxidation ability as exposed in LEO environment. The improved anti-oxidation ability was attributed to the more compact microstructure and a passivation effect that the dangling bonds at the edge planes of MoS 2 platelets were probably occupied by the partial doping atoms. [ABSTRACT FROM AUTHOR]

The sputtered CrN coatings, which were bombarded by the energetic Cr-ion via filtered arc ion plating layer by layer, were prepared to improve the corrosion resistance of the coated samples. By controlling the times of Cr ion bombardment, the influence of the Cr ion bombarding of the sputtered CrN were investigated from the aspect of the microstructure and corrosion behavior. The results indicated that the CrN film showed a suppressed effect on the coarse columnar structure and a more compact structure with lower porosity by introducing the Cr-ion bombardment. Potentiodynamic polarization curves showed that the CrN coated samples had an obvious improved corrosion resistance after the energetic Cr ion bombardment. With the bombarding times of Cr ion increasing from four to ten, the corrosion resistance of CrN coated samples showed a further improvement with corrosion potential increased about 100 mV and the corrosion current density decreased more than one order of magnitude when compared with the non-bombarded CrN coating. [ABSTRACT FROM AUTHOR]

CrN nanocone-array supported WS 2 film was prepared by depositing a nanocone-array CrN interlayer and then a radio frequency sputtered WS 2 layer. The microstructures of the deposited films were investigated by field emission scanning electron microscopy and grazing incidence X-ray diffraction. The CrN nanocones array have an average period of about 150 nm, and the height of each nanocone is about 100 nm. The CrN nanocone array textured WS 2 film presented an improved lubricating lifetime due to the regular CrN nanocone arrays acting as a good reservoir of the WS 2 lubricates. [ABSTRACT FROM AUTHOR]

In the present work, WS 2 –MoS 2 nanocomposite films were sputtered, based on which solid/liquid-lubrication systems were realized by combining the WS 2 –MoS 2 films with space oils including MACs (multialkylated cyclopentanes) and CPSO (chlorinated-phenyl with methyl-terminated silicone oil). The tribological behaviors of the solid/liquid systems were investigated in vacuum. It was revealed that in comparison to pure WS 2 film, the WS 2 –MoS 2 composite film exhibited an enhanced tribological performance. Moreover, our results identified that the WS 2 –MoS 2 /MACs system integrated better the advantages of the solid and liquid lubrications and thereby a synergistic lubricating effect was generated. A tribological model was established to explain the synergistic lubricating mechanism. [ABSTRACT FROM AUTHOR]

Radio frequency-sputtered MoS 2 films had been exposed for 43.5 h in real low earth orbit (LEO) space environment by a space environment exposure device (SEED) aboard China Shenzhou-7 manned spaceship. The composition, morphology, phase structure and friction property of the exposed films were investigated using X-ray photoelectron spectroscope (XPS), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), X-ray energy-dispersive spectroscopy (EDS) and ball-on-disk tribometer. XRD and EDS results revealed that the as-deposited MoS 2 films were characterized by a MoS x O y phase structure, in which x and y values were determined to be ∼0.65 and 1.24, respectively. XPS analysis revealed that due to space atomic oxygen attack, the film surface was oxidized to MoO 3 and MoS x O y with higher O concentration, while the partial S was lost. However, the affected depth was restricted within the surface layer because of protective function of the oxidation layer. As a result, the friction coefficient only exhibited a slight increase at initial stage of sliding friction. [ABSTRACT FROM AUTHOR]

Ag films, deposited by arc ion plating, had been exposed for 43.5 h in real low earth orbit (LEO) space environment by a space environment exposure device (SEED) aboard the China Shenzhou-7 manned spaceship. The structure, morphology, composition and tribological property of the Ag films after the space environment exposure (SEE) were investigated using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), X-ray photoelectron spectroscope (XPS) and ball-on-disk tribometer, respectively. Depth XPS and XRD analysis revealed that after the SEE, the surface layer of Ag films was partially oxidized to Ag 2 O, the cracking and flaking phenomena could be observed from the film surface by FESEM, and so the Ag films lose its metallic shine and became gray. As a result, the tribological performance was deteriorated and the high/unstable friction was obtained. [ABSTRACT FROM AUTHOR]

MoS 2 -Cr 3 O 4 composite films were prepared by the combination method of PVD and liquid phase synthesis. The microstructure and tribological properties of films have been investigated. The results indicate that the size of Cr 3 O 4 varied from 5 nm to 500 nm and the shape of Cr 3 O 4 changed from nanospheres to nanorods by adjusting concentration of CrCl 3. The MoS 2 -Cr 3 O 4 composite films developed excellent wear resistance and much lower friction coefficient than sputtered MoS 2 both in vacuum and 45%RH air. During friction, the Cr 3 O 4 @MoS 2 core-shell structure with Cr 3 O 4 core of high hardness and soft MoS 2 shells were formed and played the role of nano-bearing, which reduced the friction and wear of the composite film. Besides, better oxidation resistance and tribological property of the MoS 2 -Cr 3 O 4 composite films in humid air were attributed to the Cr 3 O 4 nanoparticles, which occupied the most of dangling bond sites. Unlabelled Image • Cr 3 O 4 nano-particles are connected to dangling bonds of the sputtered MoS 2 film. • Occupied dangling bonds by Cr 3 O 4 can much improved the antioxidant of MoS 2 film. • The Cr 3 O 4 @MoS 2 core-shell structure formed and played a role of nano-bearing. • The Cr 3 O 4 greatly improves tribological properties of films both in air and vacuum. [ABSTRACT FROM AUTHOR]

MoS 2 film deposited was deposited by closed-field unbalanced-magnetron sputtering (CFUBMS), and its structural and tribological properties were modified by the heat treatment at temperature range of 100–500 °C in vacuum environment. Results revealed that as-deposited MoS 2 film was composed of MoS 2 plus a little MoO 3 with a dense amorphous-like structure. After the vacuum heat treatment, MoS 2 film was still very compact, but its microstructure was changed from amorphous-like to nano-crystalline states with the increase of heat treatment temperature. As a result, a MoS 2 film with a microstructure of MoS 2 nanocrystals embedded into its own amorphous matrix was obtained at middle temperature of 200 °C. Furthermore, MoO 3 phase in the film was reduced to MoO 2 after the vacuum heat treatment at high temperatures of 400 and 500 °C. Friction tests revealed that the wear resistance of MoS 2 film in vacuum environment was significantly improved by the vacuum heat treatment at suitable temperature. The wear life of vacuum-heat-treated MoS 2 film at 200 °C for 3 h was ~6.2 × 105 r, about four times longer than that of as-deposited MoS 2 film. Unlabelled Image • Amorphous-like MoS 2 film changed structure to nanocrystal states, embedded into matrix to improve wear resistance by vacuum-heat-treatment. • Its structure and wear resistance may be significantly modified by vacuum-heat-treatment. • Film structure changed from amorphous-like to nanocrystal states by vacuum-heat-treatment. • A special structure of MoS 2 nanocrystals embedded into its own amorphous matrix was obtained at suitable temperature of heat treatment. • Wear life of vacuum-heat-treated MoS 2 film at 200 °C was about four times longer than that of as-deposited MoS 2 film. [ABSTRACT FROM AUTHOR]

In the presence of flooded imidazolium hexafluorophosphate (LP108), Ag-Cu/Ti film prepared by multi-arc ion plating is well lubricated but severely corroded due to electrochemical corrosion even by using benzotriazole as a corrosion inhibitor. Although imidazolium methyltributylammomiumbis ((trifluoromethyl)sulfonyl)imide ([HEMIM]NTf 2) is much less corrosive to Ag-Cu/Ti film, its lubricity is inferior to that of LP108. Preapplied LP108 on top of Ag-Cu/Ti film by dipping and withdrawing from 0.2 vol% LP108-ethanol solutions exhibits comparable lubricity as flooded LP108, and comparable corrosion as flooded [HEMIM]NTf 2. The localized liquid LP108 around spherical and top-flat droplets of Ag-Cu/Ti film gives birth to in-situ hybrid Ag-LP108 tribo-layer upon sliding contact. Meanwhile, tribochemical affinity between PF 6 anion and tribo-surface is another reason for good lubricity. • Ag-Cu/Ti film is coated with imidazolium hexafluorophosphate by dipping and withdrawing from 0.2 vol.% solutions in ethanol. • The distribution of LP108 is strongly affected by the surface topography of Ag-Cu/Ti film. • Formation of a hybrid Ag-LP108 tribo-layer and good boundary property of LP108 allows sliding with low friction and wear. • Low corrosion of preapplied LP108 to Ag-Cu/Ti film is observed. [ABSTRACT FROM AUTHOR]