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It is challenging to investigate fast supramolecular processes due to the lack of appropriate characterization methods with high structural resolution. In thisstudy, microfluidic nuclear magnetic resonance (μFNMR) spectroscopy was employed to monitor the kinetics of threading and dethreading of a pseudo[6]rotaxane system. By employing high time resolution μF-NMR, 1H and two-dimensional (2D) rotating frame nuclear Overhauser effect spectroscopy (ROESY) NMR spectra were recorded at any timepoint within 1.5 s after the onset of the process. This technique enabled the successful identification of kinetic intermediates and rate-determining steps,usually impossible to determine by other spectroscopic techniques. Thus, our study demonstrates the capability of μF-NMR in investigating the mechanismof complex supramolecular systems.

Hybrid supercapacitors represent a promising candidate for grid-scale energy storage devices because of their excellent high-power density, inherent safety and low cost. Here we report a novel NiSe2@rGO nanocomposite (reduced graphene oxide decorated NiSe2 nanoparticles), which shows high specific capacity of 467 C g-1 at 1 A g-1 and superior rate performance (∼72.8 % of the capacity retention at 20 A g-1). Moreover, a hybrid supercapacitor (HSC) assembled from the NiSe2@rGO positive electrode and rGO negative electrode delivers high energy density (34.3 Wh kg-1) and splendid cycling lifespan (∼93% of the capacity retention over 6500 cycles). This study provides a novel insight on high-performance hybrid supercapacitors.

The development of helicene molecules with significant chiroptical responses covering a broad range of the visible spectrum is highly desirable for chiral optoelectronic applications; however, their absorption dissymmetry factors (gabs) have been mostly lower than 0.01. In this work, we report unprecedented B,N-embedded double hetero[7]helicenes with nonbonded B and N atoms, which exhibit excellent chiroptical properties, such as strong chiroptical activities from 300 to 700 nm, record high gabs up to 0.033 in the visible spectral range, and tunable circularly polarized luminescence (CPL) from red to near-infrared regions (600 ~ 800 nm) with high photoluminescence quantum yields (PLQYs) up to 100%. As revealed by theoretical analyses, the high gabs values are related to the separate molecular orbital distributions owing to the incorporation of nonbonded B and N atoms. The new type of B,N-embedded double heterohelicenes opens up an appealing avenue to the future exploitation of high-performance chiroptical materials.

For fabricating brazed inserts in machining difficult-to-machine materials, chemical vapor deposition (CVD) diamond thick films are potential candidates for polycrystalline diamond (PCD). In the present study, monolayer microcrystalline diamond (MCD), monolayer nanocrystalline diamond (NCD), and multilayer diamond thick films were respectively deposited on the Si3N4 substrates by the high-power density (HPD) microwave plasma CVD (MPCVD) technique, which were then brazed on WC–Co. Their microstructures, growth rates, and film quality were systematically studied. Within the multilayer film, in order to enhance the secondary nucleation on as-deposited MCD layers and promote the consecutive growth of NCD layers, increasing the nitrogen addition level was much more effective than increasing the methane/hydrogen ratio. The NCD interpositions could guarantee layer thickening, while suppressing the growing up of individual micro diamond grains. As revealed by Raman spectra, the multilayer structure could help restrain the accumulation of the residual stress with increasing the thickness. Besides, the multilayer diamond thick film also presented much enhanced erosive wear resistance, as compared with the monolayer MCD or NCD, because the NCD interlayers could prevent intergranular cracks from further propagating. Finally, cutting performances of various brazed inserts were evaluated, in the case of dry-turning the high-silicon aluminum alloy (40 wt.% Si), demonstrating that the multilayer structure could result in the enhancement of the impact toughness of cutting edges, and improve the machining quality.

Single crystalline diamond (SCD) grits are usually made by a high-pressure and high-temperature (HPHT) method and exhibit cuboctahedral shapes and smooth surfaces. In this paper, we synthesized new kinds of SCD grits and nanocrystalline diamond (NCD) grits by a chemical vapor deposition (CVD) method and explored their grinding performance by single grit grinding of SiC ceramics. Grinding by HPHT grits was also conducted for comparison. The CVD-SCD grits exhibit cuboctahedral shapes, but surfaces are covered by protruded twin crystals of several microns, while the NCD grits are spherical agglomerations of nano-grains. We demonstrated that these morphological features have profound influences on material removal behavior. Results show that the wear of NCD grits is dominated by wear flat and intergranular cracks. The worn NCD grits can exert intense rubbing and ploughing effects on the workpiece. In contrast, the wear of CVD-SCD grits is dominated by fracture of the protruded twin crystals. It is proved that the twins on the grit surface are effective cutting edges to remove the material in a micro scale and thus lead to the formation of fine grinding striations and smaller cracking pits, but this process has little influence on specific grinding energy. Besides, grits with rough twins, especially on the flank face, tend to exhibit lower grinding force ratios and thus better sharpness. Moreover, for grits with smooth rake faces, there exists an explicit critical undeformed chip thickness value around 0.4–0.6 μm, above which the material removal mechanism changes from ductile to brittle rapidly. However, for grits with rough twins on rake faces, this transition process becomes vague.

Interfacial host–guest complexation offers a versatile way to functionalize nanomaterials. However, the complicated interfacial environment and trace amounts of components present at the interface make the study of interfacial complexation very difficult. Herein, taking the advantages of near-single-molecule level sensitivity and molecular fingerprint of surface-enhanced Raman spectroscopy (SERS), we reveal that a cooperative effect between cucurbit[7]uril (CB[7]) and methyl viologen (MV2+2I−) in aggregating Au NPs originates from the cooperative adsorption of halide counter anions I−, MV2+, and CB[7] on Au NPs surface. Moreover, similar SERS peak shifts in the control experiments using CB[n]s but with smaller cavity sizes suggested the occurrence of the same guest complexations among CB[5], CB[6], and CB[7] with MV2+. Hence, an unconventional exclusive complexation model is proposed between CB[7] and MV2+ on the surface of Au NPs, distinct from the well-known 1:1 inclusion complexation model in aqueous solutions. In summary, new insights into the fundamental understanding of host–guest interactions at nanostructured interfaces were obtained by SERS, which might be useful for applications related to host–guest chemistry in engineered nanomaterials.

Potassium-ion battery (KIB) is one of the emerging electrochemical energy storage technologies due to the abundance, low cost, and low redox potential of K. One of the most promising cathodes of KIBs is a layered vanadium-based compound, but it often suffers from fast capacity decay during repeated cycling. Herein, a K0.5V2O5/CNTs hybrid film composed of K0.5V2O5 nanobelt and carbon nanotube (CNT) network was synthesized by an electrostatic self-assembly and vacuum filtration process, and further used as the cathode in KIBs. The K0.5V2O5/CNTs cathode possessed a flexible and interconnected network structure, which not only offered fast kinetics for electron transfer and ion transportation, but also provided an elastic medium to buffer the large volume change of the K0.5V2O5 nanobelts during cycling. As a cathode for KIBs, the K0.5V2O5/CNTs electrode showed a reversible discharge capacity of ∼90 mA h g-1 at 50 mA g-1 and exhibited good cycling stability (88.8% capacity retention for 100 cycles at 50 mA g-1, 82.2% capacity retention for 300 cycles at 500 mA g-1) and excellent rate performance of ∼62 mA h g-1 at 500 mA g-1. K-Ion full battery testing further confirmed its good electrochemical performance by presenting a high reversible discharge capacity (68 mA h g-1 at 50 mA g-1) and long-term retention (>80% after 80 cycles). Interestingly, a cable-shaped KIB with the flexible K0.5V2O5/CNTs film as the cathode electrode was assembled and showed its further application potential as a power source for wearable electronics.

An X-shaped double [7]heterohelicene 1 bearing four thiadiazole units is synthesized by regioselective cyclodehydrogenation. Enantiopure 1 exhibits excellent chiroptical properties with an impressive absorption dissymmetry factor of up to 0.027, as well as a compact π-stacked homochiral assembly which is unprecedented in the realm of double helicenes.

Molecular face-rotating polyhedra (FRP) exhibit complex stereochemistry, rendering it challenging to manipulate their assembly in a stereoselective manner. In our previous work, stereocontrolled FRP were gained at the cost of losing the confined inner space, which hampers their host–guest interactions and potential applications. Through a rational design approach, herein we demonstrate the successful construction of hollow FRP with high diastereoselectivity. Whereas the [4 + 4] imine condensation of meta-formyl substituted C3h-symmetric TAT-m and C3-symmetric Tri-NH2 led to the formation of all feasible FRP-12 diastereoisomers; the para-substituted constitutional isomer, TAT-p, exclusively assembled into a pair of homo-directional enantiomeric FRP-13-CCCC/AAAA with a cavity size larger than 600 Å3. Detailed structural characterizations and theoretical investigations revealed the thermodynamic landscape of FRP assembly can be effectively shaped by modulating the van der Waals repulsive forces among the facial building blocks. Our work provided a novel strategy towards stereospecific assembly of pure organic cages, opening up new opportunities for further applications of these chiral materials., The rationally engineered facial units, TAT-m and TAT-p, resulted in distinct diastereoselectivity of face-rotating polyhedra (FRP).

A method based on the density functional theory calculations is proposed for predicting the influences of dopants on the diamond oxidation, by evaluating the O adsorption energy, chemical bond weakening related to desorption, and probable products. It is proven by verification tests that oxidation resistances of the diamond materials can be indeed selectively controlled (e.g., -36 to 54.3% for diamond films, -36.5 to 45.1% for diamond grits) by adding various doping sources ((CH

Electrolyte engineering is critical for developing Li metal batteries. While recent works improved Li metal cyclability, a methodology for rational electrolyte design remains lacking. Herein, we propose a design strategy for electrolytes that enable anode-free Li metal batteries with single-solvent single-salt formations at standard concentrations. Rational incorporation of –CF2– units yields fluorinated 1,4-dimethoxylbutane as the electrolyte solvent. Paired with 1 M lithium bis(fluorosulfonyl)imide, this electrolyte possesses unique Li–F binding and high anion/solvent ratio in the solvation sheath, leading to excellent compatibility with both Li metal anodes (Coulombic efficiency ~ 99.52% and fast activation within five cycles) and high-voltage cathodes (~6 V stability). Fifty-μm-thick Li|NMC batteries retain 90% capacity after 420 cycles with an average Coulombic efficiency of 99.98%. Industrial anode-free pouch cells achieve ~325 Wh kg−1 single-cell energy density and 80% capacity retention after 100 cycles. Our design concept for electrolytes provides a promising path to high-energy, long-cycling Li metal batteries. The realization of the full potential of Li metal batteries requires high-performance electrolytes. Here Z. Bao and colleagues develop low-concentration electrolytes with a single-solvent and single-salt formulation, offering promise for high-energy and long-cycling batteries.

In this work, an efficient composite of SnSb alloy particles confined in three-dimensional porous carbon framework (SnSb@C) is rationally designed and fabricated by means of NaCl template-assisted in situ freeze-drying treatment and subsequent thermal reduction method. Benefit from rational material design and the excellent structural features of the active materials, the SnSb@C can deliver a high initial reversible capacity of 457 mA h g−1 at 100 mA g−1, and excellent cycling stability with capacity retention of 84% after 200 cycles at 0.1 A g−1, when evaluated as an anode material for SIBs. Meanwhile, the SnSb@C electrode can also deliver a high reversible discharge capacity of 293 mA h g−1 at 100 mA g−1 after 100 cycles in PIBs with good rate capability and impressive cycling performance. These results demonstrated that the SnSb@C composite is a promising anode material for future high-performance SIBs and PIBs.

Covalently linked π-stacked dimers represent the most significant platform for elucidating the relationship between molecular alignments and their properties. Here, we present the one-pot synthesis of two intramolecularly π-stacked dimers and disclose how intramolecular stacking modes dictate photoswitching properties. The dimer, which features cofacially stacked chromophores and geometrically favours intramolecular photochemical [2 + 2] cycloadditions, displays a nearly irreversible photoswitching behaviour. By contrast, the dimer, bearing crosswise stacked chromophores, is geometrically unfavourable for the cycloaddition and exhibits a highly reversible photoswitching process, in which the homolysis and reformation of carbon−carbon single bonds are involved. Moreover, the chiral carbon centres of both dimers endow these photoswitches with chirality and the separated enantiomers exhibit tuneable chiroptical properties by photoswitching. This work reveals that intramolecular stacking modes significantly influence the photochemical properties of π-stacked dimers and offers a design strategy toward chiral photoswitchable materials., Covalently bridged π-stacked dimers are excellent molecular platforms for understanding the relationship between stacking orientation and properties. Here, the authors synthesize a pair of π-stacked dimers that are aligned either cofacially or crosswise, allowing them to compare how the intramolecular stacking mode affects each dimer’s photoswitching properties.

Searching for low-cost, high capacity, stable and well-designed cathode materials with good rate capability and long-life cycling performances is our long-term goal for rechargeable lithium/sodium batteries. In this work, a simple and scalable strategy is developed to synthesize metal-organic frameworks (MOFs) derived Fe7S8/C composites by sulfurizing Fe-MIL-88A MOFs. The synthesized Fe7S8/C composites are of rod-like morphology with the well-dispersed Fe7S8 nanoparticles in porous carbon matrix. Such a structure could offer distinct advantages for Fe7S8-based electrode materials for both lithium and sodium batteries. When evaluated as a cathode material for rechargeable Fe7S8/Li batteries, the Fe7S8/C composites exhibit a long and flat discharge plateau around 1.5 V and delivers a high specific discharge capacity of 473 mA h g−1 at 0.1 A g−1 after 100 cycles with excellent rate capability and long-life cycling performance at high current density (~301 mA h g−1after 1000 cycles at 1.0 A g−1). Moreover, the Fe7S8/C composites could also exhibit high specific capacities, good rate performance and high cycling stability as an anode material for sodium ion batteries. Our findings demonstrate that Fe7S8/C composites with rod-like morphology are promising electrode materials for lithium/sodium batteries.

Monolayer diamond grinding tools are commonly made by electroplating or brazing. However, electroplated tools involve weak grain/matrix adhesion due to a lack of chemical bonds, and brazed diamonds often suffer thermal damage resulting from the high-temperature brazing process. This paper reports a new method to fabricate monolayer diamond grinding tools by chemical vapor deposition (CVD) technique. First, diamond powders at the range of 7–180 μm are chosen as seeds of the abrasive grains. The seeds are randomly distributed on SiC substrates by spraying the suspension containing the seeds toward the substrates in a spin coater machine, or orderly positioned on the substrates by a patterned mask. Then CVD diamond growth is conducted on both the substrates and the seeds simultaneously. As-grown diamond films on the substrates are regarded as bonding layers of the grinding tools, and the original seeds with irregular and crushed morphologies can grow into blocky cube-octahedral grains with smooth surfaces, which are supposed to have enhanced mechanical strength. Raman spectra demonstrate that as-grown diamonds on both the substrates and the seeds are of high quality and low levels of graphitization. Besides, relatively low residual stresses are detected in the diamond grains, because both the bonding layers and the grains are made of diamond. Grinding tests are conducted using as-fabricated CVD diamond grinding tools and electroplated/brazed diamond grinding tools as comparisons. The results suggest that the CVD diamond grinding tools possess the best wear resistance in terms of the fracture of the diamond grains. This is attributed to the epitaxial grain structure that restrains the crack propagations. In addition, the wear of the CVD diamond grains can generate tiny pyramidal crystalline tips and sharp edges, indicating the unique shelf-sharpness during the grinding.

Li-rich manganese-based layered cathode Li1.2Mn0.54Ni0.13Co0.13O2 (LMNCO) nanotubes are synthesized by electrospinning and surface coated with different amounts of amorphous Al2O3. The effects of the coating content of Al2O3 on the structural and electrochemical performances of LMNCO nanotubes are investigated systematically. The results show that the morphologies and structures of the samples exhibit no apparent changes after being coated with Al2O3. Electrochemical tests indicate that the Al2O3-coated LMNCO nanotubes exhibit obviously enhanced electrochemical performances. The initial coulombic efficiency of surface modified LMNCO nanotubes increased from 74.9% to 85.2%, and the modified LMNCO nanotubes have a high capacity retention of 97.6% after 90 cycles at 1C. The improved electrochemical performances of the coated samples are attributed to the protective function of the uniform Al2O3 coating and the three-dimensional Li+ diffusion channel in the spinel interface layer.

The frictional resistance and hole quality when drilling CFRP laminates are associated with tribological behaviors of drill materials. In the present study, tribological tests are conducted on various diamond coated WC-Co balls sliding against T800/X850 CFRP laminates with [-45/90/45/0]s lay-up, under specific conditions similar to the drilling process. It is firstly found that the coefficient of friction (COF) varies with the sliding direction. The boron-doped micro-crystalline and nano-crystalline composite diamond (BDMC-NCCD) film synthesized by optimized growth durations (9 h for BDMCD and 2.5 h for NCD) presents relatively low COF and wear rate (0.193 and 0.97 × 10−8 mm3/N m, when the sliding velocity and normal load are respectively 1.5 m/s and 5.0 N), as well as high critical load for the film peeling (35 N), owing to the nano-sized diamond grains and low surface roughness (Ra~125.09 nm measured by the confocal microscopy) of the surface NCD layer, and high hardness and favorable adhesion of the underlying BDMCD layer. Besides, influences of the sliding velocity and normal load are clarified, indicating that the COF increases with the load, but decreases with increasing the velocity, while the wear rate increases with either the load or velocity.

Magnetic resonance (MR) technology has been widely employed in scientific research, clinical diagnosis and geological survey. However, the fabrication of MR radio frequency probeheads still face difficulties in integration, customization and miniaturization. Here, we utilized 3D printing and liquid metal filling techniques to fabricate integrative radio frequency probeheads for MR experiments. The 3D-printed probehead with micrometer precision generally consists of liquid metal coils, customized sample chambers and radio frequency circuit interfaces. We screened different 3D printing materials and optimized the liquid metals by incorporating metal microparticles. The 3D-printed probeheads are capable of performing both routine and nonconventional MR experiments, including in situ electrochemical analysis, in situ reaction monitoring with continues-flow paramagnetic particles and ions separation, and small-sample MR imaging. Due to the flexibility and accuracy of 3D printing techniques, we can accurately obtain complicated coil geometries at the micrometer scale, shortening the fabrication timescale and extending the application scenarios., Here, the authors combine 3D printing and liquid metal filling techniques to fabricate customised probeheads for magnetic resonance experiments. They demonstrate in situ electrochemical nuclear magnetic resonance analysis, reaction monitoring with continues-flow separation and small-sample imaging.

Recently, room-temperature flexible gas sensors have been widely studied because they can operate without being heated and create low-cost, low-power-consumption devices with long-term stability. H...

In this work, a comparative study of diamond films consisting of alternate microcrystalline (MCD) and nanocrystalline diamond (NCD) layers is conducted. Diamond films including monolayer, bilayer and multilayer diamond films are coated on cemented tungsten carbide (WC-Co) substrates by adopting a bias-enhanced hot filament chemical vapor deposition (HFCVD) technique. Tribological properties of the diamond films are evaluated by using a reciprocal tribometer without lubrication. Further milling tests are carried out to examine the cutting performances with sintered zirconia ceramics as workpiece comparatively. In friction test against zirconia ceramics, the monolayer NCD film shows the lowest friction coefficient (0.128) because of its smooth surface. Also, the bilayer diamond film with surface coating of NCD layer (MNCD) and both of the multilayer diamond films exhibit good friction property while the monolayer MCD film has the largest friction coefficient (0.292). The milling test demonstrates that the monolayer diamond (MCD and NCD) coated milling tools show poor tool life due to abrasive action of hard workpiece. Working life of all the bilayer and multilayer diamond coated tools is enhanced, but large area shedding of coatings appears after some milling passes except the multilayer diamond film with surface coating of NCD layer (MNMN-CD). The multilayer film (MNMN-CD) presents superior machining performance and its working life increases by 3–7.5 times compared with the monolayer diamond coated ones.

Lower surface roughness and sharper cutting edge are beneficial for improving the machining quality of the cutting tool, while coatings often deteriorate them. Focusing on the diamond coated WC-Co milling cutter, the abrasive flow machining (AFM) is selected for reducing the surface roughness and sharpening the cutting edge. Comparative cutting tests are conducted on different types of coated cutters before and after AFM, as well as uncoated WC-Co one, demonstrating that the boron-doped microcrystalline and undoped fine-grained composite diamond coated cutter after the AFM (AFM-BDM-UFGCD) is a good choice for the finish milling of the 6063 Al alloy in the present case, because it shows favorable machining quality close to the uncoated one, but much prolonged tool lifetime. Besides, compared with the micro-sized diamond films, it is much more convenient and efficient to finish the BDM-UFGCD coated cutter covered by nano-sized diamond grains, and resharpen its cutting edge by the AFM, owing to the lower initial surface roughness and hardness. Moreover, the boron incorporation and micro-sized grains in the underlying layer can enhance the film-substrate adhesion, avoid the rapid film removal in the machining process, and thus maximize the tool life (1040 m, four times more than the uncoated one). In general, the AFM is firstly proposed and discussed for post-processing the diamond coated complicated cutting tools, which is proved to be feasible for improving the cutting performance

When drilling the carbon fiber reinforced plastics (CFRP), the tool shape and surface coating both play important roles in the cutting performance, which are complex and comprehensive, and should be systematically studied. In this research, WC-6wt.%Co drills in typical shapes are prepared, on which high-performance composite diamond films are deposited by the hot filament chemical vapor deposition (HFCVD) method. It is firstly proved by drilling tests that the tool shape always acts as a determining factor that significantly influences the drilling force and machining quality, for either the uncoated or diamond coated drills. The shorter chisel edge, smaller actual point angle and the proper double point angles are all factors in their favor. By contrast, as-deposited diamond films can slightly reduce the drilling force, while sometimes it even deteriorates the hole quality, due to the edge roundness caused by the alkali-acid pretreatment and the film growth. However, the diamond films play critical roles in improving the wear resistance, elongating the lifetime and guaranteeing the stability of the machining quality in the long-duration drilling process. In addition, the tool lifetime is also closely associated with the tool shape, attributed to the different thrust forces, consequently the lifetime of the diamond coated standard twist drill is much shorter than those of all other coated ones.

Nano/microcrystalline composite diamond films were deposited on the holes of WC-6%Co drawing dies by a two-step procedure using alternative carbon sources, i.e., methane for the microcrystalline diamond (MCD) layer and acetone for the nanocrystalline diamond (NCD) layer. Moreover, the monolayer methane-MCD and acetone-NCD coated drawing dies were fabricated as comparisons. The adhesion and wear rates of the diamond coated drawing dies were also tested by an inner hole polishing apparatus. Compared with mono-layer diamond coated drawing die, the composite diamond coated one exhibits better comprehensive performance, including higher adhesive strength and better wear resistance than the NCD one, and smoother surface (Ra=65.3 nm) than the MCD one (Ra=95.6 nm) after polishing at the same time. Compared with the NCD coated drawing die, the working lifetime of the composite diamond coated one is increased by nearly 20 times.

Tribological tests are conducted on diamond films under different lubrications, and influences of film type, lubrication, test parameters on coefficient of friction (COF) and film wear (Id) are studied. Diamond films perform better than WC-Co under water-based emulsion lubrication, and the boron doped micro-crystalline and nano-crystalline composite diamond (BDMC-NCCD) film shows the best overall behavior. Considering the performance and economy, the water content in the emulsion is optimized as about 80 vol%. Under this drawing condition, the quality of the production is similar to that drawn by the uncoated dies under the oil lubrication, however, the coated dies present much prolonged lifetime and lower temperature. Most importantly, the use of the water-based lubrication is much more environmentally friendly.

WS2-modified SnO2 hybrid nanocomposite was synthesized by a hydrothermal method. The morphology and structure characterization revealed that the SnO2 nanocrystals were anchored to the WS2 nanosheets in the homogeneous nanocomposites. The resistive humidity sensors based as-prepared nanocomposites, pure WS2 nanosheets and pure SnO2 microspheres were fabricated and tested in a humidity range of 11–95% RH at 25 °C. The humidity sensing properties of the nanocomposites manifested a good and stable humidity sensing. The response of the hybrid nanocomposite in air with 95% RH was found to be 8.5 and 862.8 times higher than that of pure SnO2 microspheres and WS2 nanosheets, respectively. The synergistic effect between WS2 and SnO2 played an important role in improving the humidity sensing performance of the hybrid nanocomposites.

Based on the traditional deposition technique with the filament through the hole (DTFTH), the growth of high-quality diamond films on inner hole surfaces, especially those with small apertures, is rather difficult and laborious. In the present research, the deposition technique with no filament through the hole (DTNFTH) is proposed, and its feasibility and limitations are discussed on the basis of the radiation computation, temperature simulation, analyses on mean free paths of various active radicals, and the experimental verification of the “shading and distance effects”. It is indicated that the ratio of the hole depth to the hole diameter should be smaller than four. Afterwards, the drawing die with an aperture of 2 mm is designed, and a case study focusing on a single die and the mass production of diamond coated dies by the DTNFTH are both accomplished, using optimized deposition parameters. It is demonstrated that the film thicknesses are in the range of 4.8–6 μm (case study) and 3.5–5 μm (mass production), showing acceptable uniformity. Uncoated, DTFTH- and DTNFTH-diamond coated dies are all submitted to field tests, indicating that the lifetime of the DTFTH-diamond coated die is approximately eight times more than that of the uncoated one, while the DTNFTH-diamond film prolongs the lifetime of the uncoated die by a considerable factor of five.

Systematical researches were accomplished on WC–Co with different Co contents (6%, 10% and 12%, mass fraction). Based on the XPS and EDX, from orthogonal pretreatment experiments, it is indicated that the acid concentration, the time of the acid pretreatment and the original Co content have significant influences on the Co-removal depth (D). Moreover, the specimen temperature, original Co content and Co-removal depth dependences of the Co evolution in nucleation, heating (in pure H2 atmosphere) and growth experiments were discussed, and mechanisms of Co evolutions were summarized, providing sufficient theoretical bases for the deposition of high-quality diamond films on WC–Co substrates, especially Co-rich WC–Co substrates. It is proven that the Co-rich substrate often presents rapid Co diffusion. The high substrate temperature can promote the Co diffusion in the pretreated substrate, while acts as a Co-etching process for the untreated substrates. It is finally found that the appropriate Co-removal depth for the WC–12%Co substrate is 8–9 μm.

We constructed a series of novel chiral molecular face-rotating polyhedra (FRP) from two 10,15-dihydro-5H-diindolo[3,2-a:3',2'-c]carbazole (triazatruxene) derivatives and trans-1,2-cyclohexane diamine, and investigated how facial interactions and the positions of substituents determine the diastereoselectivity and geometry of the final assemblies.

Chiral tetraphenylethylene (TPE) derivatives have great potential in chiral recognition and circularly polarized luminescence. However, they were mainly constructed through introducing chiral substituents at the periphery of the TPE moiety, which required additional chemical modifications and limited the variety of chiralities of products. Herein, we constructed a series of chiral face-rotating sandwich structures (FRSs) through restricting the phenyl flipping of TPE without introducing any chiral substituents. In FRSs, the complex arrangements of TPE motifs resulted in a variety of chiralities. We also found that non-covalent repulsive interactions in vertices caused the facial hetero-directionality of FRSs, and the hydrogen bonds between imine bonds and hydroxy groups induced excited-state intramolecular proton transfer (ESIPT) emission of FRSs. In addition, the fluorescence intensity of FRSs decreases with the addition of trifluoroacetic acid. This study provides new insights into the rational design of chiral assemblies from aggregation-induced emission (AIE) active building blocks through restriction of intramolecular rotation (RIR).

The drilling performance of four typical types of single-layer diamond coated drills and two-layer boron-doped-microcrystalline/nanocrystalline diamond (BDMC-NCD) composite coated drill is compared, and the growth duration ratio of the NCD layer to the BDMCD layer ( N/B ) is optimized. It is demonstrated that the BDMC-NCD film synthesized using proper N/B shows nice adhesion, moderate diamond quality and a smooth surface mostly composed of nano-sized diamond grains, so it shows the best comprehensive performance, including the thrust force reduction, the improvement of the hole quality, the slowing of the tool wear and coating peeling, and the elongation of the tool lifetime. Taking the time of the coating peeling into consideration, 3/9 is the optimum N/B for the BDMC-NCD coated drill, and such the drill also performs the longest lifetime using delamination factors ( F d ) of 1.2 or 1.3 as the failure criteria. Moreover, the failure mode of the diamond coated drill is the flank wear when using F d = 1.1 or 1.2 as the failure criteria, while the tool failure should be related to the coating peeling when F d = 1.3.

Silicon-based anodes with carbon materials as current collectors are promising for the fabrication of flexible lithium-ion batteries with high energy density due to the high specific capacity of silicon as well as the light weight and excellent flexibility of carbon materials. Currently it is still significant and challenging to develop new preparation methods and electrode structures to achieve the combination of low cost and high performance for such anodes. In this work, we report a simple and scalable method to prepare freestanding and flexible CNT/(Fe@Si@SiO2) composite anodes with novel kernel-pulp-skin nanostructure for lithium-ion batteries. This unique kernel-pulp-skin nanostructure facilitates the charge transfer at the electrolyte/electrode interface and the diffusion of lithium in the electrode material, which significantly improves the cycle stability and rate capability of the electrode. The resultant CNT/(Fe@Si@SiO2) composite anodes exhibit a high reversible capacity (968 mAh g−1 at 1 A g−1) and stable cycling performance with a capacity retention of 83% after 500 cycles.

Ultrananocrystalline diamond (UNCD) coating possessing low surface roughness was innovatively deposited on printed circuit board (PCB) end mills in order to improve the surface smoothness and prolong the tool duration while machining 5G PCB material. Six types of diamond coatings, involving microcrystalline diamond (MCD), nanocrystalline diamond (NCD), ultrananocrystalline diamond (UNCD), microcrystalline diamond/nanocrystalline diamond (MCD/NCD), microcrystalline diamond/ultrananocrystalline diamond (MCD/UNCD), microcrystalline diamond/nanocrystalline diamond/ultrananocrystalline diamond (MCD/NCD/UNCD), were synthesized on PCB end mills. The Raman spectrum of diamond coatings were obtained to characterize the phase composition, illustrating that Raman spectra of UNCD, MCD/UNCD and MCD/NCD/UNCD present “M” shape, including dominant D peak and G peak. The adhesion levels were assessed, showing that the bottom MCD layer helps to improve the adhesion of MCD/NCD, MCD/UNCD and MCD/NCD/UNCD on WC-Co substrates and MCD/NCD/UNCD can suppress effectively the crack propagation. Moreover, the tribological properties and wear performances of these diamond coatings were compared. The comparison results of friction coefficients are in good accordance with those of surface roughness. The superior adhesion of bottom MCD, the elegant transition of middle NCD and the low friction coefficient of the top UNCD lead to the outstanding wear performances of MCD/NCD/UNCD coated end mill while machining PCB slots.

In the present study, at fixed hydrogen flow rate of 400 sccm, we demonstrate the coupling effects of methane/hydrogen ratio ηC (7.5– 15 vol%) and nitrogen flow rate fN (0– 0.9 sccm) on morphologies, mechanical properties and tribology behaviors of the diamond films deposited on cemented carbide (WC-Co) substrates. At lower ηC (7.5 vol%), increasing fN from 0 to 0.9 sccm leads the diamond film to transform from 〈110〉-oriented to 〈110〉- & 〈100〉-oriented. Besides, increasing ηC accelerates the orientation transition, i.e., {110} and {100} crystallographic planes can be formed at even lower nitrogen addition level. Furtherly increasing ηC and fN to 15 vol% and 0.9 sccm, the film morphology transforms to nanocrystalline diamond (NCD). Moderate nitrogen addition acting as a catalyst at the substrate surface increases the growth rate, by the mechanism of promoting the individual grains growth. However, supersaturated nitrogen will suppress the growth of individual grains by generating masses of secondary nucleation on the crystal faces, resulting in a slight reduction of the growth rate. The 〈110〉- & 〈100〉-oriented diamond film deposited at ηC = 7.5 vol% and fN = 0.9 sccm and the NCD film both present low small surface roughness and coefficient of friction (COF) when sliding against the Si3N4 balls, while the former has higher hardness and Young's modulus, along with lower wear rate and better adhesive strength, which has great potential for the application as wear-resistant and anti-friction coating.

Sandblasting combined with acid etching was utilized as pretreatment of Co-cemented tungsten carbide substrates for the deposition of chemical vapor deposition (CVD) diamond films. Diamond films were deposited on the pretreated surface as well as on substrates treated by a two-step alkali-acid pretreatment as a contrast. The field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Raman spectroscopy, Rockwell hardness tester and turning test were respectively conducted to characterize the pretreated substrates and deposited diamond films. Surface roughness of the treated surface was controlled by adjusting sandblasting parameters. An enhancement of surface roughness and removal of the binder phase were detected on the treated surface. The porous Co-depleted carbide layer caused by sandblasting and acid-etching pretreatment was obviously thinner compared to the two-step pretreatment. The nucleation stage of CVD process was investigated and the nucleation density was obviously enhanced by the sandblasting pretreatment. Indentation tests exhibited an improvement of adhesive strength compared to the two-step pretreatment. Moreover, the XRD patterns showed that the residual stress of diamond films was decreased. The turning tests showed that the diamond coated tools with sandblasting-acid pretreatment exhibited less area of flank wear and film shedding.

For the chemical vapor deposition (CVD) of diamond films, boron doping with appropriate boron doping levels can enhance the basic mechanical properties of the as-deposited films, especially the film-substrate adhesive strength. However, the boron doping level, which is thought to play a critical role in modifying the properties of the boron-doped diamond (BDD) film, must be further investigated. In the present investigation, the commonly used reaction-bonded silicon carbide (RB-SiC) material is selected as the substrate upon which boron-doped micro-crystalline (BDMCD) films with similar film thickness (24.8–26.3 μm) are synthesized using mixed reactant gas with different B/C atomic ratios, i.e., different boron doping levels. Systematic characterization and solid particle erosion tests are conducted on all specimens to elucidate the influence of the boron doping level on the diamond films' basic mechanical properties and erosion behavior and to elaborate the impact velocity and impact angle dependence of the erosion behavior. The results demonstrate that moderate boron doping levels (5000 and 8000 ppm) are able to maximize the growth rate, reduce the surface roughness, guarantee diamond quality and hardness, minimize the residual stress, and significantly enhance the film-substrate adhesive strength, thereby providing favorable erosion behavior. By contrast, very high boron doping levels (12,000 and 16,000 ppm) deteriorate the erosion behavior of as-deposited BDMCD films, mainly because of the excessive reduction of the film quality and hardness, together with the deterioration of the film-substrate adhesive strength caused by the transformation of the residual stress from compressive to tensile. With increasing either impact velocity or impact angle, the stable erosion rates of all specimens increase, and the film lifetime of the coated specimens become shorter. Moreover, the impact velocity dependence of stable erosion rates for diamond-coated specimens is considerably stronger than that for the uncoated RB-SiC specimen, as indicated by a much higher velocity exponent.

Chemical vapor deposition (CVD) diamond films have been widely applied as protective coatings on varieties of anti-frictional and wear-resistant components, owing to their excellent mechanical and tribological properties close to the natural diamond. In applications of some components, the inner hole surface will serve as the working surface that suffers severe frictional or erosive wear. It is difficult to realize uniform depositions of diamond films on surfaces of inner holes, especially ultra-large inner holes. Adopting a SiC compact die with an aperture of Ф80 mm as an example, a novel filament arrangement with a certain number of filaments evenly distributed on a circle is designed, and specific effects of filament parameters, including the filament number, arrangement direction, filament temperature, filament diameter, circumradius and the downward translation, on the substrate temperature distribution are studied by computational fluid dynamics (CFD) simulations based on the finite volume method (FVM), adopting a modified computational model well consistent with the actual deposition environment. Corresponding temperature measurement experiments are also conducted to verify the rationality of the computational model. From the aspect of depositing uniform boron-doped micro-crystalline, undoped micro-crystalline and undoped fine-grained composite diamond (BDM-UMC-UFGCD) film on such the inner hole surface, filament parameters as mentioned above are accurately optimized and compensated by orthogonal simulations. Moreover, deposition experiments adopting compensated optimized parameters and some typical contrastive parameters are also accomplished for further verifying the rationality of the computational model and the correctness of the compensation coefficient 0.7 defined for the downward translation determined by simulations. More importantly, on the basis of more simulations and verification tests, a general filament arrangement model suitable for Ф50–120 mm circular inner holes is determined, involving all above filament parameters that are functionally dependent on the diameter of the inner hole.

Chemical vapor deposition (CVD) diamond thick film, due to its higher hardness and better wear resistance, is a potential competitor of the poly-crystalline diamond (PCD) when used as the brazed tool tip. Besides, compared with the thin diamond coated tool, the diamond thick film brazed tool does not have the risk of catastrophic coating delamination. However, due to the fragile characteristic of the free-standing diamond thick film, the conventional polishing is complicated and inefficient. In this study, a novel CVD-diamond thick film-Si3N4 brazed WC-Co (i.e. DB) tool is proposed. The diamond thick film was deposited on the Si3N4 substrate by microwave plasma CVD (MPCVD), using the optimized deposition parameters: microwave power = 3.5 kW, reactant pressure = 20 kPa and methane concentration = 10 %. Adopting the sandblasting and nanodiamond seeding pretreatment methods could improve the film surface smoothness and suppress the voids formation on the film-substrate interlayer, which are beneficial for the post polishing process. In addition, Si3N4 as the supportive substrate could help to prevent the diamond film breaking from polishing. The polished CVD diamond thick film-Si3N4 was laser cut to small tips and then brazed on the WC-Co cutter body. The cutting performance of DB tool was tested in dry turning hypereutectic Al-Si alloy, adopting the PCD and thin diamond coated WC-Co (i.e. DC) tools as comparisons. The cutting results suggest that DB tool outperformed the PCD and DC tools in term of service life and surpassed the DC tool in machining quality. Moreover, the novel tool in this study avoided some typical problems for the conventional diamond tools, such as the coating delamination for thin diamond coated tool and preferred wear of the binder for PCD tool. Noteworthy is that the worn DB tool still presents a rather sharp cutting edge, only some micro-columnar diamond crystals chipped from the flank face.

Behaviors of diamond coated Ti-related parts are significantly affected by carbonized interlayers, so it is essential to determine or predict the carbonization depth during diamond growth. Following the Fick’s law of diffusion with carbon concentration-dependent diffusion coefficients, it is roughly predicted that carbonization depths in Ti and Ti–6Al–4V substrates hardly reach 30 μm within a long duration of 16 h. After trying some characterization methods (XPS, EDS, metallographic analysis and ToF-SIMS), the EDS line scanning is selected as the practical one with sufficient accuracy and convenience. Influences of some critical factors, including growth duration, substrate temperature, reactant pressure and acetone (carbon source) concentration, are studied and discussed. Considering all of the factors, especially those related to the diamond coverage that can suppress carbon diffusion, the modified diffusion models for describing the carbon diffusion, are constructed, defining carbon concentration and diamond coverage (duration, pressure, carbon concentration)-dependent diffusion coefficients. Such the models can be used for well predicting the carbonization depths under most conditions, which are valuable for controlling the carbonized layers during fabrications of diamond coated Ti-related components facing to various applications.

5G printed circuit boards (PCBs), composed of glass fiber, epoxy resin and ceramic, are a kind of difficult-to-machine material. The manufacture of massive high-quality micro holes on 5G PCBs raise high requirements on the tool life and machining precision of PCB micro drills. Chemical vapor deposition (CVD) diamond coatings can be used as effective protective films on PCB micro drills. The surface smoothness and coating-substrate adhesion of diamond coated micro drills are two important factors affecting the drilling performances. Different from previously reported microcrystalline diamond (MCD) or nanocrystalline diamond (NCD) coating types on cutting tools, undoped (UD-) and boron doped (BD-) ultrananocrystalline diamond (UNCD) coatings with higher surface smoothness are firstly applied on PCB micro drills to reduce the friction and cutting resistance and improve the cutting performances while machining PCBs. Moreover, different from the usual argon-rich gas atmosphere for UNCD synthesis, the synthesis mechanisms of UD-UNCD and BD-UNCD with hydrogen-rich atmosphere adopting HFCVD method are clarified. Sufficiently high renucleation rate of diamond crystallites, long mean free path of reactive precursor species and high removal rate of non-diamond carbon phases lead to the successful synthesis of UNCD films. UDMCD, UD-UNCD, UD-MCD/UD-UNCD, BD-MCD, BD-UNCD, and BD-MCD/BD-UNCD, were synthesized on PCB micro drills using HFCVD. The tribological performances and wear mechanisms of these different diamond coatings were studied systematically. The dominant wear mechanism causing tool wear and fracture of diamond coated micro drills in high-speed machining PCBs is abrasive wear. The degree of abrasive wear while machining PCBs are mainly determined by the surface smoothness, surface roughness and coefficient of friction of diamond coatings. The top layer UNCD with tiny grain size leads to the improvement of surface smoothness and tribological properties, which enhance the chip evacuation capacity and reduce the tool wear. Besides, both boron doping and middle layer MCD can contribute to the strong coating-substrate adhesion. Therefore, BD-MCD/BD-UNCD coated micro drill exhibits the best cutting performances while machining PCBs.

H-, O-, OH- and F-terminated N-doped diamond surfaces are calculated by the density functional theory in the present study. Combined effects of terminating species and substitutional N dopants in the 1st or 2nd carbon layers on several critical features (i.e., bond length, total electron density, bond population, atomic charge, Fukui function, and density-of-states) are systematically studied and discussed. The N dopant presents clear, but local, effects for all the terminating species and dopant positions. The adsorption of any individual species to the N dopant in the 1st carbon layer results in the reduction of adsorption energy (less negative), most probably owing to the full shell structure of this N dopant. The H, OH and F each provides one unpaired electron to occupy the antibonding states within the N–H, N–OH and N–F bonds, making the bonds elongated, reducing the corresponding electron densities and bond populations. On the contrary, the N dopant in the 2nd carbon layer induces slight increment of the adsorption energy for O, OH and F, attributed to the positive atomic charges of neighboring topmost C atoms. Amongst the four adsorbates, the O shows the highest reactivity to either an electrophilic or a nucleophilic attack. Besides, N dopants have slight influences on the reactivity of the adjacent adsorbates. The present results can help to understand some related chemical processes (such as the oxidation and electrochemical analysis) on N-doped diamond films.

The study concentrates on systematic investigations on the effects of extremely high or low carbon concentration (2%–14%) and gas pressure (800 Pa–3200 Pa) on crystal structures, grain sizes, phase compositions, surface and cross-sectional morphologies, growth rates, surface roughness, mechanical and tribological performances of various polycrystalline diamond films synthesized on cemented carbide (WC-Co) substrates with hydrogen-rich/argon-lean gas mixture adopting hot filament chemical vapor deposition (HFCVD) method. The crystal structure, grain size and phase composition of various diamond films synthesized with different carbon concentration and gas pressure were analyzed, indicating that as-deposited diamond films cover microcrystalline diamond (MCD), submicrocrystalline diamond (SMCD), nanocrystalline diamond (NCD) and ultrananocrystalline diamond (UNCD). The surface and cross-sectional morphologies of these various polycrystalline diamond films were observed, and the growth rates of various diamond films were calculated. The three-dimensional morphologies and surface roughness were obtained. With increasing the carbon concentration and decreasing the gas pressure during the synthesis, the crystal size decreases so that diamond film with high smoothness, low surface roughness can be obtained. Subsequently, the synthesis mechanisms of MCD, SMCD, NCD and UNCD films with different carbon concentration and gas pressure under hydrogen-rich gas mixture adopting HFCVD were discussed in detail. The elastic modulus and nanohardness of different diamond films were measured quantitatively, and the film-substrate adhesion were evaluated qualitatively. Moreover, the tribological performances of various diamond films synthesized with different carbon concentration and gas pressure were studied by sliding against silicon nitride (Si3N4) ceramic balls. Results indicate that obtaining the dynamic equilibrium between sufficiently renucleation rate of diamond nuclei and effectively removal rate of non-diamond carbon phase by adjusting carbon and gas pressure under the hydrogen-rich gas chemistry can contribute to the synthesis of high-quality UNCD film.

Printed Circuit Board (PCB) filled with a large amount of Alumina ceramics has broad application prospects in the fifth-generation industry but is hard to drill. This work focuses on high-performance diamond films to improve the working life of drilling tools and holes quality of products. By utilizing hot filament chemical vapor deposition (HFCVD) methods, the monolayer microcrystalline diamond (MCD), bilayer micro-nanocrystalline diamond (MNCD), and four-layer diamond (MNMNCD) are coated on commercial PCB drills (WC-6% Co). Solid particle erosion tests are conducted to study erosive wear mechanism of diamond films impacted by ceramic powders/particles. Besides, cutting performances of diamond coated drilling tools are evaluated by performing high-speed drilling tests with PCB as workpieces. In Erosion tests, the monolayer MCD film presents intergranular fracture and shows the lowest erosive resistance. The MNCD and MNMNCD films have similar fracture forms, where curved boundaries and steps between layers indicate their discontinuous fracture, and minor deep cone holes on the surfaces demonstrate their high resistance to crack growth. Moreover, only one minor deep cone hole is observed on the four-layer film which indicates it has the best resistance to particle impinging. In drilling tests, the number of holes drilled by the diamond coated tools before failure is regarded as criteria of working life. Then surface and sectional morphologies of holes are also observed to evaluate the quality of products. The results indicate the number of holes machined by the four-layer MNMNCD coated drills reaches 10,000, while that of the monolayer and the bilayer MNCD ones are 3000– 4000 and 6000 respectively. More importantly, different from the other two types of diamond coated tools, almost no burrs with a height of over 20 μm are observed on the hole entrance using the four-layer diamond coated tools. Therefore, considering both the working life and holes quality, the MNMNCD films excel in the cutting performance of the new type of PCB drilling.

Hot filament chemical vapor deposition (HFCVD) diamond-coated small aperture wire-drawing dies from [Formula: see text] to [Formula: see text][Formula: see text]mm are in high demand. A new deposition technique without filaments through the inner hole of wire-drawing dies is proposed, accompanied with the specially designed fixtures. Temperature distribution on the deposition surfaces is studied by computational fluid dynamics (CFD) simulation based on the finite volume method (FVM); both case study and mass production simulations are accomplished. Excellent performance and uniform multilayer MCD/NCD/MCD/NCD films are successfully deposited on the inner-hole surfaces of total 16 cemented carbide (WC-6wt.%Co) wire-drawing dies with an aperture of [Formula: see text][Formula: see text]mm in one batch. Drawing results of gas shield welding wires show that the lifespan of the multilayer diamond coated wire-drawing dies is about 20 times of the uncoated cemented carbide dies and 2 times of the monolayer MCD coated dies.

Battery-supercapacitor hybrid (BSH) device is one of the most promising candidates for next advanced energy storage systems because it can bridge the performance gap between lithium ion batteries and conventional capacitors. Herein, we report a novel porous core-shell structured Fe2O3@Fe3C@C nanochains and urchin-like Ni–Co carbonate hydroxide hybridized (denoted as NiCo–CHH) microspheres for advanced battery-type supercapacitors. The as-obtained Fe2O3@Fe3C@C anode shows high specific capacity (611 C g−1) and good rate capability. The fabricated NiCo–CHH cathode delivers high specific capacity (814 C g−1) and excellent cycling stability. When assembled into a battery-type supercapacitor, the NiCo–CHH//Fe2O3@Fe3C@C device delivers a high energy density (95.2 Wh kg−1) and excellent cycling stability. Moreover, In situ Raman spectroscopy proves the reversibility of the NiCo–CHH electrode, and the synergistic effects of Ni and Co ions, further revealing its energy storage mechanism. These findings provide a novel insight on high-performance battery-type supercapacitors.

Based on a well-designed growth procedure, a tri-material, namely, a three-layer boron-doped micro-crystalline, undoped micro-crystalline and undoped nano-crystalline composite diamond film, is deposited on the pretreated WC–6 wt% Co substrate, the basic characters of which are systematically studied and compared with some other commonly used diamond films. Besides, the growth times for three respective layers are accordingly determined. It is further clarified that the underlying boron-doped micro-crystalline diamond layer can well adhere to the WC–Co substrate due to either the reduction in the residual stress or the formation of B–Co compounds. There is no doubt that the surface undoped nano-crystalline diamond layer with relatively lower hardness and initial surface roughness is more convenient to be polished to the required surface roughness. Moreover, when the growth times for the middle undoped micro-crystalline diamond layer and the surface undoped nano-crystalline diamond layer are both appropriate, the undoped micro-crystalline diamond layer with extremely high diamond quality and hardness can effectively reinforce the surface hardness of the whole composite film. Based on the discussions on the influences of the growth times for the different layers on the performance of the composite diamond film, the growth times for the boron-doped micro-crystalline diamond, undoped micro-crystalline diamond and undoped nano-crystalline diamond layers are, respectively, determined as 4, 4 and 2 h. Under such conditions, the reinforcement effect of the middle layer on the surface hardness can be guaranteed, and the undoped nano-crystalline diamond grains have totally covered the undoped micro-crystalline diamond layer.

Micro-crystalline diamond (MCD) films are deposited on reactive sintering SiC substrates by the bias enhanced hot filament chemical vapor deposition (BE-HFCVD) method, respectively using the methane, acetone, methanol and ethanol as the carbon source. Two sets of standard tribotests are conducted, adopting Si 3 N 4 balls as the counterpart balls, respectively with the purpose of clarifying differences among tribological properties of different MCD films, and studying detailed effects of the carbon source C , normal load F n and sliding velocity v based on orthogonal analyses. It is clarified that the methane-MCD film presents the lowest growth rate, the highest film quality, the highest hardness and the best adhesion, in consequence, it also performs the best tribological properties, including the lowest coefficient of friction ( COF ) and wear rate I d , while the opposite is the methanol-MCD film. Under a normal load F n of 7 N and at a sliding velocity v of 0.4183 m/s, for the methane-MCD film, the maximum COF ( MCOF ) is 0.524, the average COF during the relatively steady-state regime ( ACOF ) is 0.144, and the I d is about 1.016 × 10 −7 mm 3 /N m; and for the methanol-MCD film, the MCOF is 0.667, the ACOF is 0.151, and the I d is 1.448 × 10 −7 mm 3 /N m. Moreover, the MCOF , ACOF , I d and the wear rate of the Si 3 N 4 ball I b will all increase with the F n , while the v only has significant effect on the ACOF , which shows a monotone increasing trend with the v .

In the present study, high-quality chemical vapor deposition (CVD) micro-crystalline diamond (MCD) film was successfully deposited on the surface of the Φ0.5 mm×120 mm tungsten wire using a special designed graphitic jig for supporting the substrate and a two-step deposition procedure for guaranteeing the uniformity of as-deposited diamond film. It is proved that as-deposited film indeed presented much more uniform thickness than that obtained using a conventional jig described in the previous literature, and a very thick WC interlayer spontaneously formed between the substrate and the diamond film, which together with as-deposited MCD film have significant effects on mechanical properties of the wire. Generally speaking, the coated wire remains extremely high surface hardness of the MCD film and considerable toughness of the substrate, along with favorable film-substrate adhesion. It is recognized that these the coated tungsten wires have broad application prospects, but the technologies for depositing diamond films that are thick enough on even longer and thinner wires still need further investigation.

Pristine and Ag nanoparticle modified TiO 2 nanofibers were fabricated by an electrospinning technique using polyvinyl pyrrolidone (PVP) and tetrabutyl titanate as precursor. The morphology and structure of the as-synthesized nanofibers were characterized by scanning electron microscopy and X-ray diffraction. It was found that the presence of Ag had a significant effect on the morphology and crystal structure of TiO 2 nanofibers, and that Ag addition could promote the phase transformation from anatase to rutile. H 2 S sensing properties of the sensors based on TiO 2 nanofibers were also investigated. The results showed that Ag/TiO 2 nanofibers exhibited better gas sensing performances than pristine TiO 2 nanofibers and the possible sensing mechanism was discussed.