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Understanding the damage evolution of alloys during a plastic deformation process is significant to the structural design of components and accident prevention. In order to visualize the damage evolution in the plastic deformation of Ti–3Al–2Mo–2Zr alloy, a series of uniaxial tensile experiments for this alloy were carried out under the strain rates of 0.1–10 s−1 at room temperature, and the stress–strain curves were achieved. On the other hand, the finite element (FE) models of these uniaxial tensile processes were established. A microvoids proliferation model, Gurson–Tvergaard–Needleman (GTN) damage model, was implanted into the uniaxial tensile models, and the simulated stress–strain curves corresponding to different GTN parameter combinations were obtained. Based on the simulated and experimental stress–strain curves, the GTN parameters of this alloy were solved by response surface methodology (RSM). The solved GTN parameters suggest that higher strain rate can enhance the proliferation and coalescence of microvoids. Furthermore, the uniaxial tensile tests over different strain rates were simulated using the solved GTN parameters. Then, the damage processes were visualized and evaluated. The result shows that the degradation speed of this alloy is slow at the initial stage of the tensile deformation and then accelerates once the voids volume fraction reaches a critical value.

Purpose The purpose of this paper is to use a combination of numerical simulation and experiment to evaluate the performance of laser surface texturing (LST) in the field of gear lubrication, and to more accurately predict the lubrication characteristics of different surfaces. Design/methodology/approach The method used in this paper is developed on the basis of the deterministic solution of the three-dimensional (3D) mixed elasto-hydrodynamic lubrication (EHL) model and the model parameters are corrected by friction test. The film pressure, film thickness and friction coefficient of different micro-textured tooth surfaces are predicted on the basis of accurate 3D mixed EHL models. Findings The results demonstrate that the micro-texture structure of the tooth surface can increase the local film thickness and enhance the lubricating performance of the tooth surface without drastically reducing the contact fatigue life. The stress distribution and friction characteristics of the tooth surface can be optimized by adjusting the micro-texture arrangement and the size of the micro-textures. Originality/value A new evaluation method using a 3D hybrid EHL model and friction test to predict the lubrication characteristics of LST is proposed, which can effectively improve the processing economy and save time. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2020-0423

Surface coating can greatly enhance the lifetime of cold extrusion die. It is a significant issue to evaluate the performance of coatings and even predict the lifetime of cold extrusion die. In this work, the titanium-based nitride coatings including TiN, TiAlN, and TiAlCrN were, respectively, deposited on the surface of high-speed steel substrate W6Mo5Cr4V2 (M2) by the physical vapor deposition technology. The hardness test, scratch test, Rockwell adhesion test, and pin-on-disc (POD) wear test were carried out aiming to investigate the performances of the three coatings including hardness, adhesion strength, and wear resistance. The results show that the TiAlCrN coating exhibits the highest hardness of 3,033 HV in comparison with TiN coating (1,222 HV) and TiAlN coating (1,916 HV), while it possesses poor adhesion strength and inferior wear resistance. Furthermore, the TiAlN coating presents the highest resistance to wear and spalling from the substrate. In addition, the Archard wear model of the coatings was solved and applied in the finite element model of cold extrusion to calculate the wear depth and lifetime of the cold extrusion dies. The results suggest that TiAlN coating is the optimal option for cold extrusion die as compared with TiAlCrN and TiN coatings. TiAlN coating can prolong the lifetime of the substrate die up to 260%.

In this work, a porous multilayer graphene film is designed as thermoacoustic speaker using laser scribing technology and a theoretical model based on thermally induced EDFs (Energy Density Fluctuations) is proposed to study its electrical-thermal-acoustic conversion behavior. According to this model, the relationship of the heat energy $Q_{air}$ with the input power is obtained, and the relationship of the sound pressure with the measuring distance, the frequency and the input power is obtained. The measurement of temperature distribution shows that the maximum temperature of graphene film increases linearly with the input power. The measurement of sound pressure shows that SPL (Sound Pressure Level) decreases with the measuring distance. SPL has a rapid growth in low frequency while slow growth in high frequency. SPL has a logarithmic relationship with the input power. The measured results have a good agreement with the theoretical results. The theoretical model based on EDFs has certain reference value for further research on thermoacoustic speakers. This porous multilayer graphene film has the characteristics of one-step fabrication, no mechanical vibration, simple structure and high performance. It could open broad applications in biology, medicine, wearable electronics and other fields.

Flexible planar microsupercapacitors (MSCs) have become one of the most crucial energy storage devices for wearable and portable electronics on account of the superiorities of miniature size and ea...

The relative sliding at the meshing point directly affects the contact and lubrication characteristics of the gear pair and is an important factor of gear wear and power loss. In this study, for investigation of a new type of low sliding ratio (LSR) gear pair whose tooth profile is constructed by a cubic function, a three-dimensional (3D) mixed elastohydrodynamic lubrication (EHL) line contact model was established with consideration of the effect of tooth profile geometry, transient motion characteristics, load distribution, and machining roughness. The distribution of the center film thickness of the LSR gear along the meshing line was predicted through an example the result of which was compared with a typical line contact EHL formula to verify the model. In addition, the difference was investigated in film thickness distribution of friction coefficient and temperature rise between LSR spur gears and involute spur gears. Hence, the effect of 3D rough tooth surface on the contact lubrication characteristics of LSR gears was discussed. The results demonstrated that the minimum center film thickness of the LSR gear appeared at the alternating point of the concave and convex tooth surfaces. At the same time, compared with the involute gear, the LSR gear significantly increased the film thickness at the start and ending points of the meshing and reduced the friction coefficient and the flash temperature rise.

An in-line microwave power detection system based on double MEMS cantilever beams is proposed in this work. It realizes the separation of power sense and power detection. A 10% coupling factor can be achieved with the double cantilever beams, and the performance of this in-line microwave power detection system based on double cantilever beams is improved compared with the single beam. The in-line microwave power detection system is designed and fabricated using GaAs MMIC process and MEMS technology. The theoretical models of cantilever beam with different structures are also established and verified. The relationship of return loss, insertion loss and coupling coefficient with the frequency and the capacitance are studied. The measurement results show the return loss is from −9.3dB to −17.7dB, and the insertion loss is from −2.9dB to −1.9dB at 9-11 GHz. The sensitivity of the in-line microwave power detection system is around 1.1 mV/W, 1.45 mV/W, 0.85 mV/W at 9, 10, 11 GHz, respectively. Therefore, this in-line type microwave power detection system can effectively detect microwave power with a high reliability.

A graphene-based flexible filter was obtained via one-step laser heating of a polyimide film. The key parameters of a laser have been confirmed by comparing simulated results and experimental data. High-frequency components of input signals were filtered out effectively for different waveforms, such as sine, rectangular, triangle and pulse waveforms. In order to study filtering performance, this paper focused on amplitude frequency curve, phase frequency curve, transient response and mechanical stability. The phase frequency curve is linear distribution, indicating that it is convenient to control phase shift. The mechanical stability of the device remains good even after 5000 bends, which is unreported in previous work. This paper demonstrated that a graphene-based flexible filter prepared by one-step laser heating has excellent performance and opens new way of thinking about flexible electronics in the future.

The solution-aging treatment parameters, including solution temperature, cooling rate and aging temperature, have significant influences on the microstructures and comprehensive mechanical properties of titanium alloy. In this work, the detailed microevolution behaviors of Ti–10V–2Fe–3Al alloy under different solution and aging conditions have been investigated through a series of heat-treatment experiments. The results of solution-treatment experiments reveal that the content of αp-phase is reduced to zero as the solution temperature is raised to a certain α → β critical transformation point. Recrystallized β-grains can be observed at the solution temperature of 820°C. In addition, the cooling way (air cooling or water cooling) has little influence on the microevolution behaviors for this alloy during the solution-treatment process. As for the solution-aging-treatment experiments, the results reveal that αs-phases are precipitated from the supersaturated β-phase, and the fraction of αs-phase increases with increasing aging temperature. However, the precipitated α-grains intend to coalesce and coarsen as the aging temperature raises above 510°C. Therefore, the advocated solution-aging-treatment program is solution treatment at 820°C with air cooling followed by aging treatment at 510°C with air cooling.

The diffusion of molecules and particles inside the aqueous suspension of soft colloids (polymer microgels) is investigated using variable length scale fluorescence correlation spectroscopy (VLS-FCS). Carbopol 940 is chosen as the model matrix system, and two factors affecting diffusion are investigated: the spatial hindrance and the diffusant-matrix interaction. By studying diffusion of molecules and particles with different sizes inside the suspension, VLS-FCS reveals the restricted motion at a short length scale, that is, in the gaps between the microgels, and normal diffusion at a larger length scale. The information on the gap's length scale is also accessed. On the other hand, by tuning the pH value, the diffusant-matrix electrostatic attraction is adjusted and the results expose a short-time fast diffusion of probe molecules inside the gaps and a long-time restricted diffusion because of trapping inside the microgels. It is proved that VLS-FCS is a powerful method, investigating anomalous diffusion at different length scales and it is a promising approach to investigate diffusion in complex soft matter systems.

Polymer electrolytes are essential for next-generation lithium batteries because of their excellent safety record. However, low ionic conductivity is the main obstacle restricting their commercial application. Composites with nanoparticles are a promising route to overcome this obstacle. In this work, lithium polystyrene sulfonate brushes (LiPSS) is anchored to silicon dioxide nanoparticles with chemical bonding using atom transfer radial polymerization (SI-ATRP). The composite polymer electrolytes are made by mixing vinylene carbonate and nanoparticles via a facile in situ polymerization process. The ionic conductivity of composite polymer electrolytes is improved to 7.2 × 10−4 S/cm at room temperature, which is attributed to the low degree of crystallinity of polymer electrolyte and the fast ion transport on the surfaces of polymer brush layers that act as a conductive network. The composite polymer electrolytes show a wide electrochemical window of approximately 4.5 V vs. Li+/Li and excellent cycling performance retention of approximately 95% after 100 cycles at ambient temperature. The results also prove that surface groups of ceramic nanoparticles are an important way to increase the electrochemical properties of composite polymer electrolytes.

Lateral diffusion of polymer molecules at the interfaces between immiscible oil and water is investigated at the single molecular level. The interfaces between water and alkanes are chosen as the model systems and polyethylene oxide (PEO) is the model polymer. Fluorescence correlation spectroscopy is used to measure the interfacial diffusion of fluorescence-labeled PEO with its molecular weight ranging over more than an order of magnitude. It is discovered that the interfacial diffusion coefficient scales with the molecular weight by the exponent of -0.5. Detailed analysis shows that the PEO chain takes an ideal two-dimensional random coil conformation at these fluidic interfaces and the bigger contribution from water's hydrodynamic friction is discovered.

An original flexible enzyme-free glucose amperometric biosensor based on Cu nanoparticles anchored on laser-induced graphene (Cu NPs-LIG) composite is successfully developed by a simple substrate-assisted electroless deposition (SAED) technique. The as-prepared Cu NPs-LIG sensor demonstrates an excellent glucose sensitivity of 495 μA mM−1 cm−2, ultrafast response time less than 0.5 s and the prominently low detection limit of 0.39 μM. Besides, the sensor shows extraordinary reproducibility, stability and selectivity in glucose sensing. Finally, a possible mechanism of the Cu NPs-LIG sensor for glucose sensing is proposed. Due to the simplicity preparation and performance reliability, the novel flexible Cu NPs-LIG sensor is an attractive candidate for next generation wearable and implantable non-enzymatic glucose diagnostic devices.

The thiazole unit can exhibit both electron-deficient and electron-rich features, which provides more possibilities for shaping the photophysical and electroluminescence (EL) properties of the Ir(III) complex emitters. Herein, a series of cyclometalated Ir(III) complexes were synthesized from the 2-phenylthiazole-type ligands bearing fluorinated benzenesulfonyl moieties. Their thermal stabilities, photophysical and electrochemical properties and EL performances were fully studied. They can emit intense orange phosphorescence with peaks ranging from 577 to 590 nm, and the phosphorescence quantum yield (Φp) can be up to 0.89. Interestingly, when the number of fluorine atoms on the phenyl ring of the benzenesulfonyl moiety increases, their absorption and emission maxima both show red-shift effects, which were interpreted by the related theoretical calculation results. Besides, their LUMO levels follow a decreasing trend as the fluorine atoms increase, leading to good electron injection/transporting (EI/ET) properties. Finally, their EL performances were characterized by their solution processed OLEDs, which achieve the best EL efficiencies with a maximal current efficiency (ηL) of 27.5 cd A−1, a maximal power efficiency (ηp) of 17.3 lm W−1 and a maximal external quantum efficiency (ηext) of 12.3%, these results can outcompete the EL efficiencies of the reported solution processed OLEDs built by the thiazole-based Ir(III) complexes. All the concerned results should offer inspirations for Ir(III) complex functionalizations and reveal the great potential of 2-phenylthiazole ligands with fluoro-benzenesulfonyl moieties in developing high performance emitters.

In this work, the frequency doubling effect of thermoacoustic speakers is studied, and a method is analyzed to suppress the frequency doubling effect. Three cases were analyzed by superimposing the DC bias on the AC excitation: (1) DC is less than AC, (2) DC is equal to AC, (3) DC is greater than AC. We found that the frequency doubling effect can be well suppressed by superimposing a larger DC excitation on the AC excitation. The laser scribing technology was used to prepare graphene film in only one step, and the screen printing technology was used to prepare conductive electrodes. The microphone and B&amp, K system was used to record the sound pressure level and study the suppression of frequency doubling effect. Finally, the sound pressure levels with the three different kinds of excitations were measured. The measured results show that they have a good agreement with the theoretical results. The suppression effect will be better when DC amplitude is greater than AC amplitude. Therefore, this work has certain reference significance for the further study and application of thermoacoustic speakers.

In this study, a method combining numerical surface generation technology and three-dimensional hot-line contact EHL is employed to evaluate the contact characteristics of micro-textured surfaces under high-load line contact. Based on numerical simulation, the film thickness, film pressure, friction coefficient and surface flashing temperature of the virtual texture surface with different cross-sectional shapes and sizes are studied. On this basis, the subsurface stress at the contact point is calculated by the DC-FFT algorithm. The results show that, compared with a smooth surface, the micro-textures of different shapes all increase the average oil film thickness of the surface and reduce the friction coefficient, but at the same time lead to an increase in the contact stress of the surface. By changing the width and depth of the texture, the maximum film pressure has changed by 11.4 and 18.5%, respectively.

In order to study the effect of shape on graphene pressure sensors, a theoretical model of polymerisation degree is proposed in this work. According to the theoretical model of polymerisation degree, it is found that the regular polygons have better sensitivity characteristics. The more the number of sides for the regular polygons, the larger the polymerisation degree, and the better the sensitivity of the graphene pressure sensors. According to the theoretical model, the polymerisation degree of the positive triangle, regular quadrilateral, regular pentagon, and circle shape is 0.5, 0.71, 0.81, and 1, respectively. The measured results show that the relative resistance change of positive triangle, regular quadrilateral, regular pentagon, and circle shape are 8.56, 9.24, 9.61, and 10.4%, respectively. The experimental results are consistent with the theoretical results. Therefore, the theoretical model of polymerisation degree can provide effective quantitative guidance for the graphene pressure sensors.

A novel optical sensing interface based on nano-opto-electro-mechanical systems (NOEMS) is proposed, in which the light can be coupled with quantum tunneled electrons via weak mechanical coupling. By taking optical pump power and mechanical coupling strength as varying parameters, respectively, bifurcation diagrams of three involved dynamical states of the NOEMS, i.e., optical, electrical and mechanical mode, are calculated, from which an effective coupling region for tunneled electrons and light is revealed. Self-oscillation, transient dynamics and the threshold of the NOEMS are further characterized, and it is found that the effective coupling region has a special transient time. The work sheds light in developing ultra-sensitive photon detectors using physical mechanisms rather than the conventional PN junction based.

The determination of intrinsic deformation parameters inducing grain refinement mechanism of dynamic recrystallization (DRX) contributes to the relative forming process design. For Ni80A superalloy, the processing maps were constructed by the derivation of the stress-strain data coming from a series of isothermal compression tests at temperatures of 1273-1473 K and strain rates of 0.01-10 s−1. According to the processing maps and microstructural validation, the deformation parameter windows with DRX mechanism were separated in an innovative deformation mechanism map. In addition, the deformation activation energy representing deformation energy barrier was introduced to further optimize such windows. Finally, the enhanced processing maps were constructed and the parameter domains corresponding to DRX mechanism and lower deformation barrier were determined as follows: at ɛ=0.3, domains: 1296-1350 K, 0.056-0.32 s−1 and 1350-1375 K, 0.035-0.11 s−1; at ɛ=0.5, domains: 1290-1348 K, 0.2-0.5 s−1 and 1305–1370 K, 0.035-0.2 s−1; at ɛ=0.7, domains: 1290–1355 K, 0.042–0.26 s−1; at ɛ=0.9, domains: 1298-1348 K, 0.037-0.224 s−1.

To improve the understanding of coupling effect between dynamic recrystallization (DRX) behaviors and flow behaviors of as-cast AlCu4SiMg, a finite element (FE) simulation equipped with the models of DRX evolution was implemented. A series of isothermal compression tests were performed primarily on a Gleeble−3500 thermo-mechanical simulator in a temperature range of 648−748 K and a strain rate range of 0.01−10 s −1 . According to the measured true stress−strain data, the strain hardening rate curves (d σ /d e versus σ ) were plotted to identify the critical strains for DRX initiation ( e c ). By further derivation of the related material constants, the DRX volume fraction equation and the strain for 50% DRX ( e 0.5 ) equation were solved. Accordingly, the aforementioned DRX equations were implanted into the FE model to conduct a series of simulations for the isothermal compression tests. The results show that during the evolution of DRX volume fraction at a fixed strain rate, the strain required for the same amount of DRX volume fraction increases with decreasing temperature. In contrast, at a fixed temperature, it increases with increasing strain rate. Ultimately, the DRX kinetics model of AlCu4SiMg alloy and the consequence of the FE analysis were validated by microstructure observations.

Among numerous research studies focusing on macromolecular crowding and confinement, few are concerned with the medium at a broad range of concentrations, let alone the interplay between the crowdi...

The physical mechanism of multiple modes in dynamics of polyelectrolyte aqueous solutions has been drawing extensive research attention for decades. This unsolved mystery makes it highly desirable to use new techniques to conduct investigations. In this study, dual-color fluorescence cross-correlation spectroscopy is applied to study the dynamics of individual molecules of a model polyelectrolyte, sodium poly(styrene sulfonate), in aqueous solutions. Anticorrelation in the cross-correlation function is discovered as a result of motion coupling due to interchain electrostatic repulsion. After correction, the self-part of the autocorrelation function is obtained, and the calculated mean square displacement data demonstrate a two-stage diffusion process—a fast one at short time lag and a slow one at long time lag. The two processes are attributed to a faster diffusion inside the cage formed by neighboring chains and a slower diffusion beyond the cage. Effects of the salt level and polyelectrolyte concentrati...

Supramolecular polymerization is influenced by many factors, especially the stiffness of the polymers, which is directly related to cyclization of the polymers. We have proposed a supramolecular “ring opening” polymerization system with DNA molecules to study the ring-chain equilibrium of supramolecular polymerization. The molecular weight of the supramolecular polymers was characterized by Asymmetric Flow Field Flow Fractionation, and the diffusion coefficient of the supramolecular polymers was characterized by Fluorescent Correlation Spectra. Tuning the ratio of the “ring opening” strand, the length of the DNA monomers and temperature could change the ring-chain equilibrium, thus influence the molecular weight and diffusion coefficient. This strategy has offered us a useful platform to dig into the kinetic mechanism of supramolecular polymerization.

In this study, we modified the well-known photothermal polydopamine nanoparticles with the poly[(2-methacryloyloxy)ethyl phosphorylcholine-b-(2-dimethylamino)ethyl methacrylate] (PMPC-b-PDMAEMA) diblock copolymers, containing both biocompatible cell membrane phosphorylcholine zwitterions segments and pH-responsive dimethylaminoethyl units on the polymer chains, to achieve both the photothermal property and pH-responsive release behavior. The results showed that the obtained nanoparticles had a narrow size distribution with the diameter about 220 nm. Besides, the modified polydopamine nanoparticles showed enhanced colloidal stability, pH-sensitive drug release behavior, excellent biocompatibility and remarkable near-infrared photothermal property. Thus, it is highly anticipated that PMPC-b-PDMAEMA modified polydopamine nanoparticles can serve as a powerful drug delivery system for combined pH-sensitive drug release and near-infrared photothermal therapeutic.

A self-healing hydrogel was synthesized via the multi-component reaction of azobenzene-methacrylamide, β-CD and 3-methacrylamido phenylboronic acid. The orthogonal method was applied to analyze the influence of host–guest inclusion complexation, cross-linker and phenylboronic acid monomers content on mechanical properties and healing efficiency of the hydrogel. The results indicated that hydrogel showed autonomic self-healing behavior. The hydrogel demonstrated light-switchable self-healing ability and pH-sensitive swelling ratio. It was found that hydrogel showed high elongation, excellent resilience and low elastic hysteresis. The design of the combined host–guest interactions and boronate esters on the hydrogel showed advantage for improving the mechanical, self-healing and recovery properties simultaneously.

In this research, an innovative cylindrical automatic battery core oven was designed to avoid the structural deformation that frequently occurs in traditional ovens. The oven could be automatically connected with the electrolyte injection process after baking, achieving improvement in a battery's baking consistency. This contributed to the feasibility of studying the internal heat conduction process of batch battery cores during actual baking processes. A mathematical model of a certain plate battery cell during the baking process was established. The simulation results of the temperature change inside the battery core during the baking process were consistent with the calculation results of the mathematical model. The temperature distribution at each point inside the battery core could be fitted through the thermal conductivity at different temperatures and the temperature distribution between the layers of the battery core. Finally, based on the thermodynamic balance energy conservation method, the relationship between the temperature change inside the battery core and the entire baking process was established. A feasible algorithm for studying the thermal conduction of complex material and internal structure objects in the baking process was obtained. Keywords: Heat and mass transfer, Vacuum drying, Li-ion battery, CFD

Stirred media mills are invoked as high energy utilization equipment to prepare superfine particles with a narrow particle size distribution. In this study, the effects of the stirrer tip speed and the grinding media diameter on the particle size distribution of lotus leaf powder (LLP) were investigated. The stress intensity and stress number, which were determined by the stirrer tip speed and grinding media diameter, were applied to estimate the wet grinding kinetics of LLP. The stress conditions with the minimum specific energy consumption were a grinding media diameter of 1.4 mm and stirrer tip speed of 8.4 m s-1. Additionally, FT-IR measurements of the samples confirmed that the chemical structures of the active ingredients were not damaged with reduction in particle size, which indicated the mildness of the grinding process.HighlightsA stirred media mill was initially applied for preparing superfine lotus leaf powder.The stress conditions with the minimum specific energy consumption were determined.The active ingredients were not denatured during the grinding process. Keywords: Grinding kinetics, Lotus leaf, Stirred media mill, Stress intensity.

The thermal and mechanical properties of the chemically imidized polyimide (CIPI) films and thermally imidized polyimide (TIPI) films were investigated systematically. Experimental results indicated that the CIPI films show dramatically enhanced tensile strength and modulus with obviously reduced coefficient of thermal expansion (CTE) in comparison with TIPI films. These enhancements results from the high in-plane orientation and close packing of the CIPI backbones. Compared with thermal imidization which starts at about 140 °C, the chemical imidization activated by acetic anhydride and isoquinoline initiates the cyclization even at room temperature. The resulting imide rings restrict the mobility of polymer chains and lead to the in-plane orientation with solvent evaporation. Additionally, fewer small molecules remain in the films after treated at 120 °C by chemical imidization than by thermal imidization. The polymer chain plasticization caused by the evaporation of small molecules at high temperature is obviously restricted. Moreover, the partially imidized polymer inhibits the decomposition of mainchains that occurs at subsequent high temperature process, being beneficial to the formation of high molecular weight PI films. Hence, chemical imidization pathway shows apparent advantage to produce PI films with great combined properties, including high modulus, strength and toughness, as well as high thermal dimension stability etc.

It is a significant issue to deeply understand the nature relationships between damage degradation and deforming parameters, and then identify the changes of initial ductile fracture time with processing parameters and further adjusting the forming processes for obtaining the fracture-free components. For Ti-6Al-4V alloy, the strain-stress data in the temperature range of 1023–1323 K and strain rate range of 0.01–10 s−1 were obtained by compression tests. The finite element model with stress-strain data was constructed to simulate the ductile damage cumulating processes under different conditions and obtained the maximum damage values. Subsequently, the ductile fracture criterion (DFC) of Ti-6Al-4V alloy was established and the effects of temperature and strain rate on DFC were discussed. The results show that the variation range of DFC under different deformation conditions is 0.07–0.15. Subsequently, the deformation conditions with higher fracture risk were identified as 1200∼1275 K & 1∼10 s−1 and verified with the experiment observations.

We studied the microstructures and isothermal oxidation of the Nb-silicide-based alloys Nb-11.5Ti-18Si-5Mo-2W-4.9Sn-4.6Ge-4.5Cr-4.7Al-1Hf (JZ4) and Nb-21Ti-18Si-6.7Mo-1.2W-4.4Sn-4.2Ge-4Cr-3.7Al-0.8Hf (JZ5), calculated their average creep rate for the creep goal conditions of T = 1200 &deg, C and &sigma, = 170 MPa, and compared properties of the two alloys with those of other refractory metal (RM) complex concentrated alloys (RCCAs). Both alloys had a density less than 7.3 g/cm3 and lower than the density of multiphase bcc solid solution + M5Si3 silicide RCCAs. There was macrosegregation of Si in both alloys, which had the same phases in their as-cast microstructures, namely &beta, Nb5Si3, &alpha, Nb5Si3, A15-Nb3X (X = Al, Ge, Si, Sn), TM5Sn2X (X = Al, Ge, Si), C14-Cr2Nb, but no solid solution. After heat treatment at 1500 &deg, C for 100 h, a low volume fraction of a W-rich (Nb, W)ss solid solution was observed in both alloys together with &beta, Nb5Si3 and A15-Nb3X but not the TM5Sn2X, whereas the Laves phase was observed only in JZ4. At 800 &deg, C, both alloys did not pest, and there was no spallation of their scales at 1200 &deg, C. At both temperatures, both alloys followed parabolic oxidation kinetics and their weight changes were lower than those of Ti-rich Nb-silicide-based alloys. The oxidation of both alloys was superior to that of other RCCAs studied to date. For each alloy the Si macrosegregation, volume fraction of solid solution, chemical composition of solid solution and Nb5Si3, and weight changes in isothermal oxidation at 800 and 1200 &deg, C that were calculated using the alloy design methodology NICE agreed well with the experimental results.

The helicopter transmission system generally employs oil injection lubrication, while the tooth surface often operates under mixed lubrication. In the case of mixed lubrication, the relationship among the fluid flow, rough contact, and material wear renders it quite difficult to establish a predictive model for wear and lubrication coupling. The present study involved, in consideration of the effect of tooth surface micro-morphology, establishing a coupling analysis model for the wear characteristics of involute gear mixed lubrication. The effects of the mixture of squalane base oil and 15% (by weight) polyisoprene(SQL+PIP), polyalphaolefin oil (PAO6) and mineral SN100 on the distribution of lubrication performance parameters and the wear characteristics were analyzed. The results revealed that the film thickness of SQL+PIP was higher than that of PAO6 and SN100, and the coefficient of friction is lower. In addition, the increase in lubricant viscosity was conducive to reducing the contact area and load ratios of direct rough contact, which was, in turn, beneficial to reducing wear.

Indolocarbazoles (ICZs) and their derivates were immensely studied in the fields of organic opto-electronics, sensors and anti-cancer agents. However, the afterglow researches, the comprehensive syntheses and crystal structures of the isomeric ICZs remained shortages. Currently, the organic afterglows were mainly focused on the crystalline states, showing restrictions and inconveniences in practical applications, the organic amorphous afterglows were more favorable but were limitedly documented. Herein, the syntheses, single crystal structures, afterglow studies and data protection applications of the ICZ families with five isomers were together presented for the first time. For these ICZ crystals, the planar configurations and high void rates made them prone to stack and vulnerable to the O2 and humidity, affected by these factors, they were hard to radiate phosphorescence at room temperature, which can be more easily aroused at 77 K. By doping the ICZ into PVA, a rigid and confined environment was built by the hydrogen bond interaction between the –NH and –OH unit in the ICZ and PVA chain, greatly hindering the molecular motion, O2 and humidity quenchers. Consequently, the triplet states were efficiently stabilized, the nonradiative transitions were highly suppressed, blooming the phosphorescence of these ICZs at room temperature, the brilliant afterglow can be straight witnessed by the naked eyes. Impressively, the highest photoluminescence efficiency of 31.06% was obtained by the ICZ–o, the longest afterglow lasting time and phosphorescent lifetime of 35 s and 2.32 s were achieved by the ICZ–p2, rivaling to the reported organic amorphous afterglows. It’s believed that the synthetic, crystal structural and afterglow studies of the ICZ families should find a promising avenue for developing new organic amorphous afterglow materials and their applications.

Flexible planar microsupercapacitors (MSCs), with the advantages of small size, easy integration and expansion on electronic devices, have emerged as one of the most critical power devices in wearable and portable electronics. However, most processes involve independent preparation of electrode materials, patterned microelectrodes, and subsequent modular integration, making the steps very complicated. Herein, we have developed a novel, simple and one-step laser direct writing process to design planar shape-controllable MnO2 nanoparticles evenly embedded in laser-induced graphene (MnO2/LIG) MSCs on different flexible substrates. The obtained MnO2/LIG MSCs show an outstanding areal specific capacity of 15.04 mF cm−2, a high energy density of 1.22 mWh cm−2 at a good power density of 1.278 mW cm−2, good mechanical flexibility and remarkable modular integration due to effective design of pseudocapacitive MnO2 nanoparticles evenly embedded in highly conductive LIG with 3D porous structure. This universal manufacturing route for controllable assembly of flexible planar MSCs with other pseudocapacitive nanoparticles embedded into LIG, thus broadening their flexible and wearable application as a promising storage device to meet the modular integration and biocompatibility.

The microstructures and properties of the alloys JZ3 (Nb-12.4Ti-17.7Si-6Ta-2.7W-3.7Sn-4.8Ge-1Hf-4.7Al-5.2Cr) and JZ3+(Nb-12.4Ti-19.7Si-5.7Ta-2.3W-5.7Sn-4.9Ge-0.8Hf-4.6Al-5.2Cr) were studied. The densities of both alloys were lower than the densities of Ni-based superalloys and many of the refractory metal complex concentrated alloys (RCCAs) studied to date. Both alloys had Si macrosegregation and the same phases in their as cast and heat treated microstructures, namely &beta, Nb5Si3, &alpha, Nb5Si3, A15-Nb3X (X = Al, Ge, Si, Sn), C14-Cr2Nb and solid solution. W-rich solid solutions were stable in both alloys. At 800 &deg, C only the alloy JZ3 did not show pest oxidation, and at 1200 &deg, C a thin and well adhering scale formed only on JZ3+. The alloy JZ3+ followed parabolic oxidation with rate constant one order of magnitude higher than the single crystal Ni-superalloy CMSX-4 for the first 14 h of oxidation. The oxidation of both alloys was superior to that of RCCAs. Both alloys were predicted to have better creep at the creep goal condition compared with the superalloy CMSX-4. Calculated Si macrosegregation, solid solution volume fractions, chemical compositions of solid solution and Nb5Si3, weight changes in isothermal oxidation at 800 and 1200 &deg, C using the alloy design methodology NICE agreed well with the experimental results.

Creating densified and stable liquid is a straightforward strategy for the fabrication of strong and ultra-stable amorphous or glassy materials. The current study has discovered that a liquid polymeric thin film is densified under the application of a high frequency surface acoustic wave (SAW). The experimental evidence is the decrease in film thickness and the increase in refractive index, measured by ellipsometry, of polyisobutylene thin films deposited on the solid substrates, when a high frequency SAW (39.5 MHz) is applied to the system. Further investigations by polarization-resolved single molecule fluorescence microscopy have demonstrated that the rotational motion of fluorescent probes doped inside the liquid film is retarded and the dynamical heterogeneity is reduced. The results demonstrate that the application of SAW of high frequency makes the thin polymeric liquid film densified and more dynamically homogeneous.

The structural parameters of 23 ionic liquids were calculated by the Hartree–Fock ab initio method. The relationship between the antiwear properties of ionic liquids dissolved in dimethyl sulfoxide and the structural parameters of the ionic liquids was studied using multiple linear regression analysis. A quantitative structure tribo-ability relationship model with good fitting and prediction ability was established. The results show that entropy is the most important structural parameter affecting the antiwear performance of ionic liquid-dimethyl sulfoxide systems. The entropy of the ionic liquid is related to the hydrogen bonding in the system, and an orderly arrangement of this hydrogen bonding is beneficial in terms of improving antiwear performance.

In this paper two Nb-silicide-based alloys with nominal compositions (at.%) Nb-12Ti-18Si-6Ta-2.5W-1Hf-2Sn-2Ge (JZ1) and Nb-12Ti-18Si-6Ta-2.5W-1Hf-5Sn-5Ge (JZ2) were studied. The alloys were designed using the alloy design methodology NICE to meet specific research objectives. The cast microstructures of both alloys were sensitive to solidification conditions. There was macro-segregation of Si in JZ1 and JZ2. In both alloys the &beta, Nb5Si3 was the primary phase and the Nbss was stable. The A15-Nb3X (X = Ge,Si,Sn) was stable only in JZ2. The Nbss+&beta, Nb5Si3 eutectic in both alloys was not stable as was the Nb3Si silicide that formed only in JZ1. At 800 &deg, C both alloys followed linear oxidation kinetics and were vulnerable to pesting. At 1200 &deg, C both alloys exhibited parabolic oxidation kinetics in the early stages and linear kinetics at longer times. The adhesion of the scale that formed on JZ2 at 1200 &deg, C and consisted of Nb and Ti-rich oxides, silica and HfO2 was better than that of JZ1. The microstructure of JZ2 was contaminated by oxygen to a depth of about 200 &mu, m. There was no Ge or Sn present in the scale. The substrate below the scale was richer in Ge and Sn where the NbGe2, Nb5(Si1-xGex)3, W-rich Nb5(Si1-xGex)3, and A15-Nb3X compounds (X = Ge,Si,Sn) were formed in JZ2. The better oxidation behavior of JZ2 compared with JZ1 correlated well with the decrease in VEC and increase in &delta, parameter values, in agreement with NICE. For both alloys the experimental data for Si macrosegregation, vol.% Nbss, chemical composition of Nbss and Nb5Si3, and weight gains at 800 and 1200 &deg, C was compared with the calculations (predictions) of NICE. The agreement was very good. The calculated creep rates of both alloys at 1200 &deg, C and 170 MPa were lower than that of the Ni-based superalloy CMSX-4 for the same conditions but higher than 10&minus, 7 s&minus, 1.

Polyborosiloxane gel (PBS-gel) with shear hardening properties was prepared by cross-linking boric acid and hydroxyl-terminated polydimethylsiloxane through B&ndash, O&ndash, Si dynamic covalent bonding. The prepared PBS gel was mixed with methyl vinyl silicone rubber (MVQ), and a benzoyl peroxide (BPO) cross-linking agent was added to vulcanize the silicone rubber. At the same time, the gel molecules were co-vulcanizing with MVQ to produce molecular cross-linking. The effects of PBS-gel on the damping properties of silicone rubber were analyzed by dynamic rheological test, Fourier transform infrared spectroscopy and dynamic mechanical analysis. The results demonstrated that the damping performance of MVQ/PBS rubber is greatly improved and the rubber has a tan&delta, &gt, 0.3 in the range of &minus, 25~125 &deg, C. The shear-hardening gel is uniformly dispersed in the system, due to the combined action of covalent bonds and intermolecular forces, which act as an active molecular chain that can efficiently dissipate and transfer energy inside the silicone rubber.

Structure and dynamics inside permanently charged polyelectrolyte brushes, sodium polystyrene sulfonate brushes, during their response to the introduction of external ions (NaCl) are investigated by neutron reflectivity and dielectric spectroscopy. Neutron reflectivity measurements show that the segmental density of the inner part of the brushes decreases and that of the outer part increases when the salt level is tuned from the salt-free condition to a moderate level (

The droplet escape condition in laser welding is established in this paper. A three-dimensional numerical model is developed to study the weld pool convection and spatter formation at full penetration during the fiber laser welding of 5083 aluminum alloy. It is found that when laser power is 9 kW, the bottom of the keyhole is dynamically opened and closed. When the bottom of the keyhole is closed, the molten metal at the bottom of the back keyhole wall flows upwards along the fusion line. When the bottom of the keyhole is opened, few spatters can be seen around the keyhole at the top surface, two flow patterns exists in the rear part of the keyhole: a portion of molten metal flows upwards along the fusion line, other portion of molten metal flows to the bottom of the keyhole, which promote the spatter formation at the bottom of the keyhole rear wall.

Hybrid modification processes are used to improve the working surface of 9Cr18Mo bearing steel by plasma immersion ion implantation (PIII) combined with magnetron sputtering (MS). The untreated and treated samples were evaluated by the microhardness and vacuum fiction coefficient tests. Wear morphology of surfaces were also evaluated. It has been found that the microhardness of treated samples increased substantially, and the maximum microhardness was increased 31.9%, the adhesion force at the interface of the film and substrate was improved from 79mN to 107mN, the vacuum friction coefficient was decreased from 0.43 to 0.15, the wear scar diameter was reduced 28.6%. By the comparison of the comprehensive properties of different surface modification processes, hybrid process is better than single process.

Three novel AuI polyynes have been prepared in high yield by copolymerization between an AuI complex precursor and different ethynyl aromatic ligands. The investigation of their photophysical behavior has indicated that forming polyynes through polymerization not only maintains the high transparency of the corresponding AuI polyynes similar to those of their corresponding small molecular AuI acetylides, but also effectively enhances their triplet (T1) emission ability. Critically, owing to their enhanced T1 emission ability, all the AuI polyynes exhibit a stronger optical power limiting (OPL) ability against a 532 nm laser than the corresponding small molecular AuI acetylides. The AuI polyynes based on fluorene and triphenylamine ligands show even better OPL performance than the state-of-the-art OPL material C60, indicating their great potential in the field of laser protection. More importantly, in a prototype OPL device made by doping the fluorene-based AuI polyyne into a polystyrene (PS) solid matrix, substantially improved OPL activity has been observed compared with that in the solution, demonstrating its great potential for practical application. All these results have provided a new strategy to achieve a balance between high OPL activity and good transparency for OPL materials, representing a valuable attempt towards developing new OPL materials with high performance to cope with the key problems in the field of nonlinear optics.

Polymers doped with photosensitive molecules/nanoparticles are believed to be promising optical data storage media. In this communication, a simple method is reported to incorporate multilayers of photosensitive molecules with controlled concentration and spatial distribution into a polymer matrix. This simple hot pressing-based method makes it compatible with existing polymer processing techniques. It is demonstrated that this approach is effective to fabricate free-standing and multi-layered optical data storage media with commonly available polymers. The formation of a multilayer architecture within the polymer matrix involves no adhesives or polymers of other kinds, thus eliminating the concern of refractive index-mismatch between adjacent layers and making the whole material macroscopically homogeneous in structure. When polymers with good ductility and high glass transition temperature are used as the matrix, the macroscopically homogeneous structure can help the material to endure deformation and heat without losing the recorded information.

SnS2 material is considered as a promising anode material for Na-ion batteries (NIBs) because of its unique layered structure and high theoretical capacity. However, SnS2 nanosheets are easily overlapped during synthesis and cycling process. Also, they have to experience large volume change during repeated sodiation-desodiation processes. A promising concept is the application of hierarchical hollow structures for improving electrode stability upon cycling. However, they usually rely on template methods that require complex procedures such as chemical etching or calcination to remove inner template. Here, we demonstrate a simple and innovative strategy for fabricating the SnS2 nanosheets assembled hierarchical tubular structures (SnS2 NS ⊂ HTSs) by using cobalt-nitrilotriacetic acid chelate nanowires as soluble template, which makes shell growth and core template dissolution occur simultaneously in one step reaction. Owing to the hollow interior and well separated nanosheets with maximally exposed edges, the SnS2 NS ⊂ HTSs exhibit excellent electrochemical performance. When evaluated as the anode material for NIBs, it delivers a high discharge capacity of 708 mAh g−1 at 50 mA g−1 and still remains up to 414 mAh g−1 after 50 cycles.

The re-entrant phase separation inside an evaporating droplet of poly (N-isopropyl acryl amide) (PNIPAM) solution with the binary solvent of ethanol and water is discovered and monitored continuously by optical microscopy. Because of the higher evaporation rate of ethanol than water, the solvent composition is changed by evaporation. As a result, the cononsolvency of PNIPAM makes the polymer precipitate into the solution and redissolve afterwards along the proceeding of the evaporation. Such a simple strategy enables a continuous observation of the re-entrant phase separation due to cononsolvency. Direct optical microscopic observation is made with quantitative description of the process and the details of the flow patterns during the process. The phase separation is found to occur at the air-liquid interface and the precipitates are brought into the droplet by circulations induced by Marangoni flow, providing a new way of mass transportation during phase separation.