- Ei，ESCI收录期刊
- 中国科学引文数据库(CSCD)核心期刊
- 中文核心期刊
- 文摘与引文数据库(Scopus)
- 剑桥科学文摘(CSA)
Ceramics are widely used as dental restorative materials because of their superior wear resistance, chemical stability, biocompatibility, and aesthetic features. In this paper, the chemical compositions, microstructures and mechanical properties of dental ceramics were introduced, based on the wear mechanisms of typical dental ceramics and their abrasiveness with opposing human teeth, the main progress concerning the tribological performance optimization of dental ceramics were summarized, and it was pointed out that the mismatch of tribological properties between ceramics and human teeth seriously restricts the clinical application of dental ceramics. Then the in vitro test methods of tribological properties of dental ceramic materials are analyzed and summarized from the aspects of laboratory test medium, friction pair, load, displacement and cycle times. Finally, the future development trends of dental ceramics were discussed from the perspective of bionic tribology. It was pointed out that bionic design of ceramic matrix composites is a promising strategy for overcoming the mismatch of tribological property between dental ceramic restorations and human teeth.
Degradable hydrogels are widely used in the repair and regeneration of articular cartilage because of their good biocompatibility and biodegradability. Three application strategies of degradable hydrogels in cartilage tissue engineering were focused in this review. Firstly, the proteoglycan materials and nanocomposite materials for in-situ formed injectable hydrogels were reviewed. Secondly, the advantages and disadvantages of traditional technology for tissue engineering scaffolds and the preparation methods of combination of various technologies were systematically summarized. Importantly, the research progress of 3D printed tissue engineering scaffolds from pure cartilage to bone/cartilage integration, from single layer to multi-layer in recent years were summarized. Finally, the limitations of degradable hydrogel as articular cartilage scaffold material in micro-directional structure and bioactivity functionalization were discussed.It was prospected that developing highly biomimetic gradient scaffolds with multi-material, multi-scale and multi-inducement will be an important research direction of articular cartilage tissue engineering in the future.
Human skin can sense the information from the environment and play a significant role in the contact with the outside world. Electronic skins, which mimic the characteristics of human skin and the ability to perceive the environment have a wide range of applications in the fields of medical monitoring, bionic prostheses and robotic tactile perception. Compared with traditional wearable sensors, electronic skin is lighter, more flexible, more malleable, and has the characteristics of wireless, transparent, and compatibility with human skin, therefore, has become one of the emerging research fields. The electronic skin can continuously sense large number of physical and biochemical parameters of the human body, human motion and gas to monitor human health, sports condition and surrounding gases in various environments in real-time. In this review, the state-of-the-art of the materials used to making electronic skins, including zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D) micro/nano-materials, polymeric materials, hydrogel materials and their composites, were discussed, and the practical applications of the electronic skin constructed based on these core materials were concluded in terms of health monitoring, motion monitoring as well as gas monitoring. It was pointed out that there are still some remaining technical problems in the research process of electronic skin such as high cost and complex process.The development trend of electrode skin was towards multi-function and simultaneous detection of multiple external stimuli, and it had broad application prospects in the fields of medical equipment robbotics and future manufacturing.
Osteochondral defects are the main cause of joint morbidity and disability in elderly patients, and osteochondral tissue engineering is one of the methods to repair osteochondral defects. The method of osteochondral tissue engineering involves the manufacture of osteochondral biomimetic gradient scaffolds that should mimic the physiological properties of natural osteochondral tissue (e.g., the gradient transition between cartilage surface and subchondral bone). The osteochondral biomimetic gradient scaffolds exhibit discrete gradients or continuous gradients to establish the characteristics of osteochondral tissue in many studies, such as biochemical composition, structure and mechanical properties. An advantage of the continuous osteochondral biomimetic gradient scaffold is that there is no obvious interface between each layer, therefore it more closely mimics the natural osteochondral tissue. Although promising results have been achieved so far on the regeneration of the osteochondral biomimetic gradient scaffold, there are still differences between the osteochondral biomimetic gradient scaffold and natural osteochondral tissue. Due to these differences, the current clinical treatment of osteochondral biomimetic gradient scaffolds to repair osteochondral defects needs further research. Firstly, the research progress on discrete and continuous gradient scaffolds from the background of osteochondral defects, the micro-scale structure and mechanical properties of osteochondral to the materials and methods related to the manufacture of osteochondral biomimetic gradient scaffolds was summarized in this article. Secondly, due to the 3D printing method of the osteochondral biomimetic gradient scaffold having the ability to precisely control the geometry of the scaffold hole and the mechanical properties of the scaffold, the application of computational simulation models in osteochondral tissue engineering was further introduced, for example, optimizing scaffold structure and mechanical properties are considered to predict tissue regeneration. Finally, the challenges related to the repair of osteochondral defects and prospects for the future research of osteochondral tissue regeneration were presented.For example, continuous osteochondral bionic gradient scaffolds need to more similarly simulate the structure of natural osteochondral tissue units, that is, the transition of mechanical properties and biochemical properties is more smooth naturally. At the same time, although most osteochondral biomimetic gradient scaffolds have achieved good results in in vivo and in vitro experiments, clinical research and application still need to be further studied.
The high fusion welding hot cracking sensibility of the next-generation alloy is the key technological difficulty that hinders its widely application in the aeronautic and astronautic industry. A critical review of the fusion welding hot cracking from the perspective of basic mechanism and the experimental research of typical materials was presented in this article. The fusion welding hot cracking phenomena include solidification cracking (occurs within the fusion zone) and liquidation cracking (occurs at the interface between fusion zone and partial melting zone). The formation factors of the fusion welding hot cracking include alloying composition, welding thermal cycle and thermal stress. Based on the comprehensive understanding of the formation mechanism of the fusion welding hot cracking, the relative research progress in the field of aluminum alloys, magnesium alloys, advanced high strength steel and nickel alloys was summarized. The establishment of the quantitative criterion that involves the effects of complicated multi-component and the morphology of the dendrite on the cracking sensibility is the key development direction. Optimizing the alloying composition of the base metal or filler metal, adding nucleanting agent or auxiliary facilities are the practical method for restraining the fusion welding hot cracking. Conducting the research on the mechanism and restraining method of the fusion welding hot cracking helps to solve the difficulty of the next generation alloys processing, which can realize their application in the field of aeronautic and astronautic industry.
Natural enzymes are trace proteins produced by living cells in human body. It is precisely because of the existence of enzyme that the daily operation of organisms can be carried out orderly. At present, enzymes are used in many fields such as biomedicine, catalysis and detection. However, natural enzymes have many disadvantages, such as easy inactivation, poor stability, difficult synthesis, complex purification and high price, which hinder the large-scale application. In the past decades, as a new generation of artificial enzymes, nanomaterials mimic enzymes has gradually become a substitute for natural enzyme due to their high stability and good repeatability. Nanomaterial mimetic enzymes play an important role in many fields. The application of nanomaterial mimetic enzymes in the detection of O2·- and salvianolic acid in the field of electrochemical sensing was focused on in this paper, as well as in the detection of small biological molecules such as glutathione, glucose, cholesterol and H2O2, which can effectively detect the content of heavy metal salts and pesticides in the field of environmental pollution prevention and control, nanomaterials mimic enzymes can also prevent cancer, virus infection and other diseases by detecting specific sequences of DNA. Finally, it was expected that the future research of nanomaterials mimic enzymes will focus on the coupling between nanomaterials mimic enzymes, reaction mechanism, optimization of enzyme reaction environment and substrate selectivity, which will be the key research direction in the future.
Polymer materials are widely used in the mechanical lubricant field owing to their light, low-cost, anti-corrosion, and excellent self-lubricating performance. Adding functional fillers with anti-friction and reinforcing character can overcome the inherent defects of intrinsic polymer materials and then obtaining tribological composites materials with the low friction coefficient, high-wearing, high-bearing, and heat-resisting performance. The anti-friction and anti-wear effect and mechanism of composites by adding functional fillers such as carbon-based materials, transition metal sulfides, microcapsules, soft metals, ceramic nanoparticles, mineral salts, and self-lubricant polymer materials were summarized in this paper. Meanwhile, the mechanical property is the key parameter that can guarantee the service performance and application deadline of polymer materials and also gives the significant influence of tribological performance. The enhanced and toughening mechanism of composites by adding nanoparticles and fiber was also mainly discussed in this paper. Finally, The synergistic effect of functional fillers on mechanical and tribological properties was prospected, as well as the development trend of computer simulation in tribology of composite materials.
AlMg4.5Sc0.55Mn0.5Zr0.2 alloys were fabricated by selective laser melting.The effects of artificial ageing parameters on Vickers hardness of the alloy were investigated. The room temperature tensile properties and microstructures of as-built and optimized artificial ageing treated alloys were analyzed. Results indicate that the Vickers hardness of the alloy increases from 102HV to more than 140HV by artificial ageing treatment. As the rising of ageing temperature, ranging from 305℃ to 335℃, or prolongation of the ageing duration, from 1.5 h to 48 h, Vickers hardness presents increasing first, then decreasing and finally trends to be stable. The room temperature tensile properties of the alloys aged at 315℃ for 3 h or 12 h are almost equal, and there is no obvious anisotropy. The ultimate tensile strength and yield strength reach 470 MPa and 410 MPa respectively, with elongation of about 15.0%.The improvement of mechanical properties is due to the dispersion precipitation of nano-reinforced particles Al3(Sc, Zr), which possess a coherent interface with the matrix during artificial ageing.
The N-doped carbon nanofiber coated graphene nanosheets (NFGNs) were designed and constructed using EGNs as the skeleton and PPy as the carbon source. The samples were characterized by SEM, XRD, Raman, FTIR, XPS and BET. The results show that the interconnected N-doped carbon nanofibers are uniformly coated on the surface of EGNs. The NFGNs-800 presents high-level nitrogen atom doping of 11.53% and large specific surface area of 477.65 m2·g-1. The capacitance performance test results show that the NFGNs-800 electrode material exhibits high specific capacitance of 323.3 F·g-1 (1.0 A·g-1) and good rate characteristic. NFGNs-800 supercapacitor shows high energy density of 87.1 Wh·kg-1 at power density of 10500 W·kg-1. The specific capacitance of the supercapacitor is 95.9% of the initial specific capacitance and the columbic efficiency still remains above 99% after 10000 constant current charge discharge cycles.
Li6PS5Cl (LPSC), a sulfide solid-state electrolyte with an argyrodite structure, is one of the ideal electrolyte materials for the construction of all-solid-state lithium-ion batteries.It has good development prospects because of its high ionic conductivity (>3×10-3 S·cm-1) and good stability to lithium. In this work, LPSC was prepared by the combination of high-energy ball milling and inert atmosphere solid-phase sintering, and powder X-ray diffraction, Raman spectra, and scanning electron microscopy were used to investigate the effects of the preparation process on the structure, composition, electrical properties, and ion conductivity of LPSC. The results show that the extended ball milling time is beneficial to the amorphization and subsequent sintering of the LPSC precursor powder. The increase of the sintering temperature will promote the physical purity and electrical conductivity of the prepared LPSC electrolyte, but the high sintering temperature will lead to the decomposition of LPSC. The LPSC prepared by 8 h ball milling and 500℃ sintering has the highest ion/electron conductivity ratio (2.091×105) at room temperature, with ionic conductivity up to 4.049×10-3 S·cm-1 and electronic conductivity only 1.936×10-8 S·cm-1. The 712 NCM/LPSC/In-Li all-solid-state battery prepared with this electrolyte has a first-turn discharge specific capacity of 151.3 mAh·g-1 at a charge/discharge ratio of 0.1 C, and has excellent cycling stability.
Flaky FeSiAl particles show excellent magnetic properties at low frequency but exhibit large permittivity and impedance mismatch at high frequency. The surface of the flake FeSiAl alloy particles was coated with thin layer of styrene-butadiene-styrene block copolymer (SBS) by a process consisting of dissolving organic polymer, mixing with the FeSiAl particles, emulsifying and then evaporating the solvent. Then the electromagnetic properties of the coated FeSiAl particles were studied. The results show that SBS forms a layer of thin, uniform and dense coating on the surface of the flake FeSiAl alloy particles, which significantly improves the resistivity of the alloy powder. The real part of the complex dielectric constant of the coated alloy particles mixed with paraffin 2:1 is decreased from 72 to around 30. The low frequency magnetic properties are not adversely affected, and its high-frequency performance is significantly improved due to the improvement of impedance matching. Therefore, the coating of SBS endow a better performance to the flaky FeSiAl alloy particles in broadband microwave absorption.
In order to explore the ablation characteristics of C/SiC ceramic composite nozzles in the working environment of liquid rocket engines, 3D C/SiC composite nozzle was prepared by the precursor impregnation pyrolysis(PIP) process, and the ablation test of the nozzle in various working conditions was carried out. The results show that 3D C/SiC composite nozzle can meet the requirements of anti-ablation performance of the liquid rocket engine under various working conditions. The wire ablation rate of nozzle throat is about 3.92×10-4 mm/s; after the hot test vehicle ablation test, a large amount of white matter SiO2 remains on the inlet cylindrical section, convergent section, throat section and expansion section outer surface of the nozzle, and the ablation pit appears in the throat; the ablation mechanisms of C/SiC composites under liquid rocket engine are mainly mechanical erosion ablation and oxidation ablation.
With the development of technology, the amount of heat generated by electronic components has increased significantly. Therefore, it is increasingly urgent to develop materials with high thermal conductivity and high insulation properties. Thermally conductive composites were prepared by mechanical blending using methyl vinyl silicone rubber (SR) as the matrix, and some particles including carbon nanotubes (CNTs), hexagonal boron nitride (BN) and aluminum nitride (AlN) as thermally conductive fillers. The effect of hybridization of three kinds of fillers on the thermal conductivity, electrical insulation and mechanical properties of the composites was studied. The influence of the filler orientation on the thermal conductivity of the composites was investigated. The effect of the heating time on the surface temperature of the composites was also investigated and the theoretical thermal conductivity of the composites was fitted according to Agari model. The composites were characterized by an infrared thermal image, scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results show that with the decreased addition of AlN and the increased loadings of BN and CNTs, the thermal conductivity of the composites is gradually increased. When the content of AlN, BN and CNTs is 80, 68 phr and 2 phr respectively, the composites show better overall performance, where the out-plane and in-plane thermal conductivity of the composites is 1.857 W·m-1·K-1 and 2.853 W·m-1·K-1, and the volume resistivity and the tensile strength is 2.18×1012 Ω·cm and 4.3 MPa, respectively.
The effects of hydrophilic and hydrophobic SiO2 composite organic resin on the properties of FeSiCr magnetic powder cores and the effects of annealing treatment on magnetic properties were studied. After phosphating, the FeSiCr alloy powders were coated by two types of SiO2 composite resin, which are hydrophobic and hydrophilic, respectively. The FeSiCr magnetic powder cores were prepared by compaction and curing. The results show that the coating effect of coupling modified hydrophilic SiO2 composite organic resin is better than that of hydrophobic SiO2 composite organic resin. With the increase of SiO2 addition, the specific resistance and coercivity of the magnetic powder cores are increased, while the density, saturation magnetization and effective permeability are decreased. The FeSiCr magnetic powder cores coated with 0.5% hydrophobic SiO2 composite organic resin have excellent comprehensive performance after annealing. Under the condition of 20 mT, 100 kHz, the magnetic core loss is 49.84 kW/m3, which is 16.9% lower than that of the magnetic powder cores coated with pure resin. Annealing can effectively promote magnetic properties of FeSiCr magnetic powder cores.
TiO2 sol was prepared by sol-gel method using tetrabutyl titanate as precursor and acetic acid as catalyst, and then hydrophobically modified TiO2 sol was obtained by reducing its surface energy with γ-methacryloxypropyl trimethoxysilane (KH570), the modified TiO2 sol was sprayed on the surface of the filter media to make it superhydrophobic. The wettability, surface morphology, chemical composition and filtration performance of the filter media before and after modification were analyzed.The results show that the modified coating is uniformly deposited on the surface of the filter media and the fiber surface completely wrapped, and the water contact angle of the modified filter media reaches 156.29°. By testing the filtration performance of the particles with the size of 0.3 μm at the filtration velocity of 0.043-0.127 m/s, it can be seen that the filtration efficiency of the modified filter media is increased by an average of 2.7672% compared with the unmodified filter media, and the filter quality factor is increased by 0.34%, which improves the filtration performance of the filter media. In addition, the hydrophobic filter media still has superhydrophobicity after 50 times of sandpaper abrasion cycles and 30 h acid-base solution immersion. The modified filter media has excellent self-cleaning performance by cleaning the surface of coal powder pollution.
The composite nanocontainer of corrosion inhibitor (MSN-QB) was prepared by loading octahydroxyquinoline (8-HQ) and benzotriazole (BTA) on mesoporous silica nanoparticles(MSN) simultaneously using vacuum adsorption and layer-by-layer self-assembly technology, and added to the epoxy coating to obtain a new coating (MQB). SEM, TEM, FT-IR, Zeta-potential and TGA were used to study the structure changes of the nanocontainer before and after loading corrosion inhibitors and the stimulus response release behavior of the corrosion inhibitors, and electrochemical test and salt spray test were used to study the improvement of coating protection performance by layer-by-layer self-assembly technique. The results show that the loadings of 8-HQ and BTA in MSN-QB are 6.8%(mass fraction) and 7.1%, respectively. MSN-QB has pH response characteristics. The release of 8-HQ and BTA are both inhibited under neutral conditions, but can be released under alkaline (pH=10) and acidic (pH=4) conditions. The release rate under alkaline conditions is higher. MQB coating has the best corrosion resistance. After immersed in 3.5%NaCl solution 20 d, the MQB coating has the largest|Z|0.01 Hz value(2.0×109 Ω·cm2), more than twice that of MQ+MB coating.
Porous α-Mn2O3 with irregular granular morphology stacked from microplates was synthesized through thermal decomposition of oxalate, and its performance as a catalyst to activate peroxymonosulfate(PMS) for degradation of simulated dyestuff wastewater with methylene blue(MB)as main component was explored. Influences of calcination temperature, catalyst addition, PMS dosage and anion species on MB degradation efficiency were investigated.The results show that the product obtained at 450℃ exhibits the most excellent catalytic ability. The degradation ratio of MB is 75.88% in the system of α-Mn2O3/PMS, while its counterpart is only 22.19% and 5.72% for PMS or α-Mn2O3 alone, respectively.The optimization reaction additions for degradation of MB of 500 mL with a concentration of 10 mg/L are: 3 mL of PMS (0.1 mol/L), 0.05 g of α-Mn2O3. At this condition, a MB degradation ratio of 83.55% can be achieved in 50 min. In addition, it is found that introduction of C2O42- or PO43- has a negative effect on MB degradation, whose inhibition rate is 49.11% and 10.27%, respectively. However, Cl- has no inhibitory effect for MB degradation. Furthermore, the active species in the reaction system are identified by the quenching experiments and electron paramagnetic resonance(EPR) tests.The results confirm that there are ·OH, SO4-·, ·O2- and 1O2 in the reaction system, and 1O2 is the most important active intermediate involved in the direct oxidation degradation of MB.Kinetic analysis demonstrates that the degradation of MB solution with PMS catalyzed by α-Mn2O3 is a secondary reaction, and the kinetic reaction rate constant is 3.53 L·mmol-1·min-1.
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