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      20 August 2021, Volume 49 Issue 8 Previous Issue    Next Issue
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    Research progress in high-entropy alloys used in brazing and surface engineering fields
    Hong LI, Yi HAN, Jian CAO, Bober MARIUSZ, Senkara JACEK
    2021, 49 (8): 1-10.   DOI: 10.11868/j.issn.1001-4381.2020.000950
    Abstract ( 632 ( PDF (2207KB)( 436 Citation

    With the improvement of alloy manufacturing level and the complexity of performance requirements, high-entropy alloys (HEAs) have gradually attracted great attention.At present, the research in the field of material processing mainly focuses on brazing and surface engineering.In the field of brazing, HEAs can be used as filler material for brazing at high temperature and low temperature, the empirical parameters related to high entropy were summarized. The application of the simulation and calculation methods such as first-principle method and calculation of phase diagram were described in the field of HEAs design for filler metals development. The latest research progress of HEAs fillers for brazing of nickel-based superalloys and dissimilar ceramics-metals, as well as low temperature packaging was introduced. The influence of welding process parameters on microstructure and properties of HEAs brazing joints was also analysed.In the field of surface engineering, the application direction and preparation methods of HEAs in film/coating were discussed. The research progress in high-temperature protective coating, hard protective layer and other application directions was summarized. At the same time, the problems existing in the research and application of HEAs in the fields of brazing and surface engineering were summarized. The future trends were put forward in order to decrease the melting temperature of HEAs filler, improve high temperature mechanical properties of welds, and develop the eutectic HEAs filler/coating.

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    Research progress in titanium alloy in the field of orthopaedic implants
    Jian-qiao LIU, Jia LIU, Yu-jin TANG, Li-qiang WANG
    2021, 49 (8): 11-25.   DOI: 10.11868/j.issn.1001-4381.2020.000380
    Abstract ( 445 ( PDF (8424KB)( 412 Citation

    Owing to the excellent biocompatibility and corrosion resistance of titanium and its alloys in the biological environments, they are one of the best materials in the medical implant applications. Moreover, it has a lower elastic modulus (comparable to bone) than traditional metal implant materials which is an influential property due to the stress-shielding effect. There are some requirements for implant materials according to their clinical use and the periphery tissues. Hence, some factors should be considered, such as metal degradation, toxicity issues, surface characteristics, biocompatibility, and fusion with bone. Considering the above-mentioned information, titanium material design with superior performance to meet the essential clinical needs is an important challenge and attracts much attention from the academicians in the biomaterial field. This paper discusses the structural and performance characteristics of medical titanium alloys and the current research status in the direction of orthopedic applications. Furthermore, in future research, through changing the elemental composition, increasing the surface modification, and optimizing the production process, titanium alloy materials could have the excellent comprehensive performance to serve human beings better.

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    Research progress on lithium anode and interface engineering of lithium/solid-state electrolyte in all-solid-state lithium metal battery
    Jie YANG, Kai WANG, Ya-nan XU, Ke-jian WANG, Yan-wei MA
    2021, 49 (8): 26-42.   DOI: 10.11868/j.issn.1001-4381.2020.000786
    Abstract ( 480 ( PDF (19443KB)( 412 Citation

    Lithium metal has a low redox potential (-3.04 V vs standard hydrogen electrode) and high specific capacity (3860 mAh/g), making it an ideal anode material for lithium secondary batteries. The solid-state lithium battery assembled by metal lithium negative electrode/solid electrolyte/lithium-inserted positive electrode is expected to become the power source of related technology industries such as aerospace, robotics, high-end electronics and electric vehicles in the future. However, during the charging and discharging process, due to the uneven deposition and dissolution of lithium, a large number of dendrites are produced on the contact surface between lithium and the electrolyte, and they continue to grow along the direction of the electrolyte, eventually causing the internal short circuit and failure of the battery. The use of a solid electrolyte with a higher Young's modulus can block the growth of lithium dendrites to a large extent, but still cannot meet the requirements of battery long-term cycling and safety. In addition, metal lithium is in solid-solid contact with the solid electrolyte surface, causing problems such as high electrical resistance across the interface and interfacial reaction between metal lithium and solid electrolyte, which severely hinders the development and use of solid lithium metal batteries. The strategies for inhibiting the growth of lithium dendrites and improving the compatibility of solid-solid interface in metal lithium batteries based on solid electrolytes in recent years were reviewed in this article, and prospects for future development on the interface engineering of Li metal and solid-state electrolytes were prospected.

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    Research progress of photonic crystals in photocatalysis
    Zhao-ran CHU, Gong CHEN, Xue-ling ZHAO, Dong-hai LIN, Cheng CHEN
    2021, 49 (8): 43-53.   DOI: 10.11868/j.issn.1001-4381.2020.000885
    Abstract ( 408 ( PDF (9997KB)( 308 Citation

    Photonic crystals are dielectric structure materials with photonic band gaps which are composed of matters with different dielectric constants and arranged in space periodically. The slow photon and band gap reflection in the photonic band gap can promote the photonic capture and control the interaction between light and matter. Based on the unique optical properties and large specific surface area of photonic crystals, the photonic crystal structure is introduced into the design of semiconductor photocatalytic materials, which can effectively enhance the photocatalytic reaction activity. The preparation methods of three-dimensional photonic crystals and slow photons effect was introduced in this paper, the research progress was especially summarized in the inverse opal photonic crystal as catalysts in wastewater purification of light, hydrogen production, carbon dioxide conversion and etc, and for the challenge faced by the photonic crystal light catalyst, multilayer three-dimensional photonic crystals with different refractive index and the periodicity were put forward, in order to promote photonic crystals applications in the field of photocatalysis.

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    Research progress on controllable preparation of TiO2/MXene nanocomposites and applications in photocatalysis and electrochemistry
    Hua-peng LI, Xu-sheng DONG, Bin SUN, Guo-wei ZHOU
    2021, 49 (8): 54-62.   DOI: 10.11868/j.issn.1001-4381.2020.000556
    Abstract ( 560 ( PDF (7984KB)( 541 Citation

    TiO2 nanomaterials have many disadvantages, including high photo-generated electron-hole recombination rate, low electron mobility, poor electrical conductivity and low reversible capacity, which have restricted application in the fields of photocatalysis and electrochemistry. MXene (Mn+1XnTx), a new type of two-dimensional transition metal carbides, nitrides, or carbonitrides, has a unique two-dimensional layer structure, excellent electrical conductivity, and high carrier mobility. By introducing MXene into TiO2 nanomaterials to construct the TiO2/MXene nanocomposites, the synergistic effect of MXene and TiO2 can further improve photocatalysis and electrochemistry properties. From the perspective of TiO2 nanomaterials, the latest research progress on the controllable preparation, structural properties, applications in photocatalysis and electrochemistry of zero-dimensional, one-dimensional, and two-dimensional TiO2 with MXene nanocomposites were reviewed. In particular, the construction mechanism of namocomposites and the enhancement mechanism of photocatalysis and electrochemistry properties of TiO2 by MXene were emphasized. The shortcomings of the existing research on preparation of TiO2/MXene composites and its applications in photocatalysis and electrochemistry were analyzed.Furthermore, the future research directions of TiO2/MXene composites from the aspects of optimizing the preparation process, improving the properties and exploring the property enhancement mechanism were also prospected.

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    Research Article
    Effect of cooling speed and ultrasonic vibration on solidification structure and mechanical properties of 7085 aluminum alloy
    An-qing LI, Li-hua ZHANG, Ri-peng JIANG, Xiao-qian LI, Yun ZHANG
    2021, 49 (8): 63-71.   DOI: 10.11868/j.issn.1001-4381.2020.001142
    Abstract ( 232 ( PDF (18572KB)( 110 Citation

    Three different cooling methods of furnace cooling, air cooling and water cooling were adopted, and ultrasonic outfield assisted technology was applied to study the effects of cooling speed and ultrasonic outfield on the solidification structure and properties of 7085 aluminum alloy. Metallographic microscope, scanning electron microscope and electronic universal mechanics testing machine were used to characterize the matrix structure, second phase, tensile strength and elongation of the samples, and the solidification mechanism was analyzed. The results show that under the above three cooling methods of furnace cooling, air cooling and water cooling, after ultrasonic field the microstructure refinement rate of α-Al in each group is 40.2%, 14.6%, and 21.6%, respectively. The fitting relationship between grain size and cooling speed is as follows: LW=154.4+25.33/v, LS=148.1+15.3/v, the second phase of the area fraction are relatively reduced by 32.1%, 16.9% and 18.5%, the average length and width of the second phase are also relatively less, the tensile strength of 7085 aluminum alloy, which is increased by 21.7%, 21.7% and 3.6%, respectively, after the introduction of ultrasonic outfield auxiliary technology, compared to the group without ultrasound. Elongation of 7085 aluminum alloy is further enhanced by 31.3%, 15.7% and 41.4% respectively. Under the synergistic effect of ultrasonic field and water cooling, the microstructure and mechanical properties of 7085 aluminum alloy are better.

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    Modeling of residual stress evolution of 7050 aluminium alloy component during heat treatment and cold forming
    Hao WANG, Na-min XIAO, Hui-qu LI, Xiao WANG
    2021, 49 (8): 72-80.   DOI: 10.11868/j.issn.1001-4381.2021.000242
    Abstract ( 289 ( PDF (14415KB)( 234 Citation

    A thermal mechanical coupling numerical model of 7050 aluminium alloy was established using the Hansel-Spittel constitutive model. The stress state of the samples during quenching and cold deformation was analyzed using the finite element simulation technology at first, which is in good accordance with the measured result by ultrasonic test. Then, residual stress evolution rule during heat treatment and cold deformation of an aluminium component with rib structure was studied and ultrasonic residual stress inspection and matching deformation verification were carried out on the structural component. The results show that residual stress after quenching is in the state of external compression and internal tension. The reduction degree of quenching induced residual stress by different cold deformation methods is obviously different. For cold compression, when deformation exceeds 2%, compression on the web obviously improves stress state of the whole web region while compression on the lib has relatively less improvement. For cold stretching, 3% deformation can effectively improve the stress uniformity for both web region and lib region. After cold stretching, the distortion during machining can be obviously improved.

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    Effect of pre-bending deformation on mechanical properties of complex phase steel CP800
    Hao-fei SUN, Zhi XIAO, Kai WEI, Xu-jing YANG, Jun QI
    2021, 49 (8): 81-88.   DOI: 10.11868/j.issn.1001-4381.2020.001012
    Abstract ( 216 ( PDF (18850KB)( 192 Citation

    The pre-bending specimens were obtained by stamping with complex phase steel CP800, and the effect of pre-bending deformation on microstructure, residual stress and mechanical properties of the steel were studied by using EBSD, X-ray residual stress measurement system, tensile testing machine, DIC technique, etc. The results show that the distribution of residual stress of pre-bending specimens exhibits stress distribution of tension-compression-tension-compression, which means that the inside surface (compression layer) is tension stress and outside surface (tension layer) is compression stress. Such special distribution leads to a 16% reduction of yield stress of specimens after pre-bending. Meanwhile, due to the dislocation strengthening and hardening caused by cold deformation, the elongation of material decreases by 25% and the tensile strength increases by 24% after pre-bending. Furthermore, it is found that the inside surface produces greater plastic strain and is broken earlier than the outside surface due to the existence of tensile residual stress.

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    Mechanical properties of SiC whiskers reinforced SiCf/SiC composites
    Zhuo-yu JIANG, Xiao-wen SHU, Xiao-xu LYU, Ye GAO, Yi-ran ZHOU, Yu-fei DONG, Jian JIAO
    2021, 49 (8): 89-96.   DOI: 10.11868/j.issn.1001-4381.2020.000806
    Abstract ( 264 ( PDF (23213KB)( 277 Citation

    Multi-stage reinforced SiCf/SiC-SiCw composites were prepared by introducing SiC whiskers into SiCf/SiC composite, and BN interphase was deposited on the surface of SiC whiskers by chemical vapor infiltration (CVI). The mechanical properties of composites were evaluated. The results show that the compressive strength of the composites can be significantly improved on account of the reinforcing mechanism of SiC whiskers, such as the whisker pull-out, whisker bridging and crack deflection, which can extend the crack propagation path and increase the energy consumption capacity. The compressive strength of the composites is increased from 549.7 MPa to 673.9 MPa, with an increase of 22.6%, when the addition of SiC whisker is 20%(volume fraction). After depositing the BN interphase on SiC whiskers, the tensile strength, flexural strength and fracture toughness of the composites were 414.0 MPa, 800.3 MPa and 22.2 MPa·m1/2, which are increased by 13.9%, 8.8% and 19.0%, respectively, compared with the composite reinforced with the uncoated whisker.

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    Effects of Si addition on microstructure and properties of martensitic stainless steel treated by quenching and partitioning process
    Guan-tao WANG, Yong-lang ZHOU, Zhuo ZHAO, Li-jun WANG, Chun-ming LIU
    2021, 49 (8): 97-103.   DOI: 10.11868/j.issn.1001-4381.2020.000810
    Abstract ( 280 ( PDF (15271KB)( 168 Citation

    In order to improve the strength-plasticity and corrosion resistance, two nitrogen-alloyed martensitic stainless steels 10Cr13N and 10Cr13Si2N with different Si contents were designed and fabricated. The experimental steels were subjected to a quenching-partitioning (Q&P) process with constant quenching finish temperature and partitioning temperature but changing partitioning time.The effect and mechanism of Si addition were investigated from the changes of microstructure and mechanical properties. The results show that lath martensite and retained austenite can be obtained through quenching and partitioning process, and its strength-plasticity is significantly higher than that of quenching and tempering. As the partitioning time prolongs, the volume fractions of retained austenite in microstructures of two steels increase to a maximum first and then decrease gradually, which has slight effect on strength, but significant effect on elongation. Increasing Si content in steel is beneficial to inhibit the precipitation of carbonitride in martensite and improve the volume fraction and stability of retained austenite, it can significantly improve the deformability of steel but reduce the impact toughness slightly.

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    Microstructure and mechanical properties of copper-steel TIG filling-wire welding joint assisted by AC magnetic field
    Long WANG, De-an HU, Peng-yuan ZOU, Zhen-yu XIONG, Yi-ping CHEN, Dong-hai CHENG
    2021, 49 (8): 104-110.   DOI: 10.11868/j.issn.1001-4381.2020.000673
    Abstract ( 208 ( PDF (14203KB)( 59 Citation

    By adding a longitudinal AC magnetic field and using HS201 pure copper wire as the filler metal, TIG butt joint experiments were conducted on T2 copper and Q235 steel plates, both with the thickness of 2 mm, to study the joint formation, organization and mechanical properties when the magnetic field was added. The results show that the surface of weld zone is formed well after adding magnetic field. The best technological parameter is as follows: when welding current I=95 A, welding speed v=95 mm/min, magnetic field frequency f=25~35 Hz, magnetic field current IE=0.4~0.6 A, the mechanical properties of the joint is good, and the maximum tensile strength is 223.5 MPa, which is 44.5% higher than that without magnetic field. Copper-steel TIG welding joint is mainly divided into steel-HAZ, fusion zone, weld zone and copper-HAZ. After the addition of AC magnetic field, the morphology of ferrite in steel side heat affected zone changes from massive to needle like and lateral strip; the microstructure of weld zone changes from cellular crystal to fine and uniform cellular dendrite; the microstructure of copper-HAZ is obviously refined. After adding magnetic field, the types of phases in the fusion zone and weld zone of the joint have no change, which are composed of (α-Fe)+(ε-Cu); the solute segregation in the fusion zone is improved, and the (α-Fe)+(ε-Cu) particles change from coarse dispersion to fine aggregation; the microstructure of the weld zone is refined and its uniformity is obviously improved, which makes the hardness gradient of fusion zone and weld zone relatively decrease.

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    Effect of pre-oxidation treatment of TiH2 and foaming temperature on cell structure of Al-7Si closed-cell aluminum foams
    Xu-dong YANG, Ming-rui XIE, Tian-chun ZOU, Rong-rong ZONG
    2021, 49 (8): 111-119.   DOI: 10.11868/j.issn.1001-4381.2020.000710
    Abstract ( 249 ( PDF (12736KB)( 75 Citation

    A powder metallurgy rapid foaming method was used to prepare Al-7Si closed-cell aluminum foam, and the influence of the preparation process parameters on the expansion rate, porosity, cell number and pore diameter of the aluminum foam after using high thermal conductivity foaming mold was studied. The results show that the TiH2 which is pre-oxidation treated isothermally at 450-500 ℃ for 1 h can refine the particle size, increase the onset decomposition temperature and the peak hydrogen release temperature of TiH2. Excessive pre-oxidation treatment of TiH2 reduces the gas released and expansion rate of aluminum foam. The increase of foaming temperature is beneficial to increase the expansion rate and the number of cells, and has little effect on the porosity and average pore size, but too high temperature can increase the distribution range of low-circularity crack-like cells on the top of the sample. The foaming mold can constrain the direction of expansion and improve the uniformity of the pore size during the cooling process. The powder metallurgy rapid foaming method can obtain aluminum foams with uniform cell structure. The aluminum foams can be obtained with the porosity of 78.1%, the pore diameter of (2.29±0.8) mm and the optimal structure, when TiH2 pretreated at 450 ℃ for 90 min and foaming temperature at 720 ℃ for 160 s.

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    Constructing robust superhydrophobic interface with self-assembled Cu6Sn5 arrays and application in copper corrosion inhibition
    Zhao-qing GAO, Chen WANG, Yin-bo CHEN, Sheng-yan SHANG, Fei CHEN, Hai-tao MA, Yun-peng WANG
    2021, 49 (8): 120-126.   DOI: 10.11868/j.issn.1001-4381.2020.001007
    Abstract ( 196 ( PDF (4898KB)( 71 Citation

    The superhydrophobic scallop-like Cu6Sn5 micro/nano structure were successfully constructed on pure copper substrate by heat-induced Cu/Sn interfacial metallurgical reaction and simple chemical modification process. The microstructure, chemical composition and corrosion resistance of as-prepared samples were characterized by field emission scanning electron microscopy and X-ray photoelectron spectroscopy, etc. The results show that the averaged shear resistance strength between micro Cu6Sn5 and Cu substrate is higher than 40 MPa. After modified with myristic acid and Cu2+, copper myristate with low surface energy is formed on the armor Cu6Sn5 surface. The wetting angle of water droplets on as-modified surface is higher than 150° and its rolling angle is 7.2°. Compared with pure copper, the self corrosion current density of the samples modified by copper myristate in 3.5%NaCl(mass fraction) solution is about 1/10 of that of the samples before modification, showing better corrosion resistance. Based on the metallurgical bonding mechanism between intermetallic compounds and metal matrix, the armor formation strategy of metal materials in micro-scale by heat-induced interfacial reaction is proposed, which can successfully solve the open and key scientific problem of low mechanical stability for artificial superhydrophobic interface.

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    Preparation and electrochemical performance of nano-silver-graphene composite by electroless plating
    Jin-lei LI, Ling-feng DENG, Shu-xian ZHANG, Jie-hui TAN, Rong-rong QIN, Zhuang WANG
    2021, 49 (8): 127-138.   DOI: 10.11868/j.issn.1001-4381.2020.000903
    Abstract ( 301 ( PDF (17302KB)( 90 Citation

    Using glucose as the reducing agent, the nano-silver-graphene composite material (Ag/GR) was synthesized in situ by electroless plating, the structural morphology of the material was characterized and analyzed by X-ray diffraction (XRD), X-ray energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and Fourier infrared spectrometry (FTIR). The results show that the loading morphology of silver on the graphene surface is the single state that meets the expectation. The average particle size of AgNPs is about 21 nm. At the same time, the electrochemical response of ascorbic acid (AA) on Ag/GR/GCE electrochemical sensors was studied using the electrochemical test methods of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV). The electrochemical test results show that the Ag/GR composite has the highest response electrochemical signal of 212.9 μA and the lowest resistance of charge transfer of 90.5 Ω. The peak current is about twice that of the graphene electrode (110 μA) and about five times that of the glassy carbon electrode (42.5 μA). Due to the good synergistic effect of AgNPs and graphene, it has obvious electrocatalytic activity for AA. And the anode peak current and concentration show positive correlation linear change trend in the range of 5-120 μmol/L. However, the anode peak current of AA is highly correlated with the natural logarithm of the concentration range from 50 μmol/L to 120 μmol/L. The low limits of detection is 0.06 μmol/L.

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    Effect of heat oxygen aging on mechanical properties and heat resistance of wood rubber plastic ternary composites
    Wei-dong WANG, Qi LI, Xue-song ZHAO, Ge-hao ZHANG
    2021, 49 (8): 139-144.   DOI: 10.11868/j.issn.1001-4381.2020.000366
    Abstract ( 257 ( PDF (2983KB)( 38 Citation

    Reasonable use of waste rubber and plastic can avoid environmental pollution and improve composite materials performance. Recycled high density polyethylene (PE-HD), salix wood powder and waste tire powder were used as raw materials to prepare wood rubber plastic ternary composite materials (WRPC) by compression molding. The change rules of mechanical properties and heat resistance of WRPC were investigated under different heat oxygen aging time, and aging mechanism and surface topography were analyzed by FTIR and SEM. The study results indicate that heat oxygen aging reduces the mechanical properties of WRPC. After aging for 100 h, the retention rates of static flexural strength, elastic modulus, tensile strength and impact strength are 93.40%, 84.74%, 79.75% and 82.63%. The retention rates of storage modulus and loss modulus are 84.34% and 89.18%. Material rigidity and damping performance are all decreased. The vicat softening temperature and heat distortion temperature show an upward trend and then a downward trend. The ability of materials to resist external deformation is reduced. According to FTIR and SEM analysis, the oxidation reaction occurs on the surface of WRPC during aging. The carbonyl index shows an upward trend and then a downward trend. Cracks and holes appear on the surface of WRPC.

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    Processing rheological properties of ethylene-vinyl alcohol copolymer/nylon 6 composites
    Zhu-wu YI, Yue-jun LIU, Xiao-chao LIU, Jian YANG, Xiang-gang LI, Shu-hong FAN
    2021, 49 (8): 145-152.   DOI: 10.11868/j.issn.1001-4381.2019.001133
    Abstract ( 248 ( PDF (7436KB)( 96 Citation

    Ethylene-vinyl alcohol copolymer/nylon 6 (EVOH/PA6) composites were prepared by a melt blending method. The processing rheological properties of EVOH/PA6 composites were studied by advanced capillary rheometer and rotational rheometer. The relationship between viscosity and shear rate () of EVOH/PA6 composites were fitted by power law model, and the relationship between viscosity and temperature of composites were described by Arrhenius equation. The results show that the EVOH/PA6 composites are pseudoplastic fluid. Apparent viscosity (ηa) and non Newtonian constant (n) of EVOH/PA6 composites are all enhanced with the increasing contents of EVOH. In the angular frequency (ω) scan range, the storage modulus (G'), loss modulus (G″), and complex viscosity |η*| of EVOH/PA6 composites are enhanced by the addition of EVOH. Han curve, cole-cole curve and scanning electron microscope (SEM) study show that EVOH and PA6 have good compatibility. Furthermore, EVOH/PA6 composite forms a microphase separation structure when containing 15% (mass fraction) EVOH.

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    Preparation of chitosan/sodium lignosulfonate adsorbent and its removal of Pb2+ and Cd2+
    Dong-liang HAO, Qi-lin WANG, Xin-yu MAO, Ya-li LIANG, Xiao-hou SHAO
    2021, 49 (8): 153-161.   DOI: 10.11868/j.issn.1001-4381.2020.001138
    Abstract ( 217 ( PDF (14086KB)( 74 Citation

    Industrial wastewater has brought huge disasters to water bodies and soil, and seriously affected the growth of crops. In order to obtain clean water, a stable, effective and sustainable treatment agent must be prepared to control water pollution. The lignin-based hydrogel adsorbent was prepared on polyacrylic acid by free radical polymerization of sodium lignosulfonate and chitosan, which was applied to remove Pd2+ and Cd2+. The orthogonal method was used to optimize the content of sodium lignosulfonate, chitosan, cross-linking agent and initiator. Fourier infrared spectrometer, scanning electron micrograph, thermal analyzer and Zeta potentiometer were used to characterize the adsorbent. The effects of different conditions on the adsorption of Pb2+ and Cd2+ by lignin-based hydrogels were discussed, and the kinetics and isotherm models on the basis were established. The results show that when the adsorbent is 0.015 g, the concentration of heavy metal ions is 100 mg·L-1, and the pH value is 7, the adsorption capacity for Pd2+ is 367 mg·g-1 and the adsorption capacity for Cd2+ is 296 mg·g-1. Simultaneously, it is revealed that the adsorption process of lignin-based hydrogels is an adsorption mode in which electrostatic adsorption is supplemented by chemical adsorption.

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    Effect of nanostructure on catalytic degradation of chlorobenzene over Ce-V catalysts
    Qi SHI, Long DING, Hong-ming LONG, Yi-fan WANG, Tie-jun CHUN
    2021, 49 (8): 162-168.   DOI: 10.11868/j.issn.1001-4381.2019.001111
    Abstract ( 189 ( PDF (6503KB)( 36 Citation

    Ce-V catalysts were synthesized by a hydrothermal method. In order to change the chemical environment of solution during the preparation process, NaOH solution and ammonia were used to adjust the pH value, and surfactant P123 was added to limit the grain growth direction of Ce-V catalysts. And then different Ce-V catalysts with nano-cubic(CV-1), nano-particles (CV-2) and nano- robs (CV-3) were obtained, respectively.The chlorobenzene conversion of Ce-V catalysts with different nano-structure were investigated. The Ce-V catalysts were characterized by XRD, BET and TEM, and the controlling mechanism of nano-structure on the catalytic activity was analysed.The results show that the particles size order of Ce-V catalysts is CV-1 > CV-2 > CV-3, and the catalytic activity order of Ce-V catalysts is CV-3 > CV-2 > CV-1.New phase CeVO4 forms in CV-2 and CV-3 catalysts, which weakens the agglomeration of VOx on the catalyst surface and promotes catalytic activity. The kinetics calculation results of Ce-V catalysts show that the apparent activation energy of CV-3 is the highest, which is 9.26±3.76 kJ·mol-1. It is consistent with the catalytic activity test.

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    Tensile fatigue properties of carbon fiber reinforced composite orthogonal laminates after moisture absorption
    Xiang-lin ZHANG, Qing-chun MENG, Ming-rui XU, Ben-yin ZENG, Xiao-quan CHENG, Wei SUN
    2021, 49 (8): 169-177.   DOI: 10.11868/j.issn.1001-4381.2020.000662
    Abstract ( 229 ( PDF (13291KB)( 132 Citation

    The fatigue performance of composite structures in wet environment will be degraded seriously, which will affect the structure safety. Therefore, the influence of wet environment should be taken into consideration when determining the structure life. The tensile fatigue properties of carbon fiber reinforced composite orthotropic laminates in wet and dry state at room temperature were tested. The influence of saturated moisture absorption on the tensile fatigue properties was studied. The S-N curves of two kinds of environments were obtained. On this basis, the finite element models were established, and the fatigue life and damage evolution of the orthotropic laminate after moisture absorption were predicted. The calculated results agree well with the test results, which prove the validity of the model. The results show that the saturated moisture absorption has a great influence on the tensile fatigue properties of orthogonal laminate. After moisture absorption, the tensile fatigue life of the laminates is significantly lower than that of the laminates in dry state, and the slope of S-N curve is slightly lower. The fiber damage initiation and propagation of laminate are also different from those in dry state.

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    Poisson effects of 2D-C/SiC composite under axial loading conditions
    Hong-bao GUO, Zhi-liang HONG, Kai-yuan LI, Wen-bin MEI
    2021, 49 (8): 178-183.   DOI: 10.11868/j.issn.1001-4381.2019.001217
    Abstract ( 214 ( PDF (4513KB)( 64 Citation

    By using monotonic and cyclic loading tests, the Poisson curves along the fiber bundles directions of a 2D-C/SiC composite were obtained during various axial tensile and compressive loading processes. And the effects of axial damage evolution process on the Poisson effect of composite were studied. The results show that composite shows significant negative Poisson's ratio behaviors with increasing tensile damage during loading process, but the Poisson's ratio behaviors become almost linear and positive when the damage evolution process stops. In addition, the Poisson effect becomes weaker with increasing damage degree within composite. The SEM (scanning electron microscope) analysis results of fractured surfaces on tensile specimens indicate that, during tensile damage evolution process, the matrix cracks and interface debondings occurring along the loading direction will generate vertical extension deformation on composite, which is large enough to cover up the transverse elastic Poisson contraction caused by applied tensile load, so 2D-C/SiC composite shows significant negative Poisson' ratio behaviors. And the weaker Poisson effect of composite is mainly caused by the increasing discontinuity of composite, which is caused essentially by increasing cracking damage during tensile damage evolution process.

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