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      20 December 2020, Volume 48 Issue 12 Previous Issue    Next Issue
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    Research progress in nano-meso scale modelling of carbon nanotube reinforced FRP composites
    Xiang-na LIAO, Yong-lyu HE, Jian-wei ZHANG, Su JU, Da-zhi JIANG, Jia-yin LIU, Jun LIU
    2020, 48 (12): 1-11.   DOI: 10.11868/j.issn.1001-4381.2020.000154
    Abstract ( 555 ( PDF (10498KB)( 349 Citation

    As one of the most promising nanofiller, carbon nanotube has attracted more and more attention due to its extraordinary stiffness and strength. While it is not feasible to obtain the effects of carbon nanotubes on the mechanical properties of composites by solely relying on experimental methods, cleaving and analysing the influence of various parameters of carbon nanotubes on the mechanical properties of composites through numerical simulation methods has become a tendency. Based on the morphology of carbon nanotubes, the nano-meso scale model was proposed. Then three numerical simulation methods were classified depending on the differences between the way of modelling and the objects of discussing. In the end, the influencing law of carbon nanotubes on the mechanical properties of composites was reviewed from two aspects(intrinsic properties of carbon nanotubes, content and distribution of carbon nanotubes), which is expected to provide support to the credibility of results from numerical simulation method. In addition, due to the variety of numerical simulation methods and the diversity of carbon nanotube variables, the numerical simulation research of carbon nanotubes reinforced FRP composites still has great potential.

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    Research progress in polyelectrolyte complexes based on layer-by-layer self-assembly technology and their applications
    Shuai ZHANG, Yan-ping HUANG, Guo-min ZHAO, Ming-zhu PAN
    2020, 48 (12): 12-23.   DOI: 10.11868/j.issn.1001-4381.2019.000763
    Abstract ( 437 ( PDF (9780KB)( 318 Citation

    Polyelectrolytes (PEs) are a class of polymers with ionizable groups on molecular chains and could dissociate into a highly charged polymeric molecule in ionizing solvent. According to their surface charges, PEs can be classified into three groups: cationic PEs, anionic PEs and amphoteric PEs. PEs have received the attention of scientists for nearly a century ever since the discovery that some natural PEs could interact in water to form colloidal complexes known as polyelectrolyte complexes (PECs). PECs with three-dimensional macromolecule structure can be formed by mixing opposite charged PEs in solution. Formation of PECs will significantly influence the solubility, rheology, turbidity and conductivity of polymer solution and as-formed PECs contain the feature of stimulus responsiveness to change of external environment. Layer-by-layer self-assembly (LBL) of multilayers based on alternately adsorbing opposite charged PEs or multi-charged molecules on solid surfaces is a simple and multifunctional interface supramolecular self-assembly technology that developed in 1990 s. With the application of LBL technology, PECs with certain structures and properties are designed and are widely used in different kinds of industry. This review focuses on the preparation method, formation mechanism, influencing factors of PECs based on LBL technology. In addition, applications of PECs in nanoreactors, drug release, biosensor and fabric flame retardant fields were also summarized. Finally, it was pointed out that future research will focus on simplifying the production process, accurately controlling over the structure and realizing the multi-function of PECs.

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    Research on the fabrication of 3D graphene and its application in chemiresistive gas sensors
    Fei AN, Bing SUN, Na LI, Shi-qiang WANG, Hao-zhi WANG
    2020, 48 (12): 24-35.   DOI: 10.11868/j.issn.1001-4381.2020.000605
    Abstract ( 395 ( PDF (13341KB)( 136 Citation

    Most common chemiresistive gas sensors, based on metal oxide semiconductors, have high energy consumption and poor gas response, which are not suitable for gas detection in factory. With the development of the research on 3D graphene, 3D graphene and its composites become a hotspot of gas sensor researches, because of its large specific surface area and high electrical conductivity. In this paper, the fabrication, performance and application of gas sensors based on 3D graphene and its composites were summarized.At the same time, in view of the slow response recovery speed and small production scale of the current 3D graphene-based gas sensor, solutions such as miniaturization and intelligent production of the sensor chip were proposed, so that it can become the front end of the industrial Internet of Things in the future.

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    Research progress on lightweight design and technology of fiber reinforced plastics components in automobile industry
    Yi-zhe CHEN, Yue ZHAO, Hui WANG
    2020, 48 (12): 36-43.   DOI: 10.11868/j.issn.1001-4381.2019.001103
    Abstract ( 516 ( PDF (3500KB)( 247 Citation

    The fiber reinforced plastics (FRP) material is composed of reinforcing fiber and matrix material. It has the characteristics of high strength, low density, good corrosion resistance and strong designability. It has been widely used in the field of automobiles. As the automobiles continue to develop toward low cost, high efficiency, and automation, the manufacturing of composite components faces higher requirements of lightweight. The research progress of lightweight of fiber composite components in automobile field was reviewed from three aspects of materials, structure and forming process. The development and application of continuous fiber composite parts were introduced. The design and forming technology of lightweight composites for FRP in automobile field were given. Prospects and challenges for the development of FRP were presented as well. Under the background of energy saving and emission reduction, fiber composite materials will be widely used in automobile lightweight design.Meanwhile, how to reduce the cost of composite products will become a new challenge.

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    Research progress in high thermal conductivity diamond/aluminum composites
    Yuan LIU, Yan CUI, Kai-jin GUO, Lei-gang CAO, Yue YANG
    2020, 48 (12): 44-52.   DOI: 10.11868/j.issn.1001-4381.2019.000781
    Abstract ( 343 ( PDF (5023KB)( 183 Citation

    The mainstream fabrication technologies and the key factors affecting their thermal conductivity of diamond/aluminium composites with high thermal conductivity for thermal manag-ement were reviewed. The vacuum hot pressing sintering, spark plasma sintering, pressureless infiltration, vacuum pressure infiltration and squeeze casting were emphatically introduced, and their advantages and disadvantages as well as their applicability were reviewed. The influence of characteristics of diamond particles, matrix alloy elements and diamond surface coating on the interface configuration and thermal conductivity of diamond/aluminium composites was discussed. It was pointed out that matrix alloying and diamond surface metallization can improve the interface bonding of the composites. In order to improve the thermal conductivity of diamond/aluminium composites, the regulation of interface microstructure and the mechanism of interface heat transfer should be paid more attention to.

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    Research Article
    Preparation and lithium storage properties of free-standing and three-dimensional porous Cu@SnO2 membrane electrode
    Huan YANG, Zhi-jun QIAO, Zhi-jia ZHANG, Jian-li KANG, Zhen-yang YU
    2020, 48 (12): 53-59.   DOI: 10.11868/j.issn.1001-4381.2019.000986
    Abstract ( 440 ( PDF (11775KB)( 112 Citation

    In order to solve the problem of the low load of nano active materials in traditional electrodes, the free-standing and three-dimensional porous Cu@SnO2(3DCu@SnO2) membrane electrode with high loading capacity was obtained by nonsolvent induced phase separation method and reduction/sintering process to inherit the three-dimensional porous structure of polymer membrane. The morphology, structure and electrochemical properties of free-standing membrane electrodes were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD) analysis and electrochemical workstations. The effects of material ratio and sintering temperature on the structure and properties of self-supporting membrane electrodes were clarified. The results show that the membrane electrode with 60%(mass fraction, the same below) copper powder sintered at 600 ℃ has three-dimensional bicontinuous porous structure with SnO2 loading up to 30%. At the current density of 100 mA·g-1, the reversible specific capacity can reach 715 mAh·g-1, and remains 433.9 mAh·g-1 after 50 cycles. The specific capacity retention rate can reach 72% when the current density increases to 600 mA·g-1. The resistance of the 3DCu@SnO2 membrane electrode is 70% lower than that of traditional coating electrode.

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    Preparation of injectable sodium alginate/ poloxamer composite hydrogel for sustained drug release
    Bing-na HOU, Ze-lin ZHENG, Zi-nian ZHAO, Jin LI, Kai NI, Lin-lin ZHAO, Zheng-zheng LI
    2020, 48 (12): 60-67.   DOI: 10.11868/j.issn.1001-4381.2020.000283
    Abstract ( 583 ( PDF (7373KB)( 299 Citation

    Poloxamer is a thermo-sensitive synthetic polymer that can achieve sol-gel transition with temperature change, but its relative molecular mass is low, and the hydrogel structure is difficult to maintain for a long time. The thermo-sensitive sodium alginate/poloxamer composite hydrogel (SA/P407) was synthesized by mixing poloxamer with sodium alginate. The chemical structures, temperature sensitivity, microscopic morphology, dynamic viscoelasticity and in vitro drug release behaviors of sodium alginate/poloxamer composite hydrogels were investigated by FT-IR, test tube inversion, SEM, rheometer and UV-Vis spectroscopy. In addition, the swelling properties of sodium alginate/poloxamer composite hydrogels were also studied. These results show that the sodium alginate/poloxamer composite hydrogel is thermo-sensitive, and the gelation concentration (mass fraction is 6%) of poloxamer at body temperature can be reduced by adding sodium alginate. By controlling the mass ratio of sodium alginate and poloxamer, the sol-gel transition temperature can be kept between room temperature and body temperature (25-37 ℃), and the gelation time can be shortened to 84 s. The sodium alginate/poloxamer composite hydrogel has a structural feature of high porosity and interconnected pores, and its pore size ranges from 20 μm to 80 μm. With the increase of sodium alginate, the swelling rate of the sodium alginate/poloxamer composite hydrogel is gradually decreased. The sodium alginate/poloxamer composite hydrogel shows sustained release of the anticancer drug gemcitabine, and the drug release time can reach 72 hours. Sodium alginate/poloxamer composite hydrogel has an important application prospect in the field of injectable carriers for sustained drug release.

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    Gelatin-mediated coprecipitation synthesis of copper sulfide nanoparticles for photothermal ablation of cancer cells
    Wan-jian YU, Peng GENG, Mei WEN, Zhi-gang CHEN
    2020, 48 (12): 68-74.   DOI: 10.11868/j.issn.1001-4381.2019.001037
    Abstract ( 411 ( PDF (15608KB)( 118 Citation

    CuS nanomaterials were prepared through a gelatin-mediated co-precipitation method. The effects of gelatin amount, reaction temperature and time on the morphology, phase and photo absorption were investigated. The results show that the optimized gelatin amount is 0.25~0.5 g, and the increased temperature or time can enhance the size and crystalline of CuS nanomaterials. CuS nanoparticles prepared with 0.5 g gelatin at 80 ℃ for 6 h have the strongest near-infrared (NIR) photoabsorption. The 0.1 mL aqueous dispersion containing 0.4 mg/mL CuS-gelatin which is continuously irradiated by the 1064 nm laser with a power density of 1.0 W/cm2, and the temperature rising reaches a maximum value of 30.8 ℃ at 300 s, yielding a photothermal conversion efficiency of 35.7%. In addition, compared with bare CuS nanoparticles, CuS-gelatin exhibits the lower cytotoxicity. Importantly, cancer cells in vitro can be efficiently ablated by the photothermal effect of CuS-gelatin with the irradiation of 1064 nm laser for 10 min.

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    Effect of annealing temperature on properties of SiO2/Si3N4 optical films prepared by PECVD method
    Li-yu WU, Xiao-qiang LI, Bin WANG, Sheng-guan QU
    2020, 48 (12): 75-81.   DOI: 10.11868/j.issn.1001-4381.2019.000894
    Abstract ( 414 ( PDF (5690KB)( 285 Citation

    Based on the basic principle and algorithm of multi-layer optical thin films, SiO2/Si3N4 double-layer antireflection films for three-junction reverse GaAs solar cells were prepared on GaAs substrate by plasma enhanced chemical vapor deposition (PECVD). The relationships between post-annealing and the morphology, structure and optical properties of the multilayer films were characterized by atomic force microscope (AFM), Fourier transform infrared spectrometer (FT-IR), elliptical polarizer, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis spectrophotometer. The results indicate that the films are crystalline state both before and after annealing. With the increase of annealing temperature, the roughness and average reflectance gradually decrease. SiO2/Si3N4 films annealed at 700 ℃ have the best performance with the lowest average reflectance of 12.65% and roughness of 1.64 nm. The spectral curve of the films move towards to short-wave direction about 30 nm, showing a typical "blue-shift" phenomenon, which indicates that the optical thickness of the films demonstrates a declining trend with the rising of annealing temperature.

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    Preparation of g-C3N4 nanosheets photoelectrode and its photoelectrocatalytic activity for tetracycline degradation
    Xiao-feng HU, Qing-qi PENG, Wen-hua ZHANG, Wen-hua YE, Hui-hu WANG
    2020, 48 (12): 82-89.   DOI: 10.11868/j.issn.1001-4381.2019.000576
    Abstract ( 316 ( PDF (10043KB)( 103 Citation

    g-C3N4 nanosheets photoelectrode was prepared by a facile drop coating method. The influences of precursor materials and bias voltages on the photoelectrocatalytic properties towards tetracycline degradation using as-prepared g-C3N4 nanosheets photoelectrode (DUCN) were studied. The results demonstrate that the DUCN photoelectrode prepared by calcination of urea and dicyandiamide precursor mixtures exhibits the highest pollutant removal efficiency, which may be due to its best film formation property and highest photoelectron-hole separation efficiency. In addition, in the process of photoelectrocatalysis (PEC), photocatalysis (PC) and electrocatalysis (EC) promote and optimize each other, showing a significant synergistic effect. The DUCN photoelectrode displays the highest removal rate of tetracycline with an initial concentration of 5 mg/L at a bias of 1.0 V, which are 5.6 times and 3.8 times of that obtained by single photocatalytic and electrocatalytic process, respectively. The reason for the enhanced pollutant removal efficiency may be that the external bias voltage enables the photogenerated electrons transfer to the counter electrode more efficiently under the photoelectric synergistic effect, which promotes the separation of photogenerated electrons and holes.

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    Influence of doping Zr on the performance of CeO2-ZrO2-Al2O3 composite oxide after reductive heat treatment
    Huang-gen YANG, Yu-fang TAN, Qing-min WEI, Quan YAN, Yuan CHEN, Li-gang ZHU, Li-qin QIN, Yi-hong XIAO
    2020, 48 (12): 90-96.   DOI: 10.11868/j.issn.1001-4381.2019.000455
    Abstract ( 312 ( PDF (4373KB)( 154 Citation

    Ceria-zirconia-alumina composite oxides CZxA (the molar ratios of Ce, Zr and Al are 1:x:2, x=0, 0.5, 1, 1.5 and 2) fresh samples were prepared by the co-precipitation method. The samples were thermally aged in a flowing air atmosphere and in 10% H2/Ar flow. The structure and performance of the composite oxides were studied by X-ray powder diffraction (XRD), N2 adsorption-desorption (BET), oxygen storage capacity (OSC) measurements, and H2 temperature-programmed reduction (H2-TPR). The results show that for CZxA samples, with the increase of the content of Zr, no CeAlO3 phase is observed in the CZ1.5A-H2-1100 and CZ2A-H2-1100 samples which are reductively aged at 1100 ℃; the oxygen storage capacity (OSC) is 713 μmol·g-1 and 548 μmol·g-1, respectively, far higher than the 23 μmol·g-1 of CZA-H2-1100; and the hydrogen consumption of H2-TPR is 1995 μmol·g-1 and 2087 μmol·g-1, respectively, while the hydrogen consumption of CZA-H2-1100 was significantly reduced to 310 μmol·g-1. The OSC of CZxA is affected by the formation of CeAlO3 during the reductive treatment, which is consistent with the change result of the hydrogen consumption of H2-TPR. It was found that CA samples are more likely to produce CeAlO3 after reductive treatment, and the CZ1.5A and CZ2A samples doped with a certain amount of Zr elements in CA can inhibit the formation of CeAlO3, thus significantly improve the oxygen storage performance and the hydrogen consumption of H2-TPR of the material. Furthermore, CZxA have better reduction performance at low temperature after reductive treatment.

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    Preparation of phase change wax@polyvinyl alcohol thermo-regulated finishing agents and its applications on cotton fabrics
    Guo-jin LIU, Feng SHI, Guo-qing ZHANG, Lan ZHOU
    2020, 48 (12): 97-102.   DOI: 10.11868/j.issn.1001-4381.2019.000959
    Abstract ( 380 ( PDF (8510KB)( 125 Citation

    The thermo-regulated finishing agents were prepared by high speed shear emulsification with phase change wax as energy storage and temperature control materials, polyvinyl alcohol (PVA) as coating materials, and then the cotton fabrics were treated by the prepared finishing agent by a padding-curing process. The basic properties of the phase change wax and the film forming properties of PVA were analyzed, the effects of the phase change wax and PVA ratios and the amounts of emulsifier on the performance of the finishing agent were investigated, and the surface morphology, heat storage and temperature regulation performance and washing fastness of resultant thermo-regulating cotton fabrics were characterized by SEM, DSC, TG, mini temperature recorder and water washing experiments. The results show that the melting temperature of the phase change wax is 30.24 ℃, the thermal enthalpy value is 190.0 J/g, the degree of supercooling is 5.82 ℃. PVA has high film formation speed, good film-forming ability and strong adhesion to the substrate when the temperature is above 70 ℃; when the ratio of the phase change wax to PVA is 5 :1 and the amount of the emulsifier is 4.8%(mass fraction) of the phase change wax, the prepared thermo-regulating finishing agent is relatively stable; after a padding-curing process, the surface of the cotton fibers is wrapped by an apparent film, and the prepared thermo-regulating cotton fabrics have phase change heat enthalpy of 20.51 J/g and phase transition temperature of 27.67 ℃. Under the same cooling conditions, the finished cotton fabrics exhibit good heat storage and temperature regulation performance, and can withstand 30 times of washing.

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    Effect of cold rolling deformation before intermediate annealing on microstructure and properties of 6A16 aluminum alloy
    Li-zhen YAN, Yong-an ZHANG, Bai-qing XIONG, Xi-wu LI, Zhi-hui LI, Kai-xin CHEN
    2020, 48 (12): 103-110.   DOI: 10.11868/j.issn.1001-4381.2019.001064
    Abstract ( 409 ( PDF (42622KB)( 124 Citation

    Effect of different cold rolling deformations before intermediate annealing on the microstructure and forming properties of 6A16 aluminum alloy sheet during subsequent processing was investigated by means of EBSD and mechanical properties tests.The results show that with the increase of cold deformation before intermediate annealing, the size of the grains after annealing decreases, the proportion of complete recrystallization increases, and the sheet possesses a typical deformed structure after cold rolling, and the grain size increases gradually.After T4P treatment, with the increase of the cold deformation before the intermediate annealing, the grain size of the cold-rolled sheet increases, the work hardening exponent n10%-20% value does not change and the plastic strain ratio r10% value increases.It shows that, the forming ability of the sheet is the best when the cold rolling deformation before annealing is 66.67%.

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    Expansion-continuous shear deformation behavior of 6061 aluminum alloy
    Yao XIANG, Li-wei LU, Mu-yi WU, Min MA, Wei KANG, Huan LIU, Lun-yuan TANG
    2020, 48 (12): 111-118.   DOI: 10.11868/j.issn.1001-4381.2019.001043
    Abstract ( 409 ( PDF (16330KB)( 99 Citation

    A new expansion-continuous shear deformation technique was used to prepare the 6061 aluminum alloy sheet. The extrusion deformation behavior of 6061 aluminum alloy was discussed by the finite element simulation. The microstructure and mechanical properties of 6061 aluminum alloy were studied via the testing and analysis tools of electron back-scatter diffraction, tensile test and scanning electron microscope. The results show that the expansion-continuous shear deformation can coordinate the stability of metal flow velocity during the deformation process of the aluminum alloy. The severe plastic deformation can produce a large and uniform equivalent strain in the extrusion billet, which can effectively trigger continuous dynamic recrystallization, moreover, the orientation distribution of fine grains is scattered, which can effectively refine the grain and weaken the texture. After extrusion, 6061 aluminum alloy presents excellent mechanical properties, and the tensile strength and the elongation can reach up to 380 MPa and 21%, respectively. A large number of dimples emerge in the tensile fracture, which can be attributed to ductile fracture.

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    Effect of ball milling time on microstructure and mechanical properties of ultrafine- grained Mg-3Al-Zn alloy prepared by powder metallurgy
    Wa FANG, Ji-guang LI, Zheng-yong DU
    2020, 48 (12): 119-125.   DOI: 10.11868/j.issn.1001-4381.2019.001123
    Abstract ( 345 ( PDF (11082KB)( 112 Citation

    The ultrafine-grained Mg-3Al-Zn alloy was prepared by high energy ball milling, cold vacuum press and warm extrusion. The influence of ball milling time on the microstructure and mechanical properties of the alloy was studied. The results show that Al and Zn elements completely dissolve into the magnesium matrix in the process of ball milling. The single phase solid solution is formed. After the ball-milling for 20 h, the average particle size of the powder particles is about 25 μm, and the average grain size is about 45 nm. After the powder is densified by cold pressing and warm extruded, the average grain size of the alloy milled for 20 h is 600 nm, and the grain shape is regular and equiaxed crystal. All ultrafine-grained alloys show higher mechanical properties. The yield strength, tensile strength and breaking strain of the alloy after ball milling for 20 h are 369 MPa, 401 MPa and 3.5%, respectively. The tensile true stress-true strain curve of ultrafine-grained magnesium alloy shows a characteristic of ideal rigid plasticity. The compression true stress-true strain curve can be divided into three stages: working hardening, working softening and working hardening.

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    Instability deformation analysis of laser welded joint of 316L ultra-thin plate
    Jing-qi ZHANG, Jian LIN, Yong-ping LEI, Hai-liang XU, Xi-bo WANG
    2020, 48 (12): 126-134.   DOI: 10.11868/j.issn.1001-4381.2019.001168
    Abstract ( 356 ( PDF (11709KB)( 105 Citation

    Based on the thin plate stability theory determined by energy criterion, the finite element model of unstable deformation of ultra-thin plate laser welded joint was established. The temperature field and stress field of 316L steel foil plate surfacing welding with 0.07 mm thickness were simulated by ABAQUS, and the distribution of inherent strain was obtained. The eigenvalue buckling analysis of the post-welding instability deformation behavior in thin plate was carried out by using inherent strain obtained by integral calculation as equivalent load. Compared with the measured deformation results of laser welding, it was found that the ultra-thin metal plate presents concave-convex deformation mode after lower heat input, while convex-concave deformation occurs after higher heat input in the thin plate. The parameters of the numerical model were optimized, and the reasons for the change of the deformation mode of the thin plate were discussed. The nonlinear buckling analysis was carried out by introducing the low-order eigenvalue buckling mode as the initial deformation trend, and the unstable deformation was simulated, which is basically consistent with the actual deformation measurement results. Keeping the ratio of length to width of the thin plate at 1:1 and changing the size of the thin plate, the numerical relationship between the critical instability load and the size of the thin plate was fitted. The results show that the smaller the area of the thin plate is, the greater the critical buckling load of the thin plate is. With the increase of the thickness of the thin plate, the critical buckling load is increased significantly.

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    Effect of cyclic heat treatment on carbide evolution and impact toughness of 1Cr-0.5Mo steel
    Guang-xing CHEN, Yong-wei ZHANG, Xiao-chang XU, Chen XU, Hong-ying LI, Ming-chun ZHAO
    2020, 48 (12): 135-140.   DOI: 10.11868/j.issn.1001-4381.2019.001098
    Abstract ( 308 ( PDF (8634KB)( 122 Citation

    The effects of the evolution behavior of carbide on impact toughness of 1Cr-0.5Mo steel during cyclic heat treatment were investigated by quantitative metallographic method and electrolytic extraction method with SEM, XRD, EPMA and low temperature impact test. The results show that with the increasing number of cyclic heat treatment, the lamellar carbides in the pearlite structure dissolve and spheroidize gradually, and the type of carbide also changes: M3C→M23C6. Increasing the number of cyclic heat treatments promotes the precipitation and connection of M23C6 along the grain boundaries, significantly deteriorates the impact toughness of 1Cr-0.5Mo steel.When the number of cyclic heat treatments reaches 4, the M23C6 grows to chain-like at the grain boundary and the impact toughness of 1Cr-0.5Mo steel can no longer meet the requirements. During the cyclic heat treatment, the average equivalent circle diameter of the overall carbide in 1Cr-0.5Mo steel shows a trend of decrease first and then increase because of the dissolution of lamellar carbides and the Ostwald ripening of carbides.

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    Effect of strain rate on deformation mechanism of metastable β grains in TB17 titanium alloy
    Yun-peng XIN, Zhi-shou ZHU, Xin-nan WANG, Guo-qiang SHANG, Li-wei ZHU, Ming-bing LI, Jing LI, Ge-chen LIU
    2020, 48 (12): 141-147.   DOI: 10.11868/j.issn.1001-4381.2019.000974
    Abstract ( 342 ( PDF (12949KB)( 94 Citation

    The effect of different strain rates (0.001, 1, 3×103 s-1) on metastable β grain deformation mechanism of TB17 titanium alloy was studied by optical microscope (OM), electron backscattered diffraction (EBSD), and transmission electron microscope(TEM). The results show that metastable β grains are highly sensitive to strain rate. The compressive strength of the alloy at strain rate of 1 s-1 is about 25% higher than that at strain rate of 0.001 s-1. Under dynamic loading with strain rate of 3×103s-1, the compressive strength of the alloy is also greatly improved. At lower strain rate (< 1 s-1), slip is the main deformation mechanism and small angle grain boundaries are formed around slip lines. At high strain rate (3×103 s-1), the main deformation mechanism is stress-induced martensitic transformation.

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    Effect of Y on ZL114A eutectic silicon and mechanical properties with gravity casting under different cooling rates
    Zhen WU, Shan-guang LIU, Zheng LU, Guo-ling MAO, Han YAN
    2020, 48 (12): 148-155.   DOI: 10.11868/j.issn.1001-4381.2019.000806
    Abstract ( 273 ( PDF (17891KB)( 109 Citation

    The effects of different content of Y element on the morphology, mechanical properties and fracture mode of ZL114A alloy in as-cast and solid-solution-quenched state were studied by SEM and room temperature tensile test under the conditions with different cooling rates. The results show that Y can degrade eutectic Si and improve the mechanical properties of the as-cast alloy under both slow cooling (V=0.16 ℃/s) and fast cooling (V=3.2 ℃/s) while the effect is more obvious under fast cooling. Eutectic Si deteriorated by Y element is more likely to be fusible and spheroid during solid solution treatment. Therefore, the mechanical properties of the alloy in the solid solution quenching state are better and the elongation is greatly improved. With the addition of Y element, the crack initiation mode of ZL114A alloy is changed from being generated at the interface of eutectic Si and aluminum matrix to the combination of fracture of eutectic Si and being generated at the interface of eutectic Si and aluminium matrix.

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    Effects of original layer thickness ratio on exothermic and mechanical properties of Ni/Al multilayered energetic structural composites
    Qing-yun DING, Xin-yi LUO, Jie TAO, Sha LIAO
    2020, 48 (12): 156-162.   DOI: 10.11868/j.issn.1001-4381.2019.000954
    Abstract ( 300 ( PDF (8911KB)( 82 Citation

    Ni/Al multilayered energetic structural composites with micron scale were prepared by electroless plating followed by hot press process. The effects of original layer thickness ratio on the microstructure, exothermic properties and mechanical properties of the fabricated composites were investigated, and then the fracture mechanism was analyzed. The results show that the interface bonding of Ni/Al multilayered energetic structural composites is perfect and the initial temperature of interface reaction increases with the increase of original layer thickness ratios. The 2/3 Ni/Al multilayered energetic structural composite not only has the highest reaction energy density of 1051.62 J/g, but also has good strength and plasticity. The tensile strength, elongation and bending strength reach 285.05 MPa, 8.87% and 309.09 MPa respectively. When the layer thickness ratio increases from 1/2 to 1/1, both the tensile strength and bending strength increase, the plasticity decreases. This is related to the composition and interfacial structure. Failure mode of Ni/Al multilayered energetic structural composite is delamination mixed with fracture, and the interface delamination gets more serious with the increase of the layer thickness ratio.

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