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      20 January 2020, Volume 48 Issue 1 Previous Issue    Next Issue
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    Research progress in layered double hydroxides catalysts for oxygen evolution reaction
    Bo-yao XIE, Ji-mei ZHANG, Shuai-shuai HAO, Ming-gang BI, Hai-bin ZHU, Li-ping ZHANG
    2020, 48 (1): 1-9.   DOI: 10.11868/j.issn.1001-4381.2018.000900
    Abstract ( 978 ( PDF (1934KB)( 540 Citation

    The layered double hydroxides become research hot spot of oxygen evolution catalyzer for its easy preparation, feasible moderation of interlayer object, low cost and good stability but due to its low transmission speed of its electric charge, higher overpotential, so the modification is needed before mass application. The constructional character of the layered twinned material was firstly introduced, the catalytic mechanism of its oxygen evolution reaction was briefly described, then different kinds of optimization modification strategies to enhance its catalytic activity were introduced. The optimization modification strategies include:combination with conductive substrate, synthesis ultrathin nanometer plate, graphene compounding process, hybrid modification. The application of the stratified dihydride oxygen evolution catalyst in electrolysis of water to hydrogen and the advantages and disadvantages of different modification methods were put forward. The better-efficient oxygen evolution catalyst can be achieved through different kinds of modification. In the end, the difficulties in this kind of catalyzer were pointed out, including low recycle rate, catalyst stability, current density not meeting the requirements of industrialization and massive production.

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    Research progress in improving heat transfer and heat storage performance of molten nitrate by nanomaterials
    Yan-ze WU, Min WANG, Jin-li LI, You-jing ZHAO, Huai-you WANG, Ming WEI
    2020, 48 (1): 10-18.   DOI: 10.11868/j.issn.1001-4381.2018.001380
    Abstract ( 863 ( PDF (1626KB)( 410 Citation

    Concentrating solar power is the ideal way to solve the conflicts between energy and environment. Heat transfer and heat storage are the key links in solar thermal power generation, while molten salt is an excellent heat transfer and heat storage medium. Most of the solar thermal power stations operating at home and abroad use binary nitrates (solar salt) and ternary nitrates (Hitec). However, their low heat transfer and heat storage performance will affect the efficiency of solar energy utilization. The unique spatial structure of nanomaterials enables it to have excellent thermal conductivity and good stability. Introducing nanomaterials as additives into the nitrate molten salt system is expected to improve the thermal properties of the material such as heat transfer and heat storage, thereby improving the efficiency of solar thermal utilization and reducing the cost of power generation. In this paper, the related studies of nano metal particles, nano metal oxides, carbon nanomaterials, and other inorganic nanomaterials as doping additives in nitrate molten salt systems were reviewed. The changes in the thermal properties of molten salts after modification were discussed and the mechanism of action was explored, which can provide references for preparation of energy storage molten salt with excellent thermal properties. In the future research, the measurement of thermophysical properties, mechanism of heat transfer, quantitative structure-activity relationship and industrial pilot will be focused on, so that nitrate molten salt with excellent heat transfer and heat storage performance can be applied in the field of solar thermal power generation, which will play a more important role in the development and utilization of clean energy.

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    Research progress in corrosion behavior of biomedical magnesium alloys
    Tian WAN, Shu-peng SONG, Jin-zhao WANG, He-rong ZHOU, Yu-xu MAO, Shao-cong XIONG, Meng-jun LI
    2020, 48 (1): 19-26.   DOI: 10.11868/j.issn.1001-4381.2017.000301
    Abstract ( 848 ( PDF (2205KB)( 424 Citation

    As a biodegradable material, magnesium alloys has been attracted by more researchers, recently. Due to good biocompatibility, mechanical properties and biodegradable absorption charac-teristics, it has been honored as revolutionary biological materials. However, current bio-magnesium alloy still could not meet the requirements of clinical application, due to its shortcomings of rapid corrosion rate and local corrosion. In this paper, the progress of bio-magnesium alloy in improving the corrosion performance was reviewed from the aspects of high purity, alloying, heat treatment process and surface modification. The paper makes a prospect on how to develop the biodegradable materials with better corrosion performance in terms of adding non-toxic alloying elements, proper surface coating, advanced preparation technology and heat treatment process.

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    Rsearch Article
    Optimization of process parameters of three-dimensional needled preforms for C/C-SiC composites
    Yun-chao QI, Guo-dong FANG, Jun LIANG, Jun-bo XIE
    2020, 48 (1): 27-33.   DOI: 10.11868/j.issn.1001-4381.2019.000041
    Abstract ( 704 ( PDF (2138KB)( 328 Citation

    A surrogate model was established to optimize needling process parameters of three dimensional needled C/C-SiC composites by using back propagation (BP) neural network and improved genetic algorithm. The relationship between needling process parameters and composites stiffness was obtained. The stiffness prediction obtained by BP neural network is in good agreement with the finite element calculated results. The maximum error of training data is 0.526%, and the maximum error of test data is 0.454%. Thus, the BP neural network model exhibits the high prediction accuracy. The genetic and optimization strategies of genetic algorithm were improved to optimize the needling process parameters. The calculated needling process parameters by the model can significantly improve the stiffness of the C/C-SiC composites. The in-plane tensile modulus increase by 11.07% and 11.48%, and the out-of-plane tensile modulus increase by 49.64% and 48.13%, respectively. The comprehensive stiffness performance of composite material increase by 18.17% and 18.21%, respectively.

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    Coarse-grained model and force field development for predicting phase change and thermal transport in polyethylene
    Zhuang-li CAI, Ling-ling ZHAO, Xi-fan YU, Chao CHEN
    2020, 48 (1): 34-40.   DOI: 10.11868/j.issn.1001-4381.2019.000102
    Abstract ( 566 ( PDF (3005KB)( 330 Citation

    Coarse-grained model and force field for predicting phase change and thermal transport in meso-scale polyethylene were developed and its accuracy was validated. The coarse-grained force field was obtained through coarse-grained molecular dynamics simulations by multistate iterative Boltzmann inversion with all-atom molecular dynamics simulations as a benchmark. The simulations results show that the coarse-grained force field consisting of functional potential terms allows better transferability and more accurate description of the static structural properties of bulk polyethylene compared with those in all-atom simulations. Meanwhile, the deviations between values in coarse-grained simulations and experimental results of densities of bulk polyethylene at 300 K and 500 K are both within 3%. The values of glass transition temperature and melting temperature obtained from coarse-grained simulation are both close to experimental values. In addition, thermal conductivities of extended single polyethylene chain with various lengths in coarse-grained simulations match those in all-atom simulations well and thermal conductivity of disordered bulk polyethylene in coarse-grained simulation is close to the experimental value. The results provide a more powerful simulation method for the investigation of thermal conduction of meso-scale polyethylene.

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    Low velocity impact response and post impact compression behaviour of ESTM-fabric/3266 composites
    Hui-min DONG, Li YAN, Xue-feng AN, Huang-hai QIAN, Zheng-tao SU, Xiao-su YI
    2020, 48 (1): 41-47.   DOI: 10.11868/j.issn.1001-4381.2018.000960
    Abstract ( 641 ( PDF (9041KB)( 226 Citation

    A novel kind of lattice-distributed ESTM-fabrics (ES-L) and random-distributed ESTM-fabrics (ES-R) were developed by using polyethersulfone (PES) and U3160 according to ex-situ toughening technology. ESTM-fabrics reinforced 3266 moderate temperature curing epoxy resin composites (ESTM-fabric/3266) were prepared through RTM process. Impact resistance and residual strength of ESTM-fabric/3266 were studied and the ex-situ toughening mechanism was analyzed by fluorescence microscope and SEM. The untoughened U3160 fabrics reinforced 3266 moderate temperature curing epoxy resin composites were studied to compare performance of composites as well. The result of low velocity impact testing shows that the toughened ESTM-fabric/3266 composites exhibit the higher delamination damage threshold load, the lower projected delaminated areas, the slower damage development, compared to U3160/3266 composites without toughener PES (ES-U).The major failure mode is intralaminar crack (transverse matrix cracking), debonding between fibre and matrix in fiber-bundle regions as well as local ply breakage along with ply-matrix debonding.The ES-L allows an increase of 37% in CAI compared to ES-U. Microstructural observation of damage zone reveals that ES-R composite has a homogeneous distribution of phase inversion in the interlaminar regions while ES-L composite exhibits a hard phase composing of the 3266 epoxy resin continuous matrix and a soft phase composing of the nodular structure of BMI in the 3266 epoxy resin continuous matrix. The excellent impact resistance and damage tolerance of ES-L composite are due to synergistic effects of hard phase and soft phase, which can release the stress concentration, give the extra strain energy dissipated and subsequently terminate crack via crack blunting mechanism.

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    Modification treatment and properties research of fiber reinforced silicon dioxide composites
    Bing-qing ZHANG, Xiao-bo YANG, Zhi-qiang SUN, Zhen-jiang MIAO, Hua-dong WANG, Yi LYU
    2020, 48 (1): 48-53.   DOI: 10.11868/j.issn.1001-4381.2019.000217
    Abstract ( 602 ( PDF (1878KB)( 115 Citation

    The fiber reinforced quartz composites were modified by gaseous phase grafting method, and then the microcosmic pattern, specific surface area, dielectric properties, mechanic properties, moisture absorption rate and other properties of composites were measured and analyzed. The results indicate that the modification treatment and subsequent heat treatment have little influence on microcosmic pattern and specific surface area of composite, moreover no damage to dielectric properties or mechanic properties of composite occurs. After modification, the range of dielectric loss variation with frequency of composites is decreased significantly from 4.7×10-3-6.8×10-3 to 1.7×10-3-2.9×10-3, while the tensile strength of composites is increased evidently from 48.58 MPa to 63.49 MPa. The optimized processing condition of modification is (Tbp+30℃)/72 h/80% M. The ultimate moisture absorption rate of the composites shows significant decrease from 6.35% to 0.32% after the modification, demonstrating the excellent moisture prevention effects of this method.

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    Research Article
    Mix structure of high nitrogen austenitic stainless steel and 316L stainless steel formed by wire and arc additive manufacturing based on size controlling of beads
    Xiang-hong YAO, Qi ZHOU, Ke-hong WANG, Xiao-yong ZHANG
    2020, 48 (1): 54-60.   DOI: 10.11868/j.issn.1001-4381.2018.000423
    Abstract ( 550 ( PDF (4385KB)( 193 Citation

    Wires of high nitrogen austenitic stainless steel and 316L stainless steel were used, the surface forming characteristics of single bead, single-bead multi-layer and single-layer multi-bead were analyzed on high nitrogen austenitic stainless steel, better process parameters were screened. The most suitable process parameters of forming mix structure were obtained by size controlling of both beads. The optimum step-over distance of both beads was obtained by different step-over distance experiments, and mix structure was formed by wire and arc additive manufacturing with a reasonable path. The results show that the varies of process parameters have a great influence on surface forming characteristics of high nitrogen austenitic stainless steel beads, which pores emerge easily on the bead surface; the matching error method on geometry size and cross section area of both beads is proposed, by which optimum process parameters are obtained. The wire-feed rate of two wires are 5.7 m/min and 5.6 m/min, welding speed are both 0.6 m/min. Forming precision of mix structure is improved by reducing the number of arcing times and adopting a closed path, in addition, post processing decr-eases.

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    Effect of annealing process parameters and properties of base material on magnetic properties of ultra-thin grain-oriented silicon steel strip
    Yun-chao TU, Cheng-xu HE, Li MENG, Leng CHEN
    2020, 48 (1): 61-69.   DOI: 10.11868/j.issn.1001-4381.2018.001084
    Abstract ( 519 ( PDF (6332KB)( 233 Citation

    The cold-rolled ultra-thin gain-oriented silicon steel strips with different annealing parameters were studied by EBSD technology. The relationship between microstructure, texture and magnetic properties of annealed samples was analyzed, and the effect of properties of the base material on the performance of the ultra-thin strip was discussed. The results show that the annealing microstructure uniformity, high Goss orientation and better magnetic properties of the base material can effectively improve magnetic properties of the ultra-thin strip, and the annealing heating rate mainly affects the grain size, Goss orientation and magnetic properties; the change of the average grain size of recrystallization structure influences the magnetic induction and iron loss of the final ultra-thin band. Recrystallization obviously occurs after annealing at 900℃ for 5 min, magnetic properties of ultra-thin strips change little after annealing for 10-30 min while the best magnetic properties can be obtained after annealing for 15 min. In addition, the annealing time should not exceed 10 min at 1000℃ and 1100℃, otherwise the magnetic properties will deteriorate.

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    Microstructure evolution of 022Cr25Ni7Mo4N duplex stainless steel during isothermal treatment
    Han FENG, Bao-shun WANG, Xiao-han WU, Man WANG, Qi-liang NAI, Zhi-gang SONG
    2020, 48 (1): 70-76.   DOI: 10.11868/j.issn.1001-4381.2018.001225
    Abstract ( 586 ( PDF (4258KB)( 219 Citation

    The microstructure evolution of 022Cr25Ni7Mo4N duplex stainless steel after isothermal treatment for 2-20 h at 1100℃ was studied. The morphology evolution of austenite grain was observed and the grain size was quantitatively characterized. The change of element content in austenite and ferrite phase was measured. The effect of microstructure evolution on the anisotropy of volume fraction of ferrite phase and low temperature impact toughness of test steels was analysed subsequently. The results show that with the increase of holding time, there is obvious accumulation, growth and coarsening of austenite grain, accompanied by significant changes in grain morphology. The volume fraction of rod-like crystal grains with a/b value above 4.0 dropped from nearly 20% to below 5%, and that of equiaxed grains with a/b value between 1.0 and 1.9 increases significantly, while the number of grains with size above 20 μm increases rapidly. The prolongation of the holding time makes molybdenum and chromium elements diffuse and enrich to the ferrite phase further, which leads to the increase of pitting resistance equivalent number (PREN) value in ferrite phase. The significant decrease in the volume fraction of slender rod-like austenite crystallites is the primary reason for the improvement in anisotropy of austenite volume fraction and the increase of low temperature impact toughness of test steel.

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    Effects of check corrosion on high cycle fatigue properties of nickel-base single crystal superalloy
    Jian-min DONG, Jia-rong LI, Mei HAN
    2020, 48 (1): 77-83.   DOI: 10.11868/j.issn.1001-4381.2019.000229
    Abstract ( 577 ( PDF (4571KB)( 254 Citation

    In order to study the effects of check corrosion on the high cycle fatigue properties of a kind of nickel base single crystal superalloy, the samples with standard heat treatment were corroded twice and four times with FeCl3+HCl+H2O, respectively. Then the surface topographies of uncorroded, twice corroded and four-time corroded samples were observed with Leica DCM8 confocal microscope and SEM. After that, in ambient atmosphere, the uncorroded and four-time corroded samples were subjected to rotary bending high cycle fatigue (HCF) testing at 760℃and 980℃, respectively. The results show that the surface roughness of uncorroded samples is low, and there are many longitudinal fine scratches in parallel resulting from polishing on the surface. After twice corrosion, the scratches are reduced, the corrosion pits appear in interdendrite areas, and the surface roughness increases. After four-time corrosion, the scratches are removed completely, and the depth of corrosion pits and surface roughness further increase. The high cycle fatigue property of the alloy at 760℃ decreases after four-time corrosion, and the high stress amplitude zone is more affected than low stress amplitude zone. However, the high cycle fatigue property at 980℃ is rarely affected after four-time corrosion.

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    Effect of Sc on microstructure and mechanical properties of ZL205A alloy
    Shan-guang LIU, Guo-ai LI, Chuan-biao LUO, Hai-chao LI, Zheng LU, Sheng-long DAI
    2020, 48 (1): 84-91.   DOI: 10.11868/j.issn.1001-4381.2018.000086
    Abstract ( 679 ( PDF (9028KB)( 279 Citation

    The microstructure and ageing precipitation behavior of ZL205A alloy with different addition of Sc were investigated by OM, SEM and TEM. The results show that the grain refinement effect of Sc (up to 0.12%, mass fraction, the same below) is not observed in ZL205A alloy; the residual particle W (AlCuSc) phase is formed after heat treatment when the Sc content is 0.06%, and transformed to strip-liked structure with the increase of Sc content in the grain interface; the dispersed phases Al3 (Zrx, Ti1-x) in ZL205A alloy are transformed to Al3 (Zrx, Tiy, Sc1-x-y), and the number of the dispersed phases increase with the increase of Sc content; when the Sc content is 0.06%, the ageing response, peak hardness increase slightly, and the yield strength increases by 4%; while the Sc content increases to 0.12%, the decrease of the solute concentration may reduce the number of the θ' phase due to the strip-liked W phase formed in the grain interface, which results in the dramatic decrease of the ageing response, peak hardness and mechanical properties; traces of Sc help to slow down the growth of θ' phase during the over-aged stage.

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    Effect of Ce on microstructure and thermal conductivity of as-cast Mg-6Zn alloy
    Xiao-teng DAI, Ming-long MA, Kui ZHANG, Yong-jun LI, Jia-wei YUAN, Xiao-dao LIU, Sheng-qing WANG
    2020, 48 (1): 92-97.   DOI: 10.11868/j.issn.1001-4381.2018.001138
    Abstract ( 487 ( PDF (3984KB)( 236 Citation

    The microstructure of as-cast Mg-6Zn-xCe alloy was investigated by optical microscope (OM), X-ray diffraction (XRD), scanning election microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM)and the changing rule of thermal conductivity with the content of Ce was investigated using the flash method. The results show that Mg-6Zn alloy is mainly composed of α-Mg and Mg7Zn3 phases. The ternary phase Ce5 (Mg, Zn)41 which is mainly distributed between grain boundaries and dendrites appears in the alloy after the addition of the rare earth element Ce, and the appearance of ternary phase has an inhibitory effect on Mg7Zn3 phase. The content of eutectic structure is increased by the addition of Ce, and the distribution continuity is improved with the increase of Ce content. The thermal conductivity of the alloy is decreased with the increase of Ce content, which may be caused by the increase of volume fraction, more continuous distribution of eutectic structure in the alloy, the enhanced electron scattering, the extended electron conduction paths and the increased thermal resistance, ultimately the thermal conductivity of the alloy is reduced.

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    Effect of chlorella vulgaris on corrosion behavior of Mg-3Y-1.5Nd alloy in natural seawater
    Meng-xiao LIN, Jie ZHANG, Quan-tong JIANG, Jia-run LI, Dong-zhu LU, Bao-rong HOU, Yuan-yuan SUN
    2020, 48 (1): 98-107.   DOI: 10.11868/j.issn.1001-4381.2018.000157
    Abstract ( 544 ( PDF (5924KB)( 211 Citation

    The effect of chlorella vulgaris on corrosion behavior of Mg-3Y-1.5Nd alloy in f/2 culture medium was studied by means of X-ray diffraction, scanning electron microscope, energy dispersive analysis system of X-ray and other electrochemistry test. Results show that the main corrosion products on the surface of alloy with and without chlorella vulgaris are Mg (OH)2, Mg3 (PO4)2 and Mg2 (OH)3Cl; Mg and O are present on the specimen surface, and the content of Mg in culture medium with chlorella vulgaris (29.6%) is lower than that without chlorella vulgaris (39.8%); and corrosive ions invade the loose corrosion product structure and promote further corrosion of the alloy; the high O2 concentration produced by the photosynthesis of chlorella vulgaris results in the increase of local O2 concentration underneath the biofilm, which adds oxygen reduction cathodic currents and enhances corrosion. It is conduded that the average corrosion rate in the presence of chlorella vulgaris is more serious than that in the absence of chlorella vulgaris.

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    Comparison on the rolling-sliding dry friction property of AZ91 and AZ91-Y alloy
    Chun-hua LI, Han WANG, Hai HAO
    2020, 48 (1): 108-114.   DOI: 10.11868/j.issn.1001-4381.2018.001159
    Abstract ( 593 ( PDF (3728KB)( 172 Citation

    The rolling-sliding dry friction properties of AZ91 and AZ91-Y (1.0% Y) (mass fraction)were studied with 45 steel as friction pair. The experiment was carried out under different normal loads (100, 200, 300 N), respectively. The worn surfaces of AZ91 and AZ91-Y samples were investigated by energy dispersive spectrometer (EDS), scanning electron microscopy (SEM) and X-ray diffraction (XRD) so as to analyze wear mechanism. The results indicate that the wear rates of AZ91 and AZ91-Y samples boost linearly but the friction coefficients are decreased gradually with the increase of normal loads. Al2Y particles can refine grains, weaken the tendency of interface cracking to improve the wear resistance.Hence, the wear rates of AZ91-Y are decreased by 21.7% and 5.9% compared with AZ91 alloy when normal loads are 100, 300 N, respectively. Meanwhile, the main wear mechanisms of AZ91-Y alloy are abrasive wear and delamination wear, which is the same with AZ91 alloy.

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    Effect of heat treatment temperatures on microstructure and mechanical property of linear friction welded joints of titanium alloys TC17(α+β)/TC17(β)
    Xiao-hong LI, Yan-hua ZHANG, Zan LI, Ju LI, Tian-cang ZHANG
    2020, 48 (1): 115-120.   DOI: 10.11868/j.issn.1001-4381.2018.000295
    Abstract ( 575 ( PDF (3871KB)( 223 Citation

    The heat treatment experiments were carried on titanium alloys (TC17 (α+β) + TC17 (β)) linear friction welded joint. Optical microscope (OM), scanning electron microscope (SEM) and microhardness instrument were used to investigate the effects of different heat treatment temperatures on the microstructure and mechanical properties of welded joints. The results show that recrystallization occurs at the weld zone (as weld). Metastable β phase structure is formed at the weld interface of as-welded joint. The microhardness of as-welded joint is lower than base metal and high cycle fatigue strength of as-welded joints is 345 MPa. Because welding speed is rapid, a large number of primary α phase is retained in thermal mechanically affected zone (TMAZ) of TC17 (α+β). After post-weld heat treatment, the metastable β phase structure is decomposed and dispersed (α+β) phase is separated out at the welded joints. With the increase of the heat treatment temperature, small secondary α phase is grown up and phases are partly spheroidized. After heat treatment, because metastable β phase structure is decomposed, the micro-hardness is greatly increased at the weld zone and TMAZ, and fatigue strength is increased by an average of 65 MPa at the welded joints. With the increase of the heat treatment temperature, the fracture toughness is improved at the TMAZ of welded joints.

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    Performance of PDC-SiBCN ceramic based wireless passive temperature sensor
    Yu-xi YU, Bin HAN
    2020, 48 (1): 121-127.   DOI: 10.11868/j.issn.1001-4381.2018.001319
    Abstract ( 728 ( PDF (4705KB)( 243 Citation

    The high temperature resistant polymer derived ceramic (PDC-SiBCN) was used as a temperature sensitive dielectric material, and metal platinum was used as a resonant cavity material, and a coplanar antenna was formed by slotting on the surface of the ceramic to fabricate a wireless passive temperature sensor integrating the slot antenna and the resonator. The sensor can realize the wireless passive transmission of temperature information. The results show that the resonant frequency of the sensor is declined monotonically with the increase of the testing temperature, the dielectric constant of PDC-SiBCN ceramic is increased monotonously with increasing temperature, and the sensor with a pyrolysis temperature of 1000℃ is tested up to 1100℃, which has excellent high temperature resistance and dielectric temperature properties. At the same test temperature, the resonant frequency of the sensor is decreased with increasing diameter and also is reduced with increasing pyrolysis temperature. The sensitivity equation is obtained by performing a first-order partial derivative of the resonant frequency-temperature fitting curve of the sensor, and the sensor has a high sensitivity at a high temperature of 1100℃. The sensor has good cycle stability, and it has an actual wireless transmission distance of 42 mm at room temperature and a transmission distance of up to 8 mm when the testing temperature is 1100℃, which can be used for temperature monitoring of aero-engine in high temperature and harsh environments.

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    AC+Li(NiCoMn)O2/Li4Ti5O12+MWCNTs hybrid capacitors
    Wei CHEN, Xiao-gang SUN, Hao HU, Jie WANG, Xu LI, Guo-dong LIANG, Ya-pan HUANG, Cheng-cheng WEI
    2020, 48 (1): 128-135.   DOI: 10.11868/j.issn.1001-4381.2018.000310
    Abstract ( 583 ( PDF (5586KB)( 234 Citation

    The hybrid capacitors were assembled by using lithium titanate/multi-walled carbon nanotubes composite as anode and activated carbon/nickel cobalt manganese acid lithium composite as cathode. The electrode materials were analyzed by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractomer (XRD), Raman spectrometer (Raman) and thermal gravimetric analyzer (TGA). The electrochemical performance of hybrid capacitors was tested by galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS). The results indicate that the addition of multi-walled carbon nanotubes and lithium nickel cobalt manganese oxide can greatly improve the electrochemical performance of hybrid capacitors. The hybrid capacitors achieve a specific capacitance of 161.5 mAh/g at the current density of 0.1 A/g with an additive of 5% (mass fraction) multi-walled carbon nanotubes. The maximum power density and energy density reach 993.2 W/kg and 52.2 Wh/kg in the current range of 0.1-1 A/g, respectively. The continuous galvanostatic charge-discharge cycling tests reveal that the hybrid capacitors maintain capacitance rate retention of 92.2% and Coulomb efficiency of 99.1% after 5000 cycles. The hybrid capacitors show an excellent cycle performance with high energy and power density.

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    Hydrothermal synthesis and crystal growth mechanism of hydroxyapatite nanorods
    Hua JIAO, Kang ZHAO, Rui SHI, Li-ning MA, Tie-rong BIAN, Yu-fei TANG
    2020, 48 (1): 136-143.   DOI: 10.11868/j.issn.1001-4381.2018.001206
    Abstract ( 644 ( PDF (3467KB)( 269 Citation

    Hydroxyapatite (HA) nanorods were synthesized by hydrothermal process using anhydrous CaCl2 and (NH4)2HPO4 as raw materials, urea was used as a homogeneous precipitation agent; hexadecyltrimethy ammonium bromide (CTAB) was used as a template agent. Phase composition and microstructure of the products were characterized via X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The results show that the morphologies of HA nanorods can be controllably fine-tuning by changing the reaction temperature and time. Hexagonal single crystal HA nanorods single structure can be obtained at 120℃ for hydrothermal 12 h, its length is about 0.5-1.0 μm, diameter is about 15-30 nm. Finally, the role of CTAB was studied by the formation process of nanorods crystalline structure in details, and verified by experiment.

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    Fabrication of hierarchical micro/nano structure surface on copper by EDM and its hydrophobicity
    Zhao-rong HE, Xiao-hua JIE, Wei-qi LIAN
    2020, 48 (1): 144-149.   DOI: 10.11868/j.issn.1001-4381.2018.000010
    Abstract ( 532 ( PDF (3472KB)( 182 Citation

    The hierarchical micro-nano structure surface on copper was fabricated by electrical discharge machining (EDM). The hydrophobic property was increased due to the hierarchical micro/nano structure (HMNS), which consisted of the micro/nano scale holes, molten balls, recast regions and the micro thermal cracks. The effects of the pulse width on the hydrophobicity of HMNS were investigated. The results indicate that with the increase of the pulse width, the quantity of the micro-nano scale holes increases. The distribution of other hierarchical micro structures is more homogeneous. The effective area of "air cushion" increases, which can trap more air in the HMNS. And the hydrophobicity of HMNS also increases. The proportion of the solid-liquid interface area (fsl) reduces. The contact area between the water droplet and "air cushion" in the HMNS increases. Therefore, the effect of the physical adsorption for the HMNS on the water droplet is weakened. The contact angles of the HMNSs can be increased up to (144.7±2.1)°, and the range of contact angle hysteresis is (8.46±3.3)°-(14.10±1.2)°.

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    Visible light photocatalytic properties of SmFeO3 powders prepared via carbon adsorption co-precipitation method
    Jin-xing LI, Qiao-xian WANG, Gui-bao GUO, Jin-yan LIU
    2020, 48 (1): 150-155.   DOI: 10.11868/j.issn.1001-4381.2018.000091
    Abstract ( 445 ( PDF (1988KB)( 201 Citation

    SmFeO3powders were synthesized by carbon adsorption co-precipitation method. The as-prepared samples were characterized by TG-DTA analysis, X-ray diffraction, UV-Vis absorption spectra and transmission electron microscopy, respectively. The photocatalytic activity of SmFeO3 powders was investigated under visible light irradiation of dysprosium lamp with methyl orange (MO) as the target pollutant. The results show that SmFeO3 powders are obtained with less agglomeration, small particle size and uniform distribution due to the addition of carbon black. The absorption wavelength of SmFeO3 shifts toward the long wavelength and the absorption intensity of SmFeO3 enhances in the ultraviolet and visible regions. The degradation rate of SmFeO3 powder prepared by carbon adsorption co-precipitation method reaches 82% within 60 min, which is 2.6 times of samples synthesized by precipitation method. The photocatalytic effects are significantly enhanced.

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    Preparation and characterization of diatom-based As(Ⅴ) surface imprinted materials
    Xiao-ming LIANG, Yi-jian ZHONG, Li-li MA, Cong LI, Nan-chun CHEN, Qing-lin XIE
    2020, 48 (1): 156-161.   DOI: 10.11868/j.issn.1001-4381.2018.001389
    Abstract ( 502 ( PDF (2326KB)( 183 Citation

    Using diatom as a material carrier, silane coupling agent aminopropyltrimethoxysilane (APS) was selected as the functional monomer, As (Ⅴ) was used as the template ion, and epichlorohydrin (ECH) was used as the crosslinking agent, the imprinted composite material with natural mineral material as carrier was prepared by the condensation reflux method. The results of scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy show that the functional monomer APS is grafted successfully on the surface of diatom, and a stable imprinted pore forms after cross-linking with ECH. There are obvious grafts in the pores and surroundings of the diatom, and the internal regularity of the pores is more obvious. The selectivity coefficient of As (Ⅴ) imprinted composites under different binary systems was obtained by selective experiments. The selection ability and utilization prospect of As (Ⅴ) were summarized and evaluated based on experimental data.

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