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      20 December 2019, Volume 47 Issue 12 Previous Issue    Next Issue
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    Research progress in bio-based synthetic rubber
    Hai-jun JI, He QIAO, Zhao WANG, Hui YANG, Run-guo WANG, Li-qun ZHANG
    2019, 47 (12): 1-9.   DOI: 10.11868/j.issn.1001-4381.2019.000207
    Abstract ( 954 ( PDF (4244KB)( 715 Citation

    As entering the 21st century, the development of petrochemical synthetic rubber is unsustainable, and is gradually constrainted by energy saving and emission reduction. The production of natural rubber is limited and affected by factors such as climates, epidemic diseases, etc. China's natural rubber self-supporting is insufficient, rely heavily on imports. In the face of the above challenges, the development of a new generation of bio-based rubber resources independent of fossil resources from solar energy is an effective means to solve the shortage of rubber resources and the only way to ensure the safe, long-term and stable supply of global rubber resources. At present, there are two main ideas for the preparation of bio-based synthetic rubber. The research progress of two types of bio-based synthetic rubber was mainly reviewed in this paper. One is to further convert bio-based monomers (such as ethanol) obtained by fermentation of biomass into conventional monomers (such as ethylene), then the bio-based conventional rubber such as bio-based ethylene propylene rubber and bio-based isoprene rubber will be prepared by a conventional synthetic process, and its performance is almost identical to that of a conventional non-bio-based engineering elastomer, and the existing engineering rubber can be directly replaced; the other is to prepare a novel structure of bio-based rubber materials through polymerization using the existing bio-based chemicals, such as itaconic acid, propylene glycol, succinic acid, etc. The raw materials can be easily obtained, the cost is low, and with the rapid development of fermentation technology, more and more bio-based chemicals will be available for selection and use, and bio-based synthetic rubber has bright prospects.

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    Research progress on two-dimensional nanomaterials MXenes and their application for lithium-ion batteries
    Xin QI, Xiang CHEN, Si-kan PENG, Ji-xian WANG, Nan WANG, Shao-jiu YAN
    2019, 47 (12): 10-20.   DOI: 10.11868/j.issn.1001-4381.2019.000510
    Abstract ( 1463 ( PDF (2239KB)( 782 Citation

    Lithium-ion batteries (LIBs) have been considered a promising candidate of new energy storage device. Numerous researchers around the world are committed to develop new materials for high-performance LIBs. MXenes are new type of two-dimensional nanomaterials, which are composed of transition metal, carbides or/and nitrides, with large specific surface area, good electrical conductivity, high lithium storage capacity, excellent cycling and rate performances, etc., making them as LIBs materials with bright application prospects. A variety of MXenes materials (such as Ti2CTx, Ti3C2Tx, V2CTx, Nb2CTx, etc.) have been reported to be useful as LIBs electrode materials. In addition, MXenes materials can be combined with other LIBs active materials to build good conductive network, accelerate electron transport and lithium ion diffusion, and inhibit materials pulverization caused by volume expansion of active materials during electrochemical processes. Besides, researches on MXenes materials in solid electrolytes, binders, and conductive agents for LIBs have also been reported. In this paper, the major breakthroughs in the application of MXenes materials for LIBs were reviewed. The preparation methods, structural properties and lithium storage mechanism of MXenes materials were introduced. Moreover, the specific application, existing problems of MXenes materials in LIBs have been concentrated on.This review points out that researches of MXenes materials should take advantages of their hydrophilicity and conductivity poperties, and focus on the development of composite electrode meterials, self-supporting electrodes materials etc., which will bring breakthroughs to the key technologies of high-performance lithium-ion batteries.

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    Research progress in liquid phase exfoliation of boron nitride and their applications in thermal management of electronic devices
    Chuan SUN, Xue-qing QIU, Fa-mei QIN, Zi-xian DING, Zhi-qiang FANG
    2019, 47 (12): 21-32.   DOI: 10.11868/j.issn.1001-4381.2018.001461
    Abstract ( 697 ( PDF (5008KB)( 426 Citation

    Boron nitride nanosheets (BNNS) exhibit prominent thermal conductivity, good electrical insulation, as well as high chemical and thermal stability, thus showing their promising application in thermal management of electronic devices. However, it is still challenging to obtain BNNS with high quality by facile and scalable production methods. Liquid phase exfoliation is considered to be one of the most promising methods to prepare BNNS due to its facile and scalable preparation procedure of nanosheets with high quality. Recent advances in liquid phase exfoliation methods for the preparation of BNNS were summarized in this review, with specially focusing on solvent selection of h-BN exfoliation, non-covalent and covalent surface modification of boron nitride. Furthermore, the exfoliation mechanism of the above three methods and the existing shortcomings were discussed in details(environmental problems caused by organic solvents, poor compatibility in some modifiers, difficulties in covalent bond modification).With the further study of the exfoliation mechanism, the liquid phase exfoliation method will be able to meet the requirement of high quality and high efficiency preparation of BNNS, making it play an important role in the thermal management of electronic devices.

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    Research progress in preparation of functionalized polyhedral oligomeric silsesquioxanes
    Hao-dong LIU, Guang-ming ZHU, Tian-ning REN
    2019, 47 (12): 33-42.   DOI: 10.11868/j.issn.1001-4381.2018.001292
    Abstract ( 686 ( PDF (1813KB)( 512 Citation

    As a series of novel organic/inorganic hybrid nanomaterials, nanostructured POSS(polyhedral oligomeric silsesquioxanes) particles are one of the best choices for molecular structure design and modification owing to their fascinating physical and chemical properties. The preparation of functionalized POSS has attracted widespread attention, and it is of major academic significance to investigate the synthesis methods and reaction mechanism in depth. The development process and structural characteristics of POSS were summarized and the synthesis methods of functionalized POSS commonly used in polymer modification were reviewed in this paper, including silane hydrolysis/condensation reactions, functional group transformation derivation method and corner-capping reactions. The nanomaterials investigated in this review include methylacryloxypropanyl-POSS, vinyl-POSS, amino-POSS, epoxy-POSS, hydroxyl-POSS and partial mono-functional POSS. Finally, the influencing factors of these methods were discussed and the domestic research on functionalized POSS was prospected:the future research will focus on the further clarification of the synthesis mechanism and the stability of the existing processes for reducing the cost based on the improvement of the yield and providing technical support for industrial production; likewise, the introduction of functional groups can be precisely designed to prepare additional up-to-date reactive POSS.

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    Research progress in carbon-based/carbonyl iron composite microwave absorption materials
    Chao-qun GE, Liu-ying WANG, Gu LIU
    2019, 47 (12): 43-54.   DOI: 10.11868/j.issn.1001-4381.2018.000220
    Abstract ( 1060 ( PDF (3629KB)( 668 Citation

    Carbon-based/carbonyl iron composite microwave absorption materials have become a hot topic in recent years because of the combination of their respective advantages and unique physical and chemical characteristic and good absorbing properties. In this paper, the most recent and important research advances in carbon-based/carbonyl iron composite microwave absorption materials were reviewed. Firstly, the recent research of property improving of carbonyl iron itself was introduced. Then, the research achievements of carbon-based/carbonyl iron composite microwave absorption materials were summarized in six major categories, graphene/carbonyl iron microwave absorption materials, carbon nanotubes/carbonyl iron microwave absorption materials, carbon fibre/carbonyl iron microwave absorption materials, carbon black/carbonyl iron microwave absorption materials, graphite/carbonyl iron microwave absorption materials and the other composites were reviewed in detail. Finally, the performance control and lightweight of carbon-based/carbonyl iron composite microwave absorption materials were pointed out, and its development prospect in broadband stealth was prospected.

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    Research Article
    Effect of scanning path on thermo-mechanical field of laser solid forming TC4 part
    Xu-fei LU, Xin LIN, Liang MA, Yang CAO, Wei-dong HUANG
    2019, 47 (12): 55-62.   DOI: 10.11868/j.issn.1001-4381.2018.001474
    Abstract ( 592 ( PDF (6014KB)( 202 Citation

    In order to mitigate both residual stress and distortion induced by large thermal gradient in laser solid forming (LSF) process, the in-situ measurement first was used to monitor the thermal and distortion evolutions of the substrate during LSF and to calibrate the finite element model. Using the validated model, the effect of different scanning paths on the evolution of thermo-mechanical fields in LSF was analysed. The results show that good agreement is obtained between the numerical results and the experimental measurements. The maximum thermal gradient and the maximum tensile stress occur in the deposition of the first layer, and with the increasing of the layers, the temperature gradient is reduced gradually. The largest distortion is resulted from the long edge unidirectional scanning mode while the minimum residual stress and distortion is produced by short edge reciprocating scanning. The checkerboard scanning method can effectively reduce distortion of the substrate while hardly reduce the residual stress. In addition, the transverse bending of the substrate can notably curb the longitudinal bending of the substrate. Stress relaxation induced by the phase transformation has a significant effect on both residual stress and distortion of LSF part.

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    Effect of compound cryogenic treatment on microstructure and thermal fatigue properties of ZCuAl10Fe3Mn2 alloy
    Ling ZHAO, Guang-lei LIU, Si-yuan ZHANG, Mao-jun LI, Jian-ning LIU, Ming-hui LI
    2019, 47 (12): 63-70.   DOI: 10.11868/j.issn.1001-4381.2018.001042
    Abstract ( 513 ( PDF (4687KB)( 222 Citation

    The microstructure, mechanical properties and thermal fatigue behavior at room temperature to 450℃ of ZCuAl10Fe3Mn2 alloy treated by T6, cryogenic treatment and T6 + cryogenic treatment were investigated. The microstructure and crack morphology of the alloy were observed and analyzed by XRD, OM, SEM and EDS. The results show that the mechanical properties and microstructure of ZCuAl10Fe3Mn2 alloy can be significantly improved by T6+cryogenic composite treatment. Compared with T6 treatment, the tensile strength, hardness and elongation of the alloy are increased by 7.28%, 16.96% and 23.53%, respectively; the α phase is further refined and distributed more uniformly, the density of dislocation is increased, which make the microstructure uniformity and compactness of the alloy better. The thermal fatigue properties of the alloy are also effectively improved through the improvement of comprehensive properties and the resistance to thermal stress and oxidation corrosion is enhanced. Under the same thermal cycling, the fatigue crack length is the shortest and the crack growth rate is the slowest.

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    Ultrasonic characterization of recrystallized microstructure evolution for Al0.26CoCrFeNiMn high-entropy alloys
    Ning DING, Shi-jie JIN, Liang-ming PENG, Ming-kai LEI, Li LIN
    2019, 47 (12): 71-77.   DOI: 10.11868/j.issn.1001-4381.2018.000557
    Abstract ( 479 ( PDF (4911KB)( 195 Citation

    Al0.26CoCrFeNiMn high-entropy alloys were prepared by vacuum induction melting and casting method, and processed by homogenized annealing, rolling and recrystallized annealing. The microstructure evolution of the alloys during thermomechanical treatment was investigated based on ultrasonic method. The results show that the microstructure is coarse equiaxed grain after homogenized annealing, retaining deformed grain when recrystallized annealing temperature is 800℃, forming fine equiaxed grain when recrystallization is completed at 900℃, and then the grain grows at 1000℃.Besides, the grain size decreases with the increase of rolling ratio at the same recrystallized annealing temperature. At the aspect of ultrasonic characterization, the attenuation coefficient for probe testing with nominal frequency of 5MHz increases with the increase of grain size, and the attenuation coefficient with average grain size is corresponded in a cubic relationship, having a strong correlation. In order to further verify the feasibility of the method, the probe with nominal frequency of 7.5MHz was used to test, and the similar correlation was acquired. The attenuation coefficient can reveal the microstructure evolution of high-entropy alloys during thermomechanical treatment, especially for the relationship between grain size and thermomechanical treatment process.

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    Effect of ultrasonic field on friction and wear properties of in-situ TiB2/2A14 composite materials
    Kai HUANG, Ri-peng JIANG, Xiao-qian LI, Rui-qing LI, Li-hua ZHANG
    2019, 47 (12): 78-84.   DOI: 10.11868/j.issn.1001-4381.2018.000823
    Abstract ( 558 ( PDF (3243KB)( 179 Citation

    The 3%TiB2/2A14 (volume fraction) aluminum matrix composites were prepared by in-situ salts-metal reaction under ultrasonic field. The wear experiments with four different load (20, 30, 40, 50N) were carried out with a reciprocating tribometer. The abrasive resistance and friction behavior of composites with different ultrasonic vibration treatment (UVT) process were studied. The mircohardness of matrix and composites were measured by the microhardness tester. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) were applied to identify the phase compositions and observe the microstructure and morphology of worn surfaces. And the wear mechanism was also studied. The results manifest that the ultrasonic can efficiently scatter the particle agglomerations, improve the state of particle distribution and reinforce the interfacial bonding strength between particles and matrix. Therefore, the abrasive resistance and microhardness of composites with UVT are obviously superior to alloy matrix. The wear rate and hardness of composites obtained by 120s UVT are about 57.43% and two times of that of the matrix alloy under 50N load. Under the dry friction condition, the main wear mechanism of alloy matrix is adhesion wear and composites is hybrid wear with adhesion wear and abrasive wear and the wear resistance is better.

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    Microstructure and mechanical properties of Al2O3/AZ31 composites prepared by multi-pass hot extrusion
    Shuai-hu WEI, Mao-liang HU, Ze-sheng JI, Hong-yu XU, Ye WANG
    2019, 47 (12): 85-91.   DOI: 10.11868/j.issn.1001-4381.2018.000863
    Abstract ( 553 ( PDF (4403KB)( 195 Citation

    Multi-pass hot extrusion was used to prepare the Al2O3/AZ31 composite.The microstru-cture was characterized by optical microscopy, scanning electron microscopy, transmission electron microscopy, and mechanical properties were tested by Vickers hardness tester and electron universal strength tester. The results show that Al2O3 particles are uniformly distributed in AZ31 magnesium matrix by multi-pass hot extrusion. The grain refining effect of Al2O3 particles on the matrix is enhanced, and the grain size of the composite decreases significantly with the increase of the pass. During the hot extrusion process, the dislocation density around the Al2O3 particles increases, and the high-density dislocation region facilitates the dynamic recrystallization nucleation, so that the grains of the Al2O3/AZ31 composite are significantly refined. The Al2O3 particles are gradually distributed into a long strip from the initial island distribution, then distributed in a linear pattern, and finally distributed uniformly in the form of particles in the AZ31 magnesium matrix. After fourth-pass hot extrusion, the mechanical properties of Al2O3/AZ31 composite are significantly improved, and hardness, tensile strength and yield strength are 89HV, 305MPa and 198MPa, respectively. The hardness, tensile strength and yield strength increase by 19.2%, 14.8%, and 14.1%, respectively, compared with the first-pass hot extrusion.

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    Effects of pre-deformation on grain refinement and superplasticity of 2050 Al-Li alloy
    Ling-ying YE, Quan SUN, Hong-ping LI, Sheng-dan LIU, Xin-ming ZHANG
    2019, 47 (12): 92-97.   DOI: 10.11868/j.issn.1001-4381.2018.000746
    Abstract ( 661 ( PDF (3541KB)( 225 Citation

    Fine-grain 2050 Al-Li alloy sheets were prepared by thermomechanical treatment processing(TMTP). The effects of pre-deformation on second phase distribution, grain structure and superpl-asticity of alloy sheets were studied by optical microscope and scanning electron microscope. The results show that after pre-deformation, a large amount of subgrains are formed in the plate during high temperature overaging. A large number of subgrain boundaries promote the precipitation of TB phase and increase the roughening rate, which significantly increases the size of intragranular TB phase. The volume fraction of second phase particles that effectively stimulates recrystallization nucleation increases from 0.92% to 3.28%. Compared with the non-predeformed sheets, the average grain size of the center layer of the sheets is reduced from 12.59μm to 9.59μm, the average grain size of the surface layer is reduced from 10.79μm to 8.60μm, the grain refinement effect is obviously improved, the superplastic deformation ability is significantly improved. The elongation of superpla-stic deformation increases from 230% to 470% under the condition of 490℃ and 2×10-4s-1.

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    Effect of ageing process on microstructure and properties of 2124 aluminum alloy thick plate
    Jin-xin ZANG, Jun-zhou CHEN, Lin-na YI, Ji-gang RU
    2019, 47 (12): 98-103.   DOI: 10.11868/j.issn.1001-4381.2018.000899
    Abstract ( 582 ( PDF (5001KB)( 235 Citation

    Mechanical properties of 2124 aluminum alloy thick plate in short-transverse direction were investigated when ageing at 170-180℃ for different time by room temperature tensile test.The microstructure morphology of alloy after different ageing processes was studied by TEM and SEM.The results show that the suitable ageing process of 2124 aluminum alloy plates is 175℃ for 10h.Yield strength, tensile strength and elongation are 372, 422MPa and 2.9%, respectively.The main precipit-ation is S' phase, and also a small quantity of GPB zone and coarse T phase exist at this moment.Ageing temperature is the main factor affecting the density and size of the alloy precipitation.The higher the ageing temperature is, the quicker the rising of strength, the shorter time to reach the maximum strength.The increasing strength difference between the matrix and grain boundary is the main cause for the decrease of the elongation.

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    Preparation of GO/TiO2 composite photocatalyst and treatment of synthetic dye wastewater
    Dan-dan LI, Guang-zheng YAO, Gui-yan LIANG, Xu-fa RONG, Ruo-yu XUE, Zhong-tian FU
    2019, 47 (12): 104-110.   DOI: 10.11868/j.issn.1001-4381.2018.000701
    Abstract ( 567 ( PDF (2686KB)( 277 Citation

    A series of composite photocatalysts were prepared by using graphene oxide (GO) and TiO2 hydrogel. The composite photocatalyst was characterized through SEM, XRD and Raman spectroscopy, the decolorization effect of pure TiO2 and composite photocatalyst on methylene blue (MB) dye wastewater under different experimental conditions was studied. The results show that TiO2 in composite photocatalyst is mainly anatase phase and its photocatalytic activity is better than pure TiO2. When the addition of GO reaches 15%(mass fraction), the photocatalytic activity is the highest. When 250mg composite photocatalyst is added to 30mL synthetic wastewater with a concentration of 10mg/L and an initial pH value of about 8, the decolorization rate can reach 93.1% after 2.5 hours, and the composite photocatalyst has visible photocatalytic activity. It is presumed that the photogenerated charges of GO/TiO2 composite photocatalyst may directly destroy the luminescent groups in the MB molecule, and no other new luminescent groups are generated during the treatment.

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    Preparation and optical properties of SiO2 photonic crystal structure color films
    Hong-yan DU, Yu-fan QI, Chen-xue WU, Yue-jun LIU, Li-ping LIANG, Wen-ying GUO, Zi-dong ZHANG
    2019, 47 (12): 111-117.   DOI: 10.11868/j.issn.1001-4381.2018.001044
    Abstract ( 596 ( PDF (4406KB)( 316 Citation

    In order to study the band gap performance of structural color films under different conditions, Monodisperse submicron silica microspheres with different particle sizes were prepared by the modified Stöber method, and a photonic crystal structure color film with silica as a structural element was prepared on the surface of the glass by vertical deposition self-assembly. The morphology and optical properties of microspheres and films were analyzed by scanning electron microscope, infrared spectrometer and UV-vis spectrophotometer. The results show that during the synthesis process, with the increase of the reaction temperature, the particle size of silica microspheres gradually reduces; with the increase of the diameter of SiO2 microspheres, the corresponding photonic band gap of photonic crystals occurs red shifting. It is found through further study that as the angle between the incident light and the normal line of color film increases, the center wavelength corresponding to the photonic band gap becomes shorter, then blue shifting occurs.

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    Preparation of Co doped carbon nanofibers composites synthesized by electrospinning and its microwave absorption properties
    Sa ZHANG, Jian-jiang WANG, Fang ZHAO, Jia-wei LIU
    2019, 47 (12): 118-123.   DOI: 10.11868/j.issn.1001-4381.2018.000101
    Abstract ( 574 ( PDF (3374KB)( 269 Citation

    Carbon nanofibers with various contents of Co nanoparticle were synthesized by a two step process of electrospinning and subsequent heat treatment. The thermal stability, phase composition, microstructure and electromagnetic characteristics of the carbon nanofibers were characterized by differential scanning calorimetry-thermogravimmetric analysis (DSC-TGA), X-ray diffraction(XRD), scanning electron microscope(SEM) and vector network analyzer(VNA), and the microwave absorption performance was studied.The results indicate that the crystallinity of composite nanofibers is moderate when the carbonization temperature is 800℃.The amorphous carbon is partially converted into graphite and CoAc2 completely reduces to face-centered cubic structured Co nanoparticle. The fiber is intact and beads-on-string structure exists in the fiber networks. The electromagnetic characteristics of the carbon nanofibers significantly improve by the doping of Co. The Carbon nanofibers containing 7%(mass fraction) as fillers with thickness of 1.5mm exhibit maximum effective absorption bandwidth of 4.5GHz, and it is obviously improved compared to pure carbon nanofibers.

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    Preparation of rapid expansion alginate/silica fiber composite scaffold and application of rapid hemostatic function
    Hua-jin SHU, Chun-xuan WU, Kang YANG, Ting-wu LIU, Chen LI, Chuan-liang CAO
    2019, 47 (12): 124-129.   DOI: 10.11868/j.issn.1001-4381.2019.000699
    Abstract ( 603 ( PDF (4715KB)( 237 Citation

    Silica nanofibers were prepared by electrospinning technique, and then a sodium alginate coated three-dimensional silica hemostatic sponge (ALG/SiO2/Ca2+ sponge) was obtained by freeze-drying method and Ca2+ crosslinking. The structure, composition, cytotoxicity, biocompatibility and hemostatic function were characterized by scanning electron microscopy, cell experiments and in vivo hemostasis experiment. The results show that the ALG/SiO2/Ca2+ hemostatic sponge has a highly porous structure and fast swelling performance. Immersed in water for 10s, the volume expands to 219% compared with the original. The results of cell experiments show that the new hemostatic sponge has good cytocompatibility; the results of in vivo hemostasis show that hemostasis is achieved within 10s using the ALG/SiO2/Ca2+ hemostatic sponge, and the amount of bleeding is significantly reduced compared with medical gauze. Therefore, this new type of hemostatic sponge has excellent properties such as rapid water swelling and hemostasis in the deep wound and providing a moist environment for wound.

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    Preparation of diamond/vitrified bond composite sintered by sol-gel method and its performance characterization
    Qiu HONG, Long WAN, Jian-wei LI
    2019, 47 (12): 130-135.   DOI: 10.11868/j.issn.1001-4381.2018.001329
    Abstract ( 457 ( PDF (2074KB)( 292 Citation

    Based on the diamond and inorganic sol, sol-gel(S-G) method was used to prepare diamond/vitrified bond composite powder and then the bulk samples were obtained after the powder was pressed and sintered, and the bond composite powder was characterized by XRD, SEM, electronic universal testing machine, Rockwell hardness tester, etc. The results show that diamond/vitrified bond composite powder with good uniformity can be prepared by S-G method, and the bending strength, Rockwell hardness, volume density and porosity of samples sintered at 680℃/2h are 58.54MPa, 55.8HRB, 1.74g/cm3and 24.16%, respectively; when these samples were obtained by melting method, the corresponding figures are 51.32MPa, 72.5HRB, 1.92g/cm3and 21.47%, respectively. Compared to the melting method, the microstructure of grinding disc prepared by S-G method is uniform and high quality is observed on the machined surface of TC4 titanium alloy, whose Ra reaches 0.051μm.

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    Preparation and characterization of Al2O3 bulk aerogel with high specific surface area and low density
    Yu-xi YU, Rui MA, Guan-chun WANG, Rui-qian ZHANG, Xiao-ming PENG
    2019, 47 (12): 136-142.   DOI: 10.11868/j.issn.1001-4381.2017.000852
    Abstract ( 605 ( PDF (3034KB)( 291 Citation

    We report a facile approach to synthesize alumina aerogel through sol-gel reaction followed by supercritical drying, in which ASB is as co-precursors, EtOH as solvents, Etac as chelating reagent, HAc as catalysts. The as-prepared aerogel was treated at different temperatures.Moreover, the effect of the amount of ethanol and chelating agent ethylacetoacetate on the microstructures of aerogels and the changes of specific surface areas under different conditions were also discussed by SEM, XRD, FT-IR, TG-DTA and nitrogen adsorption-desorption. The results indicate that the monolithic alumina aerogel has nanoporous network structure consisted of randomly connected leaf-like particles, which also has high specific surface area of 744.5m2/g and low density of 0.063g/cm3. The specific surface area of the aerogel is gradually reduced with the increase of heat treatment temperature, but it is still as high as 153.45m2/g after 2h treatment under 1200℃.After heat treatment at different temperatures, the leaf-like porous structure of alumina aerogel does not change significantly, indicating that this alumina aerogel has high temperature stability.

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    Photocuring kinetics properties of hybrid UV-curing resin for 3D printing
    Guang-hong LIN, Jing-feng YIN, Hong HUANG, Wei-bin HUANG, Mu-hua CAI, Hong-ping XIANG, Xiao-xuan LIU
    2019, 47 (12): 143-150.   DOI: 10.11868/j.issn.1001-4381.2018.000667
    Abstract ( 767 ( PDF (3914KB)( 412 Citation

    Free radical-cationic hybrid UV-curable resin applied to UV-cured 3D printing was developed with epoxy resin (EPON828) and polyurethane acrylate (RJ429) as photosensitive prepolymers. The influences of types, ratios and dosages of free radical and cationic photoinitiators on photocuring kinetics, mechanical properties and prototyping precision of hybrid UV-curing resin were investigated. The results show that cationic photoinitiator Gencure 842 and free radical photoinitiator Doracur 1173 are the most appropriate hybrid photoinitiators, with an optimum mass ratio of 0.75:1 and mass fraction of 6%. The optimum mass ratio of EPON828 and RJ429 is determined as 1:1, and the viscosity of the developed resin is 50.5Pa·s. The tensile strength, impact strength, volume shrinkage and warpage of UV-cured resin items are 6.60MPa, 8.28kJ·m-2, -3.986% and 3.62%, respectively. The hybrid UV-curing resin can basically satisfy the requirements of UV-cured 3D printing.

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    Enhancement of chopped fibers on welding strength of composites
    Xu CUI, Pu ZHAO, Xu-hai XIONG, Zhong-bao ZHANG, Shu LI, Ping CHEN
    2019, 47 (12): 151-156.   DOI: 10.11868/j.issn.1001-4381.2018.001487
    Abstract ( 676 ( PDF (4005KB)( 238 Citation

    The enhancement of chopped fiber as a reinforcing agent on the welding interface of composite materials was explored. Glass fiber reinforced polyetherimide (GF/PEI) laminate was joined using the pulse resistance welding technology, using a stainless steel (SS) mesh as the heating element. A single lap shear test was performed on the weldments of aramid fiber (AF), glass fiber (GF), and carbon fiber (CF) as reinforcing agents to evaluate the strength of the welded joint. The results show that the fiber achieves the welding interface strengthening by cooperating with the SS mesh heating element to contribute to the mechanical properties of the welded joint. Fracture analysis shows that under the reinforcement of fiber, the main failure mode in the initial stage of welding is fiber and matrix debonding. When the strength of the weldment achieves the best, the failure mode is changed into the simultaneous tearing of SS mesh heating element and fiber tear.

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    Effect of compound emulsifier on properties and mechanism of phase change and humidity controlling composites
    Hao ZHANG, Hai-li LI
    2019, 47 (12): 157-162.   DOI: 10.11868/j.issn.1001-4381.2018.001493
    Abstract ( 513 ( PDF (1836KB)( 177 Citation

    Sipan-80, Tween-80 and sodium lauryl sulfate were used to synthesize the compound emulsifier with different formulations, and SiO2 as the carrier, hexadecanol-palmitic acid-lauric acid as a phase change material, a series of phase change and humidity controlling composites were made by sol-gel method. Effects of different compound emulsifier formulations on particle size distribution, microstructure, composition structure, thermal properties and humidity properties were studied by LPSA, SEM, FTIR, DSC and DVS, the influence mechanism of compound emulsifier on thermal properties and humidity properties of phase change and humidity controlling composites was analyzed. The results show that with Sipan-80, Tween-80 and sodium lauryl sulfate as compound emulsifier, phase change and humidity controlling composites with good thermal properties and humidity properties were prepared, such as phase change material with mass fraction of 70.34% to 74.00%, and the moisture content with relative humidity between 40% and 60% is 0.0361-0.0390g/g. With Sipan-80, Tween-80 and sodium lauryl sulfate as compound emulsifier can effectively improve the particle size distribution and uniformity coefficient of phase change and humidity controlling composites, and improve the dispersion of phase change and humidity controlling composites.

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