- 徐天星;WU Jie;李亚娟;肖宏;
We synthesized size-controllable nanoparticles with homogeneous distribution of carbon and Sn/SnO_2 by a solvothermal method.The effects of different carbon content and hydrothermal time on the composition,morphology and electrochemical properties of the materials were investigated.Compared with bulk materials,nanoparticles materials not only have high specific surface area,but also can provide abundant reaction sites,thus enhancing the electrochemical activity of electrode materials.More importantly,the optimized microspheres Sn/8C-24 delivers a superior electrochemical performance,achieving a specific discharge capacity of 700.4 mAh_·g~(-1) after 150 cycles at 0.5 A_·g~(-1),and the Coulomb efficiency reaches 98.65%,which is promising for anode of LIBs.
2024年04期 v.39;No.180 805-813页 [查看摘要][在线阅读][下载 1372K] - 王鹏;ZHANG Binbin;LIU Xiaofei;ZHANG Xin;TU Rong;ZHANG Song;李宝文;
It remains a big challenge to synthesize two-dimensional (2D) GaN material for applications in power nanodevices.Traditional synthetic methods require complex equipment and processes and time consuming.Here,we reported a two-step route to prepare polycrystalline 2D GaN film.The amorphous ultrathin Ga_2O_3 film was first exfoliated from the surface of liquid gallium.In a vapor phase reaction,2D Ga_2O_3 film was then converted into 2D GaN film while maintaining the 2D morphology.Raman and high-resolution transmission electron microscope (HRTEM) analysis implies the successful synthesis of wurtzite-type GaN ultrathin film.This simple strategy proposed in this work will provide more opportunities for applications of GaN ultrathin film in many devices.
2024年04期 v.39;No.180 814-818页 [查看摘要][在线阅读][下载 1016K] - 田崇霏;LUO Zhongtao;LIU Lei;LIU Xiaohai;张美香;陈萌;HAI Ran;
Up to 1.5wt% of Cr(Ⅲ) salts (CrCl_3,and Cr_2O_3) and Cr(Ⅵ) salts (Na_2CrO_4,and CaCr_2O_7) were incorporated into red mud-based geopolymers,respectively.The solidification/stabilization,compressive strength,and durability of the Cr-containing geopolymers were investigated.The experimental results indicate that the red mud-based geopolymer could effectively solidify/stabilize different types of Cr salts with solidification/stabilization rates of above 99.61%.Geopolymers are environmentally safe when the dosage of CaCr_2O_7 is ≤1.0wt%,or the dosage of CrCl_3,Cr_2O_3,and Na_2CrO_4 is ≤1.5wt%,respectively.The effects of Cr salts on the compressive strength varies with the type and content of Cr salts.The freeze-thaw cycle is more destructive to geopolymer properties than sulfate attack or acid rain erosion.The solidification/stabilization of Cr is mainly attributed to the following reasons:a) The chemical binding of Cr is related to the formation of Cr-containing hydrates (eg,magnesiochromite ((Mg,Fe)(Cr,Al)_2O_4)) and doping into N-A-S-H gel and C-A-S-H gel framework;b) The physical effect is related to the encapsulation by the hydration products (e g,N-A-S-H gel and C-A-S-H gel).This study provides a reference for the treatment of hazardous Cr-containing wastes by solid waste-based geopolymers.
2024年04期 v.39;No.180 819-830页 [查看摘要][在线阅读][下载 1610K] - 宋昊月;CAI Meng;袁萍;邹朝勇;
Using a titration setup to accurately control the reaction conditions and in situ monitor the reaction,we showed that fluoride exhibited negligible effects on the ion association process of calcium and phosphate and the formation of ACP nanospheres in a buffer solution with constant ionic strength.However,the stability of ACP increased with increasing fluoride concentration,which was ascribed to the inhibitory effect of fluoride on the aggregation of ACP nanospheres and the nucleation of nanocrystals on the surface of ACP nanospheres.Furthermore,fluoride could inhibit the lateral growth of HAP nanosheets and promote the formation of rod-like crystals.These results further improve our understanding of the crystallization pathway of HAP crystals and the regulatory effects of fluoride.
2024年04期 v.39;No.180 831-838页 [查看摘要][在线阅读][下载 1085K] - 徐吉祥;TAO Weijie;LIU Canhui;XU Haoyao;LI Lixuan;贺振华;
To study the effect of different deposition temperatures on the optical properties of porous SiC films,single crystal Si was used as the substrate,a layer of anodic aluminum oxide (AAO) film was transferred on the Si substrate by chemical method,and then a layer of SiC was deposited on anodic aluminum oxide (AAO) template to prepare porous fluorescent SiC film by magnetron sputtering.The deposition temperature was ranged from 373 to 873 K.The thickness of the porous SiC film coated on the AAO surface was around 283 nm.It is found that the porous SiC with the deposition temperature of 873 K has the strongest photoluminescence (PL) intensity excited by 375 nm laser.The time-resolved PL spectra prove that the PL is mainly from intrinsic light emitting of SiC.With the optimized process,porous amorphous SiC film may have potential applications in the field of warm white LEDs.
2024年04期 v.39;No.180 839-844页 [查看摘要][在线阅读][下载 1163K] - 余海燕;WANG Yingxiang;WANG Ruizhi;HU Lintong;WANG Tianlei;
Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material combining the solvent evaporation method and spray drying method.The protection by the outer capsule wall was used to prolong the service life of the corrosion inhibitor.The dispersion,encapsulation,thermal stability of microcapsules,and the degradation rate of capsule wall in concrete pore solution were analyzed by ultra-deep field microscopy,scanning electron microscopy,thermal analyzer,and sodium ion release rate analysis.The microcapsules were incorporated into mortar samples containing steel reinforcement,and the effects of double-layered microcapsule corrosion inhibitors on the performance of the cement matrix and the actual corrosion-inhibiting effect were analyzed.The experimental results show that the double-layered microcapsules have a moderate particle size and uniform distribution,and the capsules were completely wrapped.The microcapsules as a whole have good thermal stability below 230 ℃.The monolayer membrane structure microcapsules completely broke within 1 day in the simulated concrete pore solution,and the double-layer membrane structure prolonged the service life of the microcapsules to 80 days in the simulated concrete pore solution before the core material was completely released.The mortar samples containing steel reinforcement incorporated with the double-layered microcapsule corrosion inhibitors still maintained a higher corrosion potential than the monolayer microcapsule corrosion inhibitors control group at 60 days.The incorporation of double-layered microcapsules into the cement matrix has no significant adverse effect on the setting time and early strength.
2024年04期 v.39;No.180 845-853页 [查看摘要][在线阅读][下载 1246K] - 闵捷;YUAN Wenxu;CHEN Yufei;LAN Yapeng;YAN Mengdi;LIU Hanze;CHENG Xudong;代路;
AlMoON based solar selective absorption coatings were deposited on stainless steel substrate by magnetron sputtering.The coatings included infrared reflection layer Mo,absorption layer AlMoN,absorption layer AlMoON and antireflection layer AlMoO from bottom to top.The surface of the deposited coatings is flat without obvious defects.The absorptivity and emissivity are 0.896 and 0.09,respectively,and the quality factor is 9.96.After heat treatment at 500 ℃-36 h,the surface roughness of the coating increases,a small number of cracks and other defects appear,and the broken part is still attached to the coating surface.A certain degree of element diffusion occurs in the coatings,resulting in the decline of the optical properties of the coatings.The absorptivity and emissivity are 0.883 and 0.131,respectively,the quality factor is 7.06,and the PC value is 0.0335.The coatings do not fail under this condition and have certain thermal stability.
2024年04期 v.39;No.180 854-862页 [查看摘要][在线阅读][下载 1191K] - 严明;ZHU Yu;HUANG Jiangtao;CHEN Haoyu;DENG Yuxiao;CHEN Yanlin;王娟;Jan-Michael Albina;
We described a method for obtaining fluorine-free Ti_3C_2Cl_2 MXene phases by melting copper in CuCl_2 instead of aluminum in Ti_3AlC_2.XRD results show that when molten salt CuCl_2 etches Ti_3AlC_2,it forms an intermediate product Ti_3CuC_2,and then reacts with Ti_3CuC_2 to obtain Ti_3C_2Cl_2.The reaction of Ti_3AlC_2 and CuCl_2 at a temperature of 800 ℃ for 2 h to obtain Ti_3C_2Cl_2 with an optimal lamellar structure is shown in SEM results.The pseudopotential plane-wave (PP-PW) method is used to calculate on the electronic structure.The etching mechanism is investigated by the total energies of each substance.The chemical reaction of Ti_3AlC_2 and CuCl_2 will first become Ti_3CuC_2 and Cu,and then become Ti_3C_2Cl_2 during the Lewis acid etching process,which are consistent with the experimental results.
2024年04期 v.39;No.180 863-868页 [查看摘要][在线阅读][下载 1029K] - 张雁伟;WANG Yanze;LI Junguo;XIE Jingjing;王文宣;FU Zhengyi;
We synthesized BiVO_4 mesocrystals with ordered assembly structure,and studied the structural order and the relationship between the photodegradation of Rhodamine B.Au nanoparticles (NPs) were successfully loaded onto Meso-BiVO_4 by light-assisted induction,and Cd nanoparticles were further selected to be deposited on Au nanoparticles to form Z-scheme photocatalyst Meso-BiVO_4-Au-CdS heterostructures.We try and propose to analyze its ordered assembly structure by XRD for the first time.The results show that Meso-BiVO_4 is a mesocrystal with highly exposed (001) plane and directional assembly structure.The charge separation efficiency of all samples was studied by PL spectroscopy.The results show that the Z-scheme Meso-BiVO_4-Au-CdS can promote the charge separation and obtain the best carrier separation efficiency.Thus,it has the best photocatalytic activity in the experiment of photocatalytic degradation of rhodamine B.The main active species in the degradation process were confirmed by free radical trapping experiment,and the degradation mechanism was put forward.
2024年04期 v.39;No.180 869-876页 [查看摘要][在线阅读][下载 1140K] - 王浪;李超凡;RAN Maojin;YUAN Manman;胡执一;LI Yu;
The nucleation and growth mechanism of nanoparticles is an important theory,which can guide the preparation of nanomaterials.However,it is still lacking in direct observation on the details of the evolution of intermediate state structure during nucleation and growth.In this work,the evolution process of bismuth nanoparticles induced by electron beam was revealed by in-situ transmission electron microscopy(TEM) at atomic scale.The experimental results demonstrate that the size,stable surface and crystallographic defect have important influences on the growth of Bi nanoparticles.Two non-classical growth paths including single crystal growth and polycrystalline combined growth,as well as,corresponding layer-by-layer growth mechanism along {012} stable crystal plane of Bi nanoparticles with dodecahedron structure were revealed by in-situ TEM directly.These results provide important guidance and a new approach for in-depth understanding of the nucleation and growth kinetics of nanoparticles.
2024年04期 v.39;No.180 877-887页 [查看摘要][在线阅读][下载 2077K] - 舒启江;YANG Linjing;LIU Hongxing;黄鹏儒;
The effect of deposition temperature on the morphology and optoelectronic performance of Ge/Si QDs grown by magnetron sputtering under low Ge deposition (～ 4 nm) was investigated by atomic force microscopy,Raman spectroscopy,and photoluminescence (PL) tests.The experimental results indicate that temperatures higher than 750 ℃ effectively increase the crystallization rate and surface smoothness of the Si buffer layer,and temperatures higher than 600 ℃ significantly enhance the migration ability of Ge atoms,thus increasing the probability of Ge atoms meeting and nucleating to form QDs on Si buffer layer,but an excessively high temperature will cause the QDs to undergo an Ostwald ripening process and thus develop into super large islands.In addition,some PL peaks were observed in samples containing small-sized,high-density Ge QDs,the photoelectric properties reflected by these peaks were in good agreement with the corresponding structural characteristics of the grown QDs.Our results demonstrate the viability of preparing high-quality QDs by magnetron sputtering at high deposition rate,and the temperature effect is expected to work in conjunction with other controllable factors to further regulate QD growth,which paves an effective way for the industrial production of QDs that can be used in future devices.
2024年04期 v.39;No.180 888-894页 [查看摘要][在线阅读][下载 951K] - 韩宗盈;DONG Hui;DING Guoyang;ZHANG Jiale;SONG Xiufang;
The lignite-derived carbon from self-protection pyrolysis was employed to balance the fracturing and cold-welding of magnesium during ball milling.Particle size analysis indicates that the introduction of lignite-derived carbon can effectively reduce the particle size of Mg while the introduction of graphite does no help.Besides,the effect of lignite-derived carbon on crystallite size reduction of Mg is also better than graphite.A moderate cold-welding phenomenon was observed after ball-milling Mg with the lignite-derived carbon,suggesting less Mg is wasted on the milling vials and balls.Molecular dynamic simulations reveal that the balanced fracturing and cold-welding of magnesium during ball milling is mainly attributed to the special structure of the lignite-derived carbon:graphitized short-range ordered stacking function as dry lubricant and irregular shape/sharp edge function as milling aid.The preliminary findings in current study are expected to offer implications for designing efficient Mg-based hydrogen storage materials.
2024年04期 v.39;No.180 895-903页 [查看摘要][在线阅读][下载 1384K] - 易卓然;DENG Haoyuan;QIN Mei;孙一;LUO Guoqiang;
Graphene prepared by non-covalent modification of sulfonated poly(ether-ether-ketone) (SPG) was combined with polyvinylidene fluoride(PVDF)/Al to improve the PVDF/Al thermal conductivity while reducing the effect of the thermal resistance at the graphene-polymer interface.The regulation rule of SPG with different contents on the energy release of fluorine-containing system was studied.When the content of SPG is 4%,the peak pressure and rise rate of SPG/PVDF/Al composite powder during ignition reach the maximum of 4 845.28 kPa and 8 683.58 kPa/s.When the content of SPG is 5%,the PVDF/Al composite powder is completely coated by SPG,and the calorific value of the material reachs the maximum of 29.094 kJ/g.Through the design and micro-control of the composite powder,the calorific value of the material can be effectively improved,but the improvement of the mass release rate still depends on the graphene content and surface modification state.
2024年04期 v.39;No.180 904-911页 [查看摘要][在线阅读][下载 1034K] - 张超;任秀华;BA Dongzhe;ZHANG Jianhua;LI Jianyong;GUO Mengnan;GAO Yinghao;WANG Guixin;LI Jiayang;
Because inferior mechanical strength of granite polymer composite (GPC) has become the main drawback limiting its application and popularization,Mo fibers were added into (GPC) to improve its mechanical strength.Mechanical properties of matrix materials with different mass ratio of resin and stabilizer (MRRS) were investigated systematically.The influences of MRRS on interface bonding strength of Mo fiber-matrix,wettability and mechanical strength of GPC were discussed,respectively,and the theoretical calculation result of MRRS k was obtained,with the optimal value of k=4.When k=4,tensile strength,tensile strain and fracture stress of the cured resin achieve the maximum values.But for k=7,the corresponding values reach the minimum.With the increase of MRRS k,surface free energy of the cured resin first increases and then decreases,while contact angles between Mo sample and matrix have displayed the opposite trend.Wettability of resin to Mo fiber is the best at k=4.Pulling load of Mo fiber and interface bonding strength appear the maximum at k=4,followed by k=5,k=3 the third,and k=7 the minimum.When k=4,mechanical properties of Mo fiber-reinforced GPC are optimal,which is consistent with the result of theoretical calculation.This study is of great significance to get better component formulas of Mo fiber reinforced GPC and to improve its application in machine tools.
2024年04期 v.39;No.180 912-920页 [查看摘要][在线阅读][下载 1090K] - 刘文洁;WANG Yang;LI Jingtao;李宝让;
Industrial wastes such as steel slag and coal gangue etc.were chosen as raw materials for preparing ceramic via the conventional solid-state reaction method.With steel slag and coal gangue mixed in various mass ratios,from 100% steel slag to 100% coal gangue at 10% intervals,microstructure and possible phase evolution of the coal gangue-steel slag ceramics were investigated using X-ray powder diffraction,scanning electron microscopy,mercury intrusion porosimetry and Archimedes boiling method.The experimental results suggest that the phase compositions of the as-prepared ceramics could be altered with the increased amount of coal gangue in the ceramics.The anorthite-diopside eutectic can be formed in the ceramics with the mass ratios of steel slag to coal gangue arranged from 8:2 to 2:8,which was responsible for the melting of the steel slag-coal gangue ceramics at relatively high temperature.Further investigations on the microstructure suggested that the addition of the proper amount of steel slag in ceramic compositions was conducive to the pore formation and further contributed to an increment in porosity.
2024年04期 v.39;No.180 921-930页 [查看摘要][在线阅读][下载 1888K] - 童伊琳;杨坤;HAN Xuecai;YU Kan;BAO Jiaqi;
A composite was created by incorporating the quantum dot-enhanced SiO_2 nanoparticles within this hydrogel.Based on this composite,a temperature-controlled fluorescent probe for DCP was developed.A meticulous examination of this probe revealed its attributes and factors affecting its performance. By using temperature modulation,the probe was adept at detecting DCP concentrations ranging between 1.0×10~(-6) and 9.0×10~(-6) mol/L.Such a probe offers remarkable selectivity,repeatability,and robust stability,so that the detection of DCP can be carried out at different temperatures,and a fast,reliable,sensitive and low-cost intelligent detection method is realized.
2024年04期 v.39;No.180 931-936页 [查看摘要][在线阅读][下载 852K] - 谭艳;HAO Panpan;HE Yang;ZHU Rufeng;王跃丹;
Poly(3,4-ethylenedioxyethiophene)-polystyrene sulfonic acid (PEDOT:PSS)/polyallyl dimethyl ammonium chloride modified reduced graphene oxide (PDDA-rGO) was layer by layer self-assembled on the cotton fiber.The surface morphology and electric property was investigated.The results confirmed the dense membrane of PEDOT:PSS and the lamellar structure of PDDA-rGO on the fibers.It has excellent electrical conductivity and mechanical properties.The fiber based electrochemical transistor (FECTs) prepared by the composite conductive fiber has a maximum output current of 8.7 mA,a transconductance peak of 10 mS,an on time of 1.37 s,an off time of 1.6 s and excellent switching stability.Most importantly,the devices by layer by layer self-assembly technology opens a path for the true integration of organic electronics with traditional textile technologies and materials,laying the foundation for their later widespread application.
2024年04期 v.39;No.180 937-944页 [查看摘要][在线阅读][下载 1135K] - 王俊凯;李来时;LIU Feng;WANG Yuzheng;吴玉胜;
A method to promote aluminum hydroxide crystal growth through pickling Al(OH)_3 as seed in the ammonia system was proposed to overcome these defects.The experimental results show that,under the conditions of pickling time of 15 min,the acid concentration of 10%,the addition of 70 g/L pickling-Al(OH)_3 seed,and the coarse granular Al(OH)_3 products (d_(0.5)=85.667) can be obtained.The characterization results show that the phase of the product is gibbsite,consistent with the seed.Moreover,the steps and ledges can be formed on pickling Al(OH)_3 seed surface under the ammonia system,effectively promoting crystal growth.During crystal growth,the roughness of the crystal surface was first increased and then decreased,and the lamellar structure was deposited on the crystal seed surface.The final particles are approximately round,the surface is compact and dense.The growth of the product is surface reaction controlled.In addition,the content of the AlO_6 unit is increased and contributed to Al(OH)_3 crystal growth.
2024年04期 v.39;No.180 945-953页 [查看摘要][在线阅读][下载 1191K] - 张峰;XIONG Dehua;谢俊;张继红;HAN Jianjun;CHEN Dequan;WEN Zhongquan;FAN Zhenhua;CHEN Lina;SUN Tengfei;
The calcium aluminosilicate-based glasses (CaO-Al_2O_3-SiO_2,CAS) with different Fe_2O_3 content (0.10wt%,0.50wt%,0.90wt%,and 1.30wt%) were prepared by traditional melt-quenching method.The glass network structure,thermal and mechanical properties,and crystallization behavior changes were investigated by nuclear magnetic resonance spectrometer,Fourier-transform infrared spectro-photometer,X-ray diffractometer,differential scanning calorimetry and field emission scanning electron microscope measurements.The change of Q~n in glass structures reveals the glass network connectivity decreases due to the increasing content of Fe_2O_3 addition,resulting in the increasing of non-bridging number in glass structure.The glass densities slightly rise from 2.644 to 2.681 g/cm~3,while Vickers’s hardness increases at first,from 6.469 to 6.901 GPa,then slightly drops to 6.745 GPa,with Fe_2O_3 content increase.There is almost no thermal expansion coefficient change from different Fe_2O_3 content.The glass transmittance in visible range gradually decreases with higher Fe_2O_3 content,resulting from the strong absorption of Fe~(2+) and Fe~(3+) ions.The calculated activation energy from thermal analysis results first decreases from 282.70 to 231.18 kJ/mol,and then increases to 244.02 kJ/mol,with the Fe_2O_3 content increasing from 0.10wt% to 1.30wt%.Meanwhile,the maximum Avrami constant of 2.33 means the CAS glasses exhibit two-dimensional crystallization.All of the CAS glass-ceramics samples contain main crystal phase of anorthite,the microstructure appears lamellar and columnar crystals.
2024年04期 v.39;No.180 954-961页 [查看摘要][在线阅读][下载 1165K] - 刘志刚;TANG Zezheng;杨立荣;WANG Chunmei;XIE Yuantao;LIU Yisen;
The retarding effect of protein retarder on phosphorus building gypsum (PBG) and desulfurization building gypsum (DBG) was investigated,and the results show that protein retarder for DBG can effectively prolong the setting time and displays a better retarding effect,but for PBG shows a poor retarding effect.Furthermore,the deterioration reason of the retarding effect of protein retarder on PBG was investigated by measuring the pH value and the retarder concentration of the liquid phase from vacuum filtration of PBG slurry at different hydration time,and the measure to improve the retarding effect of protein retarding on PBG was suggested.The pH value of PBG slurry (<5.0) is lower than that of DBG slurry (7.8-8.5).After hydration for 5 min,the concentration of retarder in liquid phase of DBG slurry gradually decreases,but in liquid phase of PBG slurry continually increases,which results in the worse retarding effect of protein retarder on PBG.The liquid phase pH value of PBG slurry can be adjusted higher by sodium silicate,which is beneficial to improvement in the retarding effect of the retarder.By adding 1.0% of sodium silicate,the initial setting time of PBG was efficiently prolonged from 17 to 210 min,but little effect on the absolute dry flexural strength was observed.
2024年04期 v.39;No.180 962-967页 [查看摘要][在线阅读][下载 997K]
- 吴瑜;孙明清;ZHU Lutao;SONG Qiulei;CHEN Jianzhong;
The frequency-dependent electrical properties and strain self-sensing behaviour of ultra-high performance concrete (UHPC) as cement-based stress/strain self-sensing (CBSS) smart materials were investigated in the frequency range from 100 Hz to 300 kHz.By using the electrical parameters of the equivalent electric circuit model,the quantitative relations of capacitance and conductance of CBSS with the measurement frequency were derived.The capacitance and the conductance exhibit power-law type dependence on the measurement frequency.The calculated capacitance values at frequencies beyond 2 kHz and conductance values are consistent with the experimental results.The sweep-frequency test and the fixed-frequency test were performed to examine effects of the excitation frequencies on strain self-sensing properties of CBSS.The fractional change in capacitance (FCC) and resistance (FCR) of CBSS are frequency-dependent in the frequency range from 100 Hz to the f_B,but frequency-independent in the frequency range from the f_B to 300 kHz.The f_A and the f_B are 1.7-4.0 kHz and 11-78 kHz depending on the fiber dosages,respectively.FCC and FCR reach their maximum at the f_A and 100 Hz,respectively.The responses of capacitance and resistance of CBSS to strain show good repeatability during cyclic loading.As the fiber dosage increases,capacitance-based sensitivity to strain increases initially and then decreases at the f_A,and resistance-based sensitivity to strain of CBSS increases with increasing fiber contents.
2024年04期 v.39;No.180 968-978页 [查看摘要][在线阅读][下载 1625K] - 李立辉;牛开民;TIAN Bo;CHEN Xin;FU Ziqian;ZHU Xuwei;
In order to ascertain the effects of atmospheric pressure on developmental characteristics and the stability of AEA (air-entraining agent) solution bubbles,AEA solution experiments and AEA solution bubble experiments were,respectively,conducted in Peking (50 m,101.2 kPa) and Lhasa (3,650 m,63.1 kPa).Surface tensions and inflection-point concentrations were tested based on AEA solutions,whilst developmental characteristics,thicknesses and elastic coefficients of liquid films were tested based on air bubbles of AEA solutions.The study involved three types of AEAs,which were TM-O,226A,and 226S.The experimental results show that initial sizes of TM-O,226A,and 226S are,respectively,increased by 43.5%,17.5%,and 3.8%.With the decrease of ambient pressure,the drainage rate and the drainage index of AEA solution bubbles increase.Interference experiments show that the liquid film thicknesses of all tested AEA solution bubbles are in micron scales.When the atmospheric pressure decreases from 101.2 to 63.1 kPa,the liquid film thicknesses of three types of AEA solutions decrease in various degrees;and film elasticities at critical thicknesses increase.Liquid film of 226S solution bubbles is the most stable,presenting as a minimum thickness variation.It should be noted that elastic coefficient of liquid film only represents the level at critical thickness,thus it can not be applied as the only evaluating indicator of bubble stability.For a type of AEA,factors affecting the stability of its bubbles under low atmospheric pressure include initial bubbles size,liquid film thickness,liquid film elasticity,ambient temperature,etc.
2024年04期 v.39;No.180 979-989页 [查看摘要][在线阅读][下载 1762K] - 代金鹏;HE Jie;WANG Qicai;LOU Xuyu;
The effects of the water-cement ratio and the molding temperature on the hydration heat of cement were investigated with semi-adiabatic calorimetry.The specimens were prepared with water-cement ratios of 0.31,0.38,and 0.45,and the molding temperature was specified at 10 and 20 ℃.The experimental results show that,as the water-binder ratio increases,the value of the second temperature peak on the temperature curve of the cement paste decreases,and the age at which the peak appears is delayed.The higher the water-cement ratio,the higher the hydration heat release in the early period of cement hydration,but this trend reverses in the late period.There are intersection points of the total hydration heat curve of the cement pastes under the influence of the water-cement ratio,and this law can be observed at both molding temperatures.With the increase in the molding temperature,the age of the second temperature peak on the temperature curve of the cement paste will advance,but the temperature peak will decrease.The higher the molding temperature,the earlier the acceleration period of the cement hydration began,and the larger the hydration heat of the cement in the early stage,but the smaller the total heat in the late period.A subsection function calculation model of the hydration heat,which was based on the existing models,was proposed in order to predict the heat of the hydration of the concrete.
2024年04期 v.39;No.180 990-998页 [查看摘要][在线阅读][下载 1479K] - 刘芯州;郭远臣;WANG Rui;XIANG Kai;WANG Xue;YE Qing;
To improve the brittleness characteristics of magnesium phosphate cement-based materials (MPC) and to promote its promotion and application in the field of structural reinforcement and repair,this study aimed to increase the toughness of MPC by adding jute fiber,explore the effects of different amounts of jute fiber on the working and mechanical properties of MPC,and prepare jute fiber reinforced magnesium phosphate cement-based materials (JFRMPC) to reinforce damaged beams.The improvement effect of beam performance before and after reinforcement was compared,and the strengthening and toughening mechanisms of jute fiber on MPC were explored through microscopic analysis.The experimental results show that,as the content of jute fiber (JF) increases,the fluidity and setting time of MPC decrease continuously;When the content of jute fiber is 0.8%,the compressive strength,flexural strength,and bonding strength of MPC at 28 days reach their maximum values,which are increased by 18.0%,20.5%,and 22.6% compared to those of M0,respectively.The beam strengthened with JFRMPC can withstand greater deformation,with a deflection of 2.3 times that of the unreinforced beam at failure.The strain of the steel bar is greatly reduced,and the initial crack and failure loads of the reinforced beam are increased by 192.1% and 16.1%,respectively,compared to those of the unreinforced beam.The JF added to the MPC matrix dissipates energy through tensile fracture and debonding pull-out,slowing down stress concentration and inhibiting the free development of cracks in the matrix,enabling JFRMPC to exhibit higher strength and better toughness.The JF does not cause the hydration of MPC to generate new compounds but reduces the amount of hydration products generated.
2024年04期 v.39;No.180 999-1009页 [查看摘要][在线阅读][下载 1380K]
- 黄西娜;MA Xiaowen;XU Tianyi;
Cryogenic treatment was used to improve the tribological properties of Ti6Al4V artificial hip joint implants.Cryogenic treatment at-196 ℃ with different holding time were carried out on Ti6Al4V specimens fabricated using electron beam melting (EBM),and their microstructure and tribological properties evolution were systematically analyzed by scanning electron microscopy (SEM),vickers hardness,and wear tests.The experimental results show that the as-fabricated specimen consists of lamellar α phase and β columnar crystal.While,the thickness of lamellar α phase decreased after cryogenic treatment.In addition,it can be found that the fine α phase was precipitated and dispersed between the lamellar α phase with the holding time increase.Vickers hardness shows a trend of first increasing and then decreasing.The wear rate of the specimen cryogenic treated for 24 h is the minimum and the average friction coefficient is 0.50,which is reduced by 14.61% compared with the as-fabricated.The wear mechanism of the as-fabricated specimen is severe exfoliation,adhesive,abrasive,and slight fatigue wear.However,the specimen cryogenic treated for 24 h shows slight adhesive and abrasive wear.It can be concluded that it is feasibility of utilizing cryogenic treatment to reduce the wear of EBMed Ti6Al4V.
2024年04期 v.39;No.180 1010-1017页 [查看摘要][在线阅读][下载 1584K] - 田密;成博;
The experiment employed the use of melt purification and cyclic superheating technique to achieve maximum undercooling of Ni65Cu31Co4 alloy at 300K.Simultaneously,high-speed photography techniques were used to capture the process of alloy liquid phase interface migration,and analyzed the relationship between the shape characteristics of the front end of alloy solidification and undercooling.The microstructure of the alloy was observed through metallographic microscopy,and the micro-morphological characteristics and evolution of the rapidly solidified microstructure were systematically studied.It is found that the grain refinement mechanism of Ni-Cu-Co ternary alloy is similar to that of Ni-Cu binary alloy.Grain refinement at low undercooling is caused by intense dendritic remelting,while grain refinement at high undercooling is attributed to recrystallization,driven by the stress and plastic strain accumulated from the interaction of liquid flow and primary dendrites caused by rapid solidification.It also shows that the addition of the third element Co plays a significant role in solidification rate and re-ignition effect.
2024年04期 v.39;No.180 1018-1024页 [查看摘要][在线阅读][下载 1305K] - 胡玉;ZHOU Fan;ZHANG Nan;PAN Xiaobin;LI Shiying;ZHANG Dong;LI Li;张玲帆;
Three kinds of iron nanoparticles (FeNPs) were prepared via green route based on pomegranate (PG),green tea (GT),and mulberry (ML) extracts under ambient conditions.The obtained materials were characterized by scanning electron microscopy (SEM),transmission electronic microscopy (TEM),X-ray energy-dispersive spectrometer (EDS),X-ray diffraction (XRD),fourier transform infrared spectroscopy (FTIR),and X-ray photoelectron spectroscopy (XPS) techniques.The experimental results show that FeNPs were in the form of amorphous iron (Ⅱ,Ⅲ)-polyphenol complex with different dispersity and morphologies.GT-Fe has the smallest size range of 25-35 nm,PG-Fe has a moderate size-distribution of 30-40 nm,while ML-Fe formed a tuberous net-type with a sheeting structure.PG-Fe displays the highest removal efficiency of 90.2% in 20 min towards cationic dye of malachite green (16.6% by ML-Fe and 69.3% by GT-Fe),which is attributed to its highest polyphenol content,lowest zeta potential,as well as the most Fe~(2+) on the surface of FeNPs.The removal mechanism was mainly induced by electrostatic adsorption based on pH and zeta potential tests.
2024年04期 v.39;No.180 1025-1030页 [查看摘要][在线阅读][下载 1037K] - 贺跃;王海峰;YANG Pan;WANG Song;CHEN Xiaoliang;YANG Chunyuan;王家伟;
The in-situ oxidation of manganese sulfate solution with H_2O_2,sodium hypochlorite,potassium permanganate and oxygen as oxidants was investigated by means of SEM,EDS,XRD,BET and infrared analysis,and the effects of different oxidants on the morphology,phase composition,surface properties and specific surface area of manganese oxides were investigated.The experimental results show that the diameter of manganese oxide particles prepared with H_2O_2 is the smallest,about 50 nm,and the specific surface area is the largest,63.8764 m~2/g.It has the advantages of abundant surface hydroxyl groups,no introduction of other impurities and large adsorption potential.It is most suitable to be used as an oxidant for oxidizing manganese sulfate solution to prepare manganese oxide by in-situ oxidation.Nano manganese oxide prepard by H_2O_2 in-situ oxidation method is used as adsorbent to adsorb cobalt and nickel impurities in manganese sulfate.When the reaction pH is 6,the reaction time is 30min and the amount of adsorbent is 1.0 g,the adsorption rates of cobalt and nickel impurities in 100ml manganese sulfate solution are 97.59% and 97.67%,respectively.The residual amounts of cobalt and nickel meet the industrial process standard of first-class products (Co,Ni w/%≤0.005) of high-purity manganese sulfate (Hg/t4823-2015) for batteries.The study plays a guiding role in the preparation and regulation of manganese oxide,and provides a new method with high efficiency,purity and adsorbent availability for the preparation of high-purity manganese sulfate solution.
2024年04期 v.39;No.180 1031-1040页 [查看摘要][在线阅读][下载 1180K] - 杜文华;HOU Kai;XU Xuguang;Ismal Saad;Willey Liew Yun Hsien;AN Hongen;Nancy Julius Siambun;Bih-Lii Chuab;王洪福;
Through the use of purification and recirculation superheating techniques on molten glass,the Ni65Cu33Co2 alloy was successfully undercooled to a maximum temperature of 292 K.High-speed photography was employed to capture the process of interface migration of the alloy liquid,allowing for an analysis of the relationship between the morphological characteristics of the alloy liquid solidification front and the degree of undercooling.Additionally,the microstructure of the alloy was examined using metallographic microscopy,leading to a systematic study of the microscopic morphological characteristics and evolution laws of the refined structure during rapid solidification.The research reveals that the grain refining mechanism of the Ni-Cu-Co ternary alloy is consistent with that of the binary alloy (Ni-Cu).Specifically,under low undercooling conditions,intense dendritic remelting was found to cause grain refinement,while under high undercooling conditions,recrystallization driven by accumulated stress and plastic strain resulting from the interaction between the liquid flow and the primary dendrites caused by rapid solidification was identified as the main factor contributing to grain refinement.Furthermore,the study highlights the significant role of the Co element in influencing the solidification rate and reheat effect of the alloy.The addition of Co was also found to facilitate the formation of non-segregated solidification structure,indicating its importance in the overall solidification process.
2024年04期 v.39;No.180 1041-1047页 [查看摘要][在线阅读][下载 1132K]