Optimizing the microchannel design of the next generation of chips requires an understanding of the in situ property evolution of the chip-based materials under fast cooling.This work overcomes the conventional relian...Optimizing the microchannel design of the next generation of chips requires an understanding of the in situ property evolution of the chip-based materials under fast cooling.This work overcomes the conventional reliance on reheating data of melt-quenched glasses by demonstrating direct observations of glass transition on cooling curves utilizing the most advanced fast differential scanning calorimetry.By leveraging an MEMS chip sensor that allows for rapid heat extraction from microgram-sized samples to a purged gas coolant,the device is able to reach ultra-fast cooling rates of up to 40,000 K·s^(−1).Four thermal regions are identified by examining the cooling behaviors of two metallic glasses.This is because the actual rate of the specimen can differ from the programmed rate,especially at high set rate when the actual rate decreases before the glass transition is completed.We define the operational window for reliable cooling curve analysis,build models with empirical and theoretical analyses to determine the maximum feasible cooling rate,and demonstrate how optimizing sample mass and environment temperature broaden this window.The method avoids deceptive structural relaxation effects verified by fictivetemperature analysis and permits the capture of full glass transition during cooling.展开更多
An optimal test method for paint is proposed; additionally, the Field and Laboratory Emission Cell （FLEC） method used in Europe is applied as a substitute for the 20 L small chamber method. The emission factors of t...An optimal test method for paint is proposed; additionally, the Field and Laboratory Emission Cell （FLEC） method used in Europe is applied as a substitute for the 20 L small chamber method. The emission factors of total volatile organic compounds （TVOC） and formaldehyde from oil-based paint, emulsion paint, and water-dispersion paint with a coating weight of 300 g/m2, cured for 24/48 hours, were measured using the 20 L small chamber method. The emission rate of TVOC and formaldehyde from all paints began to stabilize after approximately 7 days after 24/48 hours of curing even though Korean standards stipulate that paint should be measured and analyzed after the third day of application. The emission factor of TVOC and formaldehyde from oil-based, emulsion, and water-dispersion paints were also measured using the FLEC method. There was good correlation between the 20 L small chamber method and the FLEC method for oil-based, emulsion, and water-dispersion paint emissions. With the FLEC method, using paints prepared under identical conditions, the emission rate was stable 24 hours after installation of samples because the air flow rate of FLEC is much higher than that of a 20 L small chamber, and the relative cell volume of FLEC is much smaller than that of a 20 L small chamber.展开更多
By using Stroh' complex formalism and Cauchy's integral method, the electro-elastic fundamental solutions of an infinite anisotropic piezoelectric solid containing an elliptic hole or a crack subjected to a Li...By using Stroh' complex formalism and Cauchy's integral method, the electro-elastic fundamental solutions of an infinite anisotropic piezoelectric solid containing an elliptic hole or a crack subjected to a Line force and a line charge are presented in closed form. Particular attention is paid to analyzing the characteristics of the stress and electric displacement intensity factors. When a line force-charge acts on the crack surface, the real form expression of intensity factors is obtained. It is shown through a special example that the present work is correct.展开更多
Activities of space materials science research in China have been continuously supported by two main national programs.One is the China Space Station(CSS)program since 1992,and the other is the Strategic Priority Prog...Activities of space materials science research in China have been continuously supported by two main national programs.One is the China Space Station(CSS)program since 1992,and the other is the Strategic Priority Program(SPP)on Space Science since 2011.In CSS plan in 2019,eleven space materials science experimental projects were officially approved for execution during the construction of the space station.In the SPP Phase Ⅱ launched in 2018,seven pre-research projects are deployed as the first batch in 2018,and one concept study project in 2019.These pre-research projects will be cultivated as candidates for future selection as space experiment projects on the recovery of scientific experimental satellites in the future.A new apparatus of electrostatic levitation system for ground-based research of space materials science and rapid solidification research has been developed under the support of the National Natural Science Foundation of China.In order to promote domestic academic activities and to enhance the advancement of space materials science in China,the Space Materials Science and Technology Division belong to the Chinese Materials Research Society was established in 2019.We also organized scientists to write five review papers on space materials science as a special topic published in the journal Scientia Sinica to provide valuable scientific and technical references for Chinese researchers.展开更多
The nanocrystalline samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))were prepared using the citrate combustion method.The X-ray diffraction(XRD)pattern confirmed that the nanoparticles were synthesized...The nanocrystalline samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))were prepared using the citrate combustion method.The X-ray diffraction(XRD)pattern confirmed that the nanoparticles were synthesized in an orthorhombic structure.The particle size of Nd_(1-x)M_(x)FeO_(3) is in the range of 29-59 nm.The selected area electron diffraction(SAED)indicates the samples were prepared in a polycrystalline nature.The samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))have anti ferromagnetic behavior.The Fe^(3+)spins are aligned antiparallel,forming the antiferromagnetic(AFM)properties,which are affected by many factors such as the bond angle between the Fe^(3+)(Fe^(3+)-O_(2)--Fe^(3+))and the Dzyaloshinskii-Moriya(D-M)interaction.The doping of Co^(2+)and Ni^(2+)ions in NdFeO_(3) enhances the magnetic properties of the NdFeO_(3).The saturation magnetization(Ms)of Nd_(0.90)Co_(0.10)FeO_(3) increases 1.8times more than that of NdFeO_(3).The exchange bias field(HEX)of the Co-doped sample is two times greater than that of NdFeO_(3).The magnetic anisotropy constant(K)of the 10%Co-doped sample increases by 11 factors compared to that of NdFeO_(3).The Tauc plot illustrates that the samples have a direct optical transition.The divalent cation substitution(Co^(2+)and Ni^(2+))decreases the optical band gap of NdFeO_(3),leading to the recommendation of using the samples Nd_(0.90)Co_(0.10)FeO_(3) and Nd_(0.90)Ni_(0.10)FeO_(3) in photocatalysis of dye degradation from water.The removal efficiencies of Cr6+at pH=6 are 88.06%,85.54%,and 85.52%for the samples NdFeO_(3),Nd_(0.90)Co_(0.10)FeO_(3),and Nd_(0.90)Ni_(0.10)FeO_(3),respectively.The Freundlich isotherm mode is the best-fit model for NdFeO_(3) to adsorb Cr6+ions from aqueous solutions.展开更多
Thermal barrier coatings(TBCs)are extensively utilized in aero-engines and heavy-duty gas turbines due to their outstanding properties,including low thermal conductivity,corrosion,high-temperature oxidation,and wear r...Thermal barrier coatings(TBCs)are extensively utilized in aero-engines and heavy-duty gas turbines due to their outstanding properties,including low thermal conductivity,corrosion,high-temperature oxidation,and wear resistance.The rising thrust-to-weight ratio and service temperature in engine hot sections have presented a significant challenge in TBC's materials,structure,and preparation process;it is one of the current research hotspots in the aviation field.This paper reviews the recent advancement in turbine blade TBCs.It focuses on the TBC's structure,deposition mechanism and the key performance evaluation indexes for TBCs applied to turbine blades.Finally,the future research field of TBCs for turbine blades is also be prospected.展开更多
A1 doped SmFeO3 （SmFel_xmlxO3; 0.0〈x〈0.15; step 0.05） were prepared by double sintering ceramic technique. The obtained samples were crystallized in single phase structure except the sample with x=0.15. The unit c...A1 doped SmFeO3 （SmFel_xmlxO3; 0.0〈x〈0.15; step 0.05） were prepared by double sintering ceramic technique. The obtained samples were crystallized in single phase structure except the sample with x=0.15. The unit cell volume was found to decrease with increasing AI substitution in orthoferrite. The effective magnetic moment （μeff） and the Curie constant （C） were calculated from the reciprocal of the molar magnetic susceptibility （Z-1） versus absolute temperature plot and found to attain maximum value for the parent sample. The magnetic behavior showed two different magnetic transitions, viz, N6el temperature （TN） and spin reorientation （TsR） transitions. The M-H hysteresis loop of the parent sample took butterfly-shape as a result of different contributions anisotropies. From the magnetic properties measurements, it was obviously found that B-site cation dilution resulted in a drastic decrease in the magnetization. Surprisingly large value of the coercive field was obtained for the undoped sample;Hc=6198.80e. Based on the mentioned results, one can recommend the use of such orthoferrite in magnetic recording media and as pining layer in spin valve for spin- tronic applications.展开更多
Porous and functionally graded materials have seen extensive applications in modern biomedical devices—allowing for improved site-specific performance;their appreciable mechanical,corrosive,and biocompatible properti...Porous and functionally graded materials have seen extensive applications in modern biomedical devices—allowing for improved site-specific performance;their appreciable mechanical,corrosive,and biocompatible properties are highly sought after for lightweight and high-strength load-bearing orthopedic and dental implants.Examples of such porous materials are metals,ceramics,and polymers.Although,easy to manufacture and lightweight,porous polymers do not inherently exhibit the required mechanical strength for hard tissue repair or replacement.Alternatively,porous ceramics are brittle and do not possess the required fatigue resistance.On the other hand,porous biocompatible metals have shown tailorable strength,fatigue resistance,and toughness.Thereby,a significant interest in investigating the manufacturing challenges of porous metals has taken place in recent years.Past research has shown that once the advantages of porous metallic structures in the orthopedic implant industry have been realized,their biological and biomechanical compatibility—with the host bone—has been followed up with extensive methodical research.Various manufacturing methods for porous or functionally graded metals are discussed and compared in this review,specifically,how the manufacturing process influences microstructure,graded composition,porosity,biocompatibility,and mechanical properties.Most of the studies discussed in this review are related to porous structures for bone implant applications;however,the understanding of these investigations may also be extended to other devices beyond the biomedical field.展开更多
The heat transfer in a steelmaking ladle was studied. The evaluation of heat transfer of the steel was performed by measuring steel temperature in points including all refining steel process. In the ladle, the tempera...The heat transfer in a steelmaking ladle was studied. The evaluation of heat transfer of the steel was performed by measuring steel temperature in points including all refining steel process. In the ladle, the temperatures in the refractories and the shell were also measured. To evaluate the thermal profile between the hot and cold faces of the ladle in the slag line position, an experiment which shows the importance of thermal contact resistance was carried out. Higher heat losses in the tapping and the vacuum were verified. The temperature measurements of the ladle indicate distinct thermal profiles in each stage of steel refining. Moreover, as each stage of the process depends on the previous one, the complexity of the ladle thermal control is incremental. So a complete model of heat losses in the ladle is complex.展开更多
In this research, the dynamic recrystallization （DRX） behavior of an as-cast precipitation hardenable （PH） stainless steel was investigated by conducting hot compression tests at temperatures between 950-1150℃ an...In this research, the dynamic recrystallization （DRX） behavior of an as-cast precipitation hardenable （PH） stainless steel was investigated by conducting hot compression tests at temperatures between 950-1150℃ and under strain rates of 0.001-1 s^-1. The flow stress curves show that the DRX is responsible for flow softening during hot compression. The effects of temperature and strain rate on the strain and stress corresponding to peak point （εp and σp） of flow curve were analyzed individually. It is realized that, they increase with strain rate and decrease with temperature. The relationship between Zener-Hollomon parameter （Z） and εp was investigated and the equation of εp=4.3×10^-4^0.14 was proposed. The strain for the maximum rate of DRX （εmax） was determined under different deformation conditions. Therefore, it is realized that it increases with Z parameter and vise versa. On the basis of obtained results, the equation of εmax=9.5 × 10^-4Z0.12 was proposed.展开更多
Silica aerogels were prepared at ambient drying by using ethanol/trimethylchlorosilane （TMCS）/heptane solution as pore water exchange and surface modification of the wet gel before drying. The obtained silica aeroge...Silica aerogels were prepared at ambient drying by using ethanol/trimethylchlorosilane （TMCS）/heptane solution as pore water exchange and surface modification of the wet gel before drying. The obtained silica aerogels exhibit a sponge-like structure with uniform pore size distribution. The effects of heat-treatment on the hydrophobicity, specific surface area and other properties were investigated. The results indicated that the hydrophobicity of silica aerogels could be maintained up to 350℃. With increasing heating temperature, hydrophobicity decreased, and became completely hydrophilic after heat-treatment at 500℃. Brunaueremmitt-teller （BET） surface area results indicated that the specific surface area of silica aerogels increased with increasing heating temperature in the range of 150-500℃. The effects of heat-treatment on the morphology and chemical bonding state of silica aerogels were investigated by scanning electron microscopy （SEM）, differential temperature analysis （DTA） and Fourier-transform infrared spectroscopy （FT-IR）.展开更多
The inhibition efficiency of 1,4-bis （2-nitrobenzylidene） thiosemicarbazide （BBTS） on the corrosion of mild steel in 1 mol/L HCI was investigated by potentiodynamic polarization and electrochemical impedance metho...The inhibition efficiency of 1,4-bis （2-nitrobenzylidene） thiosemicarbazide （BBTS） on the corrosion of mild steel in 1 mol/L HCI was investigated by potentiodynamic polarization and electrochemical impedance methods. Inhibition efficiency （IE）, corrosion rate and surface coverage were evaluated at different concentrations of BBTS. The results of the investigation showed that this compound had good inhibiting properties for mild steel corrosion in hydrochloric acid and BBTS was a mixed-type inhibitor. BBTS chemisorbed at the electrode surface obeyed Langmuir adsorption isotherm and formed a stable surface complex on the mild steel surface. The synergistic effect of halide ion in acid solution suggested a co-adsorption of BBTS inhibitor by the adsorbed iodide ion.展开更多
Fe-doped ZnO (Zn0.99Fe0.01O) powders are successfully prepared by ball milling with different milling time, and are inves- tigated using X-ray diffraction (XRD), scanning electron microscope (SEM), ultraviolet-visible...Fe-doped ZnO (Zn0.99Fe0.01O) powders are successfully prepared by ball milling with different milling time, and are inves- tigated using X-ray diffraction (XRD), scanning electron microscope (SEM), ultraviolet-visible (UV-VIS) spectroscopy, vibrating sample magnetometer (VSM) and electron paramagnetic resonance (EPR) spectroscopy. The structural analysis using XRD reveals that the Fe-doped ZnO milled at different milling time can crystallize in a wurtzite structure, and in the XRD patterns, the secondary phase related to Fe cluster with the sensitivity of the XRD instrument can not be found. The SEM image of the sample milled for 24 h shows the presence of spherical nanoparticles. From the optical analysis, the optical band gap is found to decrease with increasing the milling time, which indicates the incorporation of Fe2+ ions into the ZnO lattice. The magnetization measurement using VSM reveals that the nanoparticles exhibit ferromagnetic behavior at room temperature, and the magnetization increases gradually with increasing the milling time. The conclusion is further confirmed by the electron paramagnetic resonance of the nanoparticles examined at room temperature, which shows an intense and broad ferromagnetic resonance signal related to Fe ions.展开更多
Rechargeable aluminum-ion batteries(AIBs)are a new generation of low-cost and large-scale electrical energy storage systems.However,AIBs suffer from a lack of reliable cathode materials with insufficient intercalation...Rechargeable aluminum-ion batteries(AIBs)are a new generation of low-cost and large-scale electrical energy storage systems.However,AIBs suffer from a lack of reliable cathode materials with insufficient intercalation sites,poor ion-conducting channels,and poor diffusion dynamics of large chloroaluminate anions(AlCl4−and Al2Cl7−).To address these issues,surfacemodified graphitic carbon materials[i.e.,acidtreated expanded graphite(AEG)and base-etched graphite(BEG)]are developed as novel cathode materials for ultra-fast chargeable AIBs.AEG has more turbostratically ordered structure covered with abundant micro-to nano-sized pores on the surface structure and expanded interlayer distance(d002=0.3371 nm)realized by surface treatment of pristine graphite with acidic media,which can be accelerated the diffusion dynamics and efficient AlCl4−ions(de)-intercalation kinetics.The AIB system employing AEG exhibits a specific capacity of 88.6 mAh g^(−1)(4 A g^(−1))and~80 mAh g^(−1) at an ultra-high current rate of 10 A g^(−1)(~99.1%over 10,000 cycles).BEG treated with KOH solution possesses the turbostratically disordered structure with high density of defective sites and largely expanded d-spacing(d002=0.3384 nm)for attracting and uptaking more AlCl4−ions with relatively shorter penetration depth.Impressively,the AIB system based on the BEG cathode delivers a high specific capacity of 110 mAh g^(−1)(4 A g^(−1))and~91 mAh g^(−1)(~99.9%over 10,000 cycles at 10 A g^(−1)).Moreover,the BEG cell has high energy and power densities of 247 Wh kg^(−1) and 44.5 kW kg^(−1).This performance is one of the best among the AIB graphitic carbon materials reported for chloroaluminate anions storage performance.This finding provides great significance for the further development of rechargeable AIBs with high energy,high power density,and exceptionally long life.展开更多
Colloidal silver nanoparticles （Ag-NPs） were obtained through γ-irradiation of aqueous solutions containing AgNO3 and gelatin as a silver source and stabilizer, respectively. The absorbed dose of γ-irradiation inf...Colloidal silver nanoparticles （Ag-NPs） were obtained through γ-irradiation of aqueous solutions containing AgNO3 and gelatin as a silver source and stabilizer, respectively. The absorbed dose of γ-irradiation influences the particle diameter of the Ag-NPs, as evidenced from surface plasmon resonance （SPR） and transmission electron microscopy （TEM） images. When the γ-irradiation dose was increased （from 2 to 50 kGy）, the mean particle size was decreased continuously as a result of γ-induced Ag-NPs fragmentation. The antibacterial properties of the Ag-NPs were tested against Methicillinresistant Staphylococcus aureus （MRSA） （Gram-positive） and Pseudomonas aeruginosa （P.a） （Gram-negative） bacteria. This approach reveals that the γ-irradiation-mediated method is a promising simple route for synthesizing highly stable Ag-NPs in aqueous solutions with good antibacterial properties for different applications.展开更多
1 Introduction In the last decades,many fluidic actuators have been developed for numerous applications,e.g.,artificial muscles(Wang and Qu,2016),soft spatial finger(Mao et al.,2020a,2020c),soft robots(Shepherd et al....1 Introduction In the last decades,many fluidic actuators have been developed for numerous applications,e.g.,artificial muscles(Wang and Qu,2016),soft spatial finger(Mao et al.,2020a,2020c),soft robots(Shepherd et al.,2011),and compliant gripper(Li et al.,2021).Differing in their dimensions,they can be categorized into two groups:piston-cylinder fluidic actuators and elastic fluidic actuators(de Voider and Reynaerts,2010;Ye et al.,2019).展开更多
Understanding the material flow facilitated by tool geometry in friction stir welds is challenging for quality weld production in industrial applications.The optimal tool shoulder and pin design combination,which play...Understanding the material flow facilitated by tool geometry in friction stir welds is challenging for quality weld production in industrial applications.The optimal tool shoulder and pin design combination,which plays a vital role in material flow was addressed.The flow of plasticized material was analyzed using a marker insert technique.The results show that the knurling shoulder design with square and hexagonal pin design facilitated constant stability force with reference to weld length/time.The uniform mixing and distribution of plasticized material were facilitated by the knurling shoulder design with square tool pin shape(TK)S(sticking length minimum)below which fragmented copper was observed.(TK)S tool facilitated higher mechanical properties for the welds,i.e.strength(182 MPa)and hardness(HV 78)in stir zone.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.92580120 and 52471188)。
文摘Optimizing the microchannel design of the next generation of chips requires an understanding of the in situ property evolution of the chip-based materials under fast cooling.This work overcomes the conventional reliance on reheating data of melt-quenched glasses by demonstrating direct observations of glass transition on cooling curves utilizing the most advanced fast differential scanning calorimetry.By leveraging an MEMS chip sensor that allows for rapid heat extraction from microgram-sized samples to a purged gas coolant,the device is able to reach ultra-fast cooling rates of up to 40,000 K·s^(−1).Four thermal regions are identified by examining the cooling behaviors of two metallic glasses.This is because the actual rate of the specimen can differ from the programmed rate,especially at high set rate when the actual rate decreases before the glass transition is completed.We define the operational window for reliable cooling curve analysis,build models with empirical and theoretical analyses to determine the maximum feasible cooling rate,and demonstrate how optimizing sample mass and environment temperature broaden this window.The method avoids deceptive structural relaxation effects verified by fictivetemperature analysis and permits the capture of full glass transition during cooling.
基金Supported by the National Research Foundation of Korea (NRF) by the Korea Government (MEST) (No. 2011-0001031)
文摘An optimal test method for paint is proposed; additionally, the Field and Laboratory Emission Cell （FLEC） method used in Europe is applied as a substitute for the 20 L small chamber method. The emission factors of total volatile organic compounds （TVOC） and formaldehyde from oil-based paint, emulsion paint, and water-dispersion paint with a coating weight of 300 g/m2, cured for 24/48 hours, were measured using the 20 L small chamber method. The emission rate of TVOC and formaldehyde from all paints began to stabilize after approximately 7 days after 24/48 hours of curing even though Korean standards stipulate that paint should be measured and analyzed after the third day of application. The emission factor of TVOC and formaldehyde from oil-based, emulsion, and water-dispersion paints were also measured using the FLEC method. There was good correlation between the 20 L small chamber method and the FLEC method for oil-based, emulsion, and water-dispersion paint emissions. With the FLEC method, using paints prepared under identical conditions, the emission rate was stable 24 hours after installation of samples because the air flow rate of FLEC is much higher than that of a 20 L small chamber, and the relative cell volume of FLEC is much smaller than that of a 20 L small chamber.
基金The project supported by the Fund of the State Education Commission of China for Excellent Young Teachers
文摘By using Stroh' complex formalism and Cauchy's integral method, the electro-elastic fundamental solutions of an infinite anisotropic piezoelectric solid containing an elliptic hole or a crack subjected to a Line force and a line charge are presented in closed form. Particular attention is paid to analyzing the characteristics of the stress and electric displacement intensity factors. When a line force-charge acts on the crack surface, the real form expression of intensity factors is obtained. It is shown through a special example that the present work is correct.
基金Supports by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences(XDA15013200,XDA15013700,XDA15013800,XDA15051200)the China’s Manned Space Station Project(TGJZ800-2-RW024)and the National Natural Science Foundation of China(51327901)。
文摘Activities of space materials science research in China have been continuously supported by two main national programs.One is the China Space Station(CSS)program since 1992,and the other is the Strategic Priority Program(SPP)on Space Science since 2011.In CSS plan in 2019,eleven space materials science experimental projects were officially approved for execution during the construction of the space station.In the SPP Phase Ⅱ launched in 2018,seven pre-research projects are deployed as the first batch in 2018,and one concept study project in 2019.These pre-research projects will be cultivated as candidates for future selection as space experiment projects on the recovery of scientific experimental satellites in the future.A new apparatus of electrostatic levitation system for ground-based research of space materials science and rapid solidification research has been developed under the support of the National Natural Science Foundation of China.In order to promote domestic academic activities and to enhance the advancement of space materials science in China,the Space Materials Science and Technology Division belong to the Chinese Materials Research Society was established in 2019.We also organized scientists to write five review papers on space materials science as a special topic published in the journal Scientia Sinica to provide valuable scientific and technical references for Chinese researchers.
文摘The nanocrystalline samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))were prepared using the citrate combustion method.The X-ray diffraction(XRD)pattern confirmed that the nanoparticles were synthesized in an orthorhombic structure.The particle size of Nd_(1-x)M_(x)FeO_(3) is in the range of 29-59 nm.The selected area electron diffraction(SAED)indicates the samples were prepared in a polycrystalline nature.The samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))have anti ferromagnetic behavior.The Fe^(3+)spins are aligned antiparallel,forming the antiferromagnetic(AFM)properties,which are affected by many factors such as the bond angle between the Fe^(3+)(Fe^(3+)-O_(2)--Fe^(3+))and the Dzyaloshinskii-Moriya(D-M)interaction.The doping of Co^(2+)and Ni^(2+)ions in NdFeO_(3) enhances the magnetic properties of the NdFeO_(3).The saturation magnetization(Ms)of Nd_(0.90)Co_(0.10)FeO_(3) increases 1.8times more than that of NdFeO_(3).The exchange bias field(HEX)of the Co-doped sample is two times greater than that of NdFeO_(3).The magnetic anisotropy constant(K)of the 10%Co-doped sample increases by 11 factors compared to that of NdFeO_(3).The Tauc plot illustrates that the samples have a direct optical transition.The divalent cation substitution(Co^(2+)and Ni^(2+))decreases the optical band gap of NdFeO_(3),leading to the recommendation of using the samples Nd_(0.90)Co_(0.10)FeO_(3) and Nd_(0.90)Ni_(0.10)FeO_(3) in photocatalysis of dye degradation from water.The removal efficiencies of Cr6+at pH=6 are 88.06%,85.54%,and 85.52%for the samples NdFeO_(3),Nd_(0.90)Co_(0.10)FeO_(3),and Nd_(0.90)Ni_(0.10)FeO_(3),respectively.The Freundlich isotherm mode is the best-fit model for NdFeO_(3) to adsorb Cr6+ions from aqueous solutions.
基金supported by the National Natural Science Foundation of China(Grant No.52271087).
文摘Thermal barrier coatings(TBCs)are extensively utilized in aero-engines and heavy-duty gas turbines due to their outstanding properties,including low thermal conductivity,corrosion,high-temperature oxidation,and wear resistance.The rising thrust-to-weight ratio and service temperature in engine hot sections have presented a significant challenge in TBC's materials,structure,and preparation process;it is one of the current research hotspots in the aviation field.This paper reviews the recent advancement in turbine blade TBCs.It focuses on the TBC's structure,deposition mechanism and the key performance evaluation indexes for TBCs applied to turbine blades.Finally,the future research field of TBCs for turbine blades is also be prospected.
文摘A1 doped SmFeO3 （SmFel_xmlxO3; 0.0〈x〈0.15; step 0.05） were prepared by double sintering ceramic technique. The obtained samples were crystallized in single phase structure except the sample with x=0.15. The unit cell volume was found to decrease with increasing AI substitution in orthoferrite. The effective magnetic moment （μeff） and the Curie constant （C） were calculated from the reciprocal of the molar magnetic susceptibility （Z-1） versus absolute temperature plot and found to attain maximum value for the parent sample. The magnetic behavior showed two different magnetic transitions, viz, N6el temperature （TN） and spin reorientation （TsR） transitions. The M-H hysteresis loop of the parent sample took butterfly-shape as a result of different contributions anisotropies. From the magnetic properties measurements, it was obviously found that B-site cation dilution resulted in a drastic decrease in the magnetization. Surprisingly large value of the coercive field was obtained for the undoped sample;Hc=6198.80e. Based on the mentioned results, one can recommend the use of such orthoferrite in magnetic recording media and as pining layer in spin valve for spin- tronic applications.
基金supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health under Award Number R01 AR067306-01 and R01 AR078241(PI—Bandyopadhyay)。
文摘Porous and functionally graded materials have seen extensive applications in modern biomedical devices—allowing for improved site-specific performance;their appreciable mechanical,corrosive,and biocompatible properties are highly sought after for lightweight and high-strength load-bearing orthopedic and dental implants.Examples of such porous materials are metals,ceramics,and polymers.Although,easy to manufacture and lightweight,porous polymers do not inherently exhibit the required mechanical strength for hard tissue repair or replacement.Alternatively,porous ceramics are brittle and do not possess the required fatigue resistance.On the other hand,porous biocompatible metals have shown tailorable strength,fatigue resistance,and toughness.Thereby,a significant interest in investigating the manufacturing challenges of porous metals has taken place in recent years.Past research has shown that once the advantages of porous metallic structures in the orthopedic implant industry have been realized,their biological and biomechanical compatibility—with the host bone—has been followed up with extensive methodical research.Various manufacturing methods for porous or functionally graded metals are discussed and compared in this review,specifically,how the manufacturing process influences microstructure,graded composition,porosity,biocompatibility,and mechanical properties.Most of the studies discussed in this review are related to porous structures for bone implant applications;however,the understanding of these investigations may also be extended to other devices beyond the biomedical field.
文摘The heat transfer in a steelmaking ladle was studied. The evaluation of heat transfer of the steel was performed by measuring steel temperature in points including all refining steel process. In the ladle, the temperatures in the refractories and the shell were also measured. To evaluate the thermal profile between the hot and cold faces of the ladle in the slag line position, an experiment which shows the importance of thermal contact resistance was carried out. Higher heat losses in the tapping and the vacuum were verified. The temperature measurements of the ladle indicate distinct thermal profiles in each stage of steel refining. Moreover, as each stage of the process depends on the previous one, the complexity of the ladle thermal control is incremental. So a complete model of heat losses in the ladle is complex.
文摘In this research, the dynamic recrystallization （DRX） behavior of an as-cast precipitation hardenable （PH） stainless steel was investigated by conducting hot compression tests at temperatures between 950-1150℃ and under strain rates of 0.001-1 s^-1. The flow stress curves show that the DRX is responsible for flow softening during hot compression. The effects of temperature and strain rate on the strain and stress corresponding to peak point （εp and σp） of flow curve were analyzed individually. It is realized that, they increase with strain rate and decrease with temperature. The relationship between Zener-Hollomon parameter （Z） and εp was investigated and the equation of εp=4.3×10^-4^0.14 was proposed. The strain for the maximum rate of DRX （εmax） was determined under different deformation conditions. Therefore, it is realized that it increases with Z parameter and vise versa. On the basis of obtained results, the equation of εmax=9.5 × 10^-4Z0.12 was proposed.
文摘Silica aerogels were prepared at ambient drying by using ethanol/trimethylchlorosilane （TMCS）/heptane solution as pore water exchange and surface modification of the wet gel before drying. The obtained silica aerogels exhibit a sponge-like structure with uniform pore size distribution. The effects of heat-treatment on the hydrophobicity, specific surface area and other properties were investigated. The results indicated that the hydrophobicity of silica aerogels could be maintained up to 350℃. With increasing heating temperature, hydrophobicity decreased, and became completely hydrophilic after heat-treatment at 500℃. Brunaueremmitt-teller （BET） surface area results indicated that the specific surface area of silica aerogels increased with increasing heating temperature in the range of 150-500℃. The effects of heat-treatment on the morphology and chemical bonding state of silica aerogels were investigated by scanning electron microscopy （SEM）, differential temperature analysis （DTA） and Fourier-transform infrared spectroscopy （FT-IR）.
基金University Grants Commission (UGC)New Delhi for providing the research fund to carry out this work
文摘The inhibition efficiency of 1,4-bis （2-nitrobenzylidene） thiosemicarbazide （BBTS） on the corrosion of mild steel in 1 mol/L HCI was investigated by potentiodynamic polarization and electrochemical impedance methods. Inhibition efficiency （IE）, corrosion rate and surface coverage were evaluated at different concentrations of BBTS. The results of the investigation showed that this compound had good inhibiting properties for mild steel corrosion in hydrochloric acid and BBTS was a mixed-type inhibitor. BBTS chemisorbed at the electrode surface obeyed Langmuir adsorption isotherm and formed a stable surface complex on the mild steel surface. The synergistic effect of halide ion in acid solution suggested a co-adsorption of BBTS inhibitor by the adsorbed iodide ion.
文摘Fe-doped ZnO (Zn0.99Fe0.01O) powders are successfully prepared by ball milling with different milling time, and are inves- tigated using X-ray diffraction (XRD), scanning electron microscope (SEM), ultraviolet-visible (UV-VIS) spectroscopy, vibrating sample magnetometer (VSM) and electron paramagnetic resonance (EPR) spectroscopy. The structural analysis using XRD reveals that the Fe-doped ZnO milled at different milling time can crystallize in a wurtzite structure, and in the XRD patterns, the secondary phase related to Fe cluster with the sensitivity of the XRD instrument can not be found. The SEM image of the sample milled for 24 h shows the presence of spherical nanoparticles. From the optical analysis, the optical band gap is found to decrease with increasing the milling time, which indicates the incorporation of Fe2+ ions into the ZnO lattice. The magnetization measurement using VSM reveals that the nanoparticles exhibit ferromagnetic behavior at room temperature, and the magnetization increases gradually with increasing the milling time. The conclusion is further confirmed by the electron paramagnetic resonance of the nanoparticles examined at room temperature, which shows an intense and broad ferromagnetic resonance signal related to Fe ions.
基金This work was supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF),funded by the Ministry of Education(No.NRF-2019R1I1A3A01046928)the“Human Resources Program in Energy Technology”of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)granted financial resource from the Ministry of Trade,Industry&Energy,Republic of Korea(No.20204010600100).
文摘Rechargeable aluminum-ion batteries(AIBs)are a new generation of low-cost and large-scale electrical energy storage systems.However,AIBs suffer from a lack of reliable cathode materials with insufficient intercalation sites,poor ion-conducting channels,and poor diffusion dynamics of large chloroaluminate anions(AlCl4−and Al2Cl7−).To address these issues,surfacemodified graphitic carbon materials[i.e.,acidtreated expanded graphite(AEG)and base-etched graphite(BEG)]are developed as novel cathode materials for ultra-fast chargeable AIBs.AEG has more turbostratically ordered structure covered with abundant micro-to nano-sized pores on the surface structure and expanded interlayer distance(d002=0.3371 nm)realized by surface treatment of pristine graphite with acidic media,which can be accelerated the diffusion dynamics and efficient AlCl4−ions(de)-intercalation kinetics.The AIB system employing AEG exhibits a specific capacity of 88.6 mAh g^(−1)(4 A g^(−1))and~80 mAh g^(−1) at an ultra-high current rate of 10 A g^(−1)(~99.1%over 10,000 cycles).BEG treated with KOH solution possesses the turbostratically disordered structure with high density of defective sites and largely expanded d-spacing(d002=0.3384 nm)for attracting and uptaking more AlCl4−ions with relatively shorter penetration depth.Impressively,the AIB system based on the BEG cathode delivers a high specific capacity of 110 mAh g^(−1)(4 A g^(−1))and~91 mAh g^(−1)(~99.9%over 10,000 cycles at 10 A g^(−1)).Moreover,the BEG cell has high energy and power densities of 247 Wh kg^(−1) and 44.5 kW kg^(−1).This performance is one of the best among the AIB graphitic carbon materials reported for chloroaluminate anions storage performance.This finding provides great significance for the further development of rechargeable AIBs with high energy,high power density,and exceptionally long life.
文摘Colloidal silver nanoparticles （Ag-NPs） were obtained through γ-irradiation of aqueous solutions containing AgNO3 and gelatin as a silver source and stabilizer, respectively. The absorbed dose of γ-irradiation influences the particle diameter of the Ag-NPs, as evidenced from surface plasmon resonance （SPR） and transmission electron microscopy （TEM） images. When the γ-irradiation dose was increased （from 2 to 50 kGy）, the mean particle size was decreased continuously as a result of γ-induced Ag-NPs fragmentation. The antibacterial properties of the Ag-NPs were tested against Methicillinresistant Staphylococcus aureus （MRSA） （Gram-positive） and Pseudomonas aeruginosa （P.a） （Gram-negative） bacteria. This approach reveals that the γ-irradiation-mediated method is a promising simple route for synthesizing highly stable Ag-NPs in aqueous solutions with good antibacterial properties for different applications.
文摘1 Introduction In the last decades,many fluidic actuators have been developed for numerous applications,e.g.,artificial muscles(Wang and Qu,2016),soft spatial finger(Mao et al.,2020a,2020c),soft robots(Shepherd et al.,2011),and compliant gripper(Li et al.,2021).Differing in their dimensions,they can be categorized into two groups:piston-cylinder fluidic actuators and elastic fluidic actuators(de Voider and Reynaerts,2010;Ye et al.,2019).
文摘Understanding the material flow facilitated by tool geometry in friction stir welds is challenging for quality weld production in industrial applications.The optimal tool shoulder and pin design combination,which plays a vital role in material flow was addressed.The flow of plasticized material was analyzed using a marker insert technique.The results show that the knurling shoulder design with square and hexagonal pin design facilitated constant stability force with reference to weld length/time.The uniform mixing and distribution of plasticized material were facilitated by the knurling shoulder design with square tool pin shape(TK)S(sticking length minimum)below which fragmented copper was observed.(TK)S tool facilitated higher mechanical properties for the welds,i.e.strength(182 MPa)and hardness(HV 78)in stir zone.
基金support provided by Department of Science and Technology,New Delhiall India Council for Technical Education,New Delhi for the work presented in this paper
