The effects of RE, V, Ti and B on the microstructure and properties of high chromium cast iron containing 3% molybdenum under as-cast and heat treatment conditions were investigated with the method of comparing experi...The effects of RE, V, Ti and B on the microstructure and properties of high chromium cast iron containing 3% molybdenum under as-cast and heat treatment conditions were investigated with the method of comparing experiments. The results show that with the increase of RE content, the primary austenite of high chromium cast iron is obviously refined. The morphology of carbide is changed from netlike and lath to small multiangular isolated blocks or massive blocks, the isolated degree of carbide is improved obviously, and the size is significantly refined. The addition of V and B into high chromium cast iron can refine the microstmcture, reduce coarse columnar crystals and make the carbide smaller and uniform. Through composite modification with RE, V, Ti and B, the hardness, wear resistance and impact toughness of high chromium cast iron are increased conspicuously. After heat treatment, the hardness of high chromium iron is increased significantly, but the toughness and wear resistance do not show great improvement.展开更多
A magnetic carbon composite, Fe3O4/C composite, was fabricated by one-step hydrothermal synthesis, modified by heat treatment under an inert atmosphere（N2）, and then used as an adsorbent for ciprofloxacin（CIP） rem...A magnetic carbon composite, Fe3O4/C composite, was fabricated by one-step hydrothermal synthesis, modified by heat treatment under an inert atmosphere（N2）, and then used as an adsorbent for ciprofloxacin（CIP） removal. Conditions for the modification were optimized according to the rate of CIP removal. The adsorbent was characterized by Fourier transform infrared spectroscopy, X-ray diffraction measurements, vibrating-sample magnetometry,scanning electron microscopy, transmission electron microscopy, and N2adsorption/desorption isotherm measurements. The results indicate that the modified adsorbent has substantial magnetism and has a large specific area, which favor CIP adsorption. The effects of solution p H, adsorbent dose, contact time, initial CIP concentration, ion strength, humic acid and solution temperature on CIP removal were also studied. Our results show that all of the above factors influence CIP removal. The Langmuir adsorption isotherm fits the adsorption process well, with the pseudo second-order model describing the adsorption kinetics accurately. The thermodynamic parameters indicate that adsorption is mainly physical adsorption. Recycling experiments revealed that the behavior of adsorbent is maintained after recycling for five times. Overall, the modified magnetic carbon composite is an efficient adsorbent for wastewater treatment.展开更多
Theoretical consideration was conducted on a relation between pore diameter and interfacialarea between pores and fibers when pores uniforinly distribute in C/C composites. It was shownthat bonding at the fiber/matrix...Theoretical consideration was conducted on a relation between pore diameter and interfacialarea between pores and fibers when pores uniforinly distribute in C/C composites. It was shownthat bonding at the fiber/matrix interface apparently decreased with decreasing a pore diameter,and consequently a new idea of microspace modification concept was proposed for controllingfracture behavior of C/C composites. Four types of C/C composites with various pore structureswere fabricated by hot-pressing, and their fracture behavior was investigated by three pointbending tests. The fracture behavior of the C/C composites was changed from brittle one topseudo ductile one with decreasing the pore diameter. This result supported the validity of themicrospace modification concept proposed in this paper.展开更多
Doping and substitution methods are predominantly employed in the synthesis of ceramics to achieve their desired functional properties.We studied the behavior of excessive dopants in addition to an existing stoichiome...Doping and substitution methods are predominantly employed in the synthesis of ceramics to achieve their desired functional properties.We studied the behavior of excessive dopants in addition to an existing stoichiometric composition using a high-throughput continuous compositional spread sputtering method.We paid attention to the possible formation of thermodynamically unstable phases by the addition of an excessive amount of dopants.We showed that even when dopants were added as an additive,they dissolved into the existing lattice due to the benefit of the entropy of mixing.Regardless of excessiveness,all added elements incorporated into the lattice,stabilized by the tolerance factor.We also demonstrated ourfindings exemplarily with lead iron niobate to induce magnetic properties alongside inherent ferroelectricity(M_(S)=10 emu/cm^(3),P_(S)=16μC/cm^(2)).We compare the results from CCS with those from the non-additive solid-state method,leading to a conclusion that the benefit from the entropy of mixing allows foreign elements to substitute for the elements initially residing in the lattice to a degree in compliance with the Goldschmidt tolerance factor.This observation was confirmed by a density functional theory calculation.We anticipate that our study could necessitate intensive research on achieving desired composition through industry-friendly processing.展开更多
A calcium sulfate whisker （CSW） coated with glutaraldehyde crosslinked chitosan （GACS） was prepared to reinforce polyvinyl chloride （PVC） in this study. The results show that the optimum concentration of both ch...A calcium sulfate whisker （CSW） coated with glutaraldehyde crosslinked chitosan （GACS） was prepared to reinforce polyvinyl chloride （PVC） in this study. The results show that the optimum concentration of both chitosan （CS） and glutaraldehyde （GA） is 0.05 wt%. The tensile strength, impact strength, flexural modulus and vicat softening temperature of the PVC composite with 12 wt% of modified CSW are in- creased by 1 Z5%, 40.4%, 0.8% and 3.8% compared with those of the PVC composite with 12 wt~ of unmodified CSW, and by 2.9%, 42.4%, 2Z1% and 6.8% compared with those of pure PVC, respectively. The dynamic mechanical analysis results indicate that the modified CSW/PVC composite exhibits much higher storage modulus and glass transition temperature than those of unmodified CSW/PVC composite and pure PVC. In addition, the modified CSW/PVC composite also demonstrates good thermal properties with a high rapidest decomposition temperature （Trvd） and char residue. The scanning electron microscopy images of tensile-fractured surfaces show that the modified CSW has a strong interfacial adhesion with PVC matrix.展开更多
A comprehensive survey was made of various candidate high temperature materials for gas turbine use, and their relative merits and drawbacks were assessed. It is shown that superalloys, fine-tuned, will be persistent ...A comprehensive survey was made of various candidate high temperature materials for gas turbine use, and their relative merits and drawbacks were assessed. It is shown that superalloys, fine-tuned, will be persistent for the next few decades, to be followed up by high temperature intermetallics. For advanced ceramics, the problems of reliability and cost will have to be solved before they can be used in critical parts of engines.So are C/C composites with their oxidation problem. Surface modification and development of thermal barrier coatings can effectively overcome many problems of gas turbine materials and these technologies should be emphasized.展开更多
Stimulus-responsive actuators are novel functional devices capable of sensing external stimuli and ex-hibiting specific deformation responses.MXene,owing to its unique 2D structure and efficient energy conversion effi...Stimulus-responsive actuators are novel functional devices capable of sensing external stimuli and ex-hibiting specific deformation responses.MXene,owing to its unique 2D structure and efficient energy conversion efficiency,has bridged the gap in traditional devices and shown great potential for multiple stimulus-responsive actuators.However,the drawbacks of pure MXene films,including susceptibility to oxidation and vulnerability to shear stress,hinder their applications.Through composite modification and structural design strategies,a three-layer structured MXene-carbon nanotubes hybrid film(tHCM)is fabri-cated,exhibiting a tensile strength and fracture strain of 153.8 MPa and 4.65%,respectively,representing improvements of 598.4%and 226.8%compared to the initial film.Meanwhile,the film maintains excel-lent stability demonstrating the enhancing effects of hydrogen bonds and densely packed structure.The hybrid films demonstrate unique and facile welding features due to splicing properties,enabling the for-mation of complex configurations.In terms of electro-/photo-thermal conversion performance,the hybrid film can reach a reasonably high temperature of 250℃at low voltage(2.5 V)and 110.6℃under 150 mW cm^(-2) infrared light.Leveraging the thermal expansion mismatch between tHCM and thermoplastic films,an integrated,flexible,and weldable actuator with unique electro/photo-response is developed,and vari-ous biomimetic driving applications,particularly,the light-mediated hierarchical transmission and precise motion along predetermined trajectory are realized.This work not only provides an effective strategy for modifying MXene composite films but also advances the design of novel actuators,offering broad appli-cation prospects in fields such as stimulus-responsive actuated robots and cargo transportation.展开更多
基金supported by the Harbin Scientific Research Fund for Young Scholars (No.2005AFQXJ030)the Harbin Science and Technology Project (No.2002AA5CG026)the Foundation of Heilong-jiang Educational Committee (No.11511051)
文摘The effects of RE, V, Ti and B on the microstructure and properties of high chromium cast iron containing 3% molybdenum under as-cast and heat treatment conditions were investigated with the method of comparing experiments. The results show that with the increase of RE content, the primary austenite of high chromium cast iron is obviously refined. The morphology of carbide is changed from netlike and lath to small multiangular isolated blocks or massive blocks, the isolated degree of carbide is improved obviously, and the size is significantly refined. The addition of V and B into high chromium cast iron can refine the microstmcture, reduce coarse columnar crystals and make the carbide smaller and uniform. Through composite modification with RE, V, Ti and B, the hardness, wear resistance and impact toughness of high chromium cast iron are increased conspicuously. After heat treatment, the hardness of high chromium iron is increased significantly, but the toughness and wear resistance do not show great improvement.
基金supported by the National Natural Science Foundation of China (No. 21376159)the Natural Science Foundation of Shanxi Province (No. 2013011042-2)
文摘A magnetic carbon composite, Fe3O4/C composite, was fabricated by one-step hydrothermal synthesis, modified by heat treatment under an inert atmosphere（N2）, and then used as an adsorbent for ciprofloxacin（CIP） removal. Conditions for the modification were optimized according to the rate of CIP removal. The adsorbent was characterized by Fourier transform infrared spectroscopy, X-ray diffraction measurements, vibrating-sample magnetometry,scanning electron microscopy, transmission electron microscopy, and N2adsorption/desorption isotherm measurements. The results indicate that the modified adsorbent has substantial magnetism and has a large specific area, which favor CIP adsorption. The effects of solution p H, adsorbent dose, contact time, initial CIP concentration, ion strength, humic acid and solution temperature on CIP removal were also studied. Our results show that all of the above factors influence CIP removal. The Langmuir adsorption isotherm fits the adsorption process well, with the pseudo second-order model describing the adsorption kinetics accurately. The thermodynamic parameters indicate that adsorption is mainly physical adsorption. Recycling experiments revealed that the behavior of adsorbent is maintained after recycling for five times. Overall, the modified magnetic carbon composite is an efficient adsorbent for wastewater treatment.
文摘Theoretical consideration was conducted on a relation between pore diameter and interfacialarea between pores and fibers when pores uniforinly distribute in C/C composites. It was shownthat bonding at the fiber/matrix interface apparently decreased with decreasing a pore diameter,and consequently a new idea of microspace modification concept was proposed for controllingfracture behavior of C/C composites. Four types of C/C composites with various pore structureswere fabricated by hot-pressing, and their fracture behavior was investigated by three pointbending tests. The fracture behavior of the C/C composites was changed from brittle one topseudo ductile one with decreasing the pore diameter. This result supported the validity of themicrospace modification concept proposed in this paper.
基金the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(2021-M1A3B2A01078712)This research was supported by the Korea Institute of Science and Technology Future Resource Program(2E33181)the National Research Foundation of Korea(NRF)grant by the Korea government(No.2021R1A2C2010695,RS-2023-00222719).
文摘Doping and substitution methods are predominantly employed in the synthesis of ceramics to achieve their desired functional properties.We studied the behavior of excessive dopants in addition to an existing stoichiometric composition using a high-throughput continuous compositional spread sputtering method.We paid attention to the possible formation of thermodynamically unstable phases by the addition of an excessive amount of dopants.We showed that even when dopants were added as an additive,they dissolved into the existing lattice due to the benefit of the entropy of mixing.Regardless of excessiveness,all added elements incorporated into the lattice,stabilized by the tolerance factor.We also demonstrated ourfindings exemplarily with lead iron niobate to induce magnetic properties alongside inherent ferroelectricity(M_(S)=10 emu/cm^(3),P_(S)=16μC/cm^(2)).We compare the results from CCS with those from the non-additive solid-state method,leading to a conclusion that the benefit from the entropy of mixing allows foreign elements to substitute for the elements initially residing in the lattice to a degree in compliance with the Goldschmidt tolerance factor.This observation was confirmed by a density functional theory calculation.We anticipate that our study could necessitate intensive research on achieving desired composition through industry-friendly processing.
基金supported by the National Natural Science Foundation of China (No. U 1507123)the Foundation from Qinghai Science and Technology Department (No. 2014-HZ-817)
文摘A calcium sulfate whisker （CSW） coated with glutaraldehyde crosslinked chitosan （GACS） was prepared to reinforce polyvinyl chloride （PVC） in this study. The results show that the optimum concentration of both chitosan （CS） and glutaraldehyde （GA） is 0.05 wt%. The tensile strength, impact strength, flexural modulus and vicat softening temperature of the PVC composite with 12 wt% of modified CSW are in- creased by 1 Z5%, 40.4%, 0.8% and 3.8% compared with those of the PVC composite with 12 wt~ of unmodified CSW, and by 2.9%, 42.4%, 2Z1% and 6.8% compared with those of pure PVC, respectively. The dynamic mechanical analysis results indicate that the modified CSW/PVC composite exhibits much higher storage modulus and glass transition temperature than those of unmodified CSW/PVC composite and pure PVC. In addition, the modified CSW/PVC composite also demonstrates good thermal properties with a high rapidest decomposition temperature （Trvd） and char residue. The scanning electron microscopy images of tensile-fractured surfaces show that the modified CSW has a strong interfacial adhesion with PVC matrix.
文摘A comprehensive survey was made of various candidate high temperature materials for gas turbine use, and their relative merits and drawbacks were assessed. It is shown that superalloys, fine-tuned, will be persistent for the next few decades, to be followed up by high temperature intermetallics. For advanced ceramics, the problems of reliability and cost will have to be solved before they can be used in critical parts of engines.So are C/C composites with their oxidation problem. Surface modification and development of thermal barrier coatings can effectively overcome many problems of gas turbine materials and these technologies should be emphasized.
基金support provided by the National Natural Science Foundation of China(No.52002324)the Hong Kong Scholars Program(Nos.XJ2021073 and PolyU YZ4V)the Research Grants Council of Hong Kong GRF(No.15303123).
文摘Stimulus-responsive actuators are novel functional devices capable of sensing external stimuli and ex-hibiting specific deformation responses.MXene,owing to its unique 2D structure and efficient energy conversion efficiency,has bridged the gap in traditional devices and shown great potential for multiple stimulus-responsive actuators.However,the drawbacks of pure MXene films,including susceptibility to oxidation and vulnerability to shear stress,hinder their applications.Through composite modification and structural design strategies,a three-layer structured MXene-carbon nanotubes hybrid film(tHCM)is fabri-cated,exhibiting a tensile strength and fracture strain of 153.8 MPa and 4.65%,respectively,representing improvements of 598.4%and 226.8%compared to the initial film.Meanwhile,the film maintains excel-lent stability demonstrating the enhancing effects of hydrogen bonds and densely packed structure.The hybrid films demonstrate unique and facile welding features due to splicing properties,enabling the for-mation of complex configurations.In terms of electro-/photo-thermal conversion performance,the hybrid film can reach a reasonably high temperature of 250℃at low voltage(2.5 V)and 110.6℃under 150 mW cm^(-2) infrared light.Leveraging the thermal expansion mismatch between tHCM and thermoplastic films,an integrated,flexible,and weldable actuator with unique electro/photo-response is developed,and vari-ous biomimetic driving applications,particularly,the light-mediated hierarchical transmission and precise motion along predetermined trajectory are realized.This work not only provides an effective strategy for modifying MXene composite films but also advances the design of novel actuators,offering broad appli-cation prospects in fields such as stimulus-responsive actuated robots and cargo transportation.
