This work proposed a strategy of indirectly inducing uniform microarc discharge by controlling the content and distribution ofβ-Mg_(17)Al_(12)phase in AZ91D Mg alloy.Two kinds of nano-particles(ZrO_(2)and TiO_(2))wer...This work proposed a strategy of indirectly inducing uniform microarc discharge by controlling the content and distribution ofβ-Mg_(17)Al_(12)phase in AZ91D Mg alloy.Two kinds of nano-particles(ZrO_(2)and TiO_(2))were designed to be added into the substrate of Mg alloy by friction stir processing(FSP).Then,Mg alloy sample designed with different precipitated morphology ofβ-Mg_(17)Al_(12)phase was treated by microarc oxidation(MAO)in Na_(3)PO_(4)/Na2SiO3electrolyte.The characteristics and performance of the MAO coating was analyzed using scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),contact angle meter,and potentiodynamic polarization.It was found that the coarseα-Mg grains in extruded AZ91D Mg alloy were refined by FSP,and theβ-Mg_(17)Al_(12)phase with reticular structure was broken and dispersed.The nano-ZrO_(2)particles were pinned at the grain boundary by FSP,which refined theα-Mg grain and promoted the precipitation ofβ-Mg_(17)Al_(12)phase in grains.It effectively inhibited the“cascade”phenomenon of microarcs,which induced the uniform distribution of discharge pores.The MAO coating on Zr-FSP sample had good wettability and corrosion resistance.However,TiO_(2)particles were hardly detected in the coating on TiFSP sample.展开更多
Ti_(2)AlNb-based alloy was joined in a continuous drive friction welding machine under different rotational rates(500,1000 and 1500 r/min).The microstructure and mechanical properties of the joints were investigated.I...Ti_(2)AlNb-based alloy was joined in a continuous drive friction welding machine under different rotational rates(500,1000 and 1500 r/min).The microstructure and mechanical properties of the joints were investigated.It is shown that the weld zone(WZ) is fully composed of recrystallized B2 phase,and the grain size decreases with increasing rotational rate.The thermo-mechanically affected zone(TMAZ) suffers severe deformation during welding,due to which most of original precipitation phase is dissolved and streamlines are present.In the heat affected zone(HAZ),only the fine O phase is dissolved.The as-welded joint produced using 1000 r/min has the best mechanical properties,whose strength and elongation are both close to those of the base metal,while the as-welded joint obtained using 500 r/min exhibits the worst mechanical properties.Post-weld annealing treatment annihilates the deformation microstructure and fine O phase precipitates in the joints,consequently improving the mechanical properties significantly.Decomposed α_(2) phase is a weakness for the mechanical performance of the joint since microcracks are apt to form in it in the tensile test.展开更多
The Mg-Sn alloys,with basal or prismatic Mg2Sn laths,were employed to reveal the effect of precipitate orientation on twinning behavior quantitatively.The Mg-5wt.%Sn alloys with basal or prismatic Mg2Sn were compresse...The Mg-Sn alloys,with basal or prismatic Mg2Sn laths,were employed to reveal the effect of precipitate orientation on twinning behavior quantitatively.The Mg-5wt.%Sn alloys with basal or prismatic Mg2Sn were compressed to study the twinning behaviors.Subsequently,an Orowan strengthening model was developed to quantitatively investigate the critical resolved shear stress(CRSS)increment of precipitates on twinning.The results revealed that the prismatic precipitates hindered the transfer and growth of tensile twins more effectively compared with the basal precipitates.The decreased proportion of tensile twins containing prismatic Mg2Sn might be attributed to a larger CRSS increment for tensile twins compared with that for basal precipitates.The obvious decreased twinning transfer in the alloy with prismatic Mg2Sn could be due to its higher geometrically necessary dislocation and enhanced CRSS of tensile twins.Notably,the prismatic precipitates have a better hindering effect on tensile twins during compression.展开更多
At present,there is limited research on the application of fuel cell power generation system technology using solid hydrogen storage materials,especially in hydrogen-assisted two-wheelers.Considering the disadvantages...At present,there is limited research on the application of fuel cell power generation system technology using solid hydrogen storage materials,especially in hydrogen-assisted two-wheelers.Considering the disadvantages of low hydrogen storage capacity and poor kinetics of hydrogen storage materials,our primary focus is to achieve smooth hydrogen ab-/desorption over a wide temperature range to meet the requirements of fuel cells and their integrated power generation systems.In this paper,the Ti_(0.9)Zr_(0.1)Mn_(1.45)V_(0.4)Fe_(0.15) hydrogen storage alloy was successfully prepared by arc melting.The maximum hydrogen storage capacity reaches 1.89 wt% at 318 K.The alloy has the capability to absorb 90% of hydrogen storage capacity within 50 s at 7 MPa and release 90% of hydrogen within 220 s.Comsol Multiphysics 6.0 software was used to simulate the hydrogen ab-/desorption processes of the tank.The flow rate of cooling water during hydrogen absorption varied in a gradient of(0.02 t x)m s^(-1)(x=0,0.02,0.04,0.06,0.08,0.1,0.12).Cooling water flow rate is positively correlated with the hydrogen absorption rate but negatively correlated with the cost.When the cooling rate is 0.06 m s^(-1),both simulation and experimentation have shown that the hydrogen storage tank is capable of steady hydrogen desorption for over 6 h at a flow rate of 2 L min^(-1).Based on the above conclusions,we have successfully developed a hydrogen-assisted two-wheeler with a range of 80 km and achieved regional demonstration operations in Changzhou and Shaoguan.This paper highlights the achievements of our team in the technological development of fuel cell power generation systems using solid hydrogen storage materials as hydrogen storage carriers and their application in twowheelers in recent years.展开更多
2A14-T62 butt joint was successfully welded by stationary shoulder friction stir welding(SSFSW)method.The results showed that using a pin with small shoulder could broaden the process window,and under a rotation speed...2A14-T62 butt joint was successfully welded by stationary shoulder friction stir welding(SSFSW)method.The results showed that using a pin with small shoulder could broaden the process window,and under a rotation speed of 2000 r/min and welding speed of 30 mm/min,joint with smooth surface,small reduction in thickness and little inner defects was obtained.The weld nugget zone was approx-imately circular,which was a unique morphology for SSFSW.The heat-affected zone(HAZ)and thermo-mechanically affected zone(TMAZ)were both quite narrow due to the lower heat input and slight mechanical action of the stationary shoulder.The fraction of high angle grain boundaries(HAGBs)exhibited a“W”shape along horizontal direction(from advancing side to retreating side),and the minim-um value located at HAZ.The average ultimate tensile strength and elongation of the joint were 325 MPa and 4.5%,respectively,with the joint efficiency of 68.3%.The joint was ductile fractured and the fracture surface contained two types of dimples morphology in different re-gions of the joint.Microhardness distribution in the joint exhibited a“W”shape,and the difference along the thickness direction was negli-gible.The joint had strong stress corrosion cracking susceptibility,and the slow stain rate tensile strength was 139 MPa.Microcrack and Al2O3 particulates were observed at the fracture surface.展开更多
The electrochemical CO_(2)reduction reaction to produce multi-carbon(C_(2+)) hydrocarbons or oxygenate compounds is a promising route to obtain a renewable fuel of high energy density.However,producing C_(2+)at high c...The electrochemical CO_(2)reduction reaction to produce multi-carbon(C_(2+)) hydrocarbons or oxygenate compounds is a promising route to obtain a renewable fuel of high energy density.However,producing C_(2+)at high current densities is still a challenge.Herein,we develop a Cu-Zn alloy/Cu-Zn aluminate oxide composite electrocatalytic system for enhanced conversion of CO_(2)to C_(2+)products.The Cu-Zn-Al-Layered Double Hydroxide(LDH) is used as a precursor to decompose into uniform Cu-Zn oxide/Cu-Zn aluminate pre-catalyst.Under electrochemical reduction,Cu-Zn oxide generates Cu-Zn alloy while Cu-Zn aluminate oxide remains unchanged.The alloy and oxide are closely stacked and arranged alternately,and the aluminate oxide induces the strong electron interaction of Cu,Zn and Al,creating a large number of highly active reaction interfaces composed of 0 to+3 valence metal sites.With the help of the interface effect,the optimized Cu_(9)Zn_(1)/Cu_(0.8)Zn_(0.2)Al_(2)O_(4)catalyst achieves a Faradaic efficiency of 88.5% for C_(2+)products at a current density of 400 mA cm^(-2)at-1.15 V versus reversible hydrogen electrode.The in-situ Raman and attenuate total reflectance-infrared absorption spectroscopy(ATR-IRAS) spectra show that the aluminate oxide at the interface significantly enhances the adsorption and activation of CO_(2)and the dissociation of H2O and strengthens the adsorption of CO intermediates,and the alloy promotes the C-C coupling to produce C_(2+)products.This work provides an efficient strategy to construct highly active reaction interfaces for industrial-scale electrochemical CO_(2)RR.展开更多
The effect of Ce content(0–1.6 wt.%)on the modification of Mg_(2)Si phase in the as-cast Mg-5Al-2Si alloy was investigated.The original Chinese script type Mg_(2)Si phase was refined distinctly and transformed to dis...The effect of Ce content(0–1.6 wt.%)on the modification of Mg_(2)Si phase in the as-cast Mg-5Al-2Si alloy was investigated.The original Chinese script type Mg_(2)Si phase was refined distinctly and transformed to dispersive block shape gradually by adding Ce element.The length of Chinese script type Mg_(2)Si phase was reduced from 110 to 50μm with increasing Ce content to 1.6 wt.%.The results calculated by Pandat software indicated that the added Ce element first combined with Si to form CeSi_(2)phase,which could serve as the heterogeneous nucleation of Mg_(2)Si phase due to the small lattice mismatch of 7.97%.The modification of Mg_(2)Si phase was mainly attributed to the facts that Ce changed the growth steps of Mg_(2)Si phase and CeSi_(2)promoted the nucleation of Mg_(2)Si phase.With increasing Ce content from 0 wt.%to 1.6 wt.%,the YS,UTS and EL at 150℃were improved from 67.7 MPa,91.2 MPa and 1.6%to 84.2 MPa,128 MPa and 7.5%,respectively.展开更多
Various strategies,including controls of morphology,oxidation state,defect,and doping,have been developed to improve the performance of Cu-based catalysts for CO_(2) reduction reaction(CO_(2)RR),generating a large amo...Various strategies,including controls of morphology,oxidation state,defect,and doping,have been developed to improve the performance of Cu-based catalysts for CO_(2) reduction reaction(CO_(2)RR),generating a large amount of data.However,a unified understanding of underlying mechanism for further optimization is still lacking.In this work,combining first-principles calculations and machine learning(ML)techniques,we elucidate critical factors influencing the catalytic properties,taking Cu-based single atom alloys(SAAs)as examples.Our method relies on high-throughput calculations of 2669 CO adsorption configurations on 43 types of Cu-based SAAs with various surfaces.Extensive ML analyses reveal that low generalized coordination numbers and valence electron number are key features to determine catalytic performance.Applying our ML model with cross-group learning scheme,we demonstrate the model generalizes well between Cu-based SAAs with different alloying elements.Further,electronic structure calculations suggest surface negative center could enhance CO adsorption by back donating electrons to antibonding orbitals of CO.Finally,several SAAs,including PCu,AgCu,GaCu,ZnCu,SnCu,GeCu,InCu,and SiCu,are identified as promising CO_(2)RR catalysts.Our work provides a paradigm for the rational design and fast screening of SAAs for various electrocatalytic reactions.展开更多
基金funded by China Postdoctoral Science Foundation(No.2021M700569)Chongqing Postdoctoral Science Foundation(No.7 cstc2021jcyj-bshX0087)。
文摘This work proposed a strategy of indirectly inducing uniform microarc discharge by controlling the content and distribution ofβ-Mg_(17)Al_(12)phase in AZ91D Mg alloy.Two kinds of nano-particles(ZrO_(2)and TiO_(2))were designed to be added into the substrate of Mg alloy by friction stir processing(FSP).Then,Mg alloy sample designed with different precipitated morphology ofβ-Mg_(17)Al_(12)phase was treated by microarc oxidation(MAO)in Na_(3)PO_(4)/Na2SiO3electrolyte.The characteristics and performance of the MAO coating was analyzed using scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),contact angle meter,and potentiodynamic polarization.It was found that the coarseα-Mg grains in extruded AZ91D Mg alloy were refined by FSP,and theβ-Mg_(17)Al_(12)phase with reticular structure was broken and dispersed.The nano-ZrO_(2)particles were pinned at the grain boundary by FSP,which refined theα-Mg grain and promoted the precipitation ofβ-Mg_(17)Al_(12)phase in grains.It effectively inhibited the“cascade”phenomenon of microarcs,which induced the uniform distribution of discharge pores.The MAO coating on Zr-FSP sample had good wettability and corrosion resistance.However,TiO_(2)particles were hardly detected in the coating on TiFSP sample.
基金the financial supports from the Science and Technology Special Project, China (No. K19168)the National Science and Technology Major Project of China (No. 2017-VI-0004-0075)the National Natural Science Foundation of China (No. 52231002)。
文摘Ti_(2)AlNb-based alloy was joined in a continuous drive friction welding machine under different rotational rates(500,1000 and 1500 r/min).The microstructure and mechanical properties of the joints were investigated.It is shown that the weld zone(WZ) is fully composed of recrystallized B2 phase,and the grain size decreases with increasing rotational rate.The thermo-mechanically affected zone(TMAZ) suffers severe deformation during welding,due to which most of original precipitation phase is dissolved and streamlines are present.In the heat affected zone(HAZ),only the fine O phase is dissolved.The as-welded joint produced using 1000 r/min has the best mechanical properties,whose strength and elongation are both close to those of the base metal,while the as-welded joint obtained using 500 r/min exhibits the worst mechanical properties.Post-weld annealing treatment annihilates the deformation microstructure and fine O phase precipitates in the joints,consequently improving the mechanical properties significantly.Decomposed α_(2) phase is a weakness for the mechanical performance of the joint since microcracks are apt to form in it in the tensile test.
基金National Natural Science Foundation of China(Nos.52004227,U22A20187,52201106)the China Postdoctoral Science Foundation(No.2020M683240)+1 种基金the Key Area Research and Development Program of Guangdong ProvinceChina(No.2020B090924002)。
文摘The Mg-Sn alloys,with basal or prismatic Mg2Sn laths,were employed to reveal the effect of precipitate orientation on twinning behavior quantitatively.The Mg-5wt.%Sn alloys with basal or prismatic Mg2Sn were compressed to study the twinning behaviors.Subsequently,an Orowan strengthening model was developed to quantitatively investigate the critical resolved shear stress(CRSS)increment of precipitates on twinning.The results revealed that the prismatic precipitates hindered the transfer and growth of tensile twins more effectively compared with the basal precipitates.The decreased proportion of tensile twins containing prismatic Mg2Sn might be attributed to a larger CRSS increment for tensile twins compared with that for basal precipitates.The obvious decreased twinning transfer in the alloy with prismatic Mg2Sn could be due to its higher geometrically necessary dislocation and enhanced CRSS of tensile twins.Notably,the prismatic precipitates have a better hindering effect on tensile twins during compression.
基金financed by the National Key Research and Development Program of China[grants number 2022YFB3803800]the National Natural Science Foundation of China[grants number 52071141,52271212,52201250,51771056]Interdisciplinary Innovation Program of North China Electric Power University[grants number XM2112355].
文摘At present,there is limited research on the application of fuel cell power generation system technology using solid hydrogen storage materials,especially in hydrogen-assisted two-wheelers.Considering the disadvantages of low hydrogen storage capacity and poor kinetics of hydrogen storage materials,our primary focus is to achieve smooth hydrogen ab-/desorption over a wide temperature range to meet the requirements of fuel cells and their integrated power generation systems.In this paper,the Ti_(0.9)Zr_(0.1)Mn_(1.45)V_(0.4)Fe_(0.15) hydrogen storage alloy was successfully prepared by arc melting.The maximum hydrogen storage capacity reaches 1.89 wt% at 318 K.The alloy has the capability to absorb 90% of hydrogen storage capacity within 50 s at 7 MPa and release 90% of hydrogen within 220 s.Comsol Multiphysics 6.0 software was used to simulate the hydrogen ab-/desorption processes of the tank.The flow rate of cooling water during hydrogen absorption varied in a gradient of(0.02 t x)m s^(-1)(x=0,0.02,0.04,0.06,0.08,0.1,0.12).Cooling water flow rate is positively correlated with the hydrogen absorption rate but negatively correlated with the cost.When the cooling rate is 0.06 m s^(-1),both simulation and experimentation have shown that the hydrogen storage tank is capable of steady hydrogen desorption for over 6 h at a flow rate of 2 L min^(-1).Based on the above conclusions,we have successfully developed a hydrogen-assisted two-wheeler with a range of 80 km and achieved regional demonstration operations in Changzhou and Shaoguan.This paper highlights the achievements of our team in the technological development of fuel cell power generation systems using solid hydrogen storage materials as hydrogen storage carriers and their application in twowheelers in recent years.
基金supported by the Research and Development Project of“Jianbing”in Zhejiang Province(2024C01085)Natural Science and Foundation of Ningbo(2022J052).
文摘2A14-T62 butt joint was successfully welded by stationary shoulder friction stir welding(SSFSW)method.The results showed that using a pin with small shoulder could broaden the process window,and under a rotation speed of 2000 r/min and welding speed of 30 mm/min,joint with smooth surface,small reduction in thickness and little inner defects was obtained.The weld nugget zone was approx-imately circular,which was a unique morphology for SSFSW.The heat-affected zone(HAZ)and thermo-mechanically affected zone(TMAZ)were both quite narrow due to the lower heat input and slight mechanical action of the stationary shoulder.The fraction of high angle grain boundaries(HAGBs)exhibited a“W”shape along horizontal direction(from advancing side to retreating side),and the minim-um value located at HAZ.The average ultimate tensile strength and elongation of the joint were 325 MPa and 4.5%,respectively,with the joint efficiency of 68.3%.The joint was ductile fractured and the fracture surface contained two types of dimples morphology in different re-gions of the joint.Microhardness distribution in the joint exhibited a“W”shape,and the difference along the thickness direction was negli-gible.The joint had strong stress corrosion cracking susceptibility,and the slow stain rate tensile strength was 139 MPa.Microcrack and Al2O3 particulates were observed at the fracture surface.
基金supported by the National Natural Science Foundation of China (NSFC)(22075201)the National Key Research and Development Program of China (2022YFB4101800)。
文摘The electrochemical CO_(2)reduction reaction to produce multi-carbon(C_(2+)) hydrocarbons or oxygenate compounds is a promising route to obtain a renewable fuel of high energy density.However,producing C_(2+)at high current densities is still a challenge.Herein,we develop a Cu-Zn alloy/Cu-Zn aluminate oxide composite electrocatalytic system for enhanced conversion of CO_(2)to C_(2+)products.The Cu-Zn-Al-Layered Double Hydroxide(LDH) is used as a precursor to decompose into uniform Cu-Zn oxide/Cu-Zn aluminate pre-catalyst.Under electrochemical reduction,Cu-Zn oxide generates Cu-Zn alloy while Cu-Zn aluminate oxide remains unchanged.The alloy and oxide are closely stacked and arranged alternately,and the aluminate oxide induces the strong electron interaction of Cu,Zn and Al,creating a large number of highly active reaction interfaces composed of 0 to+3 valence metal sites.With the help of the interface effect,the optimized Cu_(9)Zn_(1)/Cu_(0.8)Zn_(0.2)Al_(2)O_(4)catalyst achieves a Faradaic efficiency of 88.5% for C_(2+)products at a current density of 400 mA cm^(-2)at-1.15 V versus reversible hydrogen electrode.The in-situ Raman and attenuate total reflectance-infrared absorption spectroscopy(ATR-IRAS) spectra show that the aluminate oxide at the interface significantly enhances the adsorption and activation of CO_(2)and the dissociation of H2O and strengthens the adsorption of CO intermediates,and the alloy promotes the C-C coupling to produce C_(2+)products.This work provides an efficient strategy to construct highly active reaction interfaces for industrial-scale electrochemical CO_(2)RR.
基金supported by the Major Science and Technology projects in Qinghai province (2018-GX-A1)Global Frontier Program through the Global Frontier Hybrid Interface Materials (GFHIM) of the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (Grant No. 2013M3A6B1078874)+1 种基金funded by Shanghai Science and Technology Committee (Grant No. 18511109302)the National Natural Science Foundation of China (Grant No. 51825101)
文摘The effect of Ce content(0–1.6 wt.%)on the modification of Mg_(2)Si phase in the as-cast Mg-5Al-2Si alloy was investigated.The original Chinese script type Mg_(2)Si phase was refined distinctly and transformed to dispersive block shape gradually by adding Ce element.The length of Chinese script type Mg_(2)Si phase was reduced from 110 to 50μm with increasing Ce content to 1.6 wt.%.The results calculated by Pandat software indicated that the added Ce element first combined with Si to form CeSi_(2)phase,which could serve as the heterogeneous nucleation of Mg_(2)Si phase due to the small lattice mismatch of 7.97%.The modification of Mg_(2)Si phase was mainly attributed to the facts that Ce changed the growth steps of Mg_(2)Si phase and CeSi_(2)promoted the nucleation of Mg_(2)Si phase.With increasing Ce content from 0 wt.%to 1.6 wt.%,the YS,UTS and EL at 150℃were improved from 67.7 MPa,91.2 MPa and 1.6%to 84.2 MPa,128 MPa and 7.5%,respectively.
基金supported by the National Natural Science Foundation of China (Grant Nos.62006219 and 62001266)Guangdong Innovative and Entrepre-neurial Research Team Program (grant No.2017ZT07C341)+2 种基金the Bureau of Industry and Information Technology of Shenzhen for the 2017 Graphene Manufacturing Innovation Center Project (No.201901171523)the China Postdoctoral Science Foundation (No.2020M680506)Guangdong Basic and Applied Basic Research Foundation (No.2020A1515110338).
文摘Various strategies,including controls of morphology,oxidation state,defect,and doping,have been developed to improve the performance of Cu-based catalysts for CO_(2) reduction reaction(CO_(2)RR),generating a large amount of data.However,a unified understanding of underlying mechanism for further optimization is still lacking.In this work,combining first-principles calculations and machine learning(ML)techniques,we elucidate critical factors influencing the catalytic properties,taking Cu-based single atom alloys(SAAs)as examples.Our method relies on high-throughput calculations of 2669 CO adsorption configurations on 43 types of Cu-based SAAs with various surfaces.Extensive ML analyses reveal that low generalized coordination numbers and valence electron number are key features to determine catalytic performance.Applying our ML model with cross-group learning scheme,we demonstrate the model generalizes well between Cu-based SAAs with different alloying elements.Further,electronic structure calculations suggest surface negative center could enhance CO adsorption by back donating electrons to antibonding orbitals of CO.Finally,several SAAs,including PCu,AgCu,GaCu,ZnCu,SnCu,GeCu,InCu,and SiCu,are identified as promising CO_(2)RR catalysts.Our work provides a paradigm for the rational design and fast screening of SAAs for various electrocatalytic reactions.
